fix(maestro): scope assignment-skipping to wrappers that accept it

`command FOO=1 claude` and `nohup FOO=1 claude` are invalid shells (they
exec `FOO=1` as the program, exit 127), but the resolver skipped the
assignment unconditionally after any wrapper. Assignment prefixes are
only real at the start of a simple command or after a wrapper that itself
interprets them as env vars (env, sudo) or a keyword that restarts the
assignment grammar (time) — not after command, nohup, or a package
manager's subcommand, which just exec their next argument as the program.

Attach an accepts_assignment flag to each wrapper transition in both the
Rust and TS resolvers and gate the assignment-skip loop on the flag from
the most recently consumed wrapper. Extends the shared fixture with the
two reported cases plus every other wrapper transition and several nested
combinations (sudo+time valid, sudo+command / command+nohup / time+command
invalid, nohup+env valid) to lock the per-wrapper policy in for both
languages.

CLAUDE.md

@@ -92,6 +92,12 @@ clients — how it opens, the sigils, the key model, the match-and-rank algorith
 the two matchers must agree on, and the fixture table they are tested against.
 Read it before changing either bar or either matcher.
 
+`docs/STRUCTURED-VIEW.md` is the contract for a structured session (an agent
+run as a daemon child over ACP instead of in a tmux pane) — the eight
+transcript row kinds, the two projections and their cursor/replay semantics,
+the handshake and declined capabilities, and the approval nonce rules. Read
+it before changing anything that renders a structured session.
+
 `nix run .#dev` (or `just dev`) brings up the whole local stack under
 process-compose: a debug daemon on 127.0.0.1:7071, then Vite on :5173 once the
 daemon answers `/api/info`. The SPA proxies `/api/*` back to the daemon, so only

Cargo.lock

@@ -1644,6 +1644,7 @@ dependencies = [
  "tokio",
  "tokio-tungstenite 0.21.0",
  "tracing",
+ "unicode-width",
  "uuid",
  "vt100",
 ]

Cargo.toml

@@ -44,6 +44,7 @@ tokio-util = { version = "0.7", features = ["compat"] }
 toml = "0.8"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+unicode-width = "0.1"
 uuid = { version = "1", features = ["v4", "serde"] }
 ratatui = "0.28"
 vt100 = "0.15"

crates/maestro-acp/src/lib.rs

@@ -113,6 +113,15 @@ impl SpawnConfig {
     }
 }
 
+/// A blocked ACP permission request delivered to the daemon.
+#[derive(Debug)]
+pub struct PermissionRequest {
+    /// The prompt turn that was active when ACP delivered this callback.
+    pub turn: u64,
+    pub request: RequestPermissionRequest,
+    pub response: oneshot::Sender<RequestPermissionOutcome>,
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum AcpError {
     /// The adapter is not on `PATH`. The message names the install command
@@ -156,6 +165,7 @@ enum Command {
     Cancel,
     Prompt {
         text: String,
+        turn: u64,
         done: oneshot::Sender<Result<(), String>>,
     },
     Close,
@@ -166,6 +176,31 @@ enum ChildCommand {
     Reap(oneshot::Sender<bool>),
 }
 
+#[derive(Debug, Default)]
+struct PermissionTurnState {
+    active: Option<u64>,
+}
+
+impl PermissionTurnState {
+    fn begin(&mut self, turn: u64) {
+        self.active = Some(turn);
+    }
+
+    fn cancel_active(&mut self) {
+        self.active = None;
+    }
+
+    fn finish(&mut self, turn: u64) {
+        if self.active == Some(turn) {
+            self.active = None;
+        }
+    }
+
+    fn callback_turn(&self) -> Option<u64> {
+        self.active
+    }
+}
+
 /// Why the handshake did not produce a session id.
 enum ReadyError {
     /// The adapter answered with an error.
@@ -192,6 +227,7 @@ pub struct AcpSession {
     commands: mpsc::UnboundedSender<Command>,
     child_commands: mpsc::UnboundedSender<ChildCommand>,
     updates: Mutex<Option<mpsc::UnboundedReceiver<SessionNotification>>>,
+    permission_requests: Mutex<Option<mpsc::UnboundedReceiver<PermissionRequest>>>,
     exit: watch::Receiver<Option<ExitStatus>>,
 }
 
@@ -235,6 +271,13 @@ impl AcpSession {
         self.updates.lock().expect("updates mutex").take()
     }
 
+    pub fn take_permission_requests(&self) -> Option<mpsc::UnboundedReceiver<PermissionRequest>> {
+        self.permission_requests
+            .lock()
+            .expect("permission requests")
+            .take()
+    }
+
     /// Send `session/cancel`. Fire-and-forget: a closed connection means the
     /// child is already gone, which is the outcome cancel was after.
     pub fn cancel(&self) {
@@ -242,11 +285,16 @@ impl AcpSession {
     }
 
     /// Send a user prompt and receive completion once the agent ends the turn.
-    pub fn prompt(&self, text: String) -> Result<oneshot::Receiver<Result<(), String>>, String> {
+    pub fn prompt(
+        &self,
+        text: String,
+        turn: u64,
+    ) -> Result<oneshot::Receiver<Result<(), String>>, String> {
         let (done_tx, done_rx) = oneshot::channel();
         self.commands
             .send(Command::Prompt {
                 text,
+                turn,
                 done: done_tx,
             })
             .map_err(|_| "ACP connection is closed".to_string())?;
@@ -335,6 +383,7 @@ pub async fn spawn(config: SpawnConfig) -> Result<AcpSession, AcpError> {
     tokio::spawn(supervise_child(child, pid, child_commands_rx, exit_tx));
 
     let (updates_tx, updates_rx) = mpsc::unbounded_channel();
+    let (permission_tx, permission_rx) = mpsc::unbounded_channel();
     let (commands_tx, commands_rx) = mpsc::unbounded_channel();
     let (ready_tx, ready_rx) = oneshot::channel();
     let transport = ByteStreams::new(stdin.compat_write(), stdout.compat());
@@ -343,6 +392,7 @@ pub async fn spawn(config: SpawnConfig) -> Result<AcpSession, AcpError> {
         config.cwd.clone(),
         config.load_session.clone(),
         updates_tx,
+        permission_tx,
         commands_rx,
         ready_tx,
     ));
@@ -356,6 +406,7 @@ pub async fn spawn(config: SpawnConfig) -> Result<AcpSession, AcpError> {
                 commands: commands_tx,
                 child_commands: child_commands_tx,
                 updates: Mutex::new(Some(updates_rx)),
+                permission_requests: Mutex::new(Some(permission_rx)),
                 exit: exit_rx,
             });
         }
@@ -467,6 +518,7 @@ async fn run_connection<T>(
     cwd: PathBuf,
     load_session: Option<String>,
     updates_tx: mpsc::UnboundedSender<SessionNotification>,
+    permission_requests: mpsc::UnboundedSender<PermissionRequest>,
     mut commands_rx: mpsc::UnboundedReceiver<Command>,
     ready_tx: oneshot::Sender<Result<String, ReadyError>>,
 ) where
@@ -478,6 +530,10 @@ async fn run_connection<T>(
     // history the event log already holds (#135).
     let replaying = Arc::new(AtomicBool::new(false));
     let replaying_seen = replaying.clone();
+    // ACP callbacks have no turn id. The daemon never queues a later prompt
+    // until a cancelled prompt settles, so this active turn is unambiguous.
+    let permission_turn = Arc::new(Mutex::new(PermissionTurnState::default()));
+    let permission_turn_seen = permission_turn.clone();
     let result = Client
         .builder()
         .name("maestro")
@@ -495,15 +551,30 @@ async fn run_connection<T>(
         )
         .on_receive_request(
             async move |request: RequestPermissionRequest, responder, _cx| {
-                // Stub until #139: decline rather than grant something the
+                let turn = permission_turn_seen
-                // operator never saw.
+                    .lock()
-                tracing::warn!(
+                    .expect("permission turn state")
-                    session = %request.session_id,
+                    .callback_turn();
-                    "session/request_permission declined: not implemented yet (#139)"
+                let Some(turn) = turn else {
-                );
+                    return responder.respond(RequestPermissionResponse::new(
-                responder.respond(RequestPermissionResponse::new(
+                        RequestPermissionOutcome::Cancelled,
-                    RequestPermissionOutcome::Cancelled,
+                    ));
-                ))
+                };
+                let (response, received) = oneshot::channel();
+                if permission_requests
+                    .send(PermissionRequest {
+                        turn,
+                        request,
+                        response,
+                    })
+                    .is_err()
+                {
+                    return responder.respond(RequestPermissionResponse::new(
+                        RequestPermissionOutcome::Cancelled,
+                    ));
+                }
+                let outcome = received.await.unwrap_or(RequestPermissionOutcome::Cancelled);
+                responder.respond(RequestPermissionResponse::new(outcome))
             },
             agent_client_protocol::on_receive_request!(),
         )
@@ -575,26 +646,44 @@ async fn run_connection<T>(
                 tokio::select! {
                     cmd = commands_rx.recv() => match cmd {
                         Some(Command::Cancel) => {
+                            permission_turn
+                                .lock()
+                                .expect("permission turn state")
+                                .cancel_active();
                             let _ = cx.send_notification(CancelNotification::new(
                                 SessionId::new(session_id.as_str()),
                             ));
                         }
-                        Some(Command::Prompt { text, done }) => {
+                        Some(Command::Prompt { text, turn, done }) => {
+                            permission_turn
+                                .lock()
+                                .expect("permission turn state")
+                                .begin(turn);
                             let request = PromptRequest::new(
                                 SessionId::new(session_id.as_str()),
                                 vec![ContentBlock::from(text)],
                             );
                             let done = Arc::new(Mutex::new(Some(done)));
                             let callback_done = done.clone();
+                            let callback_turn = permission_turn.clone();
                             if let Err(error) = cx.send_request(request).on_receiving_result(move |result| {
                                 let callback_done = callback_done.clone();
+                                let callback_turn = callback_turn.clone();
                                 async move {
+                                    callback_turn
+                                        .lock()
+                                        .expect("permission turn state")
+                                        .finish(turn);
                                     if let Some(done) = callback_done.lock().expect("prompt sender").take() {
                                         let _ = done.send(result.map(|_| ()).map_err(|e| e.to_string()));
                                     }
                                     Ok(())
                                 }
                             }) {
+                                permission_turn
+                                    .lock()
+                                    .expect("permission turn state")
+                                    .finish(turn);
                                 if let Some(done) = done.lock().expect("prompt sender").take() {
                                     let _ = done.send(Err(error.to_string()));
                                 }

crates/maestro-acp/tests/fake_acp_agent.py

@@ -19,11 +19,14 @@ Environment knobs, all optional:
   FAKE_ACP_INIT_FAIL=1    answer `initialize` with a JSON-RPC error
   FAKE_ACP_DELAY_SESSION_NEW_MS=n  wait n milliseconds before answering
                              `session/new`
+  FAKE_ACP_SESSION_NEW_GATE=path  wait for `path` to exist before answering
+                             `session/new`
   FAKE_ACP_EXIT_AFTER_NEW=1  exit 0 right after answering `session/new`
   FAKE_ACP_EXIT_ON_CANCEL=1  exit 0 on `session/cancel` (default: keep running
                              so the SIGTERM path is exercised)
   FAKE_ACP_IGNORE_EOF=1      keep running after stdin closes, until signalled
   FAKE_ACP_EMIT_ON_CANCEL=1  emit a final notification before handling cancel
+  FAKE_ACP_CANCEL_SETTLES=1  complete the outstanding prompt on cancel
   FAKE_ACP_NO_LOAD=1      advertise `loadSession: false`
   FAKE_ACP_LOAD_REPLAY=n  on `session/load`, replay n `agent_message_chunk`
                             notifications ("replayed <i>") before answering,
@@ -33,6 +36,8 @@ Environment knobs, all optional:
   FAKE_ACP_PROMPT_FAIL=1  answer every `session/prompt` with a JSON-RPC error
   FAKE_ACP_PROMPT_FAIL_ONCE=1  answer only the first `session/prompt` with a
                              JSON-RPC error
+  FAKE_ACP_PERMISSION_AFTER_CANCEL=1  defer the first prompt's permission
+                             callback until a later prompt
 
 Signals: SIGUSR1 emits one `agent_message_chunk` notification ("tick <n>",
 counting from 1) and logs `emit tick <n>`, so a test can make the agent
@@ -70,6 +75,9 @@ signal.signal(signal.SIGTERM, on_sigterm)
 session_id = f"fake-{os.getpid()}"
 ticks = 0
 prompt_failures = 0
+pending_prompt_id = None
+pending_permission_id = None
+delayed_permission = False
 
 
 def chunk(text):
@@ -102,6 +110,12 @@ for raw in sys.stdin:
     method = msg.get("method")
     if method is None:
         # A response to something we sent; nothing to do.
+        if msg.get("id") == pending_permission_id:
+            log("permission response " + json.dumps(msg.get("result"), sort_keys=True))
+            send({"jsonrpc": "2.0", "id": pending_prompt_id,
+                  "result": {"stopReason": "end_turn"}})
+            pending_prompt_id = None
+            pending_permission_id = None
         continue
     log(f"recv {method}")
     rid = msg.get("id")
@@ -121,6 +135,9 @@ for raw in sys.stdin:
             "authMethods": [],
         }})
     elif method == "session/new":
+        gate = os.environ.get("FAKE_ACP_SESSION_NEW_GATE")
+        while gate and not os.path.exists(gate):
+            time.sleep(0.01)
         time.sleep(int(os.environ.get("FAKE_ACP_DELAY_SESSION_NEW_MS", "0")) / 1000)
         send({"jsonrpc": "2.0", "id": rid, "result": {"sessionId": session_id}})
         send(chunk("hello from fake"))
@@ -140,9 +157,47 @@ for raw in sys.stdin:
     elif method == "session/cancel":
         if os.environ.get("FAKE_ACP_EMIT_ON_CANCEL") == "1":
             send(chunk("final on cancel"))
+        if (os.environ.get("FAKE_ACP_CANCEL_SETTLES") == "1"
+                and pending_prompt_id is not None):
+            send({"jsonrpc": "2.0", "id": pending_prompt_id,
+                  "result": {"stopReason": "cancelled"}})
+            pending_prompt_id = None
+            pending_permission_id = None
         if os.environ.get("FAKE_ACP_EXIT_ON_CANCEL") == "1":
             sys.exit(0)
     elif method == "session/prompt":
+        if os.environ.get("FAKE_ACP_PERMISSION_AFTER_CANCEL") == "1":
+            if pending_prompt_id is None:
+                pending_prompt_id = rid
+                delayed_permission = True
+                continue
+            if delayed_permission:
+                delayed_permission = False
+                pending_permission_id = "permission-1"
+                send({"jsonrpc": "2.0", "id": pending_permission_id,
+                      "method": "session/request_permission", "params": {
+                          "sessionId": session_id,
+                          "toolCall": {"toolCallId": "tool-1", "fields": {}},
+                          "options": [
+                              {"optionId": "once", "name": "Allow once", "kind": "allow_once"},
+                              {"optionId": "deny", "name": "Deny", "kind": "reject_once"}
+                          ]
+                      }})
+                continue
+        if os.environ.get("FAKE_ACP_REQUEST_PERMISSION") == "1":
+            pending_prompt_id = rid
+            pending_permission_id = "permission-1"
+            send({"jsonrpc": "2.0", "id": pending_permission_id,
+                  "method": "session/request_permission", "params": {
+                      "sessionId": session_id,
+                      "toolCall": {"toolCallId": "tool-1", "fields": {}},
+                      "options": [
+                          {"optionId": "once", "name": "Allow once", "kind": "allow_once"},
+                          {"optionId": "session", "name": "Allow session", "kind": "allow_always"},
+                          {"optionId": "deny", "name": "Deny", "kind": "reject_once"}
+                      ]
+                  }})
+            continue
         time.sleep(int(os.environ.get("FAKE_ACP_DELAY_PROMPT_MS", "0")) / 1000)
         fail_once = os.environ.get("FAKE_ACP_PROMPT_FAIL_ONCE") == "1"
         if os.environ.get("FAKE_ACP_PROMPT_FAIL") == "1" or (fail_once and prompt_failures == 0):

crates/maestro-cli/src/attach.rs

@@ -19,6 +19,12 @@ use tokio_tungstenite::tungstenite::Message;
 pub enum AttachError {
     #[error("ws: {0}")]
     WebSocket(#[from] tokio_tungstenite::tungstenite::Error),
+    #[error("daemon returned {status} ({code}): {message}")]
+    Rejected {
+        status: String,
+        code: String,
+        message: String,
+    },
     #[error("io: {0}")]
     Io(#[from] io::Error),
     #[error("termios: {0}")]
@@ -32,6 +38,21 @@ pub enum AttachError {
 }
 
 impl AttachError {
+    fn from_websocket(error: tokio_tungstenite::tungstenite::Error) -> Self {
+        if let tokio_tungstenite::tungstenite::Error::Http(response) = &error {
+            if let Some(body) = response.body().as_deref() {
+                if let Ok(error_body) = serde_json::from_slice::<maestro_protocol::ApiError>(body) {
+                    return Self::Rejected {
+                        status: response.status().to_string(),
+                        code: error_body.error.code,
+                        message: error_body.error.message,
+                    };
+                }
+            }
+        }
+        Self::WebSocket(error)
+    }
+
     /// True when the failure was an inability to reach the WS endpoint at the
     /// transport level (connection refused), as opposed to an HTTP-level
     /// rejection from a daemon that did answer.
@@ -111,7 +132,9 @@ fn current_winsize() -> Option<(u16, u16)> {
 /// byte that exits cleanly without killing the session.
 #[allow(clippy::result_large_err)]
 pub async fn run_attach_url(url: &str, detach_byte: u8) -> Result<(), AttachError> {
-    let (ws, _resp) = tokio_tungstenite::connect_async(url).await?;
+    let (ws, _resp) = tokio_tungstenite::connect_async(url)
+        .await
+        .map_err(AttachError::from_websocket)?;
     let (mut sink, mut stream) = ws.split();
 
     let raw = RawTty::enable()?;
@@ -233,4 +256,25 @@ mod tests {
             Err(AttachError::InvalidDetachKey(_))
         ));
     }
+
+    #[test]
+    fn attach_surfaces_structured_handshake_errors() {
+        let body = serde_json::to_vec(&maestro_protocol::ApiError::new(
+            "not_terminal",
+            "session is not a terminal session",
+        ))
+        .unwrap();
+        let response = tokio_tungstenite::tungstenite::http::Response::builder()
+            .status(409)
+            .body(Some(body))
+            .unwrap();
+
+        let error =
+            AttachError::from_websocket(tokio_tungstenite::tungstenite::Error::Http(response));
+
+        assert_eq!(
+            error.to_string(),
+            "daemon returned 409 Conflict (not_terminal): session is not a terminal session"
+        );
+    }
 }

crates/maestro-cli/src/sessions.rs

@@ -6,7 +6,7 @@ use std::io::Write;
 use maestro_protocol::display::abbreviate_dir;
 use maestro_protocol::{
     ActivityState, ClientError, CreateSessionRequest, DaemonClient, DaemonInfo, SendInputRequest,
-    Session, SessionStatus, WorktreeSpec,
+    Session, SessionStatus, SessionView, WorktreeSpec,
 };
 use serde_json::Value;
 
@@ -179,8 +179,8 @@ fn print_session_table(out: &mut impl Write, sessions: &[Session], info: &Daemon
     }
     writeln!(
         out,
-        "  {:<36}  {:<8}  {:<9}  {:<28}  {:<40}  {}",
+        "  {:<36}  {:<8}  {:<10}  {:<9}  {:<28}  {:<40}  {}",
-        "ID", "STATUS", "ACTIVITY", "DIR", "COMMAND", "BLOCKED"
+        "ID", "STATUS", "VIEW", "ACTIVITY", "DIR", "COMMAND", "BLOCKED"
     )
     .ok();
     for s in sorted {
@@ -190,6 +190,10 @@ fn print_session_table(out: &mut impl Write, sessions: &[Session], info: &Daemon
             SessionStatus::Running => "running",
             SessionStatus::Dead => "dead",
         };
+        let view = match s.view {
+            SessionView::Terminal => "terminal",
+            SessionView::Structured => "structured",
+        };
         let activity = match s.activity {
             ActivityState::Active => "active",
             ActivityState::Idle => "idle",
@@ -207,8 +211,8 @@ fn print_session_table(out: &mut impl Write, sessions: &[Session], info: &Daemon
         let blocked = blocked_label(s);
         writeln!(
             out,
-            "  {:<36}  {:<8}  {:<9}  {:<28}  {:<40}  {blocked}",
+            "  {:<36}  {:<8}  {:<10}  {:<9}  {:<28}  {:<40}  {blocked}",
-            s.id, status, activity, dir, command
+            s.id, status, view, activity, dir, command
         )
         .ok();
     }
@@ -230,7 +234,7 @@ mod tests {
     use std::path::PathBuf;
 
     use chrono::{TimeZone, Utc};
-    use maestro_protocol::{ActivityState, Session, SessionStatus};
+    use maestro_protocol::{ActivityState, Session, SessionStatus, SessionView};
     use uuid::Uuid;
 
     use super::DaemonInfo;
@@ -286,6 +290,22 @@ mod tests {
         assert!(s.contains("idle"), "{s}");
     }
 
+    #[test]
+    fn table_exposes_terminal_and_structured_views() {
+        let terminal = session("/tmp", "bash", 1);
+        let mut structured = session("/tmp", "claude", 2);
+        structured.view = SessionView::Structured;
+
+        let mut buf = Vec::new();
+        super::print_session_table(&mut buf, &[terminal, structured], &info(""));
+        let out = String::from_utf8(buf).unwrap();
+        let lines: Vec<&str> = out.lines().collect();
+        let header = lines.iter().position(|line| line.contains("VIEW")).unwrap();
+
+        assert!(lines[header + 1].contains("terminal"), "{out}");
+        assert!(lines[header + 2].contains("structured"), "{out}");
+    }
+
     #[test]
     fn live_cwd_overrides_spawn_dir_in_table() {
         let mut s = session("/home/naps/maestro", "bash", 1);

crates/maestro-daemon/src/activity.rs

@@ -66,6 +66,23 @@ pub fn decide(idle_for: Duration, awaiting_input: bool) -> ActivityState {
     }
 }
 
+/// Derive a structured session's sidebar state from its ACP projection.
+pub fn decide_structured(
+    turn_active: bool,
+    pending_approval: bool,
+    turn_failed: bool,
+) -> ActivityState {
+    if turn_failed {
+        ActivityState::Error
+    } else if pending_approval {
+        ActivityState::AwaitingInput
+    } else if turn_active {
+        ActivityState::Active
+    } else {
+        ActivityState::Idle
+    }
+}
+
 /// How long a session's pane must be continuously focused (a client's pane,
 /// not a sidebar highlight) before an `AwaitingInput` glow clears: the
 /// operator has looked, so the rail stops asking for attention.
@@ -136,6 +153,17 @@ mod tests {
         );
     }
 
+    #[test]
+    fn structured_activity_follows_lifecycle_with_approval_precedence() {
+        assert_eq!(decide_structured(false, false, false), ActivityState::Idle);
+        assert_eq!(decide_structured(true, false, false), ActivityState::Active);
+        assert_eq!(
+            decide_structured(true, true, false),
+            ActivityState::AwaitingInput
+        );
+        assert_eq!(decide_structured(false, false, true), ActivityState::Error);
+    }
+
     #[test]
     fn report_is_in_force_until_exactly_its_expiry() {
         let ttl = Duration::from_secs(300);

crates/maestro-daemon/src/local_api.rs

@@ -21,13 +21,12 @@ use maestro_config::SpawnPreset;
 use maestro_protocol::{
     routes, ApiError, CatalogEvent, CreateSessionRequest, DaemonInfo, GitRoot, NameBatch,
     RenameSessionRequest, ReportActivityRequest, SendInputRequest, Session, SetFocusRequest,
-    StructuredEvent, StructuredPromptRequest, PROTOCOL_VERSION,
+    StructuredApprovalDecision, StructuredEvent, StructuredPromptRequest, PROTOCOL_VERSION,
 };
 use serde::Deserialize;
 use uuid::Uuid;
 
-use crate::projection::TurnLifecycle;
+use crate::session::{QueueAcpPrompt, SessionError, SessionManager};
-use crate::session::SessionManager;
 use crate::sidecar::EventCursor;
 
 #[derive(Debug, Clone)]
@@ -70,7 +69,11 @@ pub fn router(state: LocalApiState) -> Router {
         .route(routes::patterns::STRUCTURED, any(structured_ws))
         .route(routes::patterns::STRUCTURED_REPLAY, get(structured_replay))
         .route(routes::patterns::STRUCTURED_PROMPT, post(structured_prompt))
-        .route(routes::patterns::STRUCTURED_CANCEL, post(structured_cancel));
+        .route(routes::patterns::STRUCTURED_CANCEL, post(structured_cancel))
+        .route(
+            routes::patterns::STRUCTURED_APPROVAL,
+            post(structured_approval),
+        );
     #[cfg(feature = "haiku-autoname")]
     {
         router = router.route(routes::patterns::SESSION_PROMPT, post(session_prompt));
@@ -176,6 +179,7 @@ fn session_error_status(code: &str) -> StatusCode {
         // The session outlived its pane: nothing to type into, and nothing
         // the daemon can do about it.
         "not_running" => StatusCode::CONFLICT,
+        "not_terminal" => StatusCode::CONFLICT,
         "shutting_down" => StatusCode::SERVICE_UNAVAILABLE,
         _ => StatusCode::BAD_GATEWAY,
     }
@@ -304,11 +308,10 @@ async fn rename_session(
     }
 }
 
-/// `POST /api/sessions/:id/activity` (#105): an agent reports its own state.
+/// `POST /api/sessions/:id/activity` (#105): an agent reports a terminal
-/// The report holds above the daemon's inference for a TTL, then inference
+/// session's state. Structured sessions acknowledge and ignore these reports
-/// resumes — an agent that dies mid-run cannot pin its session at `Error`
+/// because their activity comes from ACP. Unknown session is 404; an unknown
-/// forever. Unknown session is 404; an unknown state value is rejected by the
+/// state value is rejected by the JSON decoder (422). Answers `204 No Content`.
-/// JSON decoder (422) rather than coerced. Answers `204 No Content`.
 async fn report_activity(
     State(s): State<LocalApiState>,
     Path(id): Path<Uuid>,
@@ -432,45 +435,24 @@ async fn structured_prompt(
     Path(id): Path<Uuid>,
     Json(body): Json<StructuredPromptRequest>,
 ) -> Response {
-    let (acp, turn) = match s.manager.begin_acp_turn(id).await {
+    match s.manager.queue_acp_prompt(id, body.prompt).await {
-        Ok(crate::session::BeginAcpTurn::Started(acp, turn)) => (acp, turn),
+        Ok(QueueAcpPrompt::Queued) => StatusCode::NO_CONTENT.into_response(),
-        Ok(crate::session::BeginAcpTurn::InFlight) => {
+        Ok(QueueAcpPrompt::InFlight) => error_response(
-            return error_response(
+            StatusCode::CONFLICT,
-                StatusCode::CONFLICT,
+            "turn_in_flight",
-                "turn_in_flight",
+            "the structured session already has an active turn",
-                "the structured session already has an active turn",
+        ),
-            )
+        Ok(QueueAcpPrompt::Unavailable) => error_response(
-        }
+            StatusCode::CONFLICT,
-        Ok(crate::session::BeginAcpTurn::Unavailable) => {
+            "not_structured",
-            return error_response(
+            "session is not a live structured session",
-                StatusCode::CONFLICT,
+        ),
-                "not_structured",
+        Ok(QueueAcpPrompt::Failed(message)) => {
-                "session is not a live structured session",
+            error_response(StatusCode::BAD_GATEWAY, "acp_prompt_failed", &message)
-            )
         }
         Err(e) => {
             let info = e.to_error_info();
-            return error_response(session_error_status(&info.code), &info.code, &info.message);
+            error_response(session_error_status(&info.code), &info.code, &info.message)
-        }
-    };
-    match acp.prompt(body.prompt) {
-        Ok(done) => {
-            let manager = s.manager.clone();
-            tokio::spawn(async move {
-                let lifecycle = match done.await {
-                    Ok(Ok(())) => TurnLifecycle::Finish,
-                    Ok(Err(_)) | Err(_) => TurnLifecycle::Failure,
-                };
-                let _ = manager.apply_acp_turn_lifecycle(id, lifecycle, turn).await;
-            });
-            StatusCode::NO_CONTENT.into_response()
-        }
-        Err(message) => {
-            let _ = s
-                .manager
-                .apply_acp_turn_lifecycle(id, TurnLifecycle::Failure, turn)
-                .await;
-            error_response(StatusCode::BAD_GATEWAY, "acp_prompt_failed", &message)
         }
     }
 }
@@ -490,6 +472,32 @@ async fn structured_cancel(State(s): State<LocalApiState>, Path(id): Path<Uuid>)
     }
 }
 
+async fn structured_approval(
+    State(s): State<LocalApiState>,
+    Path((id, nonce)): Path<(Uuid, String)>,
+    Json(decision): Json<StructuredApprovalDecision>,
+) -> Response {
+    let decision = match decision {
+        StructuredApprovalDecision::AllowOnce => crate::session::ApprovalDecision::AllowOnce,
+        StructuredApprovalDecision::AllowForSession => {
+            crate::session::ApprovalDecision::AllowForSession
+        }
+        StructuredApprovalDecision::Deny => crate::session::ApprovalDecision::Deny,
+    };
+    match s.manager.resolve_acp_approval(id, &nonce, decision).await {
+        Ok(Some(())) => StatusCode::NO_CONTENT.into_response(),
+        Ok(None) => error_response(
+            StatusCode::CONFLICT,
+            "not_structured",
+            "session is not a live structured session",
+        ),
+        Err(e) => {
+            let info = e.to_error_info();
+            error_response(session_error_status(&info.code), &info.code, &info.message)
+        }
+    }
+}
+
 /// Convenience constructor — pulls the bits `LocalApiState` needs from
 /// `DaemonConfig` so callers don't have to assemble it by hand. The project
 /// scanner starts with its cache cold; wire
@@ -527,12 +535,23 @@ async fn attach_ws(
     State(s): State<LocalApiState>,
     ws: axum::extract::WebSocketUpgrade,
 ) -> Result<Response, Response> {
-    let Some((replay, rx)) = s.manager.subscribe_pty_with_replay(id).await else {
+    let (replay, rx) = match s.manager.subscribe_pty_with_replay(id).await {
-        return Err(error_response(
+        Ok(subscription) => subscription,
-            StatusCode::NOT_FOUND,
+        Err(SessionError::NotFound(_)) => {
-            "unknown_session",
+            return Err(error_response(
-            "no such session on this daemon",
+                StatusCode::NOT_FOUND,
-        ));
+                "unknown_session",
+                "no such session on this daemon",
+            ));
+        }
+        Err(error) => {
+            let info = error.to_error_info();
+            return Err(error_response(
+                session_error_status(&info.code),
+                &info.code,
+                &info.message,
+            ));
+        }
     };
     let manager = s.manager.clone();
     Ok(ws.on_upgrade(move |socket| async move {

crates/maestro-daemon/src/projection.rs

@@ -4,7 +4,8 @@ use std::collections::{HashMap, HashSet};
 
 use maestro_acp::schema::{ContentChunk, SessionNotification, SessionUpdate, ToolCall};
 use maestro_protocol::{
-    ReducedState, TranscriptDelta, TranscriptRow, TranscriptRowKind, TranscriptSnapshot,
+    ActivityState, ReducedState, TranscriptDelta, TranscriptRow, TranscriptRowKind,
+    TranscriptSnapshot,
 };
 use serde_json::Value;
 
@@ -36,6 +37,7 @@ pub struct Projection {
     pending_tool_updates: HashMap<String, Vec<maestro_acp::schema::ToolCallUpdateFields>>,
     state: ReducedState,
     active_turn: Option<u64>,
+    turn_failed: bool,
     next_turn: u64,
     turn_tool_calls: HashSet<String>,
 }
@@ -109,11 +111,21 @@ impl Projection {
         self.active_turn.is_some()
     }
 
+    /// Sidebar activity derived from the live turn projection.
+    pub fn activity(&self) -> ActivityState {
+        crate::activity::decide_structured(
+            self.active_turn.is_some(),
+            self.state.pending_approval.is_some(),
+            self.turn_failed,
+        )
+    }
+
     /// Start a prompt turn and return its monotonically increasing token.
     pub fn begin_turn(&mut self) -> (u64, ProjectionUpdate) {
         self.next_turn += 1;
         let turn = self.next_turn;
         self.active_turn = Some(turn);
+        self.turn_failed = false;
         self.state.turn.responding = true;
         self.state.turn.thinking = true;
         self.turn_tool_calls.clear();
@@ -141,6 +153,7 @@ impl Projection {
             return None;
         }
         self.active_turn = None;
+        self.turn_failed = lifecycle == TurnLifecycle::Failure;
         self.state.turn.responding = false;
         self.state.turn.thinking = false;
         self.turn_tool_calls.clear();
@@ -155,6 +168,76 @@ impl Projection {
         self.active_turn
     }
 
+    /// Add a daemon-originated permission row. The nonce belongs only in the
+    /// reduced state, which is the client control surface, never in ACP data.
+    pub fn request_approval(&mut self, nonce: String, request: Value) -> ProjectionUpdate {
+        let row = self.append(
+            format!("approval:{}", uuid::Uuid::new_v4()),
+            TranscriptRowKind::Approval,
+            request.clone(),
+        );
+        self.state.pending_approval = Some(serde_json::json!({
+            "nonce": nonce,
+            "request": request,
+        }));
+        ProjectionUpdate {
+            transcript: Some(row),
+            state: self.state(),
+        }
+    }
+
+    pub fn restore_approval(&mut self, row: TranscriptRow) -> ProjectionUpdate {
+        let transcript = if !self.row_index.contains_key(&row.id) {
+            self.row_index.insert(row.id.clone(), self.rows.len());
+            self.rows.push(row.clone());
+            Some(TranscriptDelta::Append { row })
+        } else {
+            None
+        };
+        ProjectionUpdate {
+            transcript,
+            state: self.state(),
+        }
+    }
+
+    /// Clear an approval only when it is still the one the client answered.
+    pub fn resolve_approval(&mut self, nonce: &str) -> Option<ProjectionUpdate> {
+        let pending = self.state.pending_approval.as_ref()?;
+        if pending.get("nonce").and_then(Value::as_str) != Some(nonce) {
+            return None;
+        }
+        self.state.pending_approval = None;
+        Some(ProjectionUpdate {
+            transcript: None,
+            state: self.state(),
+        })
+    }
+
+    /// Terminal turn paths must not leave a recovered snapshot permanently
+    /// blocked on an ACP request whose transport no longer exists.
+    pub fn clear_approval(&mut self) -> Option<ProjectionUpdate> {
+        self.state.pending_approval.take()?;
+        Some(ProjectionUpdate {
+            transcript: None,
+            state: self.state(),
+        })
+    }
+
+    /// Undo an `append`ed row that a caller decides never happened — used
+    /// when persisting the row's own event fails (#184), so a snapshot taken
+    /// after the failure cannot show a row durable replay would never
+    /// reproduce. Only ever called for a row that was just appended and
+    /// never patched, so removing it by id fully reverses `append`.
+    pub fn rollback_row(&mut self, id: &str) {
+        let Some(index) = self.row_index.remove(id) else {
+            return;
+        };
+        self.rows.remove(index);
+        for (shifted_index, row) in self.rows.iter().enumerate().skip(index) {
+            self.row_index.insert(row.id.clone(), shifted_index);
+        }
+    }
+
     fn content(
         &mut self,
         seq: u64,
@@ -355,6 +438,16 @@ mod tests {
         .unwrap()
     }
 
+    #[test]
+    fn a_session_update_tag_the_acp_dependency_does_not_know_fails_to_deserialize() {
+        // `SessionUpdate` has no unknown-variant fallback, so this never reaches `Projection::apply`.
+        let result: Result<SessionNotification, _> = serde_json::from_value(serde_json::json!({
+            "sessionId": "acp-1",
+            "update": {"sessionUpdate": "some_future_update_variant"},
+        }));
+        assert!(result.is_err());
+    }
+
     #[test]
     fn folds_content_tool_diff_plan_and_notice_rows() {
         let mut projection = Projection::default();
@@ -632,4 +725,136 @@ mod tests {
     fn failed_turn_does_not_reactivate_unfinished_tools() {
         terminal_turn_drops_unfinished_tools(TurnLifecycle::Failure, "failed-1", "next-1");
     }
+
+    #[test]
+    fn approval_history_survives_pending_cleanup() {
+        let mut projection = Projection::default();
+        let update =
+            projection.request_approval("secret".into(), serde_json::json!({"tool":"bash"}));
+        let TranscriptDelta::Append { row } = update.transcript.unwrap() else {
+            panic!("approval row")
+        };
+        assert_eq!(row.kind, TranscriptRowKind::Approval);
+        assert!(row.data.get("nonce").is_none());
+        assert!(!row.id.contains("secret"));
+        let persisted =
+            serde_json::to_string(&crate::sidecar::PersistedEvent::Approval { row: row.clone() })
+                .unwrap();
+        assert!(!persisted.contains("secret"));
+        assert_eq!(
+            projection.state().pending_approval.unwrap()["nonce"],
+            "secret"
+        );
+        projection.clear_approval();
+        assert!(projection.state().pending_approval.is_none());
+        assert_eq!(projection.snapshot(0).rows, vec![row]);
+    }
+
+    #[test]
+    fn rollback_row_removes_only_that_row_and_keeps_others_addressable() {
+        let mut projection = Projection::default();
+        projection.apply(
+            1,
+            &event(serde_json::json!({
+                "sessionUpdate": "user_message_chunk",
+                "messageId": "m1",
+                "content": {"type": "text", "text": "hi"},
+            })),
+        );
+        let TranscriptDelta::Append { row } = projection
+            .request_approval("nonce".into(), serde_json::json!({"tool": "bash"}))
+            .transcript
+            .unwrap()
+        else {
+            panic!("approval row")
+        };
+        // A row after the one being rolled back, so removing the approval
+        // (index 1) shifts this one from index 2 down to index 1 — proving
+        // `row_index` gets reindexed, not just `rows`.
+        projection.apply(
+            2,
+            &event(serde_json::json!({
+                "sessionUpdate": "user_message_chunk",
+                "messageId": "m2",
+                "content": {"type": "text", "text": "hey"},
+            })),
+        );
+        assert_eq!(projection.snapshot(0).rows.len(), 3);
+
+        projection.rollback_row(&row.id);
+
+        assert_eq!(projection.snapshot(0).rows.len(), 2);
+        assert_eq!(projection.snapshot(0).rows[0].kind, TranscriptRowKind::User);
+        assert_eq!(projection.snapshot(0).rows[1].kind, TranscriptRowKind::User);
+
+        // The shifted row must still be independently patchable at its new
+        // index.
+        let update = projection.apply(
+            3,
+            &event(serde_json::json!({
+                "sessionUpdate": "user_message_chunk",
+                "messageId": "m2",
+                "content": {"type": "text", "text": " there"},
+            })),
+        );
+        let TranscriptDelta::Patch { row } = update.transcript.unwrap() else {
+            panic!("patched row")
+        };
+        assert_eq!(row.data.pointer("/content/text").unwrap(), "hey there");
+        assert_eq!(projection.snapshot(0).rows.len(), 2);
+    }
+
+    #[test]
+    fn rollback_row_is_a_no_op_for_an_unknown_id() {
+        let mut projection = Projection::default();
+        projection.apply(
+            1,
+            &event(serde_json::json!({
+                "sessionUpdate": "user_message_chunk",
+                "content": {"type": "text", "text": "hi"},
+            })),
+        );
+        projection.rollback_row("approval:does-not-exist");
+        assert_eq!(projection.snapshot(0).rows.len(), 1);
+    }
+
+    #[test]
+    fn recovered_approval_is_historical_not_pending() {
+        let mut live = Projection::default();
+        let TranscriptDelta::Append { row } = live
+            .request_approval("daemon-nonce".into(), serde_json::json!({"tool":"bash"}))
+            .transcript
+            .unwrap()
+        else {
+            panic!("approval row")
+        };
+        let mut recovered = Projection::default();
+        let update = recovered.restore_approval(row.clone());
+        assert_eq!(
+            update.transcript,
+            Some(TranscriptDelta::Append { row: row.clone() })
+        );
+        assert!(update.state.pending_approval.is_none());
+        assert_eq!(recovered.snapshot(0).rows, vec![row]);
+        let replay = serde_json::to_string(&recovered.snapshot(1).rows).unwrap();
+        assert!(!replay.contains("daemon-nonce"));
+    }
+
+    #[test]
+    fn stale_terminal_turn_cannot_clear_newer_approval() {
+        let mut projection = Projection::default();
+        let (first, _) = projection.begin_turn();
+        projection.turn_lifecycle(TurnLifecycle::Cancel, first);
+        let (second, _) = projection.begin_turn();
+        projection.request_approval("second-nonce".into(), serde_json::json!({"tool":"bash"}));
+
+        assert!(projection
+            .turn_lifecycle(TurnLifecycle::Finish, first)
+            .is_none());
+        assert_eq!(projection.active_turn(), Some(second));
+        assert_eq!(
+            projection.state().pending_approval.unwrap()["nonce"],
+            "second-nonce"
+        );
+    }
 }

crates/maestro-daemon/src/sidecar.rs

@@ -7,8 +7,8 @@
 //! advertised but with empty metadata (handled by the caller, not here).
 //!
 //! A structured session (#135) also owns `<id>.events.jsonl` next to its
-//! sidecar: every `session/update` notification its adapter sent, one JSON
+//! sidecar: every `session/update` notification and daemon approval row is one
-//! object per line, appended before it is broadcast. The log is the source of
+//! JSON object, appended before it is broadcast. The log is the source of
 //! truth for the transcript; `seq` is the line's 1-based position, so a
 //! client that holds seq `n` asks for [`EventCursor::Since`]`(n)`. A line
 //! that does not parse — including the partial line a hard kill leaves at
@@ -21,7 +21,7 @@ use std::io::{BufRead, BufReader, Read, Seek, SeekFrom, Write};
 use std::path::{Path, PathBuf};
 
 use maestro_acp::schema::SessionNotification;
-use maestro_protocol::Session;
+use maestro_protocol::{Session, TranscriptRow};
 use uuid::Uuid;
 
 #[derive(Debug, thiserror::Error)]
@@ -112,7 +112,7 @@ impl SidecarStore {
         }
         file.seek(SeekFrom::End(0))?;
         Ok(EventLog {
-            file,
+            file: Box::new(file),
             last_seq: lines,
         })
     }
@@ -150,10 +150,10 @@ impl SidecarStore {
                 }
                 continue;
             }
-            let Ok(notification) = serde_json::from_slice::<SessionNotification>(&line) else {
+            let Ok(event) = PersistedEvent::decode(&line) else {
                 continue;
             };
-            out.push_back(LoggedEvent { seq, notification });
+            out.push_back(LoggedEvent { seq, event });
             match cursor {
                 EventCursor::Since(_) if out.len() >= limit => break,
                 EventCursor::Before(_) if out.len() > limit => {
@@ -190,6 +190,7 @@ impl SidecarStore {
     /// whichever does not exist.
     pub fn delete(&self, id: Uuid) -> Result<(), SidecarError> {
         remove_if_present(&self.events_path_for(id))?;
+        remove_if_present(&self.dir.join(format!("{id}.approvals.jsonl")))?;
         remove_if_present(&self.recovery_path_for(id))?;
         remove_if_present(&self.path_for(id))
     }
@@ -247,22 +248,130 @@ pub enum EventCursor {
 }
 
 /// One line of a session's event log.
-#[derive(Debug, Clone, PartialEq, serde::Serialize)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct LoggedEvent {
     /// 1-based line position in the log; the cursor for [`EventCursor`].
     pub seq: u64,
-    pub notification: SessionNotification,
+    pub event: PersistedEvent,
+}
+
+/// A single entry in the structured event history.
+///
+/// ACP notifications retain their original JSON representation, so existing
+/// event logs remain readable. Daemon-generated rows use an envelope so they
+/// can share the same cursor sequence without pretending to be ACP traffic.
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
+#[serde(tag = "maestroEvent", rename_all = "snake_case")]
+pub enum PersistedEvent {
+    Approval {
+        row: TranscriptRow,
+    },
+    #[serde(skip)]
+    Notification(Box<SessionNotification>),
+}
+
+impl PersistedEvent {
+    fn decode(line: &[u8]) -> Result<Self, serde_json::Error> {
+        serde_json::from_slice::<SessionNotification>(line)
+            .map(|notification| Self::Notification(Box::new(notification)))
+            .or_else(|_| serde_json::from_slice(line))
+    }
+}
+
+impl From<SessionNotification> for PersistedEvent {
+    fn from(notification: SessionNotification) -> Self {
+        Self::Notification(Box::new(notification))
+    }
+}
+
+impl From<&SessionNotification> for PersistedEvent {
+    fn from(notification: &SessionNotification) -> Self {
+        Self::Notification(Box::new(notification.clone()))
+    }
+}
+
+impl From<&PersistedEvent> for PersistedEvent {
+    fn from(event: &PersistedEvent) -> Self {
+        event.clone()
+    }
+}
+
+/// What an [`EventLog`] appends onto: something seekable by length and
+/// truncatable back to one, so a failed append can be rolled off the end
+/// again. A real [`File`] in production; an in-memory fault double in tests
+/// (#184) — the same [`EventLog::append`] rollback logic runs over both, so
+/// the behavior under test is the production behavior, not a stand-in for
+/// it.
+pub(crate) trait LogSink: Write + Send {
+    fn len(&mut self) -> std::io::Result<u64>;
+    fn truncate(&mut self, len: u64) -> std::io::Result<()>;
+}
+
+impl LogSink for File {
+    fn len(&mut self) -> std::io::Result<u64> {
+        Ok(self.metadata()?.len())
+    }
+
+    fn truncate(&mut self, len: u64) -> std::io::Result<()> {
+        self.set_len(len)
+    }
+}
+
+/// Outcome of a failed [`EventLog::append`].
+#[derive(Debug, thiserror::Error)]
+pub enum AppendError {
+    /// The write or flush failed, but the log was rolled back to exactly the
+    /// byte it was at before the call: `last_seq` and the file agree, and
+    /// this same [`EventLog`] is safe to keep appending to. The event itself
+    /// was never persisted or broadcast.
+    #[error("event append failed, rolled back cleanly: {0}")]
+    Failed(#[source] SidecarError),
+    /// The append failed *and* the rollback did not restore the log to its
+    /// prior length, so the file's line count and `last_seq` may now
+    /// disagree. The caller must not append to this [`EventLog`] again —
+    /// treat the session as dead rather than promise consistency it cannot
+    /// keep.
+    #[error("event append failed ({cause}) and rollback did not restore consistency ({rollback})")]
+    Fatal {
+        cause: SidecarError,
+        rollback: SidecarError,
+    },
+}
+
+impl From<SidecarError> for AppendError {
+    fn from(error: SidecarError) -> Self {
+        AppendError::Failed(error)
+    }
 }
 
 /// An open, append-only handle on one session's event log. Obtained from
 /// [`SidecarStore::open_events`]; held for the session's lifetime.
-#[derive(Debug)]
 pub struct EventLog {
-    file: File,
+    file: Box<dyn LogSink>,
     last_seq: u64,
 }
 
+impl std::fmt::Debug for EventLog {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("EventLog")
+            .field("last_seq", &self.last_seq)
+            .finish_non_exhaustive()
+    }
+}
+
 impl EventLog {
+    /// Wrap an arbitrary sink as an [`EventLog`], for tests that need to
+    /// inject a deterministic append failure (#184) — a partial write, a
+    /// flush that fails after the bytes are already down, or a rollback that
+    /// cannot itself complete.
+    #[cfg(test)]
+    pub(crate) fn for_test(file: impl LogSink + 'static, last_seq: u64) -> Self {
+        Self {
+            file: Box::new(file),
+            last_seq,
+        }
+    }
+
     /// The seq of the last line, `0` for an empty log.
     pub fn last_seq(&self) -> u64 {
         self.last_seq
@@ -272,12 +381,262 @@ impl EventLog {
     /// handed to the kernel in a single write before this returns, so a
     /// caller that broadcasts afterwards never announces an event the log
     /// would not replay — short of the machine losing power.
-    pub fn append(&mut self, notification: &SessionNotification) -> Result<u64, SidecarError> {
+    ///
-        let mut line = serde_json::to_vec(notification)?;
+    /// A `write_all` that errors partway can leave an unterminated prefix on
+    /// disk; a `flush` that errors after a *complete* `write_all` leaves
+    /// ambiguity about whether that full, well-formed line should count —
+    /// counting it would silently shift every later seq by one, since
+    /// `last_seq` was never bumped for it. Both cases are rolled back to the
+    /// exact pre-append length before returning, so `last_seq` and the file
+    /// never disagree and the same [`EventLog`] can be appended to again
+    /// immediately. If the rollback itself fails, the log's consistency can
+    /// no longer be promised and [`AppendError::Fatal`] is returned instead.
+    pub fn append(&mut self, event: impl Into<PersistedEvent>) -> Result<u64, AppendError> {
+        let event = event.into();
+        let mut line = match &event {
+            PersistedEvent::Notification(notification) => serde_json::to_vec(notification)
+                .map_err(|e| AppendError::from(SidecarError::from(e)))?,
+            _ => {
+                serde_json::to_vec(&event).map_err(|e| AppendError::from(SidecarError::from(e)))?
+            }
+        };
         line.push(b'\n');
-        self.file.write_all(&line)?;
+
-        self.file.flush()?;
+        let pre_len = self
+            .file
+            .len()
+            .map_err(|e| AppendError::from(SidecarError::from(e)))?;
+
+        if let Err(cause) = self.file.write_all(&line) {
+            return Err(self.rollback_after(pre_len, cause));
+        }
+        if let Err(cause) = self.file.flush() {
+            return Err(self.rollback_after(pre_len, cause));
+        }
+
         self.last_seq += 1;
         Ok(self.last_seq)
     }
+
+    fn rollback_after(&mut self, pre_len: u64, cause: std::io::Error) -> AppendError {
+        match self.file.truncate(pre_len) {
+            Ok(()) => AppendError::Failed(SidecarError::Io(cause)),
+            Err(rollback) => AppendError::Fatal {
+                cause: SidecarError::Io(cause),
+                rollback: SidecarError::Io(rollback),
+            },
+        }
+    }
+}
+
+/// Bytes shared between a [`FaultyLogSink`] moved into an [`EventLog`] and
+/// the test that planted it, so the test can inspect what actually ended up
+/// on the "disk" after a fault without reaching into `EventLog`'s private
+/// `file` field.
+#[cfg(test)]
+#[derive(Clone, Default)]
+pub(crate) struct SharedBuf(std::sync::Arc<std::sync::Mutex<Vec<u8>>>);
+
+#[cfg(test)]
+impl SharedBuf {
+    pub(crate) fn snapshot(&self) -> Vec<u8> {
+        self.0.lock().unwrap().clone()
+    }
+}
+
+/// An in-memory [`LogSink`] double that injects one deterministic fault — a
+/// short write, a flush that fails after a full write, or a rollback that
+/// cannot itself complete — then behaves like a healthy sink from then on.
+/// Lets a test prove the *same* [`EventLog`] recovers, rather than one with a
+/// handle swapped in from a healthy disk, which production never does
+/// (#184).
+#[cfg(test)]
+#[derive(Default)]
+pub(crate) struct FaultyLogSink {
+    pub(crate) buf: SharedBuf,
+    /// Accept this many bytes on the next `write` call, then fail the
+    /// *following* call — a short write followed by an error, exactly what
+    /// `write_all` sees from a real fd that dies mid-line. `Write::write`
+    /// must not report an error on a call that made partial progress, so
+    /// the fault is delivered one call later, via `pending_write_error`.
+    pub(crate) fail_write_after: Option<usize>,
+    pub(crate) pending_write_error: bool,
+    pub(crate) fail_flush_once: bool,
+    pub(crate) fail_truncate: bool,
+}
+
+#[cfg(test)]
+impl Write for FaultyLogSink {
+    fn write(&mut self, data: &[u8]) -> std::io::Result<usize> {
+        if self.pending_write_error {
+            self.pending_write_error = false;
+            return Err(std::io::Error::other("fault: write failed mid-line"));
+        }
+        if let Some(allowed) = self.fail_write_after.take() {
+            let allowed = allowed.min(data.len());
+            if allowed == 0 {
+                // No progress was made, so it's fine to report the error
+                // from this same call.
+                return Err(std::io::Error::other("fault: write failed mid-line"));
+            }
+            self.buf
+                .0
+                .lock()
+                .unwrap()
+                .extend_from_slice(&data[..allowed]);
+            self.pending_write_error = true;
+            return Ok(allowed);
+        }
+        self.buf.0.lock().unwrap().extend_from_slice(data);
+        Ok(data.len())
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        if self.fail_flush_once {
+            self.fail_flush_once = false;
+            return Err(std::io::Error::other(
+                "fault: flush failed after a full write",
+            ));
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+impl LogSink for FaultyLogSink {
+    fn len(&mut self) -> std::io::Result<u64> {
+        Ok(self.buf.0.lock().unwrap().len() as u64)
+    }
+
+    fn truncate(&mut self, len: u64) -> std::io::Result<()> {
+        if self.fail_truncate {
+            return Err(std::io::Error::other("fault: rollback truncate failed"));
+        }
+        self.buf.0.lock().unwrap().truncate(len as usize);
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn sample_event(id: &str) -> PersistedEvent {
+        PersistedEvent::Approval {
+            row: TranscriptRow {
+                id: id.to_owned(),
+                kind: maestro_protocol::TranscriptRowKind::Approval,
+                data: serde_json::json!({"tool": "bash"}),
+            },
+        }
+    }
+
+    /// Replays `bytes` as a real on-disk log via the production read path,
+    /// so "live and durable agree" is checked with the same code a
+    /// reconnecting client would hit, not a hand-rolled line splitter.
+    fn replay(bytes: &[u8]) -> Vec<LoggedEvent> {
+        let dir = tempfile::tempdir().unwrap();
+        let store = SidecarStore::new(dir.path());
+        let id = Uuid::new_v4();
+        std::fs::create_dir_all(store.dir()).unwrap();
+        std::fs::write(store.events_path_for(id), bytes).unwrap();
+        store.read_events(id, EventCursor::Since(0), 100).unwrap()
+    }
+
+    #[test]
+    fn append_rolls_back_a_partial_write_and_the_same_instance_recovers() {
+        let buf = SharedBuf::default();
+        let writer = FaultyLogSink {
+            buf: buf.clone(),
+            fail_write_after: Some(5),
+            ..Default::default()
+        };
+        let mut log = EventLog::for_test(writer, 0);
+
+        let err = log.append(sample_event("r1")).unwrap_err();
+        assert!(
+            matches!(err, AppendError::Failed(_)),
+            "a repairable rollback must not be reported fatal"
+        );
+        assert_eq!(log.last_seq(), 0, "cursor must stay put on a failed append");
+        assert!(
+            buf.snapshot().is_empty(),
+            "the partial prefix a failed write_all leaves behind must be truncated away"
+        );
+
+        let seq = log
+            .append(sample_event("r1"))
+            .expect("the same instance must be able to append again after a clean rollback");
+        assert_eq!(seq, 1);
+        assert_eq!(log.last_seq(), 1);
+
+        let bytes = buf.snapshot();
+        assert_eq!(
+            bytes.iter().filter(|&&b| b == b'\n').count(),
+            1,
+            "exactly one well-formed line, not a partial prefix glued to the recovered append"
+        );
+
+        let replayed = replay(&bytes);
+        assert_eq!(replayed.len(), 1);
+        assert_eq!(replayed[0].seq, log.last_seq());
+        let PersistedEvent::Approval { row } = &replayed[0].event else {
+            panic!("approval event");
+        };
+        assert_eq!(row.id, "r1");
+    }
+
+    #[test]
+    fn append_rolls_back_when_flush_fails_after_a_full_write() {
+        let buf = SharedBuf::default();
+        let writer = FaultyLogSink {
+            buf: buf.clone(),
+            fail_flush_once: true,
+            ..Default::default()
+        };
+        let mut log = EventLog::for_test(writer, 0);
+
+        let err = log.append(sample_event("r1")).unwrap_err();
+        assert!(matches!(err, AppendError::Failed(_)));
+        assert_eq!(log.last_seq(), 0);
+        assert!(
+            buf.snapshot().is_empty(),
+            "a full-but-unflushed line must not survive uncounted by last_seq — it would \
+             silently shift every later seq by one"
+        );
+
+        let seq = log
+            .append(sample_event("r1"))
+            .expect("the same instance must recover once flush stops failing");
+        assert_eq!(seq, 1);
+
+        let bytes = buf.snapshot();
+        let replayed = replay(&bytes);
+        assert_eq!(replayed.len(), 1);
+        assert_eq!(replayed[0].seq, log.last_seq());
+    }
+
+    #[test]
+    fn append_reports_fatal_when_rollback_cannot_restore_consistency() {
+        let buf = SharedBuf::default();
+        let writer = FaultyLogSink {
+            buf,
+            fail_write_after: Some(3),
+            fail_truncate: true,
+            ..Default::default()
+        };
+        let mut log = EventLog::for_test(writer, 0);
+
+        let err = log.append(sample_event("r1")).unwrap_err();
+        assert!(
+            matches!(err, AppendError::Fatal { .. }),
+            "an unrepairable rollback must be surfaced as fatal, never silently treated as \
+             a clean recoverable failure"
+        );
+        assert_eq!(
+            log.last_seq(),
+            0,
+            "a fatal append must not advance the cursor either"
+        );
+    }
 }

crates/maestro-daemon/tests/acp.rs

@@ -83,7 +83,10 @@ impl Fake {
 }
 
 fn event_text(event: &maestro_daemon::sidecar::LoggedEvent) -> &str {
-    match &event.notification.update {
+    let maestro_daemon::sidecar::PersistedEvent::Notification(notification) = &event.event else {
+        panic!("unexpected daemon event")
+    };
+    match &notification.update {
         SessionUpdate::AgentMessageChunk(chunk) => match &chunk.content {
             ContentBlock::Text(text) => &text.text,
             other => panic!("unexpected content {other:?}"),
@@ -133,6 +136,7 @@ async fn structured_spawn_starts_the_adapter_in_cwd_with_session_env() {
 
     assert_eq!(session.view, SessionView::Structured);
     assert_eq!(session.status, SessionStatus::Running);
+    assert_eq!(session.activity, ActivityState::Idle);
     let acp_id = session.acp_session_id.clone().expect("acp session id");
     assert!(acp_id.starts_with("fake-"), "{acp_id}");
 
@@ -201,6 +205,77 @@ async fn structured_spawn_starts_the_adapter_in_cwd_with_session_env() {
         .exists());
 }
 
+#[tokio::test]
+async fn structured_activity_tracks_turn_completion_and_failure() {
+    let fx = DaemonFixture::new();
+    let fake = Fake::new();
+    let cwd = TempDir::new().unwrap();
+    let mut env = fake.env();
+    env.insert("FAKE_ACP_DELAY_PROMPT_MS".into(), "100".into());
+    env.insert("FAKE_ACP_PROMPT_FAIL_ONCE".into(), "1".into());
+    let session = fx
+        .manager
+        .create(structured(cwd.path(), env))
+        .await
+        .unwrap();
+
+    assert!(matches!(
+        fx.manager
+            .queue_acp_prompt(session.id, "fail".into())
+            .await
+            .unwrap(),
+        maestro_daemon::session::QueueAcpPrompt::Queued
+    ));
+    assert_eq!(
+        fx.manager
+            .snapshot()
+            .await
+            .into_iter()
+            .find(|candidate| candidate.id == session.id)
+            .unwrap()
+            .activity,
+        ActivityState::Active
+    );
+    wait_for_async(Duration::from_secs(2), || async {
+        fx.manager
+            .snapshot()
+            .await
+            .into_iter()
+            .find(|candidate| candidate.id == session.id)
+            .is_some_and(|candidate| candidate.activity == ActivityState::Error)
+    })
+    .await;
+
+    assert!(matches!(
+        fx.manager
+            .queue_acp_prompt(session.id, "succeed".into())
+            .await
+            .unwrap(),
+        maestro_daemon::session::QueueAcpPrompt::Queued
+    ));
+    assert_eq!(
+        fx.manager
+            .snapshot()
+            .await
+            .into_iter()
+            .find(|candidate| candidate.id == session.id)
+            .unwrap()
+            .activity,
+        ActivityState::Active
+    );
+    wait_for_async(Duration::from_secs(2), || async {
+        fx.manager
+            .snapshot()
+            .await
+            .into_iter()
+            .find(|candidate| candidate.id == session.id)
+            .is_some_and(|candidate| candidate.activity == ActivityState::Idle)
+    })
+    .await;
+
+    fx.manager.kill(session.id, false).await.unwrap();
+}
+
 #[tokio::test]
 async fn projection_snapshot_and_live_stream_share_one_fold() {
     let fx = DaemonFixture::new();
@@ -321,6 +396,107 @@ async fn stale_turn_completion_cannot_end_the_next_turn() {
     fx.manager.kill(session.id, false).await.unwrap();
 }
 
+#[tokio::test]
+async fn cancelled_prompt_that_never_settles_fails_the_session() {
+    let fx = DaemonFixture::new();
+    let fake = Fake::new();
+    let cwd = TempDir::new().unwrap();
+    let mut env = fake.env();
+    env.insert("FAKE_ACP_PERMISSION_AFTER_CANCEL".into(), "1".into());
+    let session = fx
+        .manager
+        .create(structured(cwd.path(), env))
+        .await
+        .unwrap();
+
+    assert!(matches!(
+        fx.manager
+            .queue_acp_prompt(session.id, "first".into())
+            .await
+            .unwrap(),
+        maestro_daemon::session::QueueAcpPrompt::Queued
+    ));
+    assert!(fx.manager.cancel_acp_turn(session.id).await.unwrap());
+    let second = fx
+        .manager
+        .queue_acp_prompt(session.id, "second".into())
+        .await
+        .unwrap();
+    assert!(
+        matches!(second, maestro_daemon::session::QueueAcpPrompt::Unavailable),
+        "{second:?}"
+    );
+    assert_eq!(
+        fx.manager.status(session.id).await,
+        Some(SessionStatus::Dead)
+    );
+    assert!(!fake.log().contains("permission response"));
+}
+
+#[tokio::test]
+async fn cancellation_settlement_allows_the_next_prompt_permission() {
+    let fx = DaemonFixture::new();
+    let fake = Fake::new();
+    let cwd = TempDir::new().unwrap();
+    let mut env = fake.env();
+    env.insert("FAKE_ACP_REQUEST_PERMISSION".into(), "1".into());
+    env.insert("FAKE_ACP_CANCEL_SETTLES".into(), "1".into());
+    let session = fx
+        .manager
+        .create(structured(cwd.path(), env))
+        .await
+        .unwrap();
+
+    assert!(matches!(
+        fx.manager
+            .queue_acp_prompt(session.id, "first".into())
+            .await
+            .unwrap(),
+        maestro_daemon::session::QueueAcpPrompt::Queued
+    ));
+    assert!(fx.manager.cancel_acp_turn(session.id).await.unwrap());
+    assert!(matches!(
+        fx.manager
+            .queue_acp_prompt(session.id, "second".into())
+            .await
+            .unwrap(),
+        maestro_daemon::session::QueueAcpPrompt::Queued
+    ));
+
+    let nonce = tokio::time::timeout(Duration::from_secs(2), async {
+        loop {
+            let (_, state, _) = fx
+                .manager
+                .subscribe_acp_projection(session.id, EventCursor::Since(0))
+                .await
+                .unwrap()
+                .unwrap();
+            if let Some(pending) = state.pending_approval {
+                break pending["nonce"].as_str().unwrap().to_owned();
+            }
+            tokio::time::sleep(Duration::from_millis(10)).await;
+        }
+    })
+    .await
+    .unwrap();
+    assert!(fx
+        .manager
+        .resolve_acp_approval(
+            session.id,
+            &nonce,
+            maestro_daemon::session::ApprovalDecision::AllowOnce,
+        )
+        .await
+        .unwrap()
+        .is_some());
+    wait_for_async(Duration::from_secs(2), || {
+        let log = fake.log();
+        async move { log.contains("permission response") }
+    })
+    .await;
+    fx.manager.kill(session.id, false).await.unwrap();
+}
+
 #[tokio::test]
 async fn recovery_loads_the_acp_session_without_duplicating_history() {
     let fx = DaemonFixture::new();
@@ -372,6 +548,16 @@ async fn recovery_loads_the_acp_session_without_duplicating_history() {
         revived.status(session.id).await,
         Some(SessionStatus::Running)
     );
+    assert_eq!(
+        revived
+            .snapshot()
+            .await
+            .into_iter()
+            .find(|candidate| candidate.id == session.id)
+            .unwrap()
+            .activity,
+        ActivityState::Idle
+    );
     let log = fake.log();
     assert!(
         log.contains(&format!("recv session/load sessionId={acp_id}")),
@@ -764,6 +950,191 @@ async fn shutdown_waits_for_structured_creation_and_rejects_new_creates() {
     assert_eq!(fake.log().matches("signal SIGTERM").count(), 1);
 }
 
+#[tokio::test]
+async fn structured_handshakes_run_independently() {
+    let fx = DaemonFixture::new();
+    let blocked = Fake::new();
+    let ready = Fake::new();
+    let cwd = TempDir::new().unwrap();
+    let gate = cwd.path().join("release-first");
+    let mut blocked_env = blocked.env();
+    blocked_env.insert(
+        "FAKE_ACP_SESSION_NEW_GATE".into(),
+        gate.to_string_lossy().into_owned(),
+    );
+
+    let first_cwd = cwd.path().to_path_buf();
+    let manager = fx.manager.clone();
+    let first =
+        tokio::spawn(async move { manager.create(structured(&first_cwd, blocked_env)).await });
+    wait_for_async(Duration::from_secs(5), || async {
+        blocked.log().contains("recv session/new")
+    })
+    .await;
+
+    let second = tokio::time::timeout(
+        Duration::from_secs(5),
+        fx.manager.create(structured(cwd.path(), ready.env())),
+    )
+    .await
+    .expect("second handshake was blocked by the first")
+    .expect("second create");
+    assert_eq!(second.status, SessionStatus::Running);
+    assert!(!first.is_finished(), "the gate must still block the first");
+
+    std::fs::write(&gate, b"release").unwrap();
+    let first = first.await.expect("first task").expect("first create");
+    fx.manager.kill(first.id, false).await.expect("kill first");
+    fx.manager
+        .kill(second.id, false)
+        .await
+        .expect("kill second");
+}
+
+#[tokio::test]
+async fn shutdown_waits_for_every_admitted_structured_create() {
+    let fx = DaemonFixture::new();
+    let a = Fake::new();
+    let b = Fake::new();
+    let late = Fake::new();
+    let cwd = TempDir::new().unwrap();
+    let gate_a = cwd.path().join("release-a");
+    let gate_b = cwd.path().join("release-b");
+    let mut env_a = a.env();
+    let mut env_b = b.env();
+    env_a.insert(
+        "FAKE_ACP_SESSION_NEW_GATE".into(),
+        gate_a.to_string_lossy().into_owned(),
+    );
+    env_b.insert(
+        "FAKE_ACP_SESSION_NEW_GATE".into(),
+        gate_b.to_string_lossy().into_owned(),
+    );
+
+    let create_a = {
+        let manager = fx.manager.clone();
+        let cwd = cwd.path().to_path_buf();
+        tokio::spawn(async move { manager.create(structured(&cwd, env_a)).await })
+    };
+    let create_b = {
+        let manager = fx.manager.clone();
+        let cwd = cwd.path().to_path_buf();
+        tokio::spawn(async move { manager.create(structured(&cwd, env_b)).await })
+    };
+    wait_for_async(Duration::from_secs(5), || async {
+        a.log().contains("recv session/new") && b.log().contains("recv session/new")
+    })
+    .await;
+
+    let shutdown = {
+        let manager = fx.manager.clone();
+        tokio::spawn(async move { manager.shutdown().await })
+    };
+    wait_for_async(Duration::from_secs(5), || async {
+        matches!(
+            fx.manager.create(structured(cwd.path(), late.env())).await,
+            Err(maestro_daemon::SessionError::ShuttingDown)
+        )
+    })
+    .await;
+    assert!(!shutdown.is_finished());
+
+    std::fs::write(&gate_a, b"release").unwrap();
+    let session_a = create_a.await.expect("create a task").expect("create a");
+    assert!(
+        !shutdown.is_finished(),
+        "shutdown ignored the second create"
+    );
+
+    std::fs::write(&gate_b, b"release").unwrap();
+    let session_b = create_b.await.expect("create b task").expect("create b");
+    shutdown.await.expect("shutdown task");
+
+    wait_for_exit(a.pid()).await;
+    wait_for_exit(b.pid()).await;
+    assert_eq!(
+        fx.manager.status(session_a.id).await,
+        Some(SessionStatus::Dead)
+    );
+    assert_eq!(
+        fx.manager.status(session_b.id).await,
+        Some(SessionStatus::Dead)
+    );
+}
+
+#[tokio::test]
+async fn cancelling_a_structured_handshake_rolls_back_and_settles_admission() {
+    let fx = DaemonFixture::new();
+    let fake = Fake::new();
+    let repo = TempDir::new().unwrap();
+    init_repo(repo.path());
+    let gate = repo.path().join("release-create");
+    let mut env = fake.env();
+    env.insert("FAKE_ACP_ECHO_ENV".into(), "MAESTRO_SESSION_ID".into());
+    env.insert(
+        "FAKE_ACP_SESSION_NEW_GATE".into(),
+        gate.to_string_lossy().into_owned(),
+    );
+    let request = CreateSessionRequest {
+        view: SessionView::Structured,
+        cwd: repo.path().to_path_buf(),
+        command: "claude".into(),
+        env,
+        metadata: HashMap::new(),
+        worktree: Some(WorktreeSpec {
+            base_repo: repo.path().to_path_buf(),
+            branch: "cancelled-create".into(),
+            create_branch: true,
+        }),
+    };
+
+    let create = {
+        let manager = fx.manager.clone();
+        tokio::spawn(async move { manager.create(request).await })
+    };
+    wait_for_async(Duration::from_secs(5), || async {
+        fake.log().contains("recv session/new")
+    })
+    .await;
+    let id = fake
+        .log()
+        .lines()
+        .find_map(|line| line.strip_prefix("env MAESTRO_SESSION_ID="))
+        .and_then(|id| uuid::Uuid::parse_str(id).ok())
+        .expect("session id in adapter log");
+    let pid = fake.pid();
+
+    create.abort();
+    let shutdown = {
+        let manager = fx.manager.clone();
+        tokio::spawn(async move { manager.shutdown().await })
+    };
+    assert!(create.await.unwrap_err().is_cancelled());
+    tokio::time::timeout(Duration::from_secs(5), shutdown)
+        .await
+        .expect("cancelled admission kept shutdown waiting")
+        .expect("shutdown task");
+    wait_for_exit(pid).await;
+    wait_for_async(Duration::from_secs(5), || async {
+        !fx.fifo_dir().join(format!("{id}.fifo")).exists()
+            && !repo.path().join("cancelled-create").exists()
+    })
+    .await;
+    assert!(fx.manager.snapshot().await.is_empty());
+    let id = id.to_string();
+    assert!(
+        std::fs::read_dir(fx.sidecar_dir())
+            .into_iter()
+            .flatten()
+            .all(|entry| !entry
+                .unwrap()
+                .file_name()
+                .to_string_lossy()
+                .starts_with(&id)),
+        "cancelled create left a sidecar artifact"
+    );
+}
+
 #[tokio::test]
 async fn shutdown_drains_final_notifications_to_the_log() {
     let fx = DaemonFixture::new();
@@ -821,6 +1192,16 @@ async fn adapter_exit_marks_the_session_dead_and_keeps_it_listed() {
         fx.manager.status(session.id).await == Some(SessionStatus::Dead)
     })
     .await;
+    assert_eq!(
+        fx.manager
+            .snapshot()
+            .await
+            .into_iter()
+            .find(|candidate| candidate.id == session.id)
+            .unwrap()
+            .activity,
+        ActivityState::Error
+    );
     assert!(fx.manager.has(session.id).await);
     assert!(
         !fx.sidecar_dir()

crates/maestro-daemon/tests/local_api.rs

@@ -11,7 +11,8 @@ use common::DaemonFixture;
 use futures_util::{SinkExt, StreamExt};
 use maestro_daemon::local_api;
 use maestro_protocol::{
-    ApiError, CreateSessionRequest, Session, SessionStatus, SessionView, WorktreeSpec,
+    ActivityState, ApiError, CreateSessionRequest, Session, SessionStatus, SessionView,
+    WorktreeSpec,
 };
 use tempfile::TempDir;
 use tokio::net::TcpListener;
@@ -142,6 +143,10 @@ impl FakeAcp {
             .next_back()
             .expect("fake ACP started")
     }
+
+    fn log(&self) -> String {
+        std::fs::read_to_string(self.dir.path().join("agent.log")).unwrap_or_default()
+    }
 }
 
 async fn structured_session(h: &Harness, fake: &FakeAcp) -> Uuid {
@@ -163,6 +168,29 @@ async fn structured_session_with_env(h: &Harness, env: HashMap<String, String>)
         .id
 }
 
+async fn wait_for_session_activity(h: &Harness, id: Uuid, expected: ActivityState) {
+    tokio::time::timeout(Duration::from_secs(2), async {
+        loop {
+            let sessions: Vec<Session> = reqwest::get(url(h.addr, "/api/sessions"))
+                .await
+                .unwrap()
+                .json()
+                .await
+                .unwrap();
+            if sessions
+                .iter()
+                .find(|session| session.id == id)
+                .is_some_and(|session| session.activity == expected)
+            {
+                return;
+            }
+            tokio::time::sleep(Duration::from_millis(10)).await;
+        }
+    })
+    .await
+    .unwrap_or_else(|_| panic!("session {id} did not reach {expected:?}"));
+}
+
 #[tokio::test]
 async fn structured_ws_sends_snapshot_then_live_projection() {
     let h = spawn("naps-laptop").await;
@@ -256,6 +284,137 @@ async fn structured_prompt_rejects_a_second_in_flight_turn_and_cancel_clears_it(
         .await
         .unwrap();
     assert_eq!(next.status(), reqwest::StatusCode::NO_CONTENT);
+    tokio::time::timeout(Duration::from_secs(2), async {
+        loop {
+            if fake.log().matches("recv session/prompt").count() == 2 {
+                break;
+            }
+            tokio::time::sleep(Duration::from_millis(10)).await;
+        }
+    })
+    .await
+    .expect("both prompt commands reach ACP");
+    let log = fake.log();
+    let first_prompt = log.find("recv session/prompt").unwrap();
+    let cancel = log.find("recv session/cancel").unwrap();
+    let second_prompt = log.rfind("recv session/prompt").unwrap();
+    assert!(first_prompt < cancel && cancel < second_prompt, "{log}");
+}
+
+#[tokio::test]
+async fn structured_approval_is_secret_single_use_and_race_safe() {
+    let h = spawn("naps-laptop").await;
+    let fake = FakeAcp::new();
+    let mut env = fake.env();
+    env.insert("FAKE_ACP_REQUEST_PERMISSION".into(), "1".into());
+    let id = structured_session_with_env(&h, env).await;
+    let client = reqwest::Client::new();
+    let (mut ws, _) = connect_async(ws_url(h.addr, &format!("/api/structured/{id}")))
+        .await
+        .unwrap();
+    ws.next().await.unwrap().unwrap();
+    ws.next().await.unwrap().unwrap();
+    assert_eq!(
+        client
+            .post(url(
+                h.addr,
+                &format!("/api/sessions/{id}/structured/prompt")
+            ))
+            .json(&serde_json::json!({"prompt":"needs permission"}))
+            .send()
+            .await
+            .unwrap()
+            .status(),
+        reqwest::StatusCode::NO_CONTENT
+    );
+
+    let nonce = tokio::time::timeout(Duration::from_secs(2), async {
+        loop {
+            let event: serde_json::Value =
+                serde_json::from_str(&ws.next().await.unwrap().unwrap().into_text().unwrap())
+                    .unwrap();
+            if let Some(nonce) = event["state"]["pending_approval"]["nonce"].as_str() {
+                assert_eq!(event["transcript"]["row"]["kind"], "approval");
+                assert!(event["transcript"]["row"]["data"].get("nonce").is_none());
+                break nonce.to_owned();
+            }
+        }
+    })
+    .await
+    .unwrap();
+    wait_for_session_activity(&h, id, ActivityState::AwaitingInput).await;
+    assert!(
+        !fake.log().contains(&nonce),
+        "daemon nonce leaked to ACP agent"
+    );
+
+    let path = format!("/api/sessions/{id}/structured/approvals/{nonce}");
+    let (a, b) = tokio::join!(
+        client
+            .post(url(h.addr, &path))
+            .json(&serde_json::json!("allow_once"))
+            .send(),
+        client
+            .post(url(h.addr, &path))
+            .json(&serde_json::json!("deny"))
+            .send(),
+    );
+    assert_eq!(a.unwrap().status(), reqwest::StatusCode::NO_CONTENT);
+    assert_eq!(b.unwrap().status(), reqwest::StatusCode::NO_CONTENT);
+    assert_eq!(
+        client
+            .post(url(h.addr, &path))
+            .json(&serde_json::json!("deny"))
+            .send()
+            .await
+            .unwrap()
+            .status(),
+        reqwest::StatusCode::NO_CONTENT
+    );
+    tokio::time::timeout(Duration::from_secs(2), async {
+        loop {
+            if fake.log().contains("permission response") {
+                break;
+            }
+            tokio::time::sleep(Duration::from_millis(10)).await;
+        }
+    })
+    .await
+    .unwrap();
+    let log = fake.log();
+    assert!(
+        log.contains("\"optionId\": \"once\"") || log.contains("\"optionId\": \"deny\""),
+        "{log}"
+    );
+    tokio::time::timeout(Duration::from_secs(1), async {
+        loop {
+            let event: serde_json::Value =
+                serde_json::from_str(&ws.next().await.unwrap().unwrap().into_text().unwrap())
+                    .unwrap();
+            if event["state"]["pending_approval"].is_null() {
+                break;
+            }
+        }
+    })
+    .await
+    .expect("resolved approval clears the reduced state");
+    wait_for_session_activity(&h, id, ActivityState::Idle).await;
+    assert_eq!(
+        client
+            .post(url(
+                h.addr,
+                &format!(
+                    "/api/sessions/{}/structured/approvals/{nonce}",
+                    Uuid::new_v4()
+                )
+            ))
+            .json(&serde_json::json!("deny"))
+            .send()
+            .await
+            .unwrap()
+            .status(),
+        reqwest::StatusCode::NOT_FOUND
+    );
 }
 
 #[tokio::test]
@@ -296,6 +455,7 @@ async fn structured_prompt_failure_clears_the_turn() {
     })
     .await
     .expect("failed turn clears promptly");
+    wait_for_session_activity(&h, id, ActivityState::Error).await;
     let second = client
         .post(url(h.addr, &path))
         .json(&serde_json::json!({"prompt":"available"}))
@@ -1151,6 +1311,39 @@ async fn attach_ws_streams_pty_bytes() {
     assert!(saw_hello, "PTY did not echo through the attach WS");
 }
 
+#[tokio::test]
+async fn pty_routes_reject_structured_sessions_as_not_terminal() {
+    let h = spawn("naps-laptop").await;
+    let fake = FakeAcp::new();
+    let id = structured_session(&h, &fake).await;
+
+    let response = reqwest::Client::new()
+        .post(url(h.addr, &format!("/api/sessions/{id}/input")))
+        .json(&maestro_protocol::SendInputRequest {
+            text: "ignored".into(),
+            submit: false,
+        })
+        .send()
+        .await
+        .unwrap();
+    assert_eq!(response.status(), reqwest::StatusCode::CONFLICT);
+    let error: ApiError = response.json().await.unwrap();
+    assert_eq!(error.error.code, "not_terminal");
+    assert_eq!(error.error.message, "session is not a terminal session");
+
+    let error = connect_async(ws_url(h.addr, &format!("/api/attach/{id}")))
+        .await
+        .expect_err("structured session must not upgrade to a PTY socket");
+    let tokio_tungstenite::tungstenite::Error::Http(response) = error else {
+        panic!("expected an HTTP handshake rejection, got {error}");
+    };
+    assert_eq!(response.status(), reqwest::StatusCode::CONFLICT);
+    let body = response.body().as_deref().expect("ApiError response body");
+    let error: ApiError = serde_json::from_slice(body).unwrap();
+    assert_eq!(error.error.code, "not_terminal");
+    assert_eq!(error.error.message, "session is not a terminal session");
+}
+
 #[tokio::test]
 async fn attach_ws_for_unknown_session_returns_404() {
     let h = spawn("naps-laptop").await;
@@ -1217,6 +1410,73 @@ async fn events_ws_sends_a_snapshot_then_streams_deltas() {
     }
 }
 
+#[tokio::test]
+async fn events_ws_streams_structured_activity_without_hook_overrides() {
+    let h = spawn("konishi").await;
+    let fake = FakeAcp::new();
+    let mut env = fake.env();
+    env.insert("FAKE_ACP_DELAY_PROMPT_MS".into(), "500".into());
+    let (mut ws, _) = connect_async(ws_url(h.addr, "/api/events"))
+        .await
+        .expect("events ws");
+    assert!(matches!(
+        next_event(&mut ws).await,
+        maestro_protocol::CatalogEvent::Snapshot { .. }
+    ));
+
+    let id = structured_session_with_env(&h, env).await;
+    let maestro_protocol::CatalogEvent::SessionAdded { session } = next_event(&mut ws).await else {
+        panic!("expected structured SessionAdded")
+    };
+    assert_eq!(session.activity, ActivityState::Idle);
+
+    let client = reqwest::Client::new();
+    let prompt = client
+        .post(url(
+            h.addr,
+            &format!("/api/sessions/{id}/structured/prompt"),
+        ))
+        .json(&serde_json::json!({"prompt": "hello"}))
+        .send()
+        .await
+        .unwrap();
+    assert_eq!(prompt.status(), reqwest::StatusCode::NO_CONTENT);
+    let report = client
+        .post(url(h.addr, &format!("/api/sessions/{id}/activity")))
+        .json(&serde_json::json!({"state": "Error"}))
+        .send()
+        .await
+        .unwrap();
+    assert_eq!(report.status(), reqwest::StatusCode::NO_CONTENT);
+    wait_for_session_activity(&h, id, ActivityState::Active).await;
+
+    let mut activities = Vec::new();
+    tokio::time::timeout(Duration::from_secs(2), async {
+        loop {
+            if let maestro_protocol::CatalogEvent::SessionUpdated { session } =
+                next_event(&mut ws).await
+            {
+                activities.push(session.activity);
+                if session.activity == ActivityState::Idle {
+                    return;
+                }
+            }
+        }
+    })
+    .await
+    .expect("structured turn returns to idle");
+    assert!(
+        activities.contains(&ActivityState::Active),
+        "{activities:?}"
+    );
+    assert!(
+        !activities.contains(&ActivityState::Error),
+        "{activities:?}"
+    );
+
+    h.manager.kill(id, false).await.unwrap();
+}
+
 /// Each subscriber has its own lag domain now that the publisher task is gone:
 /// two clients connected at different times both get their own Snapshot.
 #[tokio::test]

crates/maestro-daemon/tests/sidecar.rs

@@ -6,8 +6,8 @@ use std::collections::HashMap;
 use std::path::PathBuf;
 
 use chrono::{DateTime, Utc};
-use maestro_daemon::sidecar::SidecarStore;
+use maestro_daemon::sidecar::{PersistedEvent, SidecarStore};
-use maestro_protocol::{Session, SessionStatus, SessionView};
+use maestro_protocol::{Session, SessionStatus, SessionView, TranscriptRow, TranscriptRowKind};
 use serde_json::Value;
 use tempfile::TempDir;
 use uuid::Uuid;
@@ -186,6 +186,13 @@ fn text_of(n: &SessionNotification) -> &str {
     }
 }
 
+fn event_text(event: &maestro_daemon::sidecar::LoggedEvent) -> &str {
+    let maestro_daemon::sidecar::PersistedEvent::Notification(notification) = &event.event else {
+        panic!("expected ACP notification")
+    };
+    text_of(notification)
+}
+
 #[test]
 fn append_assigns_line_position_as_seq_and_reads_back() {
     let dir = TempDir::new().unwrap();
@@ -194,9 +201,9 @@ fn append_assigns_line_position_as_seq_and_reads_back() {
 
     let mut log = store.open_events(id).expect("open");
     assert_eq!(log.last_seq(), 0);
-    assert_eq!(log.append(&note("a")).unwrap(), 1);
+    assert_eq!(log.append(note("a")).unwrap(), 1);
-    assert_eq!(log.append(&note("b")).unwrap(), 2);
+    assert_eq!(log.append(note("b")).unwrap(), 2);
-    assert_eq!(log.append(&note("c")).unwrap(), 3);
+    assert_eq!(log.append(note("c")).unwrap(), 3);
     assert_eq!(log.last_seq(), 3);
 
     let path = store.events_path_for(id);
@@ -211,9 +218,7 @@ fn append_assigns_line_position_as_seq_and_reads_back() {
     let all = store.read_events(id, EventCursor::Since(0), 100).unwrap();
     assert_eq!(all.iter().map(|e| e.seq).collect::<Vec<_>>(), vec![1, 2, 3]);
     assert_eq!(
-        all.iter()
+        all.iter().map(event_text).collect::<Vec<_>>(),
-            .map(|e| text_of(&e.notification))
-            .collect::<Vec<_>>(),
         vec!["a", "b", "c"]
     );
 }
@@ -225,7 +230,7 @@ fn since_reads_forward_and_before_reads_backward_with_limit() {
     let id = Uuid::new_v4();
     let mut log = store.open_events(id).unwrap();
     for i in 1..=6 {
-        log.append(&note(&format!("n{i}"))).unwrap();
+        log.append(note(&format!("n{i}"))).unwrap();
     }
 
     // `since` is exclusive: what a client that already holds seq 2 needs.
@@ -278,7 +283,7 @@ fn malformed_lines_are_skipped_but_keep_their_seq() {
     let store = SidecarStore::new(dir.path());
     let id = Uuid::new_v4();
     let mut log = store.open_events(id).unwrap();
-    log.append(&note("first")).unwrap();
+    log.append(note("first")).unwrap();
     drop(log);
 
     // Garbage in the middle and a line that is JSON but not a notification.
@@ -289,11 +294,11 @@ fn malformed_lines_are_skipped_but_keep_their_seq() {
     std::fs::write(&path, raw).unwrap();
     let mut log = store.open_events(id).unwrap();
     assert_eq!(log.last_seq(), 3);
-    assert_eq!(log.append(&note("fourth")).unwrap(), 4);
+    assert_eq!(log.append(note("fourth")).unwrap(), 4);
 
     let all = store.read_events(id, EventCursor::Since(0), 10).unwrap();
     assert_eq!(all.iter().map(|e| e.seq).collect::<Vec<_>>(), vec![1, 4]);
-    assert_eq!(text_of(&all[1].notification), "fourth");
+    assert_eq!(event_text(&all[1]), "fourth");
 }
 
 #[test]
@@ -303,7 +308,7 @@ fn truncated_last_line_still_opens_and_the_next_append_starts_a_fresh_line() {
     let store = SidecarStore::new(dir.path());
     let id = Uuid::new_v4();
     let mut log = store.open_events(id).unwrap();
-    log.append(&note("whole")).unwrap();
+    log.append(note("whole")).unwrap();
     drop(log);
 
     let path = store.events_path_for(id);
@@ -319,10 +324,10 @@ fn truncated_last_line_still_opens_and_the_next_append_starts_a_fresh_line() {
     // glue onto it; the partial keeps a seq of its own.
     let mut log = store.open_events(id).unwrap();
     assert_eq!(log.last_seq(), 2);
-    assert_eq!(log.append(&note("after")).unwrap(), 3);
+    assert_eq!(log.append(note("after")).unwrap(), 3);
     let all = store.read_events(id, EventCursor::Since(0), 10).unwrap();
     assert_eq!(all.iter().map(|e| e.seq).collect::<Vec<_>>(), vec![1, 3]);
-    assert_eq!(text_of(&all[1].notification), "after");
+    assert_eq!(event_text(&all[1]), "after");
     let raw = std::fs::read_to_string(&path).unwrap();
     assert_eq!(raw.lines().count(), 3, "{raw}");
 }
@@ -334,8 +339,10 @@ fn delete_removes_the_event_log_and_load_all_ignores_it() {
     let id = Uuid::new_v4();
     store.write(&sample(id)).unwrap();
     let mut log = store.open_events(id).unwrap();
-    log.append(&note("x")).unwrap();
+    log.append(note("x")).unwrap();
     drop(log);
+    let legacy_approvals = dir.path().join(format!("{id}.approvals.jsonl"));
+    std::fs::write(&legacy_approvals, b"obsolete").unwrap();
     assert!(store.events_path_for(id).exists());
 
     let loaded = store.load_all().unwrap();
@@ -344,6 +351,47 @@ fn delete_removes_the_event_log_and_load_all_ignores_it() {
     store.delete(id).unwrap();
     assert!(!store.path_for(id).exists());
     assert!(!store.events_path_for(id).exists());
+    assert!(!legacy_approvals.exists());
     // Idempotent with the log already gone.
     store.delete(id).unwrap();
 }
+
+#[test]
+fn approval_rows_share_event_cursors_with_legacy_acp_lines() {
+    let dir = TempDir::new().unwrap();
+    let store = SidecarStore::new(dir.path());
+    let id = Uuid::new_v4();
+    let legacy = serde_json::to_vec(&note("before")).unwrap();
+    std::fs::create_dir_all(dir.path()).unwrap();
+    std::fs::write(store.events_path_for(id), [legacy, b"\n".to_vec()].concat()).unwrap();
+
+    let mut log = store.open_events(id).unwrap();
+    assert_eq!(
+        log.append(PersistedEvent::Approval {
+            row: TranscriptRow {
+                id: "approval:secret".into(),
+                kind: TranscriptRowKind::Approval,
+                data: serde_json::json!({"tool": "bash"}),
+            },
+        })
+        .unwrap(),
+        2
+    );
+    assert_eq!(log.append(note("after")).unwrap(), 3);
+
+    let all = store.read_events(id, EventCursor::Since(0), 10).unwrap();
+    assert_eq!(
+        all.iter().map(|event| event.seq).collect::<Vec<_>>(),
+        [1, 2, 3]
+    );
+    assert!(matches!(all[1].event, PersistedEvent::Approval { .. }));
+    assert_eq!(event_text(&all[0]), "before");
+    assert_eq!(event_text(&all[2]), "after");
+
+    let since = store.read_events(id, EventCursor::Since(1), 1).unwrap();
+    assert_eq!(since[0].seq, 2);
+    let before = store
+        .read_events(id, EventCursor::Before(Some(3)), 1)
+        .unwrap();
+    assert_eq!(before[0].seq, 2);
+}

crates/maestro-protocol/src/client.rs

@@ -17,7 +17,7 @@ use crate::routes::{self, UrlError};
 use crate::{
     ApiError, BranchInfo, CreateSessionRequest, DaemonInfo, DirListing, ErrorInfo, GitRoot,
     Project, RecentDirs, RenameSessionRequest, ReportActivityRequest, SendInputRequest, Session,
-    SetFocusRequest,
+    SetFocusRequest, StructuredApprovalDecision, StructuredPromptRequest,
 };
 
 /// Time budget for establishing a TCP connection to the daemon.
@@ -105,6 +105,11 @@ impl DaemonClient {
         Ok(routes::attach_url(&self.base, id)?)
     }
 
+    /// `WS /api/structured/:id` URL for this daemon.
+    pub fn structured_url(&self, id: Uuid) -> Result<String, ClientError> {
+        Ok(routes::structured_url(&self.base, id)?)
+    }
+
     // -- typed calls --------------------------------------------------------
 
     pub async fn list_sessions(&self) -> Result<Vec<Session>, ClientError> {
@@ -179,6 +184,57 @@ impl DaemonClient {
         Ok(())
     }
 
+    /// Send one prompt to a structured session. The daemon rejects a second
+    /// prompt while the preceding ACP turn is still active.
+    pub async fn send_structured_prompt(&self, id: Uuid, prompt: &str) -> Result<(), ClientError> {
+        let req = StructuredPromptRequest {
+            prompt: prompt.to_string(),
+        };
+        let resp = self
+            .send(
+                Method::POST,
+                &routes::structured_prompt(id),
+                &[],
+                Some(&req),
+            )
+            .await?;
+        check(resp).await?;
+        Ok(())
+    }
+
+    /// Cancel the structured session's active ACP turn.
+    pub async fn cancel_structured_turn(&self, id: Uuid) -> Result<(), ClientError> {
+        let resp = self
+            .send(
+                Method::POST,
+                &routes::structured_cancel(id),
+                &[],
+                None::<&()>,
+            )
+            .await?;
+        check(resp).await?;
+        Ok(())
+    }
+
+    /// Resolve the currently pending structured-session permission request.
+    pub async fn resolve_structured_approval(
+        &self,
+        id: Uuid,
+        nonce: &str,
+        decision: StructuredApprovalDecision,
+    ) -> Result<(), ClientError> {
+        let resp = self
+            .send(
+                Method::POST,
+                &routes::structured_approval(id, nonce),
+                &[],
+                Some(&decision),
+            )
+            .await?;
+        check(resp).await?;
+        Ok(())
+    }
+
     pub async fn daemon_info(&self) -> Result<DaemonInfo, ClientError> {
         self.get(routes::INFO, &[]).await
     }

crates/maestro-protocol/src/display.rs

@@ -166,45 +166,32 @@ pub fn merge_linear<T>(folder: TreeFolder<T>) -> TreeFolder<T> {
     cur
 }
 
-/// Command wrappers that run another program: the program is what follows.
-const WRAPPERS: [&str; 8] = [
-    "sudo", "env", "npx", "bunx", "uvx", "pnpm", "yarn", "command",
-];
-
 /// The program a command line runs, basenamed and stripped of its arguments —
 /// what a session card shows per `docs/SIDEBAR.md`, which names the program
 /// and never its flags. Leading `FOO=bar` assignments and wrappers (`sudo`,
-/// `npx`, `pnpm dlx`, …) are looked through. Mirrors the web's `splitCommand`.
+/// `npx`, `pnpm dlx`, …) are looked through, and quoting/escaping is honoured
+/// (never evaluated — no `$var`/`` `cmd` ``/`$(cmd)` expansion). A command a
+/// shell would need real grammar for (pipelines, `&&`/`;`, redirections,
+/// substitution, an unterminated quote) falls back to the naive first word
+/// rather than guessing through it (#199). Mirrors the web's `splitCommand`.
 pub fn command_program(command: &str) -> String {
-    let words: Vec<&str> = command.split_whitespace().collect();
+    match resolve(command) {
-    let mut i = 0;
+        Some(r) => match r.words.get(r.program_index) {
-    while i < words.len() {
+            Some(word) => basename(word).to_string(),
-        let word = words[i];
+            // Nothing but wrappers and assignments: say what was there
-        if is_env_assignment(word) {
+            // rather than rendering an empty fragment.
-            i += 1;
+            None => command.trim().to_string(),
-            continue;
+        },
-        }
+        None => legacy_first_word(command),
-        let wrapper = basename(word).to_lowercase();
-        if WRAPPERS.contains(&wrapper.as_str()) {
-            i += 1;
-            if (wrapper == "pnpm" || wrapper == "yarn") && words.get(i) == Some(&"dlx") {
-                i += 1;
-            }
-            continue;
-        }
-        break;
-    }
-    match words.get(i) {
-        Some(word) => basename(word).to_string(),
-        // Nothing but wrappers and assignments: say what was there rather than
-        // rendering an empty fragment.
-        None => command.trim().to_string(),
     }
 }
 
 /// Program name (already basenamed and lowercased) -> the tool id its mark
 /// stands for. Mirrors the web's `BY_PROGRAM` in `web/src/toolIcon.ts`;
 /// recognition is deliberately narrow, so an unrecognised program has no tool.
+/// `claude-code-acp` — the daemon's actual structured-session child — is
+/// deliberately absent: the daemon launches it directly and ignores
+/// `req.command`, so it is never itself a valid user-facing launch form.
 const BY_PROGRAM: [(&str, &str); 17] = [
     ("claude", "claude"),
     ("claude-code", "claude"),
@@ -226,29 +213,491 @@ const BY_PROGRAM: [(&str, &str); 17] = [
 ];
 
 /// The tool id a command line's icon stands for (`claude`, `codex`,
-/// `opencode`, ...), or `None` when the program is not one we have a mark for.
+/// `opencode`, ...), or `None` when the program is not one we have a mark for
-/// The command bar matches this field (`docs/COMMAND-BAR.md`), so it must name
+/// — including a command line [`resolve`] would only guess at. The command
-/// the same tools the web's `splitCommand().tool` does.
+/// bar matches this field (`docs/COMMAND-BAR.md`), so it must name the same
+/// tools the web's `splitCommand().tool` does.
 pub fn command_tool(command: &str) -> Option<&'static str> {
-    let program = command_program(command).to_lowercase();
+    let r = resolve(command)?;
+    let program = basename(r.words.get(r.program_index)?).to_lowercase();
     BY_PROGRAM
         .iter()
         .find(|(name, _)| *name == program)
         .map(|(_, tool)| *tool)
 }
 
-/// `FOO=bar`, the shell's own prefix for one command's environment.
+/// [`resolve`]'s outcome: the tokenized command line, and the index within it
-fn is_env_assignment(word: &str) -> bool {
+/// of the word that is the actual program (past every assignment/wrapper it
-    let mut chars = word.chars();
+/// resolved through).
+struct Resolution {
+    words: Vec<String>,
+    program_index: usize,
+}
+
+/// Tokenize `command` and walk past leading `FOO=bar` assignments and known
+/// wrapper forms (interleaved in any order/count) to find the program. An
+/// assignment run is only consumed at the very start of the line or right
+/// after a wrapper whose own semantics accept one there ([`Wrapper::accepts_assignment`]) —
+/// `command FOO=1 claude` and `nohup FOO=1 claude` stop at `FOO=1` rather than
+/// skipping to `claude`, since `command`/`nohup` just exec their next argument
+/// as the program, they don't setenv from an assignment-shaped one (#199).
+/// `None` when [`tokenize`] can't safely make sense of the line at all.
+fn resolve(command: &str) -> Option<Resolution> {
+    let words = tokenize(command)?;
+    let refs: Vec<&str> = words.iter().map(|w| w.text.as_str()).collect();
+    let mut i = 0;
+    let mut assignment_allowed = true;
+    loop {
+        if assignment_allowed {
+            while matches!(words.get(i), Some(word) if is_env_assignment(word)) {
+                i += 1;
+            }
+        }
+        let Some(word) = words.get(i) else { break };
+        let wrapper = basename(&word.text).to_lowercase();
+        let Some(w) = wrapper_resolver(&wrapper) else {
+            break;
+        };
+        match (w.resolve)(&refs, i) {
+            Some(next) if next > i => {
+                i = next;
+                assignment_allowed = w.accepts_assignment;
+            }
+            // Not a form of the wrapper we recognise (an unknown option, or
+            // — for `pnpm`/`yarn`/`bun` — no `dlx`/`x` subcommand behind it):
+            // the wrapper word itself is the program, not a launcher.
+            _ => break,
+        }
+    }
+    Some(Resolution {
+        words: words.into_iter().map(|w| w.text).collect(),
+        program_index: i,
+    })
+}
+
+/// The naive "first whitespace word, basenamed" reading used only when
+/// [`tokenize`] rejects the line outright — still something sane to show,
+/// never a wrapper/tool match to act on.
+fn legacy_first_word(command: &str) -> String {
+    match command.split_whitespace().next() {
+        Some(word) => basename(word).to_string(),
+        None => command.trim().to_string(),
+    }
+}
+
+/// One token from [`tokenize`]: its dequoted text, and — when both the name
+/// and `=` were entirely unquoted/unescaped in the source — the byte length
+/// of the name. Quoting or escaping either (`"FOO"=1`, `F\OO=1`, `FOO\=1`)
+/// makes the word an executable named `FOO=1`; quoting/escaping only the value
+/// preserves the assignment, matching Bash's assignment-word grammar (#199).
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct Word {
+    text: String,
+    plain_eq: Option<usize>,
+}
+
+/// Word-split `command` the way a shell would (honouring `'…'`, `"…"` and
+/// `\` quoting/escaping — POSIX quote *removal*, not evaluation) and return
+/// `None` the moment it needs real shell grammar this resolver doesn't
+/// attempt: a pipeline/list operator (`|`, `&`, `;`, `<`, `>`), a subshell or
+/// substitution (`(`, `)`, `` ` ``, `$(`), an unescaped newline (a command
+/// separator, like `;` — #199), or an unterminated quote/escape. Never
+/// expands `$var`/`` `cmd` ``/`$(cmd)` — a bare `$` is kept literal. A
+/// backslash immediately before a newline, quoted or not, is a line
+/// continuation: removed entirely rather than embedding the newline or
+/// ending the word (#199).
+fn tokenize(command: &str) -> Option<Vec<Word>> {
+    let mut words = Vec::new();
+    let mut current = String::new();
+    let mut has_current = false;
+    let mut plain_eq: Option<usize> = None;
+    let mut assignment_name_is_plain = true;
+    let mut chars = command.chars().peekable();
+
+    while let Some(c) = chars.next() {
+        match c {
+            ' ' | '\t' | '\r' => {
+                if has_current {
+                    words.push(Word {
+                        text: std::mem::take(&mut current),
+                        plain_eq: plain_eq.take(),
+                    });
+                    has_current = false;
+                    assignment_name_is_plain = true;
+                }
+            }
+            '\n' => return None,
+            '|' | '&' | ';' | '<' | '>' | '(' | ')' | '`' => return None,
+            '$' if chars.peek() == Some(&'(') => return None,
+            '\'' => {
+                has_current = true;
+                if plain_eq.is_none() {
+                    assignment_name_is_plain = false;
+                }
+                loop {
+                    match chars.next() {
+                        Some('\'') => break,
+                        Some(c2) => current.push(c2),
+                        None => return None, // unterminated single quote
+                    }
+                }
+            }
+            '"' => {
+                has_current = true;
+                if plain_eq.is_none() {
+                    assignment_name_is_plain = false;
+                }
+                loop {
+                    match chars.next() {
+                        Some('"') => break,
+                        Some('\\') => match chars.next() {
+                            Some(c2 @ ('"' | '\\' | '$' | '`')) => current.push(c2),
+                            Some('\n') => {} // line continuation, removed entirely
+                            Some(c2) => {
+                                current.push('\\');
+                                current.push(c2);
+                            }
+                            None => return None, // trailing backslash
+                        },
+                        Some(c2) => current.push(c2),
+                        None => return None, // unterminated double quote
+                    }
+                }
+            }
+            '\\' => match chars.next() {
+                Some('\n') => {} // line continuation, removed entirely
+                Some(c2) => {
+                    has_current = true;
+                    if plain_eq.is_none() {
+                        assignment_name_is_plain = false;
+                    }
+                    current.push(c2);
+                }
+                None => return None, // trailing backslash
+            },
+            other => {
+                has_current = true;
+                if other == '=' && plain_eq.is_none() && assignment_name_is_plain {
+                    plain_eq = Some(current.len());
+                }
+                current.push(other);
+            }
+        }
+    }
+    if has_current {
+        words.push(Word {
+            text: current,
+            plain_eq,
+        });
+    }
+    Some(words)
+}
+
+/// A wrapper's known `-`/`--` options: which take no value, and which
+/// consume either a following word or a `--flag=value` as theirs. A
+/// `-`-prefixed word this table doesn't know halts resolution rather than
+/// guessing past it (#199) — callers read that as [`OptionTable::consume`]
+/// returning `None`.
+struct OptionTable {
+    flags: &'static [&'static str],
+    valued: &'static [&'static str],
+    /// Whether this wrapper's short options may be combined (`-iv`) or take
+    /// an attached value (`-uroot`), the way real getopt-based tools do
+    /// (#199). JS-toolchain wrappers (`npx`, `pnpm`, `yarn`, bun's `x`/
+    /// `dlx`) don't get this — guessing at bundling they don't actually
+    /// support would resolve through options they'd reject outright.
+    bundles_short_options: bool,
+}
+
+impl OptionTable {
+    /// Consume this table's options starting at `words[i]`, returning the
+    /// index just past them (which may equal `i` if there are none) — or
+    /// `None` on an option this table doesn't recognise, or a valued option
+    /// missing its operand.
+    fn consume(&self, words: &[&str], mut i: usize) -> Option<usize> {
+        loop {
+            let Some(&word) = words.get(i) else {
+                return Some(i);
+            };
+            if word == "--" {
+                return Some(i + 1);
+            }
+            if word == "-" || !word.starts_with('-') {
+                return Some(i);
+            }
+            if let Some((flag, value)) = word.split_once('=') {
+                return if self.valued.contains(&flag) && !value.is_empty() {
+                    i += 1;
+                    continue;
+                } else {
+                    None
+                };
+            }
+            if self.flags.contains(&word) {
+                i += 1;
+                continue;
+            }
+            if self.valued.contains(&word) {
+                let value = words.get(i + 1)?;
+                if value.is_empty() || value.starts_with('-') {
+                    return None;
+                }
+                i += 2;
+                continue;
+            }
+            if self.bundles_short_options
+                && !word.starts_with("--")
+                && word.len() > 2
+                && self.matches_short_cluster(word)
+            {
+                i += 1;
+                continue;
+            }
+            return None;
+        }
+    }
+
+    /// `-iv` (bundled boolean short flags) or `-uroot` (a valued short
+    /// option with its value attached) — getopt's traditional short-option
+    /// forms. `false` the moment a character isn't a short option this
+    /// table knows, or a valued one ends the word with no attached value
+    /// left to be its operand (#199: rejected rather than guessed to come
+    /// from the next word instead).
+    fn matches_short_cluster(&self, word: &str) -> bool {
+        if !word.is_ascii() {
+            return false;
+        }
+        let bytes = word.as_bytes();
+        let mut buf = [b'-', 0];
+        let mut idx = 1;
+        while idx < bytes.len() {
+            buf[1] = bytes[idx];
+            let short = std::str::from_utf8(&buf).expect("ascii buffer");
+            if self.flags.contains(&short) {
+                idx += 1;
+                continue;
+            }
+            if self.valued.contains(&short) {
+                return idx + 1 < bytes.len();
+            }
+            return false;
+        }
+        true
+    }
+}
+
+const NO_OPTIONS: OptionTable = OptionTable {
+    flags: &[],
+    valued: &[],
+    bundles_short_options: false,
+};
+
+const ENV_OPTS: OptionTable = OptionTable {
+    flags: &[
+        "-i",
+        "--ignore-environment",
+        "-0",
+        "--null",
+        "-v",
+        "--debug",
+    ],
+    valued: &["-u", "--unset", "-C", "--chdir"],
+    bundles_short_options: true,
+};
+
+const SUDO_OPTS: OptionTable = OptionTable {
+    flags: &[
+        "-i",
+        "--login",
+        "-n",
+        "--non-interactive",
+        "-E",
+        "--preserve-env",
+        "-H",
+        "--set-home",
+        "-A",
+        "--askpass",
+        "-b",
+        "--background",
+        "-k",
+        "--reset-timestamp",
+        "-K",
+        "--remove-timestamp",
+        "-S",
+        "--stdin",
+    ],
+    valued: &["-u", "--user", "-g", "--group"],
+    bundles_short_options: true,
+};
+
+/// `-v`/`-V` only print what would run — they never execute it — so
+/// resolving through them would claim a program runs that `command` never
+/// launches (#199). Only `-p`, which still executes normally, is safe to
+/// look through.
+const COMMAND_BUILTIN_OPTS: OptionTable = OptionTable {
+    flags: &["-p"],
+    valued: &[],
+    bundles_short_options: true,
+};
+
+/// The bash *keyword* `time` only ever parses `-p` (POSIX output format);
+/// `-o`/`-v`/`-a`/`-f`/`--verbose`/... belong to the external GNU
+/// `/usr/bin/time`, a different program a bare `time` word doesn't
+/// necessarily name. Assuming them here would be guessing which `time`
+/// resolves (#199).
+fn resolve_time(words: &[&str], i: usize) -> Option<usize> {
+    let mut next = i + 1;
+    if words.get(next) == Some(&"-p") {
+        next += 1;
+    }
+    if words.get(next) == Some(&"--") {
+        next += 1;
+    }
+    match words.get(next) {
+        Some(word) if word.starts_with('-') => None,
+        _ => Some(next),
+    }
+}
+
+/// `-c`/`--call` embeds a whole shell command string rather than naming the
+/// program positionally — resolving past it would mean guessing at a
+/// program buried inside that string, so it's left unrecognised and
+/// resolution stops at `npx` (#199).
+const NPX_OPTS: OptionTable = OptionTable {
+    flags: &["-y", "--yes", "--no", "-q", "--quiet", "--ignore-existing"],
+    valued: &["-p", "--package", "--shell"],
+    bundles_short_options: false,
+};
+
+const PNPM_OPTS: OptionTable = OptionTable {
+    flags: &[
+        "--silent",
+        "-s",
+        "--stream",
+        "--aggregate-output",
+        "--no-progress",
+    ],
+    // `--package`/`--package=value` is documented in this pre-`dlx`
+    // position (`pnpm --package=x dlx y`), alongside the identical flag
+    // `dlx` itself also accepts (`PNPM_DLX_OPTS`).
+    valued: &["-C", "--dir", "--filter", "--package"],
+    bundles_short_options: false,
+};
+
+const YARN_OPTS: OptionTable = OptionTable {
+    flags: &["--silent", "-s", "--no-progress", "--non-interactive"],
+    valued: &["--cwd"],
+    bundles_short_options: false,
+};
+
+const PNPM_DLX_OPTS: OptionTable = OptionTable {
+    flags: &["-s", "--silent"],
+    valued: &["--package"],
+    bundles_short_options: false,
+};
+
+const YARN_DLX_OPTS: OptionTable = OptionTable {
+    flags: &["-q", "--quiet"],
+    valued: &["-p", "--package"],
+    bundles_short_options: false,
+};
+
+const BUN_X_OPTS: OptionTable = OptionTable {
+    flags: &["--bun", "--no-install", "--verbose", "--silent"],
+    valued: &["-p", "--package"],
+    bundles_short_options: false,
+};
+
+/// A resolver for one wrapper form: given the tokenized command and the
+/// index of the wrapper word itself, the index of the word after it (past
+/// its options and any subcommand it requires), or `None` if this occurrence
+/// isn't a form we resolve through.
+type WrapperResolver = fn(&[&str], usize) -> Option<usize>;
+
+/// One recognised wrapper form: how to walk past it, and whether an
+/// assignment word is a valid follow-on once it's been walked past.
+struct Wrapper {
+    resolve: WrapperResolver,
+    /// `true` only for wrappers that themselves interpret a following
+    /// `FOO=bar` as an environment assignment for the command they launch
+    /// (`env`, `sudo`), or a shell keyword that restarts the assignment-prefix
+    /// grammar for a brand new simple command (`time`). Every other wrapper
+    /// here is a plain executable that execs its next argument as the
+    /// program outright — an assignment-shaped one names a program literally
+    /// called `FOO=1`, not an env var (#199).
+    accepts_assignment: bool,
+}
+
+fn wrapper_resolver(name: &str) -> Option<Wrapper> {
+    let (resolve, accepts_assignment): (WrapperResolver, bool) = match name {
+        "env" => (|words, i| ENV_OPTS.consume(words, i + 1), true),
+        "sudo" => (|words, i| SUDO_OPTS.consume(words, i + 1), true),
+        "command" => (|words, i| COMMAND_BUILTIN_OPTS.consume(words, i + 1), false),
+        "nohup" => (|words, i| NO_OPTIONS.consume(words, i + 1), false),
+        "time" => (resolve_time, true),
+        "npx" => (|words, i| NPX_OPTS.consume(words, i + 1), false),
+        "pnpm" => (
+            |words, i| resolve_dlx(&PNPM_OPTS, &PNPM_DLX_OPTS, words, i),
+            false,
+        ),
+        "yarn" => (
+            |words, i| resolve_dlx(&YARN_OPTS, &YARN_DLX_OPTS, words, i),
+            false,
+        ),
+        "bun" => (resolve_bun, false),
+        "bunx" => (|words, i| BUN_X_OPTS.consume(words, i + 1), false),
+        "uvx" => (|_words, i| Some(i + 1), false),
+        _ => return None,
+    };
+    Some(Wrapper {
+        resolve,
+        accepts_assignment,
+    })
+}
+
+/// `pnpm`/`yarn` only look through to the package behind an explicit `dlx`
+/// — without it, the next word is a `package.json` script name, not a
+/// package to run (#199: `pnpm claude` is not `pnpm dlx claude`). `dlx`
+/// itself takes launcher-specific options too, consumed before the executable.
+fn resolve_dlx(
+    opts: &OptionTable,
+    dlx_opts: &OptionTable,
+    words: &[&str],
+    i: usize,
+) -> Option<usize> {
+    let j = opts.consume(words, i + 1)?;
+    if words.get(j) != Some(&"dlx") {
+        return None;
+    }
+    dlx_opts.consume(words, j + 1)
+}
+
+/// `bun x <pkg>` is bun's `dlx`/`npx` equivalent; `bun run <script>` is not
+/// (the same package-script ambiguity as bare `pnpm`/`yarn`), so only an `x`
+/// subcommand is looked through. `--bun` (`BUN_X_OPTS`) may follow it before
+/// the executable.
+fn resolve_bun(words: &[&str], i: usize) -> Option<usize> {
+    if words.get(i + 1) != Some(&"x") {
+        return None;
+    }
+    BUN_X_OPTS.consume(words, i + 2)
+}
+
+/// `FOO=bar`, the shell's own prefix for one command's environment —
+/// recognised only when the `=` came from plain, unquoted/unescaped source
+/// text (#199): `"FOO=1"` and `FOO\=1` name a program called `FOO=1`, not
+/// an assignment.
+fn is_env_assignment(word: &Word) -> bool {
+    let Some(eq) = word.plain_eq else {
+        return false;
+    };
+    let name = &word.text[..eq];
+    let mut chars = name.chars();
     match chars.next() {
         Some(c) if c.is_ascii_alphabetic() || c == '_' => {}
         _ => return false,
     }
-    let rest: String = chars.collect();
+    chars.all(|c| c.is_ascii_alphanumeric() || c == '_')
-    match rest.split_once('=') {
-        Some((name, _)) => name.chars().all(|c| c.is_ascii_alphanumeric() || c == '_'),
-        None => false,
-    }
 }
 
 fn basename(word: &str) -> &str {
@@ -497,38 +946,122 @@ mod tests {
             "claude"
         );
         assert_eq!(command_program("  zsh   -l  "), "zsh");
-        assert_eq!(command_program("hx src/main.rs"), "hx");
     }
 
+    /// The #199 resolver contract: every case in the shared parity fixture,
+    /// asserted identically here and by `web/src/toolIcon.test.ts`, so a
+    /// resolver regression in either language fails its own suite.
     #[test]
-    fn command_program_looks_through_paths_env_and_wrappers() {
+    fn resolves_the_shared_command_resolution_fixture() {
-        assert_eq!(command_program("/usr/local/bin/claude -p hi"), "claude");
+        #[derive(serde::Deserialize)]
-        assert_eq!(command_program("FOO=1 BAR=2 claude"), "claude");
+        struct Case {
-        assert_eq!(command_program("npx opencode"), "opencode");
+            command: String,
-        assert_eq!(command_program("pnpm dlx opencode run"), "opencode");
+            program: String,
+            tool: Option<String>,
+        }
+        #[derive(serde::Deserialize)]
+        struct Fixture {
+            cases: Vec<Case>,
+        }
+        let raw = include_str!("../../../fixtures/command-resolution.json");
+        let fixture: Fixture = serde_json::from_str(raw).expect("valid fixture JSON");
+        assert!(!fixture.cases.is_empty());
+        for case in &fixture.cases {
+            assert_eq!(
+                command_program(&case.command),
+                case.program,
+                "program for {:?}",
+                case.command
+            );
+            assert_eq!(
+                command_tool(&case.command),
+                case.tool.as_deref(),
+                "tool for {:?}",
+                case.command
+            );
+        }
     }
 
-    #[test]
+    fn word(text: &str) -> Word {
-    fn command_program_keeps_a_line_that_is_only_wrappers() {
+        Word {
-        assert_eq!(command_program("sudo"), "sudo");
+            text: text.into(),
-        assert_eq!(command_program(""), "");
+            plain_eq: None,
+        }
     }
 
-    /// The command bar's `tool` field (docs/COMMAND-BAR.md) names the same
+    /// Shell-aware tokenization (#199): quoting/escaping is honoured, never
-    /// tools the web's `splitCommand().tool` does.
+    /// evaluated — no `$var`/`` `cmd` ``/`$(cmd)` expansion is attempted.
     #[test]
-    fn command_tool_names_the_mark_the_card_shows() {
+    fn tokenize_handles_quotes_and_escapes_without_expanding_anything() {
-        assert_eq!(command_tool("claude --resume"), Some("claude"));
+        assert_eq!(
-        assert_eq!(command_tool("npx opencode"), Some("opencode"));
+            tokenize("claude --resume"),
-        assert_eq!(command_tool("/bin/zsh -l"), Some("shell"));
+            Some(vec![word("claude"), word("--resume")])
-        assert_eq!(command_tool("CLAUDE"), Some("claude"));
+        );
+        assert_eq!(
+            tokenize("\"/opt/my agent/claude\" --resume"),
+            Some(vec![word("/opt/my agent/claude"), word("--resume")])
+        );
+        assert_eq!(
+            tokenize("FOO=\"bar baz\" claude"),
+            Some(vec![
+                Word {
+                    text: "FOO=bar baz".into(),
+                    plain_eq: Some(3),
+                },
+                word("claude"),
+            ])
+        );
+        assert_eq!(
+            tokenize("claude --name=$HOME"),
+            Some(vec![
+                word("claude"),
+                Word {
+                    text: "--name=$HOME".into(),
+                    plain_eq: Some(6),
+                },
+            ]),
+            "a bare $ is kept literal, never expanded"
+        );
     }
 
-    /// Narrow on purpose: an unrecognised program has no mark, so the
+    /// Real shell grammar this resolver doesn't attempt — pipelines, list
-    /// candidate has no `tool` field to match rather than a wrong one.
+    /// operators, subshells/substitution, an unescaped newline, an
+    /// unterminated quote — is rejected outright rather than guessed
+    /// through (#199).
     #[test]
-    fn command_tool_is_absent_for_an_unrecognised_program() {
+    fn tokenize_rejects_ambiguous_shell_grammar() {
-        assert_eq!(command_tool("hx src/main.rs"), None);
+        for command in [
-        assert_eq!(command_tool(""), None);
+            "claude | tee log.txt",
+            "claude; echo done",
+            "claude && echo done",
+            "echo hi $(claude)",
+            "claude \"unterminated",
+            "claude 'unterminated",
+            "claude \\",
+            "claude\nclaude-code", // an unescaped newline separates commands, like `;`
+        ] {
+            assert_eq!(tokenize(command), None, "{command:?}");
+        }
+    }
+
+    /// A backslash immediately before a newline is a line continuation:
+    /// removed entirely, joining what it split rather than embedding a
+    /// literal newline or ending the command (#199).
+    #[test]
+    fn tokenize_treats_backslash_newline_as_a_continuation() {
+        assert_eq!(
+            tokenize("clau\\\nde --resume"),
+            Some(vec![word("claude"), word("--resume")])
+        );
+    }
+
+    /// Only a plain, unquoted/unescaped `=` marks an assignment boundary —
+    /// quoting or escaping the `=` itself disqualifies the word, even
+    /// though the dequoted text looks identical (#199).
+    #[test]
+    fn tokenize_only_marks_plain_unquoted_equals_signs_as_assignments() {
+        assert_eq!(tokenize("FOO=1 claude").unwrap()[0].plain_eq, Some(3));
+        assert_eq!(tokenize("\"FOO=1\" claude").unwrap()[0].plain_eq, None);
+        assert_eq!(tokenize("FOO\\=1 claude").unwrap()[0].plain_eq, None);
     }
 }

crates/maestro-protocol/src/lib.rs

@@ -156,9 +156,9 @@ pub enum SessionStatus {
     Dead,
 }
 
-/// Inferred session activity, orthogonal to [`SessionStatus`] (NAP-340). The
+/// Session activity, orthogonal to [`SessionStatus`] (NAP-340). Terminal
-/// daemon derives this from tmux pane state, PTY quiescence, and `/proc`
+/// sessions use pane/process inference and agent reports; structured sessions
-/// inspection — never by parsing the terminal byte stream.
+/// use their ACP turn lifecycle (docs/SIDEBAR.md).
 ///
 /// Deserializes leniently (#110, SIDEBAR.md Precedence): an unknown variant
 /// from a newer daemon becomes [`ActivityState::Idle`] instead of failing the
@@ -166,15 +166,14 @@ pub enum SessionStatus {
 /// forgiven.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Default)]
 pub enum ActivityState {
-    /// Producing output, or the foreground process is busy.
+    /// Producing output, the foreground process is busy, or an ACP turn is active.
     Active,
     /// Foreground process alive but quiescent. The forward-compatible default.
     #[default]
     Idle,
-    /// Blocked on a `read()` from the pty — waiting on the user.
+    /// Blocked on terminal input or waiting for an ACP approval.
     AwaitingInput,
-    /// The agent running in the session reported a failure (#102). Never
+    /// An agent reported a failure, or a structured session/turn failed.
-    /// inferred by the daemon; only set when an agent reports it (#105).
     Error,
 }
 
@@ -872,6 +871,15 @@ pub struct StructuredPromptRequest {
     pub prompt: String,
 }
 
+/// Operator decision for a pending ACP permission request.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum StructuredApprovalDecision {
+    AllowOnce,
+    AllowForSession,
+    Deny,
+}
+
 // ---------------------------------------------------------------------------
 // Client ↔ Daemon control messages (text frames on the attach WS)
 // ---------------------------------------------------------------------------

crates/maestro-protocol/src/routes.rs

@@ -91,6 +91,11 @@ pub fn structured_cancel(id: Uuid) -> String {
     format!("{SESSIONS}/{id}/structured/cancel")
 }
 
+/// `POST /api/sessions/:id/structured/approvals/:nonce` — answer ACP permission.
+pub fn structured_approval(id: Uuid, nonce: &str) -> String {
+    format!("{SESSIONS}/{id}/structured/approvals/{nonce}")
+}
+
 /// Axum-style patterns for the two parameterised routes, so the server
 /// registers the same paths [`session`] and [`attach`] build.
 pub mod patterns {
@@ -104,6 +109,7 @@ pub mod patterns {
     pub const STRUCTURED_REPLAY: &str = "/api/sessions/:id/structured/replay";
     pub const STRUCTURED_PROMPT: &str = "/api/sessions/:id/structured/prompt";
     pub const STRUCTURED_CANCEL: &str = "/api/sessions/:id/structured/cancel";
+    pub const STRUCTURED_APPROVAL: &str = "/api/sessions/:id/structured/approvals/:nonce";
 }
 
 /// A daemon base URL that could not be turned into a WebSocket base.
@@ -153,6 +159,11 @@ pub fn attach_url(http_base: &str, id: Uuid) -> Result<String, UrlError> {
     Ok(format!("{}{}", ws_base(http_base)?, attach(id)))
 }
 
+/// Full `WS /api/structured/:id` URL for a daemon reachable at `http_base`.
+pub fn structured_url(http_base: &str, id: Uuid) -> Result<String, UrlError> {
+    Ok(format!("{}{}", ws_base(http_base)?, structured(id)))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -202,6 +213,10 @@ mod tests {
             events_url("http://host:7070/").unwrap(),
             "ws://host:7070/api/events"
         );
+        assert_eq!(
+            structured_url("http://host:7070/", id()).unwrap(),
+            "ws://host:7070/api/structured/6f1a7c0e-0f5e-4a2b-9a3d-6b1c2d3e4f50"
+        );
     }
 
     #[test]

crates/maestro-tui/Cargo.toml

@@ -21,6 +21,7 @@ thiserror.workspace = true
 tokio = { workspace = true, features = ["sync", "time", "macros", "rt"] }
 tokio-tungstenite.workspace = true
 tracing.workspace = true
+unicode-width.workspace = true
 uuid.workspace = true
 vt100.workspace = true
 

crates/maestro-tui/src/app.rs

@@ -17,7 +17,10 @@ use std::time::Duration;
 use chrono::Utc;
 use crossterm::event::{Event as CtEvent, EventStream};
 use futures_util::StreamExt;
-use maestro_protocol::{routes, BranchInfo, CreateSessionRequest, DaemonClient, NameBatch};
+use maestro_protocol::{
+    routes, BranchInfo, CreateSessionRequest, DaemonClient, NameBatch, SessionView,
+    StructuredApprovalDecision,
+};
 use ratatui::Terminal;
 use uuid::Uuid;
 
@@ -38,6 +41,8 @@ use crate::render::{draw, RegionMap, RenderInputs};
 use crate::session_task::{SessionInput, SessionTask};
 use crate::sidebar::Sidebar;
 use crate::state::{AppState, Focus, OverlayKind, SidebarItem};
+use crate::structured_pane::StructuredPane;
+use crate::structured_task::{StructuredHandle, StructuredTask};
 use crate::text_input::TextInput;
 use crate::TuiError;
 
@@ -54,6 +59,7 @@ pub struct App {
     home_dir: String,
     catalog: CatalogStore,
     emulators: SessionEmulators,
+    structured: HashMap<Uuid, StructuredHandle>,
     state: AppState,
     help: HelpOverlay,
     chord: ChordState,
@@ -163,6 +169,18 @@ pub enum Effect {
         id: Uuid,
         bytes: Vec<u8>,
     },
+    StructuredPrompt {
+        id: Uuid,
+        prompt: String,
+    },
+    StructuredCancel {
+        id: Uuid,
+    },
+    StructuredApproval {
+        id: Uuid,
+        nonce: String,
+        decision: StructuredApprovalDecision,
+    },
     /// Fetch presets / projects / names for a freshly opened form (#64).
     LoadDraft,
     /// Fast-forward spawn (#67): resolve every default from the daemon and
@@ -214,6 +232,7 @@ impl App {
             home_dir: std::env::var("HOME").unwrap_or_default(),
             catalog,
             emulators: SessionEmulators::default(),
+            structured: HashMap::new(),
             state: AppState::new(),
             draft: None,
             help,
@@ -321,6 +340,11 @@ impl App {
             return Ok(false);
         }
 
+        if let Some(effects) = self.handle_structured_key(&key) {
+            self.perform(effects).await;
+            return Ok(false);
+        }
+
         if let Some(effect) = self.handle_pane_scroll(&key) {
             self.perform(effect.into_iter().collect()).await;
             return Ok(false);
@@ -419,6 +443,44 @@ impl App {
                         let _ = handle.tx.send(SessionInput::Bytes(bytes)).await;
                     }
                 }
+                Effect::StructuredPrompt { id, prompt } => {
+                    if let Err(error) = self.daemon.send_structured_prompt(id, &prompt).await {
+                        if let Some(handle) = self.structured.get(&id) {
+                            handle
+                                .state
+                                .lock()
+                                .expect("structured state mutex")
+                                .prompt_failed(prompt, error.to_string());
+                        }
+                    }
+                }
+                Effect::StructuredCancel { id } => {
+                    if let Err(error) = self.daemon.cancel_structured_turn(id).await {
+                        if let Some(handle) = self.structured.get(&id) {
+                            handle.state.lock().expect("structured state mutex").error =
+                                Some(error.to_string());
+                        }
+                    }
+                }
+                Effect::StructuredApproval {
+                    id,
+                    nonce,
+                    decision,
+                } => {
+                    if let Err(error) = self
+                        .daemon
+                        .resolve_structured_approval(id, &nonce, decision)
+                        .await
+                    {
+                        if let Some(handle) = self.structured.get(&id) {
+                            handle
+                                .state
+                                .lock()
+                                .expect("structured state mutex")
+                                .approval_failed(&nonce, error.to_string());
+                        }
+                    }
+                }
             }
         }
     }
@@ -563,13 +625,13 @@ impl App {
             Action::OpenCommandBar => effects.extend(self.open_command_bar()),
             // Escape hatch (#156): the literal byte, not the bar.
             Action::SendLiteralCtrlK => {
-                effects.extend(self.forward_to_session(&InputKey::ctrl_char('k')));
+                effects.extend(self.forward_literal_to_terminal(&InputKey::ctrl_char('k')));
             }
             // Escape hatch (#158): the leader's own byte, built from the
             // configured leader rather than a hardcoded key.
             Action::SendLiteralLeader => {
                 let leader = self.cfg.leader.clone();
-                effects.extend(self.forward_to_session(&leader));
+                effects.extend(self.forward_literal_to_terminal(&leader));
             }
             Action::OpenSpawnModal => {
                 self.open_spawn_modal();
@@ -587,7 +649,7 @@ impl App {
                         }
                         // A previewed session is already attached: committing
                         // to it keeps that stream rather than reopening one.
-                        if self.emulators.get(sid).is_none() {
+                        if !self.is_attached(sid) {
                             effects.push(Effect::Attach(sid));
                         }
                     }
@@ -595,6 +657,9 @@ impl App {
                     // preview budget.
                     self.preview_lru.retain(|s| *s != sid);
                     self.state.attach_to_focused(sid);
+                    if self.session_view(sid) == SessionView::Structured {
+                        self.state.mode = Mode::Normal;
+                    }
                 }
             }
             Action::KillHighlighted => {
@@ -663,7 +728,7 @@ impl App {
         self.state.preview = Some(sid);
         // Set outside the input path, so nothing else marks the frame stale.
         self.epoch = self.epoch.wrapping_add(1);
-        let fresh = self.emulators.get(sid).is_none();
+        let fresh = !self.is_attached(sid);
         if fresh {
             self.preview_lru.retain(|s| *s != sid);
             self.preview_lru.push(sid);
@@ -732,15 +797,27 @@ impl App {
 
     /// Open a stream for `sid` if one isn't already running.
     fn attach(&mut self, sid: Uuid) {
-        if self.emulators.get(sid).is_some() {
+        self.attach_with_view(sid, self.session_view(sid));
+    }
+
+    fn attach_with_view(&mut self, sid: Uuid, view: SessionView) {
+        if self.is_attached(sid) {
             return;
         }
-        match self.daemon.attach_url(sid) {
+        match view {
-            Ok(ws_url) => {
+            SessionView::Terminal => match self.daemon.attach_url(sid) {
-                let handle = SessionTask::spawn(ws_url, 24, 80);
+                Ok(ws_url) => {
-                self.emulators.insert(sid, handle);
+                    let handle = SessionTask::spawn(ws_url, 24, 80);
-            }
+                    self.emulators.insert(sid, handle);
-            Err(e) => self.state.toast(format!("attach failed: {e}")),
+                }
+                Err(e) => self.state.toast(format!("attach failed: {e}")),
+            },
+            SessionView::Structured => match self.daemon.structured_url(sid) {
+                Ok(ws_url) => {
+                    self.structured.insert(sid, StructuredTask::spawn(ws_url));
+                }
+                Err(e) => self.state.toast(format!("attach failed: {e}")),
+            },
         }
     }
 
@@ -748,9 +825,26 @@ impl App {
     /// dropping its vt100 parser.
     fn release_session(&mut self, sid: Uuid) {
         self.emulators.remove(sid);
+        if let Some(handle) = self.structured.remove(&sid) {
+            handle.end();
+        }
         self.last_sent_size.remove(&sid);
     }
 
+    fn session_view(&self, sid: Uuid) -> SessionView {
+        self.catalog
+            .snapshot()
+            .sessions
+            .iter()
+            .find(|session| session.id == sid)
+            .map(|session| session.view)
+            .unwrap_or_default()
+    }
+
+    fn is_attached(&self, sid: Uuid) -> bool {
+        self.emulators.get(sid).is_some() || self.structured.contains_key(&sid)
+    }
+
     /// Return the session under the sidebar highlight, falling back to the
     /// first listed session so the user can attach without arrowing first.
     fn pick_sidebar_target(&self) -> Option<Uuid> {
@@ -817,6 +911,16 @@ impl App {
     /// attached to send it to.
     fn forward_to_session(&mut self, key: &InputKey) -> Option<Effect> {
         let sid = self.state.active_session()?;
+        if let Some(handle) = self.structured.get(&sid) {
+            let mut state = handle.state.lock().expect("structured state mutex");
+            if matches!(key, InputKey::Enter) {
+                return state
+                    .begin_prompt()
+                    .map(|prompt| Effect::StructuredPrompt { id: sid, prompt });
+            }
+            state.edit_composer(key);
+            return None;
+        }
         let handle = self.emulators.get(sid)?;
         let bytes = encode_key(key)?;
         handle
@@ -827,6 +931,86 @@ impl App {
         Some(Effect::Forward { id: sid, bytes })
     }
 
+    fn forward_literal_to_terminal(&mut self, key: &InputKey) -> Option<Effect> {
+        let sid = self.state.active_session()?;
+        if self.session_view(sid) == SessionView::Structured {
+            return None;
+        }
+        self.forward_to_session(key)
+    }
+
+    fn handle_structured_key(&mut self, key: &InputKey) -> Option<Vec<Effect>> {
+        if self.state.focus != Focus::Pane || self.state.preview.is_some() {
+            return None;
+        }
+        let sid = self.state.active_session()?;
+        let handle = self.structured.get(&sid)?;
+        let mut state = handle.state.lock().expect("structured state mutex");
+        if self.state.mode == Mode::Insert {
+            if matches!(key, InputKey::Esc) && state.turn_active() {
+                return Some(vec![Effect::StructuredCancel { id: sid }]);
+            }
+            return None;
+        }
+        let effects = match key {
+            InputKey::Char {
+                c: 'j',
+                ctrl: false,
+                alt: false,
+                ..
+            }
+            | InputKey::Down => {
+                state.select(1);
+                Vec::new()
+            }
+            InputKey::Char {
+                c: 'k',
+                ctrl: false,
+                alt: false,
+                ..
+            }
+            | InputKey::Up => {
+                state.select(-1);
+                Vec::new()
+            }
+            InputKey::Enter => {
+                state.toggle_selected();
+                Vec::new()
+            }
+            InputKey::Esc => {
+                if state.turn_active() {
+                    vec![Effect::StructuredCancel { id: sid }]
+                } else {
+                    Vec::new()
+                }
+            }
+            InputKey::Char {
+                c: key @ ('a' | 'A' | 'd'),
+                ctrl: false,
+                alt: false,
+                ..
+            } => state
+                .approval_decision(*key)
+                .map(|(nonce, decision)| Effect::StructuredApproval {
+                    id: sid,
+                    nonce,
+                    decision,
+                })
+                .into_iter()
+                .collect(),
+            InputKey::PageUp => {
+                state.scroll_by(self.pane_page_rows() as isize);
+                Vec::new()
+            }
+            InputKey::PageDown => {
+                state.scroll_by(-(self.pane_page_rows() as isize));
+                Vec::new()
+            }
+            _ => return None,
+        };
+        Some(effects)
+    }
+
     fn pane_page_rows(&self) -> usize {
         self.region
             .pane
@@ -839,6 +1023,14 @@ impl App {
         let Some(sid) = self.state.active_session() else {
             return;
         };
+        if let Some(handle) = self.structured.get(&sid) {
+            handle
+                .state
+                .lock()
+                .expect("structured state mutex")
+                .scroll_by(rows);
+            return;
+        }
         let Some(handle) = self.emulators.get(sid) else {
             return;
         };
@@ -872,6 +1064,14 @@ impl App {
             _ => return None,
         };
         let sid = self.state.active_session()?;
+        if let Some(handle) = self.structured.get(&sid) {
+            handle
+                .state
+                .lock()
+                .expect("structured state mutex")
+                .scroll_by(lines);
+            return Some(None);
+        }
         let handle = self.emulators.get(sid)?;
         let pane = self.region.pane?;
         let parser = handle.screen.lock().expect("vt100 parser mutex");
@@ -1294,7 +1494,10 @@ impl App {
                 }
                 self.draft = None;
                 self.state.complete_spawn(sid);
-                self.attach(sid);
+                if session.view == SessionView::Structured {
+                    self.state.mode = Mode::Normal;
+                }
+                self.attach_with_view(sid, session.view);
             }
             Err(e) => {
                 // A failed POST belongs in the form it came from (#64), not a
@@ -1355,6 +1558,11 @@ impl App {
             self.emulators
                 .get(sid)
                 .map(|h| (sid, h.revision(), h.state()))
+                .or_else(|| {
+                    self.structured
+                        .get(&sid)
+                        .map(|h| (sid, h.revision(), h.connection()))
+                })
         });
         FrameKey {
             catalog: self.catalog.version(),
@@ -1416,6 +1624,17 @@ impl App {
                 focused: matches!(self.state.focus, Focus::Pane) && !previewing,
             })
         });
+        let structured_pane = shown_sid.and_then(|sid| {
+            let handle = self.structured.get(&sid)?;
+            let session = snap.sessions.iter().find(|session| session.id == sid)?;
+            Some(StructuredPane {
+                handle: handle.clone(),
+                focused: matches!(self.state.focus, Focus::Pane) && !previewing,
+                mode: self.state.mode,
+                session_status: session.status,
+                activity_detail: session.activity_detail.clone(),
+            })
+        });
         let pane_title = match shown_sid {
             Some(sid) => {
                 let name = snap
@@ -1439,6 +1658,7 @@ impl App {
             home_dir: &self.home_dir,
             pane_title: &pane_title,
             pane: pane.as_ref(),
+            structured_pane: structured_pane.as_ref(),
             state: &self.state,
             draft: self.draft.as_ref(),
             help: &self.help,
@@ -2805,6 +3025,53 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn create_response_selects_transport_before_catalog_event() {
+        use axum::routing::post;
+        use axum::Json;
+
+        async fn spawn_session(
+            Json(req): Json<CreateSessionRequest>,
+        ) -> Json<maestro_protocol::Session> {
+            let id = match req.view {
+                SessionView::Terminal => Uuid::from_u128(187),
+                SessionView::Structured => Uuid::from_u128(188),
+            };
+            let mut session = test_session(id, req.cwd.to_str().unwrap());
+            session.view = req.view;
+            session.command = req.command;
+            Json(session)
+        }
+
+        let router =
+            axum::Router::new().route(maestro_protocol::routes::SESSIONS, post(spawn_session));
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let base = format!("http://{}", listener.local_addr().unwrap());
+        tokio::spawn(async move { axum::serve(listener, router).await.unwrap() });
+
+        let mut app = make_app_at(&base);
+        let request = |view| CreateSessionRequest {
+            view,
+            cwd: std::path::PathBuf::from("/srv/work"),
+            command: "claude".into(),
+            env: Default::default(),
+            metadata: Default::default(),
+            worktree: None,
+        };
+
+        let structured_id = Uuid::from_u128(188);
+        app.submit_spawn(request(SessionView::Structured)).await;
+        assert!(app.catalog.snapshot().sessions.is_empty());
+        assert!(app.structured.contains_key(&structured_id));
+        assert!(app.emulators.get(structured_id).is_none());
+
+        let terminal_id = Uuid::from_u128(187);
+        app.submit_spawn(request(SessionView::Terminal)).await;
+        assert!(app.catalog.snapshot().sessions.is_empty());
+        assert!(app.emulators.get(terminal_id).is_some());
+        assert!(!app.structured.contains_key(&terminal_id));
+    }
+
     /// The full data load against a live daemon stub: presets replace the
     /// built-ins, projects land sorted, and the first generated name seeds
     /// the field.
@@ -3697,4 +3964,112 @@ mod tests {
         assert!(app.command_bar.is_none());
         assert!(app.state.overlay().is_none());
     }
+
+    fn structured_app(sid: Uuid) -> App {
+        let mut app = app_with_highlighted_session(sid);
+        let mut session = app.catalog.snapshot().sessions[0].clone();
+        session.view = SessionView::Structured;
+        app.catalog
+            .apply_event(maestro_protocol::CatalogEvent::SessionUpdated { session });
+        app.structured.insert(
+            sid,
+            StructuredHandle::test_handle(crate::structured_task::StructuredState::default()),
+        );
+        app.state.attach_to_focused(sid);
+        app
+    }
+
+    #[tokio::test]
+    async fn session_view_selects_the_structured_connection_and_cleanup_stops_it() {
+        let sid = Uuid::from_u128(141);
+        let mut app = app_with_highlighted_session(sid);
+        let mut session = app.catalog.snapshot().sessions[0].clone();
+        session.view = SessionView::Structured;
+        app.catalog
+            .apply_event(maestro_protocol::CatalogEvent::SessionUpdated { session });
+
+        app.attach(sid);
+        assert!(app.structured.contains_key(&sid));
+        assert!(app.emulators.get(sid).is_none());
+        let handle = app.structured.get(&sid).unwrap().clone();
+        app.release_session(sid);
+        assert_eq!(
+            handle.connection(),
+            crate::session_task::SessionState::Ended
+        );
+    }
+
+    #[test]
+    fn structured_normal_mode_routes_navigation_expansion_and_approval_by_row() {
+        use maestro_protocol::{ReducedState, TranscriptRow, TranscriptRowKind};
+        use serde_json::json;
+
+        let sid = Uuid::from_u128(141);
+        let mut app = structured_app(sid);
+        app.dispatch(Action::AttachHighlighted);
+        assert_eq!(app.state.focus, Focus::Pane);
+        assert_eq!(app.state.mode, Mode::Normal);
+        let handle = app.structured.get(&sid).unwrap().clone();
+        {
+            let mut state = handle.state.lock().unwrap();
+            state.rows = vec![
+                TranscriptRow {
+                    id: "text".into(),
+                    kind: TranscriptRowKind::AgentText,
+                    data: json!({"content":{"type":"text","text":"hello"}}),
+                },
+                TranscriptRow {
+                    id: "approval".into(),
+                    kind: TranscriptRowKind::Approval,
+                    data: json!({"options":[{"kind":"allow_once"}]}),
+                },
+            ];
+            state.selected = Some("text".into());
+            state.reduced = ReducedState {
+                pending_approval: Some(json!({"nonce":"n"})),
+                ..ReducedState::default()
+            };
+        }
+
+        assert_eq!(
+            app.handle_structured_key(&InputKey::char('j')),
+            Some(vec![])
+        );
+        assert_eq!(
+            app.handle_structured_key(&InputKey::char('a')),
+            Some(vec![Effect::StructuredApproval {
+                id: sid,
+                nonce: "n".into(),
+                decision: StructuredApprovalDecision::AllowOnce,
+            }])
+        );
+        assert_eq!(
+            handle.state.lock().unwrap().selected.as_deref(),
+            Some("approval")
+        );
+    }
+
+    #[test]
+    fn structured_insert_mode_edits_submits_and_cancels_without_pty_bytes() {
+        let sid = Uuid::from_u128(141);
+        let mut app = structured_app(sid);
+        assert!(app.emulators.get(sid).is_none());
+        app.forward_to_session(&InputKey::char('h'));
+        app.forward_to_session(&InputKey::char('i'));
+        assert_eq!(
+            app.forward_to_session(&InputKey::Enter),
+            Some(Effect::StructuredPrompt {
+                id: sid,
+                prompt: "hi".into(),
+            })
+        );
+        assert_eq!(
+            app.handle_structured_key(&InputKey::Esc),
+            Some(vec![Effect::StructuredCancel { id: sid }])
+        );
+        assert_eq!(
+            app.forward_literal_to_terminal(&app.cfg.leader.clone()),
+            None
+        );
+    }
 }

crates/maestro-tui/src/draft.rs

@@ -41,8 +41,10 @@ use std::time::{Duration, Instant};
 
 use chrono::{DateTime, Utc};
 use maestro_config::{builtin_presets, custom_preset};
-use maestro_protocol::display::abbreviate_dir;
+use maestro_protocol::display::{abbreviate_dir, command_tool};
-use maestro_protocol::{BranchInfo, CreateSessionRequest, Project, SpawnPreset, WorktreeSpec};
+use maestro_protocol::{
+    BranchInfo, CreateSessionRequest, Project, SessionView, SpawnPreset, WorktreeSpec,
+};
 use ratatui::layout::{Constraint, Layout, Rect};
 use ratatui::style::{Modifier, Style};
 use ratatui::text::{Line, Span};
@@ -86,9 +88,11 @@ pub enum DraftField {
     /// apply immediately, mirroring the web form's per-click choice.
     WorktreeChoice,
     Name,
-    /// Disclosure collapsing the worktree/branch controls below (#93).
+    /// Disclosure collapsing the optional view and worktree controls below.
     /// Closed by default; Enter / Space toggles.
     Advanced,
+    /// ACP-backed transcript instead of a terminal. Claude Code only.
+    StructuredToggle,
     /// Worktree on/off for this session (#65). Enter / Space toggles.
     WorktreeToggle,
     /// New-vs-existing branch source; Left / Right switches.
@@ -251,6 +255,9 @@ pub struct DraftPane {
     /// "Advanced options" disclosure (#93). Closed by default — most spawns
     /// take the default target.
     pub advanced_collapsed: bool,
+    /// ACP-backed structured transcript. Off by default and supported only
+    /// when the resolved command is Claude Code.
+    pub structured_view: bool,
     /// Enclosing repository of the chosen target — from the project scan for
     /// picked rows, `/api/gitroot` for raw paths. `None` until known.
     pub base_repo: Option<PathBuf>,
@@ -311,6 +318,7 @@ impl Default for DraftPane {
             name_touched: false,
             worktree_enabled: true,
             advanced_collapsed: true,
+            structured_view: false,
             base_repo: None,
             probed_cwd: None,
             probe_seq: 0,
@@ -348,6 +356,7 @@ impl DraftPane {
             .position(|p| !p.command.is_empty())
             .unwrap_or(0);
         self.apply_seed_command();
+        self.clear_unsupported_structured_view();
     }
 
     /// Land a seeded command on the tile that runs it: its own preset when the
@@ -663,6 +672,22 @@ impl DraftPane {
         }
     }
 
+    fn supports_structured_view(&self) -> bool {
+        command_tool(self.command()) == Some("claude")
+    }
+
+    fn clear_unsupported_structured_view(&mut self) {
+        if !self.supports_structured_view() {
+            self.structured_view = false;
+        }
+    }
+
+    pub fn toggle_structured_view(&mut self) {
+        if self.supports_structured_view() {
+            self.structured_view = !self.structured_view;
+        }
+    }
+
     /// The chosen working directory: a picked project row, else the raw path
     /// input when it holds something.
     pub fn cwd(&self) -> Option<PathBuf> {
@@ -694,7 +719,11 @@ impl DraftPane {
         }
         let worktree = self.build_worktree()?;
         Ok(CreateSessionRequest {
-            view: Default::default(),
+            view: if self.structured_view && self.supports_structured_view() {
+                SessionView::Structured
+            } else {
+                SessionView::Terminal
+            },
             cwd,
             command: command.to_string(),
             env: Default::default(),
@@ -754,6 +783,9 @@ impl DraftPane {
         order.push(DraftField::Name);
         order.push(DraftField::Advanced);
         if !self.advanced_collapsed {
+            if self.supports_structured_view() {
+                order.push(DraftField::StructuredToggle);
+            }
             if !self.cwd_raw_visible && self.selected_group_key.is_some() {
                 order.push(DraftField::WorktreeChoice);
             }
@@ -795,6 +827,7 @@ impl DraftPane {
         }
         self.selected_preset =
             ((self.selected_preset as i32) + delta).rem_euclid(len as i32) as usize;
+        self.clear_unsupported_structured_view();
     }
 
     /// Step-one boxes surviving the type-to-filter, in display order. A
@@ -1001,9 +1034,9 @@ impl DraftPane {
             // Two fields keep their own Enter instead: `DirPicker`, whose
             // highlighted row isn't the picked one until a first Enter chooses
             // it (the next Enter, now that it's active, falls through to
-            // submit); and the disclosure/toggle pair (`Advanced`,
+            // submit); and the disclosure/checkbox fields, which activate on
-            // `WorktreeToggle`), which activate on Enter like a button rather
+            // Enter like buttons rather than submitting, matching the web
-            // than submitting, same as the web form's own `<button>` controls.
+            // form controls.
             InputKey::Enter if self.focused_field == DraftField::DirPicker => {
                 let is_other_row = self.selection() >= self.visible_groups().len();
                 let choose_only =
@@ -1023,6 +1056,10 @@ impl DraftPane {
                 self.toggle_worktree();
                 DraftInputResult::Consumed
             }
+            InputKey::Enter if self.focused_field == DraftField::StructuredToggle => {
+                self.toggle_structured_view();
+                DraftInputResult::Consumed
+            }
             InputKey::Enter => DraftInputResult::Submit,
             InputKey::Char {
                 c: ' ',
@@ -1040,6 +1077,14 @@ impl DraftPane {
                 self.toggle_worktree();
                 DraftInputResult::Consumed
             }
+            InputKey::Char {
+                c: ' ',
+                ctrl: false,
+                ..
+            } if self.focused_field == DraftField::StructuredToggle => {
+                self.toggle_structured_view();
+                DraftInputResult::Consumed
+            }
             InputKey::Up if self.focused_field == DraftField::DirPicker => {
                 self.move_selection(-1);
                 DraftInputResult::Consumed
@@ -1083,7 +1128,10 @@ impl DraftPane {
             other => {
                 match self.focused_field {
                     DraftField::Preset | DraftField::Submit => {}
-                    DraftField::CustomCommand => self.custom_command.handle_key(other),
+                    DraftField::CustomCommand => {
+                        self.custom_command.handle_key(other);
+                        self.clear_unsupported_structured_view();
+                    }
                     // Typing filters the list; the highlight resets to the top
                     // so a narrowed search always starts at its best match.
                     DraftField::DirPicker => {
@@ -1121,9 +1169,9 @@ impl DraftPane {
 
         let show_custom = self.is_custom();
         let show_raw = self.cwd_raw_visible;
-        // The worktree choice step, the worktree toggle and its body all stay
+        let show_structured = !self.advanced_collapsed && self.supports_structured_view();
-        // behind the "Advanced options" disclosure (#93): collapsed hides
+        // Optional view and worktree controls stay behind the "Advanced
-        // them, regardless of what they'd otherwise show.
+        // options" disclosure (#93), regardless of what they'd otherwise show.
         let show_wt_toggle = !self.advanced_collapsed;
         let show_wt_body = show_wt_toggle && self.worktree_body_visible();
         let show_wt_choice =
@@ -1142,6 +1190,7 @@ impl DraftPane {
         let fixed: u16 = 3 /* tiles + dir + name */ + 1 /* advanced header */ + 1 /* spawn */
             + u16::from(show_custom)
             + u16::from(show_raw)
+            + u16::from(show_structured)
             + u16::from(show_wt_toggle)
             + u16::from(show_wt_choice) * wt_choice_capacity
             + u16::from(show_wt_body) * (1 + if self.branch_mode == WorktreeBranchMode::New { 1 } else { branch_rows })
@@ -1161,6 +1210,9 @@ impl DraftPane {
         }
         constraints.push(Constraint::Length(1)); // name
         constraints.push(Constraint::Length(1)); // advanced header
+        if show_structured {
+            constraints.push(Constraint::Length(1));
+        }
         if show_wt_choice {
             constraints.push(Constraint::Length(wt_choice_capacity));
         }
@@ -1359,6 +1411,24 @@ impl DraftPane {
             advanced_row,
         );
 
+        if show_structured {
+            let row = next_row();
+            f.render_widget(
+                Paragraph::new(Line::from(vec![
+                    Span::raw(format!("{:<GUTTER$}", "view:")),
+                    Span::styled(
+                        if self.structured_view {
+                            "[x] structured view"
+                        } else {
+                            "[ ] structured view"
+                        },
+                        field_style(DraftField::StructuredToggle),
+                    ),
+                ])),
+                row,
+            );
+        }
+
         if show_wt_choice {
             // Step two (#96 rule 3): "+ new" first, then the repository's
             // worktrees newest-first.
@@ -1817,6 +1887,188 @@ mod tests {
         assert_eq!(req.cwd, PathBuf::from("/srv/work"));
     }
 
+    #[test]
+    fn structured_view_is_default_off_and_only_visible_for_claude_code() {
+        let mut draft = DraftPane {
+            advanced_collapsed: false,
+            ..DraftPane::default()
+        };
+        assert!(!draft.structured_view);
+        assert!(draft.field_order().contains(&DraftField::StructuredToggle));
+        let rendered = render_to_string(100, 24, |f| draft.render(f, f.area(), true));
+        assert!(rendered.contains("[ ] structured view"), "{rendered}");
+
+        draft.toggle_structured_view();
+        assert!(draft.structured_view);
+        draft.cycle_preset(1);
+        assert_eq!(draft.command(), "opencode");
+        assert!(
+            !draft.structured_view,
+            "a hidden value must not stay checked"
+        );
+        assert!(!draft.field_order().contains(&DraftField::StructuredToggle));
+        let rendered = render_to_string(100, 24, |f| draft.render(f, f.area(), true));
+        assert!(!rendered.contains("structured view"), "{rendered}");
+    }
+
+    #[test]
+    fn structured_view_request_is_guarded_against_a_stale_command() {
+        let mut draft = DraftPane {
+            picked_cwd: Some(PathBuf::from("/srv/work")),
+            worktree_enabled: false,
+            structured_view: true,
+            ..DraftPane::default()
+        };
+        assert_eq!(draft.build_request().unwrap().view, SessionView::Structured);
+
+        draft.selected_preset = 1;
+        assert_eq!(draft.command(), "opencode");
+        assert_eq!(draft.build_request().unwrap().view, SessionView::Terminal);
+    }
+
+    /// A custom command typed into the free-text field, run through the same
+    /// resolver the daemon/web gate uses (`command_tool`, #199): a path, an
+    /// env prefix, or a wrapper still resolves to Claude, so the toggle stays
+    /// offered and the request carries `Structured`; an unrelated program
+    /// does not.
+    #[test]
+    fn structured_view_follows_command_resolution_for_custom_commands() {
+        let cases: &[(&str, bool)] = &[
+            ("claude", true),
+            ("claude --resume", true),
+            ("CLAUDE", true),
+            ("/usr/local/bin/claude -p hi", true),
+            ("./bin/claude", true),
+            ("FOO=1 BAR=2 claude", true),
+            ("npx claude-code", true),
+            ("npx --yes claude-code", true),
+            ("sudo claude", true),
+            ("sudo -u root claude", true),
+            ("env -i claude", true),
+            ("nohup claude", true),
+            ("time claude", true),
+            ("command claude", true),
+            ("pnpm --silent dlx claude-code", true),
+            ("yarn --silent dlx claude-code", true),
+            ("bun x claude-code", true),
+            ("\"/opt/my agent/claude\" --resume", true),
+            ("bash", false),
+            ("opencode", false),
+            ("/usr/local/bin/bash -l", false),
+            // A package-manager wrapper without `dlx`/`x` runs a
+            // `package.json` script, not the package (#199) — must not be
+            // mistaken for a Claude launch.
+            ("pnpm claude", false),
+            ("yarn claude", false),
+            // The daemon's structured-session child, never a valid
+            // user-facing launch form (#199).
+            ("claude-code-acp", false),
+        ];
+        for &(command, supported) in cases {
+            let mut draft = DraftPane {
+                picked_cwd: Some(PathBuf::from("/srv/work")),
+                worktree_enabled: false,
+                advanced_collapsed: false,
+                ..DraftPane::default()
+            };
+            draft.selected_preset = draft.presets.len() - 1;
+            draft.custom_command = crate::text_input::TextInput::with_value(command);
+
+            assert_eq!(
+                draft.field_order().contains(&DraftField::StructuredToggle),
+                supported,
+                "toggle visibility for {command:?}"
+            );
+            draft.toggle_structured_view();
+            assert_eq!(
+                draft.structured_view, supported,
+                "toggle takes effect for {command:?}"
+            );
+            let view = draft.build_request().unwrap().view;
+            assert_eq!(
+                view,
+                if supported {
+                    SessionView::Structured
+                } else {
+                    SessionView::Terminal
+                },
+                "request view for {command:?}"
+            );
+        }
+    }
+
+    /// A configured preset (the spawn-form "alias" for a command) is gated
+    /// the same way as free text: a preset whose command resolves to Claude
+    /// through a wrapper still offers structured view.
+    #[test]
+    fn structured_view_follows_command_resolution_for_presets() {
+        let mut draft = DraftPane {
+            picked_cwd: Some(PathBuf::from("/srv/work")),
+            worktree_enabled: false,
+            advanced_collapsed: false,
+            ..DraftPane::default()
+        };
+        draft.set_presets(vec![
+            SpawnPreset {
+                id: "claude-wrapped".into(),
+                label: "Claude (npx)".into(),
+                command: "npx claude-code --resume".into(),
+            },
+            SpawnPreset {
+                id: "aider".into(),
+                label: "Aider".into(),
+                command: "aider".into(),
+            },
+        ]);
+
+        assert_eq!(draft.command(), "npx claude-code --resume");
+        assert!(draft.field_order().contains(&DraftField::StructuredToggle));
+        draft.toggle_structured_view();
+        assert!(draft.structured_view);
+        assert_eq!(draft.build_request().unwrap().view, SessionView::Structured);
+
+        // Switching to a preset that does not resolve to Claude clears the
+        // stale selection instead of letting an invalid request through.
+        draft.cycle_preset(1);
+        assert_eq!(draft.command(), "aider");
+        assert!(!draft.structured_view, "stale selection must clear");
+        assert!(!draft.field_order().contains(&DraftField::StructuredToggle));
+        assert_eq!(draft.build_request().unwrap().view, SessionView::Terminal);
+    }
+
+    /// Editing the custom-command text away from Claude clears an armed
+    /// selection immediately, matching the preset-switch case above — an
+    /// invalid `Structured` request can never reach `build_request`.
+    #[test]
+    fn structured_view_clears_when_custom_command_edited_away_from_claude() {
+        let mut draft = DraftPane {
+            picked_cwd: Some(PathBuf::from("/srv/work")),
+            worktree_enabled: false,
+            advanced_collapsed: false,
+            focused_field: DraftField::CustomCommand,
+            ..DraftPane::default()
+        };
+        draft.selected_preset = draft.presets.len() - 1;
+        draft.custom_command = crate::text_input::TextInput::with_value("claude");
+        draft.toggle_structured_view();
+        assert!(draft.structured_view);
+
+        typed(&mut draft, " -p");
+        assert_eq!(draft.command(), "claude -p");
+        assert!(draft.structured_view, "still Claude, selection survives");
+
+        for _ in 0.."claude -p".chars().count() {
+            draft.on_input(&InputKey::Backspace);
+        }
+        typed(&mut draft, "bash");
+        assert_eq!(draft.command(), "bash");
+        assert!(
+            !draft.structured_view,
+            "editing the program away from claude clears the stale selection"
+        );
+        assert_eq!(draft.build_request().unwrap().view, SessionView::Terminal);
+    }
+
     #[test]
     fn projects_render_sorted_with_stale_dimmed_and_other_directory_last() {
         let mut draft = DraftPane {

crates/maestro-tui/src/lib.rs

@@ -23,6 +23,8 @@ pub mod render;
 pub mod session_task;
 pub mod sidebar;
 pub mod state;
+pub mod structured_pane;
+pub mod structured_task;
 pub mod terminal;
 pub mod text_input;
 

crates/maestro-tui/src/render.rs

@@ -18,6 +18,7 @@ use crate::palette;
 use crate::pane::Pane;
 use crate::sidebar::Sidebar;
 use crate::state::{AppState, Focus, OverlayKind, SidebarItem};
+use crate::structured_pane::StructuredPane;
 
 /// Tagged regions for mouse hit-testing. The input router resolves a mouse
 /// coordinate to one of these via [`RegionMap::region_at`].
@@ -80,6 +81,7 @@ pub struct RenderInputs<'a> {
     pub home_dir: &'a str,
     pub pane_title: &'a str,
     pub pane: Option<&'a Pane>,
+    pub structured_pane: Option<&'a StructuredPane>,
     /// The spawn form behind [`OverlayKind::Spawn`], when one is up.
     pub draft: Option<&'a crate::draft::DraftPane>,
     pub state: &'a AppState,
@@ -147,14 +149,22 @@ pub fn draw(f: &mut Frame, inputs: RenderInputs<'_>) -> RegionMap {
     render_title_bar(f, title_area, inputs.pane_title, pane_focused);
     if let Some(p) = inputs.pane {
         p.render(f, pane_area);
+    } else if let Some(p) = inputs.structured_pane {
+        p.render(f, pane_area);
     }
     // `RegionMap::pane` is also the PTY resize source. The title bar is
-    // chrome; every remaining cell belongs to the emulator.
+    // chrome; every remaining cell belongs to the active session pane.
     map.pane = Some(pane_area);
 
     // Status bar — always visible, never eclipsed by overlays so the user can
     // always see the current mode + key hints.
-    render_status_bar(f, status_area, inputs.state, inputs.link);
+    render_status_bar(
+        f,
+        status_area,
+        inputs.state,
+        inputs.link,
+        inputs.structured_pane.is_some(),
+    );
 
     match inputs.state.overlay() {
         Some(OverlayKind::Spawn) => {
@@ -253,7 +263,13 @@ fn render_title_bar(f: &mut Frame, area: Rect, title: &str, focused: bool) {
 /// Render the always-visible status bar at the bottom of the frame. Surfaces
 /// mode + focused panel + the most useful key hints so the user is never
 /// guessing what state they're in.
-fn render_status_bar(f: &mut Frame, area: Rect, state: &AppState, link: &LinkStatus) {
+fn render_status_bar(
+    f: &mut Frame,
+    area: Rect,
+    state: &AppState,
+    link: &LinkStatus,
+    structured: bool,
+) {
     // The daemon indicator is pinned right and sized to its own text, so a
     // narrow terminal truncates the key hints rather than the release.
     let label = link_label(link);
@@ -271,9 +287,13 @@ fn render_status_bar(f: &mut Frame, area: Rect, state: &AppState, link: &LinkSta
         Focus::Sidebar => "sidebar",
         Focus::Pane => "pane",
     };
-    let hint = match state.mode {
+    let hint = match (structured && state.focus == Focus::Pane, state.mode) {
-        Mode::Normal => "j/k: nav  •  enter: attach  •  s: spawn  •  ?: help  •  ^Wq: quit",
+        (true, Mode::Normal) => "j/k: rows  •  enter: expand  •  i: compose  •  esc: cancel",
-        Mode::Insert => "^a: return to sidebar",
+        (true, Mode::Insert) => "enter: send  •  esc: cancel  •  ^a: sidebar",
+        (false, Mode::Normal) => {
+            "j/k: nav  •  enter: attach  •  s: spawn  •  ?: help  •  ^Wq: quit"
+        }
+        (false, Mode::Insert) => "^a: return to sidebar",
     };
     let mode_style = palette::active().mode_style(state.mode == Mode::Insert);
     let line = ratatui::text::Line::from(vec![
@@ -435,6 +455,7 @@ mod tests {
             home_dir: "",
             pane_title: "session",
             pane: None,
+            structured_pane: None,
             draft: None,
             state: &state,
             help: &help,
@@ -532,6 +553,7 @@ mod tests {
             home_dir: "",
             pane_title: "session",
             pane: None,
+            structured_pane: None,
             draft: Some(&draft),
             state: &state,
             help: &help,
@@ -587,6 +609,7 @@ mod tests {
                 home_dir: "",
                 pane_title: "session",
                 pane: None,
+                structured_pane: None,
                 draft: None,
                 state: &state,
                 help: &help,
@@ -629,6 +652,7 @@ mod tests {
                 home_dir: "",
                 pane_title: "session",
                 pane: None,
+                structured_pane: None,
                 draft: None,
                 state: &state,
                 help: &help,

crates/maestro-tui/src/session_task.rs

@@ -221,7 +221,7 @@ impl SessionTask {
     }
 }
 
-fn jitter(base: Duration) -> Duration {
+pub(crate) fn jitter(base: Duration) -> Duration {
     let ms = base.as_millis() as u64;
     let now_nanos = std::time::SystemTime::now()
         .duration_since(std::time::UNIX_EPOCH)

crates/maestro-tui/src/structured_task.rs

@@ -0,0 +1,742 @@
+//! Live projection state for one structured session.
+
+use std::collections::HashSet;
+use std::sync::atomic::{AtomicU64, AtomicU8, Ordering};
+use std::sync::{Arc, Mutex};
+use std::time::Duration;
+
+use futures_util::StreamExt;
+use maestro_protocol::{
+    ReducedState, StructuredApprovalDecision, StructuredEvent, TranscriptDelta, TranscriptRow,
+    TranscriptRowKind,
+};
+use tokio::sync::watch;
+use tokio_tungstenite::tungstenite::{Error as WsError, Message};
+
+use crate::input::InputKey;
+use crate::session_task::SessionState;
+use crate::text_input::TextInput;
+
+/// Renderer and input state built directly from the daemon's two projections.
+#[derive(Debug, Clone)]
+pub struct StructuredState {
+    pub rows: Vec<TranscriptRow>,
+    pub reduced: ReducedState,
+    pub selected: Option<String>,
+    pub expanded: HashSet<String>,
+    pub scroll: usize,
+    /// Row id per rendered line from the last render pass, parallel to that
+    /// pass's `lines`. Lets the next render translate `scroll` — a raw index
+    /// into that now-stale layout — back into a row identity before mapping
+    /// it onto the freshly rebuilt layout, so growth/shrinkage above the
+    /// viewport shifts indices without shifting what's on screen.
+    pub(crate) line_rows: Vec<Option<String>>,
+    pub follow_selection: bool,
+    pub composer: TextInput,
+    pub error: Option<String>,
+    submitting: bool,
+    submission_generation: u64,
+    reconcile_submission_on_snapshot: Option<u64>,
+    approval_submitting: bool,
+}
+
+impl Default for StructuredState {
+    fn default() -> Self {
+        Self {
+            rows: Vec::new(),
+            reduced: ReducedState::default(),
+            selected: None,
+            expanded: HashSet::new(),
+            scroll: 0,
+            line_rows: Vec::new(),
+            follow_selection: true,
+            composer: TextInput::default(),
+            error: None,
+            submitting: false,
+            submission_generation: 0,
+            reconcile_submission_on_snapshot: None,
+            approval_submitting: false,
+        }
+    }
+}
+
+impl StructuredState {
+    pub fn apply(&mut self, event: StructuredEvent) {
+        match event {
+            StructuredEvent::TranscriptSnapshot { snapshot } => {
+                let selected = self.selected.clone();
+                self.rows = snapshot.rows;
+                self.selected = selected
+                    .filter(|id| self.rows.iter().any(|row| &row.id == id))
+                    .or_else(|| {
+                        self.rows
+                            .iter()
+                            .rev()
+                            .find(|row| row.kind != TranscriptRowKind::Plan)
+                            .map(|row| row.id.clone())
+                    });
+                self.expanded
+                    .retain(|id| self.rows.iter().any(|row| &row.id == id));
+            }
+            StructuredEvent::ReducedState { state } => {
+                let reconcile_submission = self
+                    .reconcile_submission_on_snapshot
+                    .take()
+                    .is_some_and(|generation| {
+                        self.submitting && generation == self.submission_generation
+                    });
+                self.apply_reduced(state, reconcile_submission);
+            }
+            StructuredEvent::ProjectionUpdate { transcript, state } => {
+                if let Some(delta) = transcript {
+                    self.apply_delta(delta);
+                }
+                self.apply_reduced(state, false);
+            }
+        }
+    }
+
+    fn apply_delta(&mut self, delta: TranscriptDelta) {
+        match delta {
+            TranscriptDelta::Append { row } => {
+                let followed_tail = self.follow_selection
+                    && self.selected.as_ref().is_some_and(|id| {
+                        self.rows
+                            .iter()
+                            .rev()
+                            .find(|old| old.kind != TranscriptRowKind::Plan)
+                            .is_some_and(|old| &old.id == id)
+                    });
+                if let Some(index) = self.rows.iter().position(|old| old.id == row.id) {
+                    self.rows[index] = row.clone();
+                } else {
+                    self.rows.push(row.clone());
+                }
+                if row.kind != TranscriptRowKind::Plan && (self.selected.is_none() || followed_tail)
+                {
+                    self.selected = Some(row.id);
+                }
+            }
+            TranscriptDelta::Patch { row } => {
+                if let Some(index) = self.rows.iter().position(|old| old.id == row.id) {
+                    self.rows[index] = row.clone();
+                } else {
+                    self.rows.push(row.clone());
+                }
+            }
+            TranscriptDelta::Remove { id } => {
+                let removed = self.rows.iter().position(|row| row.id == id);
+                self.rows.retain(|row| row.id != id);
+                self.expanded.remove(&id);
+                if self.selected.as_deref() == Some(&id) {
+                    self.selected = removed.and_then(|index| {
+                        let split = index.min(self.rows.len());
+                        self.rows[split..]
+                            .iter()
+                            .find(|row| row.kind != TranscriptRowKind::Plan)
+                            .or_else(|| {
+                                self.rows[..split]
+                                    .iter()
+                                    .rev()
+                                    .find(|row| row.kind != TranscriptRowKind::Plan)
+                            })
+                            .map(|row| row.id.clone())
+                    });
+                }
+            }
+        }
+    }
+
+    fn apply_reduced(&mut self, state: ReducedState, reconcile_submission: bool) {
+        let previous_nonce = self.pending_nonce().map(str::to_owned);
+        if reconcile_submission || state.turn.responding || state.turn.thinking {
+            self.submitting = false;
+        }
+        self.reduced = state;
+        let next_nonce = self.pending_nonce().map(str::to_owned);
+        if next_nonce != previous_nonce {
+            self.approval_submitting = false;
+            if next_nonce.is_some() {
+                self.selected = self
+                    .rows
+                    .iter()
+                    .rev()
+                    .find(|row| row.kind == TranscriptRowKind::Approval)
+                    .map(|row| row.id.clone());
+                self.follow_selection = true;
+            }
+        }
+    }
+
+    fn prepare_snapshot_reconciliation(&mut self) {
+        self.reconcile_submission_on_snapshot =
+            self.submitting.then_some(self.submission_generation);
+    }
+
+    pub fn select(&mut self, delta: isize) {
+        let selectable: Vec<&TranscriptRow> = self
+            .rows
+            .iter()
+            .filter(|row| row.kind != TranscriptRowKind::Plan)
+            .collect();
+        if selectable.is_empty() {
+            self.selected = None;
+            return;
+        }
+        let current = self
+            .selected
+            .as_ref()
+            .and_then(|id| selectable.iter().position(|row| &row.id == id))
+            .unwrap_or(selectable.len() - 1);
+        let next = if delta >= 0 {
+            current
+                .saturating_add(delta as usize)
+                .min(selectable.len() - 1)
+        } else {
+            current.saturating_sub(delta.unsigned_abs())
+        };
+        self.selected = Some(selectable[next].id.clone());
+        self.follow_selection = true;
+    }
+
+    pub fn toggle_selected(&mut self) {
+        let Some(id) = self.selected.clone() else {
+            return;
+        };
+        let expandable = self.rows.iter().any(|row| {
+            row.id == id
+                && matches!(
+                    row.kind,
+                    TranscriptRowKind::ToolCall | TranscriptRowKind::ToolDiff
+                )
+        });
+        if !expandable {
+            return;
+        }
+        if !self.expanded.insert(id.clone()) {
+            self.expanded.remove(&id);
+        }
+        self.follow_selection = true;
+    }
+
+    pub fn scroll_by(&mut self, lines: isize) {
+        self.scroll = if lines >= 0 {
+            self.scroll.saturating_sub(lines as usize)
+        } else {
+            self.scroll.saturating_add(lines.unsigned_abs())
+        };
+        self.follow_selection = false;
+    }
+
+    pub fn edit_composer(&mut self, key: &InputKey) {
+        if !self.turn_active() {
+            self.composer.handle_key(key);
+            self.error = None;
+        }
+    }
+
+    pub fn begin_prompt(&mut self) -> Option<String> {
+        if self.turn_active() || self.composer.value().trim().is_empty() {
+            return None;
+        }
+        let prompt = self.composer.value().to_string();
+        self.composer = TextInput::default();
+        self.submission_generation = self.submission_generation.wrapping_add(1);
+        self.submitting = true;
+        self.error = None;
+        Some(prompt)
+    }
+
+    pub fn prompt_failed(&mut self, prompt: String, error: String) {
+        if self.composer.value().is_empty() {
+            self.composer = TextInput::with_value(prompt);
+        }
+        self.submitting = false;
+        self.error = Some(error);
+    }
+
+    pub fn turn_active(&self) -> bool {
+        self.submitting || self.reduced.turn.responding || self.reduced.turn.thinking
+    }
+
+    pub fn pending_nonce(&self) -> Option<&str> {
+        self.reduced
+            .pending_approval
+            .as_ref()?
+            .get("nonce")?
+            .as_str()
+    }
+
+    pub fn approval_decision(&mut self, key: char) -> Option<(String, StructuredApprovalDecision)> {
+        if self.approval_submitting {
+            return None;
+        }
+        let selected = self.selected.as_deref()?;
+        let pending_row = self
+            .rows
+            .iter()
+            .rev()
+            .find(|row| row.kind == TranscriptRowKind::Approval)?;
+        if pending_row.id != selected {
+            return None;
+        }
+        let decision = match key {
+            'a' => StructuredApprovalDecision::AllowOnce,
+            'A' => StructuredApprovalDecision::AllowForSession,
+            'd' => StructuredApprovalDecision::Deny,
+            _ => return None,
+        };
+        let offered = offered_decisions(&pending_row.data);
+        if !offered.contains(&decision) {
+            return None;
+        }
+        let nonce = self.pending_nonce()?.to_string();
+        self.approval_submitting = true;
+        self.error = None;
+        Some((nonce, decision))
+    }
+
+    pub fn approval_failed(&mut self, nonce: &str, error: String) {
+        if self.pending_nonce() != Some(nonce) {
+            return;
+        }
+        self.approval_submitting = false;
+        self.error = Some(error);
+    }
+}
+
+pub fn offered_decisions(data: &serde_json::Value) -> Vec<StructuredApprovalDecision> {
+    let mut out = Vec::new();
+    for kind in data
+        .get("options")
+        .and_then(serde_json::Value::as_array)
+        .into_iter()
+        .flatten()
+        .filter_map(|option| option.get("kind").and_then(serde_json::Value::as_str))
+    {
+        match kind {
+            "allow_once" if !out.contains(&StructuredApprovalDecision::AllowOnce) => {
+                out.push(StructuredApprovalDecision::AllowOnce)
+            }
+            "allow_always" if !out.contains(&StructuredApprovalDecision::AllowForSession) => {
+                out.push(StructuredApprovalDecision::AllowForSession)
+            }
+            "reject_once" | "reject_always" if !out.contains(&StructuredApprovalDecision::Deny) => {
+                out.push(StructuredApprovalDecision::Deny)
+            }
+            _ => {}
+        }
+    }
+    out
+}
+
+/// Cheap shared handle for a structured projection connection.
+#[derive(Clone)]
+pub struct StructuredHandle {
+    pub state: Arc<Mutex<StructuredState>>,
+    connection: Arc<AtomicU8>,
+    revision: Arc<AtomicU64>,
+    stop: watch::Sender<bool>,
+}
+
+impl std::fmt::Debug for StructuredHandle {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("StructuredHandle")
+            .field("connection", &self.connection())
+            .field("revision", &self.revision())
+            .finish_non_exhaustive()
+    }
+}
+
+impl StructuredHandle {
+    pub fn connection(&self) -> SessionState {
+        match self.connection.load(Ordering::Acquire) {
+            0 => SessionState::Connecting,
+            1 => SessionState::Live,
+            2 => SessionState::Reconnecting,
+            _ => SessionState::Ended,
+        }
+    }
+
+    pub fn revision(&self) -> u64 {
+        self.revision.load(Ordering::Acquire)
+    }
+
+    pub fn end(&self) {
+        self.connection
+            .store(SessionState::Ended as u8, Ordering::Release);
+        let _ = self.stop.send(true);
+    }
+
+    #[cfg(test)]
+    pub(crate) fn test_handle(state: StructuredState) -> Self {
+        let (stop, _) = watch::channel(false);
+        Self {
+            state: Arc::new(Mutex::new(state)),
+            connection: Arc::new(AtomicU8::new(SessionState::Live as u8)),
+            revision: Arc::new(AtomicU64::new(0)),
+            stop,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct StructuredTask;
+
+impl StructuredTask {
+    pub fn spawn(ws_url: String) -> StructuredHandle {
+        let state = Arc::new(Mutex::new(StructuredState::default()));
+        let connection = Arc::new(AtomicU8::new(SessionState::Connecting as u8));
+        let revision = Arc::new(AtomicU64::new(0));
+        let (stop, mut stopped) = watch::channel(false);
+        let handle = StructuredHandle {
+            state: state.clone(),
+            connection: connection.clone(),
+            revision: revision.clone(),
+            stop,
+        };
+
+        tokio::spawn(async move {
+            let mut backoff = Duration::from_secs(1);
+            loop {
+                if *stopped.borrow() {
+                    return;
+                }
+                state
+                    .lock()
+                    .expect("structured state mutex")
+                    .prepare_snapshot_reconciliation();
+                connection.store(SessionState::Connecting as u8, Ordering::Release);
+                let connected = tokio::select! {
+                    result = tokio_tungstenite::connect_async(&ws_url) => result,
+                    _ = stopped.changed() => return,
+                };
+                let (mut ws, _) = match connected {
+                    Ok(value) => value,
+                    Err(error) => {
+                        if terminal_handshake_error(&error) {
+                            state.lock().expect("structured state mutex").error =
+                                Some(format!("cannot open structured session: {error}"));
+                            connection.store(SessionState::Ended as u8, Ordering::Release);
+                            revision.fetch_add(1, Ordering::Release);
+                            return;
+                        }
+                        connection.store(SessionState::Reconnecting as u8, Ordering::Release);
+                        revision.fetch_add(1, Ordering::Release);
+                        tokio::select! {
+                            _ = tokio::time::sleep(super::session_task::jitter(backoff)) => {},
+                            _ = stopped.changed() => return,
+                        }
+                        backoff = backoff.saturating_mul(2).min(Duration::from_secs(30));
+                        continue;
+                    }
+                };
+                backoff = Duration::from_secs(1);
+                connection.store(SessionState::Live as u8, Ordering::Release);
+                revision.fetch_add(1, Ordering::Release);
+
+                loop {
+                    let frame = tokio::select! {
+                        frame = ws.next() => frame,
+                        _ = stopped.changed() => return,
+                    };
+                    match frame {
+                        Some(Ok(Message::Text(text))) => {
+                            if let Ok(event) = serde_json::from_str::<StructuredEvent>(&text) {
+                                state.lock().expect("structured state mutex").apply(event);
+                                revision.fetch_add(1, Ordering::Release);
+                            }
+                        }
+                        Some(Ok(Message::Close(_))) | None | Some(Err(_)) => break,
+                        _ => {}
+                    }
+                }
+                connection.store(SessionState::Reconnecting as u8, Ordering::Release);
+                revision.fetch_add(1, Ordering::Release);
+                tokio::select! {
+                    _ = tokio::time::sleep(super::session_task::jitter(backoff)) => {},
+                    _ = stopped.changed() => return,
+                }
+                backoff = backoff.saturating_mul(2).min(Duration::from_secs(30));
+            }
+        });
+        handle
+    }
+}
+
+fn terminal_handshake_error(error: &WsError) -> bool {
+    matches!(error, WsError::Http(response) if response.status().is_client_error())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use maestro_protocol::{TranscriptSnapshot, TurnState};
+    use serde_json::json;
+
+    fn row(id: &str, kind: TranscriptRowKind, data: serde_json::Value) -> TranscriptRow {
+        TranscriptRow {
+            id: id.into(),
+            kind,
+            data,
+        }
+    }
+
+    #[test]
+    fn snapshots_replace_and_deltas_address_rows_by_id() {
+        let mut state = StructuredState::default();
+        state.apply(StructuredEvent::TranscriptSnapshot {
+            snapshot: TranscriptSnapshot {
+                cursor: 2,
+                rows: vec![row("a", TranscriptRowKind::AgentText, json!({}))],
+            },
+        });
+        state.apply(StructuredEvent::ProjectionUpdate {
+            transcript: Some(TranscriptDelta::Patch {
+                row: row("a", TranscriptRowKind::AgentText, json!({"n": 2})),
+            }),
+            state: ReducedState::default(),
+        });
+        state.apply(StructuredEvent::ProjectionUpdate {
+            transcript: Some(TranscriptDelta::Append {
+                row: row("b", TranscriptRowKind::Notice, json!({})),
+            }),
+            state: ReducedState::default(),
+        });
+        assert_eq!(state.rows.len(), 2);
+        assert_eq!(state.rows[0].data["n"], 2);
+
+        state.apply(StructuredEvent::TranscriptSnapshot {
+            snapshot: TranscriptSnapshot {
+                cursor: 5,
+                rows: vec![row("b", TranscriptRowKind::Notice, json!({"fresh": true}))],
+            },
+        });
+        assert_eq!(state.rows.len(), 1);
+        assert_eq!(state.rows[0].data["fresh"], true);
+    }
+
+    #[test]
+    fn selection_survives_patch_and_moves_after_remove() {
+        let mut state = StructuredState {
+            rows: vec![
+                row("a", TranscriptRowKind::Notice, json!({})),
+                row("b", TranscriptRowKind::ToolCall, json!({})),
+                row("plan", TranscriptRowKind::Plan, json!({})),
+            ],
+            selected: Some("a".into()),
+            ..StructuredState::default()
+        };
+        state.select(1);
+        assert_eq!(state.selected.as_deref(), Some("b"));
+        state.toggle_selected();
+        assert!(state.expanded.contains("b"));
+        state.apply_delta(TranscriptDelta::Remove { id: "b".into() });
+        assert_eq!(state.selected.as_deref(), Some("a"));
+
+        state.apply_delta(TranscriptDelta::Remove { id: "a".into() });
+        assert_eq!(
+            state.selected, None,
+            "collapsed plan rows are not selectable"
+        );
+    }
+
+    #[test]
+    fn approval_keys_only_offer_server_backed_decisions() {
+        let mut state = StructuredState::default();
+        state.rows.push(row(
+            "approval:1",
+            TranscriptRowKind::Approval,
+            json!({"options":[
+                {"kind":"allow_once"}, {"kind":"reject_always"}
+            ]}),
+        ));
+        state.selected = Some("approval:1".into());
+        state.reduced.pending_approval = Some(json!({"nonce":"secret"}));
+        assert_eq!(
+            state.approval_decision('A'),
+            None,
+            "allow-for-session was not offered"
+        );
+        assert_eq!(
+            state.approval_decision('a'),
+            Some(("secret".into(), StructuredApprovalDecision::AllowOnce))
+        );
+    }
+
+    #[test]
+    fn resolved_approval_ignores_its_late_failure() {
+        let mut state = StructuredState::default();
+        state.rows.push(row(
+            "approval:1",
+            TranscriptRowKind::Approval,
+            json!({"options":[{"kind":"allow_once"}]}),
+        ));
+        state.selected = Some("approval:1".into());
+        state.reduced.pending_approval = Some(json!({"nonce":"old"}));
+        assert!(state.approval_decision('a').is_some());
+
+        state.apply(StructuredEvent::ProjectionUpdate {
+            transcript: None,
+            state: ReducedState::default(),
+        });
+        state.approval_failed("old", "response lost".into());
+
+        assert_eq!(state.error, None);
+        assert!(!state.approval_submitting);
+    }
+
+    #[test]
+    fn superseded_approval_ignores_its_late_failure() {
+        let mut state = StructuredState::default();
+        state.rows.push(row(
+            "approval:1",
+            TranscriptRowKind::Approval,
+            json!({"options":[{"kind":"allow_once"}]}),
+        ));
+        state.selected = Some("approval:1".into());
+        state.reduced.pending_approval = Some(json!({"nonce":"old"}));
+        assert!(state.approval_decision('a').is_some());
+
+        state.rows.push(row(
+            "approval:2",
+            TranscriptRowKind::Approval,
+            json!({"options":[{"kind":"allow_once"}]}),
+        ));
+        state.apply(StructuredEvent::ProjectionUpdate {
+            transcript: None,
+            state: ReducedState {
+                pending_approval: Some(json!({"nonce":"new"})),
+                ..ReducedState::default()
+            },
+        });
+        assert_eq!(
+            state.approval_decision('a'),
+            Some(("new".into(), StructuredApprovalDecision::AllowOnce))
+        );
+
+        state.approval_failed("old", "response lost".into());
+
+        assert_eq!(state.error, None);
+        assert!(state.approval_submitting);
+    }
+
+    #[test]
+    fn matching_approval_surfaces_its_failure() {
+        let mut state = StructuredState::default();
+        state.rows.push(row(
+            "approval:1",
+            TranscriptRowKind::Approval,
+            json!({"options":[{"kind":"allow_once"}]}),
+        ));
+        state.selected = Some("approval:1".into());
+        state.reduced.pending_approval = Some(json!({"nonce":"current"}));
+        assert!(state.approval_decision('a').is_some());
+
+        state.approval_failed("current", "request failed".into());
+
+        assert_eq!(state.error.as_deref(), Some("request failed"));
+        assert!(!state.approval_submitting);
+    }
+
+    #[test]
+    fn composer_is_gated_by_the_projected_turn_lifecycle() {
+        let mut state = StructuredState::default();
+        state.edit_composer(&InputKey::char('h'));
+        state.edit_composer(&InputKey::char('i'));
+        assert_eq!(state.begin_prompt().as_deref(), Some("hi"));
+        assert!(state.turn_active());
+        state.prompt_failed("hi".into(), "nope".into());
+        assert_eq!(state.composer.value(), "hi");
+
+        state.reduced.turn = TurnState {
+            responding: true,
+            ..TurnState::default()
+        };
+        state.edit_composer(&InputKey::char('x'));
+        assert_eq!(state.composer.value(), "hi");
+    }
+
+    #[test]
+    fn authoritative_idle_snapshot_reconciles_a_wholly_missed_turn() {
+        let mut state = StructuredState::default();
+        state.edit_composer(&InputKey::char('h'));
+        state.edit_composer(&InputKey::char('i'));
+        assert_eq!(state.begin_prompt().as_deref(), Some("hi"));
+
+        state.apply(StructuredEvent::ProjectionUpdate {
+            transcript: None,
+            state: ReducedState::default(),
+        });
+        assert!(
+            state.turn_active(),
+            "an ordinary idle update must not reopen the composer before turn begin"
+        );
+
+        state.prepare_snapshot_reconciliation();
+        state.apply(StructuredEvent::TranscriptSnapshot {
+            snapshot: TranscriptSnapshot {
+                cursor: 0,
+                rows: Vec::new(),
+            },
+        });
+        state.apply(StructuredEvent::ReducedState {
+            state: ReducedState::default(),
+        });
+        assert!(
+            !state.turn_active(),
+            "a reconnect snapshot must settle a submission whose whole turn was missed"
+        );
+    }
+
+    #[test]
+    fn stale_handshake_state_does_not_settle_a_new_submission() {
+        let mut state = StructuredState::default();
+        state.prepare_snapshot_reconciliation();
+        state.apply(StructuredEvent::TranscriptSnapshot {
+            snapshot: TranscriptSnapshot {
+                cursor: 0,
+                rows: Vec::new(),
+            },
+        });
+
+        state.edit_composer(&InputKey::char('h'));
+        state.edit_composer(&InputKey::char('i'));
+        assert_eq!(state.begin_prompt().as_deref(), Some("hi"));
+        state.apply(StructuredEvent::ReducedState {
+            state: ReducedState::default(),
+        });
+
+        assert!(
+            state.turn_active(),
+            "state captured before this submission must not reopen the composer"
+        );
+    }
+
+    #[test]
+    fn failed_submission_reconciliation_does_not_settle_its_successor() {
+        let mut state = StructuredState::default();
+        state.edit_composer(&InputKey::char('a'));
+        assert_eq!(state.begin_prompt().as_deref(), Some("a"));
+        state.prepare_snapshot_reconciliation();
+
+        state.prompt_failed("a".into(), "nope".into());
+        state.composer = TextInput::with_value("b");
+        assert_eq!(state.begin_prompt().as_deref(), Some("b"));
+
+        state.apply(StructuredEvent::TranscriptSnapshot {
+            snapshot: TranscriptSnapshot {
+                cursor: 0,
+                rows: Vec::new(),
+            },
+        });
+        state.apply(StructuredEvent::ReducedState {
+            state: ReducedState::default(),
+        });
+
+        assert!(
+            state.turn_active(),
+            "a reconnect for the failed submission must not settle its successor"
+        );
+    }
+}

crates/maestro-tui/tests/structured_http.rs

@@ -0,0 +1,79 @@
+//! The TUI's structured actions use the shared typed daemon client; assert the
+//! exact route and bare approval decision body at the HTTP boundary.
+
+use std::sync::{Arc, Mutex};
+
+use axum::extract::{Path, State};
+use axum::routing::post;
+use axum::{Json, Router};
+use maestro_protocol::{DaemonClient, StructuredApprovalDecision, StructuredPromptRequest};
+use uuid::Uuid;
+
+#[derive(Debug, Default)]
+struct Seen {
+    prompt: Option<String>,
+    cancelled: bool,
+    approval: Option<(String, StructuredApprovalDecision)>,
+}
+
+type Shared = Arc<Mutex<Seen>>;
+
+async fn prompt(
+    State(seen): State<Shared>,
+    Path(_id): Path<Uuid>,
+    Json(body): Json<StructuredPromptRequest>,
+) {
+    seen.lock().unwrap().prompt = Some(body.prompt);
+}
+
+async fn cancel(State(seen): State<Shared>, Path(_id): Path<Uuid>) {
+    seen.lock().unwrap().cancelled = true;
+}
+
+async fn approval(
+    State(seen): State<Shared>,
+    Path((_id, nonce)): Path<(Uuid, String)>,
+    Json(decision): Json<StructuredApprovalDecision>,
+) {
+    seen.lock().unwrap().approval = Some((nonce, decision));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn prompt_cancel_and_approval_use_structured_api_contract() {
+    let seen = Shared::default();
+    let app = Router::new()
+        .route("/api/sessions/:id/structured/prompt", post(prompt))
+        .route("/api/sessions/:id/structured/cancel", post(cancel))
+        .route(
+            "/api/sessions/:id/structured/approvals/:nonce",
+            post(approval),
+        )
+        .with_state(seen.clone());
+    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let addr = listener.local_addr().unwrap();
+    tokio::spawn(async move { axum::serve(listener, app).await.unwrap() });
+
+    let client = DaemonClient::new(format!("http://{addr}"));
+    let id = Uuid::from_u128(141);
+    client.send_structured_prompt(id, "ship it").await.unwrap();
+    client.cancel_structured_turn(id).await.unwrap();
+    client
+        .resolve_structured_approval(
+            id,
+            "one-use-nonce",
+            StructuredApprovalDecision::AllowForSession,
+        )
+        .await
+        .unwrap();
+
+    let seen = seen.lock().unwrap();
+    assert_eq!(seen.prompt.as_deref(), Some("ship it"));
+    assert!(seen.cancelled);
+    assert_eq!(
+        seen.approval,
+        Some((
+            "one-use-nonce".into(),
+            StructuredApprovalDecision::AllowForSession
+        ))
+    );
+}

crates/maestro-tui/tests/structured_task_ws.rs

@@ -0,0 +1,107 @@
+//! Projection socket coverage: snapshots replace state on reconnect and live
+//! deltas patch rows without client-side event folding.
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use std::time::Duration;
+
+use axum::extract::ws::{Message, WebSocketUpgrade};
+use axum::extract::State;
+use axum::response::Response;
+use axum::routing::any;
+use axum::Router;
+use maestro_protocol::{
+    ReducedState, StructuredEvent, TranscriptDelta, TranscriptRow, TranscriptRowKind,
+    TranscriptSnapshot,
+};
+use maestro_tui::session_task::SessionState;
+use maestro_tui::structured_task::StructuredTask;
+use serde_json::json;
+
+async fn structured_handler(
+    State(connects): State<Arc<AtomicUsize>>,
+    ws: WebSocketUpgrade,
+) -> Response {
+    ws.on_upgrade(move |mut socket| async move {
+        let attempt = connects.fetch_add(1, Ordering::SeqCst);
+        let snapshot = if attempt == 0 {
+            TranscriptSnapshot {
+                cursor: 1,
+                rows: vec![row("old", json!({"content":{"type":"text","text":"old"}}))],
+            }
+        } else {
+            TranscriptSnapshot {
+                cursor: 3,
+                rows: vec![row("live", json!({"content":{"type":"text","text":"one"}}))],
+            }
+        };
+        send(
+            &mut socket,
+            StructuredEvent::TranscriptSnapshot { snapshot },
+        )
+        .await;
+        if attempt == 0 {
+            let _ = socket.close().await;
+            return;
+        }
+        send(
+            &mut socket,
+            StructuredEvent::ProjectionUpdate {
+                transcript: Some(TranscriptDelta::Patch {
+                    row: row("live", json!({"content":{"type":"text","text":"two"}})),
+                }),
+                state: ReducedState {
+                    model: Some("test-model".into()),
+                    ..ReducedState::default()
+                },
+            },
+        )
+        .await;
+        tokio::time::sleep(Duration::from_secs(3)).await;
+    })
+}
+
+fn row(id: &str, data: serde_json::Value) -> TranscriptRow {
+    TranscriptRow {
+        id: id.into(),
+        kind: TranscriptRowKind::AgentText,
+        data,
+    }
+}
+
+async fn send(socket: &mut axum::extract::ws::WebSocket, event: StructuredEvent) {
+    socket
+        .send(Message::Text(serde_json::to_string(&event).unwrap()))
+        .await
+        .unwrap();
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn reconnect_snapshot_replaces_then_delta_patches_projection() {
+    let connects = Arc::new(AtomicUsize::new(0));
+    let app = Router::new()
+        .route("/api/structured/x", any(structured_handler))
+        .with_state(connects.clone());
+    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let addr = listener.local_addr().unwrap();
+    tokio::spawn(async move { axum::serve(listener, app).await.unwrap() });
+
+    let handle = StructuredTask::spawn(format!("ws://{addr}/api/structured/x"));
+    for _ in 0..250 {
+        tokio::time::sleep(Duration::from_millis(10)).await;
+        let state = handle.state.lock().unwrap().clone();
+        if state.reduced.model.as_deref() == Some("test-model") {
+            assert_eq!(state.rows.len(), 1);
+            assert_eq!(state.rows[0].id, "live");
+            assert_eq!(state.rows[0].data["content"]["text"], "two");
+            assert!(connects.load(Ordering::SeqCst) >= 2);
+            handle.end();
+            assert_eq!(handle.connection(), SessionState::Ended);
+            return;
+        }
+    }
+    panic!(
+        "structured projection never reached reconnect delta; connection={:?}",
+        handle.connection()
+    );
+}

docs/INSTALL.md

@@ -18,10 +18,14 @@ wizard, and cleans up — only the unified `maestro` binary ends up persisted in
 
 **Updating is the same command.** Re-running `./install.sh` detects an existing
 systemd unit, refreshes it, and runs `systemctl --user restart maestro` instead
-of `start`. No `--update` flag needed. **The restart keeps your sessions:** the unit sets
+of `start`. No `--update` flag needed. **The restart keeps your terminal sessions:** the unit sets
 `KillMode=process`, so systemd signals only the daemon — the tmux server (and
-every session) survives, and the new daemon re-adopts them on start. A unit
+every tmux-backed session) survives, and the new daemon re-adopts them on
-written before this default lacks the line; re-run `./install.sh` to refresh it.
+start. Structured sessions (an agent run as a daemon child over ACP) are not
+tmux panes, so shutdown ends their active turn; the transcript survives and
+the next daemon attempts one resume (`docs/RESTART.md#structured-sessions`). A
+unit written before this default lacks the line; re-run `./install.sh` to
+refresh it.
 
 Inside the script, `cargo install --git https://git.naps.pt/naps62/maestro …`
 uses your already-configured git credentials for this host (HTTPS helper or
@@ -94,7 +98,10 @@ running a local daemon, for a host that only talks to another machine's.
 
 The daemon unit carries the same `KillMode=process` as the wizard-written one,
 so `systemctl --user restart maestro-daemon` leaves the tmux server and every
-session alive.
+terminal session alive. Structured sessions end their active turn on
+shutdown and resume once on the next daemon: ACP state comes back via
+`session/load`, while the event log only replays Maestro's own transcript
+projection (`docs/RESTART.md#structured-sessions`).
 
 ## Thin builds for single-role hosts
 
@@ -211,7 +218,10 @@ what to run. The adapter is a child of the daemon: it ends with a `DELETE
 itself. A daemon restart ends an in-flight structured turn, but preserves its
 worktree, session record, and event-log transcript. The replacement daemon
 starts a new adapter, resumes it with `session/load`, and replays the
-transcript. Terminal sessions keep surviving restarts through tmux.
+transcript. Terminal sessions keep surviving restarts through tmux. See
+`docs/STRUCTURED-VIEW.md` for the full contract — row kinds, projections, the
+handshake, and the approval and recovery rules — and `docs/RESTART.md` for
+what a client observes across the restart.
 
 ## The browser UI
 

docs/RESTART.md

@@ -2,10 +2,16 @@
 
 Maestro is upgraded in place: the operator reinstalls the binary and systemd
 restarts the daemon under every browser tab and TUI that is attached to it.
-tmux keeps the sessions alive across that (see `docs/INSTALL.md`), but clients
+tmux keeps **terminal** sessions alive across that (see `docs/INSTALL.md`),
-lose their sockets. This document is the contract for what a client does about
+but clients lose their sockets either way. This document is the contract for
-it — what the daemon publishes, how a client tells a restart from a blip, and
+what a client does about it — what the daemon publishes, how a client tells a
-what the user sees while it happens.
+restart from a blip, and what the user sees while it happens.
+
+A **structured** session (`docs/STRUCTURED-VIEW.md`) has no tmux pane behind
+it to survive on: its agent is a child of the daemon process itself, so a
+restart takes it down with the daemon. See
+[Structured sessions](#structured-sessions) below for exactly what that
+costs and what it doesn't.
 
 ## What the daemon publishes
 
@@ -68,6 +74,35 @@ resolves, so a blocked client is never a trapped one. It clears itself the
 moment a probe succeeds — there is no "retry" button, because the client is
 already retrying.
 
+## Structured sessions
+
+Everything above describes a **client's** view of a restart, and it holds for
+a structured session exactly as written — the same three verdicts, the same
+status indicator, the same overlay. What differs is what survives on the
+**daemon** side, because a structured session's agent is a daemon child, not
+a tmux pane:
+
+- A restart **ends the active turn**. There is no adapter process left to
+  finish it, and no tmux pane keeping it alive underneath.
+- The **transcript survives**, in the per-session event log
+  (`docs/STRUCTURED-VIEW.md#persistence-recovery-and-dead-sessions`) — a
+  graceful shutdown marks the session for one resume attempt. Recovery is
+  two separate operations, not one: the next daemon calls `session/load` so
+  the adapter restores its own ACP session, but whatever history the
+  adapter emits during that call is discarded, not replayed into anything —
+  the daemon already has that history on disk. Separately, the daemon
+  rebuilds its own projection by folding the persisted event log back
+  through it. An ungraceful death (a crash, `kill -9`) leaves no resume
+  marker, and the session stays dead permanently.
+- **Pending approvals and their nonces do not survive.** Both live only in
+  the old daemon's memory; any ACP permission request still mid-flight when
+  the daemon exits is answered `Cancelled` on the way down, and a resumed
+  session starts with no pending approval at all.
+
+`docs/STRUCTURED-VIEW.md` is the full contract for all of this — the event
+log's shape, the recovery marker, and exactly which kind of session death is
+resumable.
+
 ## Timing
 
 - **Grace window** — 1200 ms between the socket dropping and the overlay

docs/SIDEBAR.md

@@ -231,7 +231,24 @@ cutover points land within one tick.
 
 ## Precedence
 
-An agent-reported `ActivityState` (#105) overrides the daemon's inference for
+### Activity source by session kind
+
+The daemon supplies one `activity` field to both clients, but its source depends
+on the session kind:
+
+| Session kind | Source |
+|---|---|
+| Terminal | The existing agent-report override and five-minute TTL, falling back to PTY quiescence, foreground process and `/proc` input-block inference. |
+| Structured | ACP state directly: a pending approval is `AwaitingInput`; otherwise an in-flight turn is `Active`; no turn is `Idle`. A failed turn or dead structured session is `Error`, and the next turn clears a failed-turn error. |
+
+Structured sessions never enter the terminal inference path and ignore activity
+reports inherited through agent hooks. They have no PTY whose output or blocked
+read could describe their state. This is a second source, not a replacement for
+the terminal source.
+
+### Terminal report override
+
+For terminal sessions, an agent-reported `ActivityState` (#105) overrides the daemon's inference for
 **five minutes** (the TTL is fixed by the daemon; re-reporting extends it).
 When the TTL expires, inference resumes and the session's reported detail —
 if any — clears with the report. Clients never blend the two: whichever source
@@ -281,10 +298,10 @@ session is genuinely `Active` again — new work, not merely a refocus. Only
 after that fresh `Active` cycle does the *next* `AwaitingInput` glow again.
 Unfocusing and refocusing alone never re-arms it.
 
-This applies uniformly to `AwaitingInput` from either source — the daemon's
+This applies uniformly to `AwaitingInput` from terminal inference, an agent
-own inference or an agent's report (#105) — since the rail draws them
+report (#105), or a structured session's pending approval, since the rail draws
-identically. It does not touch `Error`; that state's own TTL (below) is
+them identically. It does not touch `Error`; terminal reports keep their TTL,
-unrelated and unaffected by focus.
+while a structured failed-turn error clears when the next turn starts.
 
 Each client reports its own pane's focus with `POST /api/sessions/:id/focus`
 (`{"focused": bool}`) whenever the pane it is showing changes — on attach, on

docs/STRUCTURED-VIEW.md

@@ -0,0 +1,389 @@
+# STRUCTURED-VIEW.md — the structured session contract
+
+The contract for a structured session (`view: Structured`, #133): an agent run
+as a daemon child over the Agent Client Protocol (ACP) instead of in a tmux
+pane. Alongside `docs/WORKTREES.md`, `docs/SIDEBAR.md` and `docs/RESTART.md`,
+read this before changing anything that renders a structured session — both
+the web and TUI renderers are written against it.
+
+It covers the eight transcript row kinds, what the daemon decides versus what
+a client decides, the two projections and their delta/cursor semantics, the
+ACP handshake and the capabilities it declines, the adapter's install
+command, and the approval nonce rules. **Non-goal: the detached runner.** It
+does not exist yet, and nothing here describes it.
+
+## What a structured session is
+
+A terminal session's agent runs inside a tmux pane; a structured session's
+agent runs as a subprocess of the daemon itself, speaking ACP over stdio. The
+daemon is the ACP **client**; the adapter process, `claude-code-acp`, is the
+ACP **agent** — it wraps Claude Code's own SDK and translates the model's
+tool calls into ACP `session/update` notifications instead of drawing them to
+a pane. `crates/maestro-acp` owns the daemon's side of that connection;
+`crates/maestro-daemon/src/projection.rs` folds what it receives into the two
+projections below.
+
+The child is a real child of the daemon process: same process group, and on
+Linux marked with `PR_SET_PDEATHSIG` so it dies with the daemon even if the
+daemon exits without cleaning up; other platforms have no such signal and
+depend on an orderly shutdown/drop to terminate it. The ordinary path on
+every platform is `AcpSession::terminate` (`session/cancel`, a short grace,
+`SIGTERM`, then `SIGKILL`), called from both `DELETE /api/sessions/:id` and
+daemon shutdown.
+`docs/WORKTREES.md`'s kill-guard rule — an unforced kill refused while the
+session's worktree holds unsaved work — applies to a structured session
+exactly as it does to a terminal one; only what gets terminated differs (an
+ACP handle instead of a tmux pane).
+
+## The adapter
+
+`ADAPTER_BIN` (`claude-code-acp`) is resolved by walking `PATH` — the
+session's own `PATH` env var if the spawn request set one, the daemon's
+otherwise — and taking the first executable file named `claude-code-acp` on
+it. Install it once per host:
+
+```sh
+npm install -g --prefix ~/.local @zed-industries/claude-code-acp
+```
+
+That is `maestro_acp::INSTALL_COMMAND`, and it is not just documentation: it
+is baked into `AcpError::AdapterMissing`'s message. When the adapter cannot
+be found, spawn still creates the session — **Dead**, with that install
+command as its `activity_detail` — so the sidebar names the fix instead of
+the session silently never appearing (see `docs/INSTALL.md` for the full
+install writeup, including the systemd `PATH` caveat). The adapter also needs
+a logged-in Claude Code (`claude /login`); a missing login surfaces the same
+way, via the adapter's own stderr tail in the failure message.
+
+The handshake is bounded by `HANDSHAKE_TIMEOUT` (60s) — long enough for a
+slow machine to boot a node process and the Claude Code SDK behind it, never
+long enough to hang a spawn indefinitely. Any handshake failure — missing
+adapter, early exit, a protocol error, or the timeout — leaves no orphaned
+process: `spawn` closes and reaps the child itself before returning the
+error.
+
+## The ACP handshake
+
+`initialize` is where the daemon states what kind of client it is. It
+declares, deliberately, almost nothing:
+
+| Capability | Declared | Why |
+| --- | --- | --- |
+| `fs.readTextFile` | `false` | The adapter uses Claude Code's own Read tool instead of asking the daemon to read a file on its behalf — the same tool a terminal-view Claude Code session uses. |
+| `fs.writeTextFile` | `false` | Same reasoning, for Write. |
+| `terminal` | `false` | The adapter runs Claude Code's own Bash tool rather than asking the daemon to open a terminal for it. |
+
+Declining all three keeps the daemon out of the file/terminal surface
+entirely — the adapter already has direct access to the session's `cwd`, and
+routing every read, write, and shell command through the daemon would only
+add a hop with no new capability. Every other capability namespace ACP
+defines (session extensions, auth, elicitation) is simply left at its
+default; the daemon does not advertise support because `claude-code-acp` has
+never asked for it, not because it was weighed and refused.
+
+The one client method that *is* implemented for real is
+`session/request_permission` (#139) — see [Approvals](#approvals) below.
+Before #139 it was a stub that declined every request; that stub is gone now
+that a live implementation exists.
+
+`session/new` opens a fresh ACP session on every ordinary spawn. A respawn
+after a daemon restart instead sets `SpawnConfig::load_session(id)` and runs
+`session/load` with the ACP session id the original handshake returned
+(`Session::acp_session_id` on the wire) — the adapter must advertise
+`agent_capabilities.load_session`, or the handshake fails outright naming
+that. Whatever history the adapter streams back while `session/load` is in
+flight is dropped on arrival, deliberately: the daemon's own event log
+already holds that history, and forwarding it too would duplicate every row
+in the projections below.
+
+## The eight transcript row kinds
+
+`TranscriptRowKind` (`maestro-protocol`) is the alphabet a structured
+transcript is written in. Every row has a stable `id` (so later deltas can
+address it), a `kind`, and a `data: Value` that preserves the underlying ACP
+payload — clients depend on ACP's *shape* without depending on ACP as a
+crate.
+
+| Kind | Carries | Row identity |
+| --- | --- | --- |
+| `User` | An echoed `user_message_chunk` — the prompt text as ACP saw it. | `user:<message_id>`, or `user:<seq>` when the chunk carries no id. |
+| `AgentText` | An `agent_message_chunk` — the agent's visible reply, streamed. | `agent:<message_id>` / `agent:<seq>`. Later chunks for the same id are appended into `data.content.text` in place, not appended as new rows. |
+| `AgentThought` | An `agent_thought_chunk` — the model's reasoning stream. | `thought:<message_id>` / `thought:<seq>`, coalesced the same way as `AgentText`. |
+| `ToolCall` | A `tool_call` / `tool_call_update` pair whose content carries no diff. | `tool:<tool_call_id>` — one row for the call's whole life; updates patch it in place, they never create a second row. |
+| `ToolDiff` | The same tool-call machinery, when the tool's content includes a `Diff` block. | Same `tool:<tool_call_id>` identity as `ToolCall`; the *kind* flips between the two as the tool's own content changes, not the row. |
+| `Approval` | A daemon-originated permission request (`RequestPermissionRequest`), serialized without its nonce. | `approval:<uuid>` — minted fresh per request, unrelated to the ACP request's own id. |
+| `Plan` | A `plan` update — the agent's current step list. | The fixed id `"plan"`. Each new plan **replaces** the row wholesale; entries are not diffed against the previous plan. |
+| `Notice` | The raw JSON of any `session/update` variant the ACP dependency already decodes but the projection does not special-case. | `notice:<seq>`. |
+
+`Notice` covers known-but-unspecialized `SessionUpdate` variants: ones the
+`agent-client-protocol` dependency's schema already deserializes (it
+currently folds `available_commands_update` and `session_info_update`
+there) but the projection's `match` doesn't fold into one of the other
+seven kinds. It is not a wire-level forward-compatibility seam:
+`SessionUpdate` is an internally-tagged enum with no unknown-variant
+fallback, so a `session/update` whose `sessionUpdate` tag this build's
+dependency has never heard of — including a variant gated behind an
+unstable ACP feature this build doesn't enable, which is compiled out of
+the enum entirely — fails to deserialize before the projection ever runs,
+rather than becoming a `Notice`. A genuinely new ACP variant needs the
+`agent-client-protocol` dependency upgraded (and, typically, the projection's
+`match` taught about it) before it can appear on this transcript at all — see
+`projection.rs`'s test asserting that an unrecognised `sessionUpdate` tag is a
+deserialization error, not a `Notice`. A client that does not know what to do
+with a `Notice` can still render it as an opaque, collapsed line — that
+remains a reasonable floor, not a client bug.
+
+Rendering is entirely a client concern. The projection's job stops at
+folding ACP into these eight shapes; markdown formatting, diff rendering,
+tool-card treatment, and how a `Notice` is presented are all renderer
+choices, not daemon ones.
+
+## Daemon decisions vs. client decisions
+
+**The daemon decides:**
+
+- Which ACP `session/update` becomes which row kind, and under what id — the
+  fold in `projection.rs` is the one place this logic lives, so the web and
+  TUI renderers can never disagree about it.
+- Turn lifecycle: when a turn begins, and whether an ACP response, a cancel,
+  or a failure ends it (`TurnState.responding` / `.thinking` /
+  `.active_tool_calls` are derived, not renderer-computed).
+- Approval nonce minting, secrecy, and the single-active-approval rule (see
+  below) — a client never sees an ACP permission request before the daemon
+  has already turned it into an `Approval` row and a nonce.
+- What happens to an ACP update variant the dependency decodes but nobody has
+  taught the projection to special-case (falls back to `Notice` rather than
+  erroring). A variant the dependency itself can't decode is a deserialization
+  error, not a `Notice` — see [The eight transcript row
+  kinds](#the-eight-transcript-row-kinds).
+- Persistence and replay: what is written to the event log, in what order,
+  and how a restart resumes it.
+
+**A client decides:**
+
+- How each row kind is drawn — markdown for `AgentText`/`AgentThought`, a
+  diff view for `ToolDiff`, a tool card for `ToolCall`, and a floor
+  presentation for `Notice`. `Plan` is the exception: both clients omit it
+  from the transcript entirely and render the current plan in a separate
+  plan rail (web) / status line (TUI) instead.
+- How `responding` vs. `thinking` are distinguished visually, if at all.
+- How the operator is asked to resolve an `Approval` row — the daemon only
+  exposes the three-way decision (`AllowOnce` / `AllowForSession` / `Deny`),
+  never the UI that solicits it.
+- Scrolling, collapsing, and every other presentation-only behaviour.
+
+## The two projections
+
+`Projection` (daemon-only) is folded once from the durable ACP stream and
+exposes two independent views, both defined in `maestro-protocol`:
+
+- **`TranscriptSnapshot { cursor, rows }`** — the complete ordered list of
+  transcript rows built so far, plus the log position (`cursor`) it reflects.
+  It is intentionally always the *whole* transcript, not a windowed one: a
+  tool row patched much later must still find its original entry.
+- **`ReducedState`** — one whole-session snapshot folded over every event
+  seen: `turn` (the per-turn indicators above), `pending_approval`, `plan`,
+  `usage`/`context`, `model`, and `mode`. Like `TranscriptSnapshot`, it is
+  always full-history, never a delta — a client that only wants "is a turn
+  active right now" never has to replay anything to answer that.
+
+Changes to the transcript travel as `TranscriptDelta`, tagged `type`:
+`Append { row }` (a new row), `Patch { row }` (an existing row, addressed by
+`id`, replaced wholesale), and `Remove { id }`. `Remove` is defined on the
+wire for forward compatibility; nothing in the current projection emits it —
+every row, once appended, is only ever patched or left alone.
+
+### Cursor and replay semantics
+
+The event log's own line position is the cursor: 1-based, shared by ACP
+notifications and daemon-generated rows alike (`sidecar.rs`'s
+`PersistedEvent` envelope is what lets an `Approval` row share a cursor
+sequence with raw ACP JSON without pretending to be ACP traffic). Two ways to
+read it:
+
+- **`WS /api/structured/:id`** — on connect, sends a `TranscriptSnapshot` and
+  a `ReducedState` covering the whole log as it stands, then streams
+  `ProjectionUpdate { transcript, state }` for everything that happens next.
+  There is no client-supplied resume cursor on this socket: every connection
+  gets the full snapshot, not a gap-filled continuation, so a client never
+  needs the replay endpoint just to obtain the current transcript. Use
+  replay instead for cursor-bounded pagination through the durable log —
+  history from before this connection, fetched a page at a time.
+- **`GET /api/sessions/:id/structured/replay`** — cursor-bounded pagination
+  over the durable log, returning one `StructuredReplayEvent` (`cursor`,
+  `transcript`, `state`) per matching line. `?since=<n>` returns the first
+  page after `n` (`since=0` selects from the beginning, i.e. the first
+  page); a client pages forward from there using the cursor of the last
+  event returned. `?before=<n>` returns the page immediately before `n`,
+  still in ascending order — passing both is a `400`. `?limit` defaults to
+  100 and is clamped to 500. Each call re-folds
+  the entire log from scratch to compute the state at every returned cursor,
+  so a page reflects exactly the *durable* state at its cursor, not an
+  approximation of it — at the cost of redoing the whole fold per request.
+  That durable state is not always identical to what a live client saw at
+  that moment, though: turn lifecycle transitions are broadcast live without
+  a durable event backing them (see [Prompt and cancel](#prompt-and-cancel-bounded-liveness)),
+  and a restored `Approval` row carries no pending nonce, because the nonce
+  never reached disk (see [Approvals](#approvals)) — replay is exact and
+  reconstructible, not a perfect record of everything the live view showed.
+  A session that is not a live structured session (terminal, or a dead
+  adapter) answers `409 not_structured` from either route rather than a
+  coherent-looking but stale reply.
+
+## Approvals
+
+An ACP `session/request_permission` callback becomes an `Approval` row plus a
+pending decision, entirely on the daemon side:
+
+- **Generation.** The daemon mints the nonce itself — a fresh
+  `Uuid::new_v4()` string per request — rather than using anything ACP's own
+  request carries. ACP permission callbacks have no request id of their own
+  that would double as one.
+- **Live-only placement.** The nonce lives in exactly one place: the
+  in-memory `pending_approvals` map keyed by nonce, and its mirror in
+  `ReducedState.pending_approval.nonce` on the live wire. It is never part of
+  the `Approval` row's `data` — the row is `RequestPermissionRequest`
+  serialized *without* the nonce.
+- **Secrecy from the agent and from durable history.** The adapter itself
+  never learns the nonce — it is a daemon-to-client secret, never sent back
+  over the ACP connection. It is likewise never written to the event log:
+  restoring an `Approval` row from disk (`Projection::restore_approval`)
+  produces a historical row with no `pending_approval` in state, because the
+  nonce that would make it "pending" never made it to disk in the first
+  place. A restart therefore cannot resume a pending approval — see
+  [Persistence](#persistence-recovery-and-dead-sessions).
+- **One live approval at a time.** A new permission request mints its own
+  nonce, then cancels whatever was already pending (`cancel_pending_approvals`)
+  before installing itself as the new pending approval — ACP serializes
+  requests through one connection, so this only ever fires if an adapter
+  nonetheless overlaps two. Either way, the prior pending request is
+  cancelled/cleared before the new one is installed, so the newest request
+  wins.
+- **Single-use and duplicate resolution.**
+  `POST /api/sessions/:id/structured/approvals/:nonce` **always answers
+  `204`** for a known, live structured session — whether the nonce is the
+  one currently pending, one already consumed by an earlier answer, or one
+  that never existed. Only an unknown or non-structured *session* answers
+  otherwise (`404` / `409`). This is deliberate: two clients racing to answer the same
+  approval must not turn a harmless duplicate click into a client-visible
+  error. Whichever `POST` reaches the daemon first removes the nonce from
+  `pending_approvals` and is the one whose decision actually reaches the
+  adapter; every later `POST` for that nonce is a no-op `204`.
+- **Cancellation vs. denial.** A turn cancel or a session shutdown resolves
+  any pending approval with ACP's `Cancelled` outcome, not a `Deny` decision
+  — the adapter should read those as "the operation was withdrawn," not "the
+  operator refused it."
+- **Decision mapping.** `AllowOnce` and `AllowForSession` select the ACP
+  option of kind `AllowOnce` / `AllowAlways` from the request's own option
+  list. `Deny` prefers a one-shot refusal (`RejectOnce`) and falls back to a
+  permanent one (`RejectAlways`) only when that is the sole rejection option
+  offered; if neither is present, it answers `Cancelled`.
+
+## Prompt and cancel: bounded liveness
+
+`POST /api/sessions/:id/structured/prompt` and `.../cancel` are serialized
+against each other through one per-session `operation` lock
+(`AcpEventStream::operation`), because ACP permission callbacks carry no
+per-request id — the daemon's own notion of "the active turn" is the only
+thing a callback can be attributed to, so at most one turn may ever be
+in flight, and a cancelled turn must fully settle before the next prompt is
+allowed to claim the daemon's idea of "the active turn."
+
+- A prompt claims the turn and dispatches it to ACP as one operation. While a
+  turn is active, a second prompt gets `409 turn_in_flight` rather than
+  queuing — one active turn per session, never a hidden queue of prompts.
+- Cancel sends `session/cancel`, clears any pending approval as `Cancelled`,
+  and ends the turn's client-visible lifecycle immediately. If the cancelled
+  turn was still *dispatched* to ACP (waiting on its response), the daemon
+  cannot simply forget it: ACP has not confirmed the cancel yet, and a new
+  prompt claiming "the active turn" while the old one is still outstanding
+  would make the next permission callback ambiguous between the two.
+- So a cancelled-but-still-dispatched turn must **settle within
+  `CANCEL_GRACE` (500ms)** — either ACP acknowledges the prompt (however it
+  resolves) or that grace period runs out. If it settles in time, the next
+  prompt proceeds normally. If it does not, the daemon does not guess: it
+  marks the whole structured session dead (`fail_cancelled_acp_turn`) rather
+  than risk a callback resolving against the wrong turn. This is the bounded
+  half of "bounded liveness" — a structured session's prompt/cancel dance
+  either resolves promptly or the session is declared unusable, never left
+  in an indefinite ambiguous state.
+
+## Persistence, recovery, and dead sessions
+
+A structured session's durable state is three files in the sidecar
+directory: the sidecar itself (`<id>.json`), plus two next to it:
+
+- **`<id>.events.jsonl`** — the unified event log. Each line is either a raw
+  ACP `SessionNotification` (kept in its original JSON so old logs stay
+  readable) or a `{"maestroEvent": "approval", "row": …}` envelope for a
+  daemon-generated row. Both share the same 1-based line-position cursor. A
+  line a hard kill left half-written is terminated before the next append, so
+  it keeps its position and is skipped as malformed rather than corrupting
+  what follows. An append that fails *while the daemon is running* — a
+  `write_all` that errors after only a prefix reached disk, or a `flush` that
+  errors after a complete write — is rolled back to the exact byte length the
+  file was at before the call, so `last_seq` and the file's line count never
+  disagree and the same log handle can be appended to again immediately (#184).
+  If that rollback itself cannot restore the prior length, the append is
+  fatal: the log's consistency can no longer be promised, so the caller kills
+  the session instead of appending to it again.
+- **`<id>.recover`** — an empty marker file. Its only meaning is "the daemon
+  that wrote this shut down gracefully while this session was running, and
+  the next daemon may attempt to resume it." It is consumed (deleted) the
+  moment a recovery attempt reads it — one recovery attempt per graceful
+  shutdown, never a standing flag.
+
+Three ways a structured session ends up `Dead`, each with different
+persistence consequences:
+
+1. **The adapter exits, or a notification append to the event log fails,
+   while the daemon keeps running.** (An approval-row append failure is
+   narrower: as long as the log rolled back cleanly, it only cancels the
+   pending approval and rolls the unpersisted `Approval` row back out of the
+   live transcript, without marking the session dead — a snapshot taken after
+   the failure must never show a row durable replay could not reproduce
+   (#184). If the rollback itself did not restore the log's prior length,
+   this narrower path does not apply either: the session is marked dead the
+   same as any other append failure, since the log can no longer promise
+   `last_seq` matches its file.)
+   `mark_session_dead` applies the same natural-exit worktree rule
+   as a terminal session's own pane exiting (`docs/WORKTREES.md`): a pristine
+   worktree is removed, one holding unsaved work is left on disk. No recovery
+   marker is written. This death is permanent — a later daemon restart's
+   `recover()` finds the sidecar, sees no marker, and leaves the session
+   `Dead` without attempting to resume it.
+2. **A cancelled turn fails to settle within `CANCEL_GRACE`.** Same
+   consequence as (1): the session is marked dead through the same path, no
+   marker, no future resumption.
+3. **Graceful daemon shutdown**, while the session was still `Running`.
+   `mark_session_dead_after_shutdown` marks the session dead **without**
+   applying the worktree exit rule — the tree is kept exactly as it is,
+   pristine or not, because there is nothing "natural" about this exit — and
+   writes the `.recover` marker. The sidecar on disk therefore says `Dead`,
+   but is eligible for resumption.
+
+Recovery, on the next daemon's `recover()`: for every `Structured` sidecar
+not already adopted, the marker is consumed. When one was present and the
+sidecar carries a stored `acp_session_id`, the daemon spawns a fresh adapter
+with `SpawnConfig::load_session(acp_session_id)`, replays the
+entire durable event log into a new `Projection` (rebuilding the transcript
+and reduced state exactly as they were, with any restored `Approval` row
+landing as history — never as a re-armed pending approval, since its nonce
+never reached disk), and only then reopens the log for further appends. What
+the adapter streams back while its own `session/load` is in flight is
+discarded rather than appended, so the replayed history is not duplicated
+(see [The ACP handshake](#the-acp-handshake)). Success flips the session back
+to `Running`/`Idle`; failure (no stored `acp_session_id`, or the handshake
+itself failing) leaves it `Dead` with the failure reason as
+`activity_detail` — the same "tell the operator what to fix" pattern as a
+missing adapter binary.
+
+Pending approvals and their nonces never survive any of this. They live only
+in the in-memory `pending_approvals` map and the live `ReducedState`, both
+gone the instant the daemon that held them exits. Whatever ACP permission
+request was mid-flight when the old daemon died was already answered
+`Cancelled` on that daemon's own shutdown path, so a resumed session always
+starts with no pending approval.
+
+See `docs/RESTART.md` for what a *client* observes across a daemon restart,
+now that structured sessions exist alongside terminal ones.

fixtures/command-resolution.json

@@ -0,0 +1,120 @@
+{
+  "_description": "the parity fixture for #199's command resolver — every case here is asserted identically by crates/maestro-protocol/src/display.rs (command_program/command_tool) and web/src/toolIcon.ts (splitCommand). `program` is the resolved, basenamed program; `tool` is the icon id it maps to, or null when unrecognised/ambiguous.",
+  "cases": [
+    { "command": "claude", "program": "claude", "tool": "claude" },
+    { "command": "claude --resume", "program": "claude", "tool": "claude" },
+    { "command": "CLAUDE", "program": "CLAUDE", "tool": "claude" },
+    { "command": "/usr/local/bin/claude -p hi", "program": "claude", "tool": "claude" },
+    { "command": "./bin/claude", "program": "claude", "tool": "claude" },
+    { "command": "FOO=1 BAR=2 claude", "program": "claude", "tool": "claude" },
+    { "command": "FOO=\"bar baz\" claude", "program": "claude", "tool": "claude" },
+    { "command": "FOO='bar baz' claude", "program": "claude", "tool": "claude" },
+    { "command": "FOO=bar\\ baz claude", "program": "claude", "tool": "claude" },
+    { "command": "'/usr/local/bin/claude'", "program": "claude", "tool": "claude" },
+    { "command": "\"/opt/my agent/claude\" --resume", "program": "claude", "tool": "claude" },
+    { "command": "env -i claude", "program": "claude", "tool": "claude" },
+    { "command": "env --ignore-environment claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo -u root claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo --user=root claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo -- claude --resume", "program": "claude", "tool": "claude" },
+    { "command": "nohup claude", "program": "claude", "tool": "claude" },
+    { "command": "time claude", "program": "claude", "tool": "claude" },
+    { "command": "time -p claude", "program": "claude", "tool": "claude" },
+    { "command": "time -- claude", "program": "claude", "tool": "claude" },
+    { "command": "time -p -- claude", "program": "claude", "tool": "claude" },
+    { "command": "time -pp claude", "program": "time", "tool": null },
+    { "command": "time -p -p claude", "program": "time", "tool": null },
+    { "command": "time -o /tmp/t.log claude", "program": "time", "tool": null },
+    { "command": "command claude", "program": "claude", "tool": "claude" },
+    { "command": "command -v claude", "program": "command", "tool": null },
+    { "command": "command -V claude", "program": "command", "tool": null },
+    { "command": "npx --yes claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "npx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm --silent dlx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm -C ./pkg dlx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm dlx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm dlx -s claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm dlx --silent claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "yarn --silent dlx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "yarn dlx -q claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "yarn dlx --quiet claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bun x claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bunx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "uvx claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bun x --bun claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bunx --bun claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bun x -p @anthropic-ai/claude-code claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bunx --package @anthropic-ai/claude-code claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bun x --package=@anthropic-ai/claude-code claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bunx --no-install claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bun x --verbose claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bunx --silent claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "bun --bun x claude-code", "program": "bun", "tool": null },
+    { "command": "pnpm dlx --package foo claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm dlx --package=foo claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "pnpm dlx --package= claude-code", "program": "pnpm", "tool": null },
+    { "command": "pnpm dlx --package", "program": "pnpm", "tool": null },
+    { "command": "pnpm dlx -c \"claude-code\"", "program": "pnpm", "tool": null },
+    { "command": "pnpm --package=typescript dlx tsc", "program": "tsc", "tool": null },
+    { "command": "pnpm dlx --unknown-flag claude-code", "program": "pnpm", "tool": null },
+    { "command": "yarn dlx --package foo claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "yarn dlx --package=foo claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "yarn dlx -p foo claude-code", "program": "claude-code", "tool": "claude" },
+    { "command": "yarn dlx --package= claude-code", "program": "yarn", "tool": null },
+    { "command": "yarn dlx -p", "program": "yarn", "tool": null },
+    { "command": "yarn dlx -p --quiet claude-code", "program": "yarn", "tool": null },
+    { "command": "bunx --package= claude-code", "program": "bunx", "tool": null },
+    { "command": "bunx --package", "program": "bunx", "tool": null },
+    { "command": "bun x -p --silent claude-code", "program": "bun", "tool": null },
+    { "command": "sudo env -i claude", "program": "claude", "tool": "claude" },
+    { "command": "FOO=1 sudo BAR=2 claude", "program": "claude", "tool": "claude" },
+    { "command": "env -iv claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo -nE claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo -uroot claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo -u", "program": "sudo", "tool": null },
+    { "command": "env --unset= claude", "program": "env", "tool": null },
+    { "command": "sudo --user= claude", "program": "sudo", "tool": null },
+    { "command": "sudo --user \"\" claude", "program": "sudo", "tool": null },
+    { "command": "sudo -nu claude", "program": "sudo", "tool": null },
+    { "command": "env -S 'python3 -u' script.py", "program": "env", "tool": null },
+    { "command": "npx -c \"claude --version\"", "program": "npx", "tool": null },
+    { "command": "npx --call \"claude --version\"", "program": "npx", "tool": null },
+    { "command": "command FOO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "nohup FOO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "npx FOO=1 claude-code", "program": "FOO=1", "tool": null },
+    { "command": "pnpm dlx FOO=1 claude-code", "program": "FOO=1", "tool": null },
+    { "command": "yarn dlx FOO=1 claude-code", "program": "FOO=1", "tool": null },
+    { "command": "bun x FOO=1 claude-code", "program": "FOO=1", "tool": null },
+    { "command": "bunx FOO=1 claude-code", "program": "FOO=1", "tool": null },
+    { "command": "uvx FOO=1 claude-code", "program": "FOO=1", "tool": null },
+    { "command": "sudo time FOO=1 claude", "program": "claude", "tool": "claude" },
+    { "command": "nohup env FOO=1 claude", "program": "claude", "tool": "claude" },
+    { "command": "sudo command FOO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "command nohup FOO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "time command FOO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "\"FOO=1\" claude", "program": "FOO=1", "tool": null },
+    { "command": "FOO\\=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "F\"O\"O=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "F\\OO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "\"FOO\"=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "F\"\"OO=1 claude", "program": "FOO=1", "tool": null },
+    { "command": "claude\nclaude-code", "program": "claude", "tool": null },
+    { "command": "clau\\\nde --resume", "program": "claude", "tool": "claude" },
+    { "command": "npx opencode", "program": "opencode", "tool": "opencode" },
+    { "command": "pnpm dlx opencode run", "program": "opencode", "tool": "opencode" },
+    { "command": "pnpm claude", "program": "pnpm", "tool": null },
+    { "command": "yarn claude", "program": "yarn", "tool": null },
+    { "command": "claude-code-acp", "program": "claude-code-acp", "tool": null },
+    { "command": "hx src/main.rs", "program": "hx", "tool": null },
+    { "command": "bash", "program": "bash", "tool": "shell" },
+    { "command": "opencode", "program": "opencode", "tool": "opencode" },
+    { "command": "sudo", "program": "sudo", "tool": null },
+    { "command": "", "program": "", "tool": null },
+    { "command": "npx --unknown-flag claude-code", "program": "npx", "tool": null },
+    { "command": "claude | tee log.txt", "program": "claude", "tool": null },
+    { "command": "claude; echo done", "program": "claude;", "tool": null },
+    { "command": "claude && echo done", "program": "claude", "tool": null },
+    { "command": "echo hi $(claude)", "program": "echo", "tool": null },
+    { "command": "claude \"unterminated", "program": "claude", "tool": null }
+  ]
+}

web/src/api.ts

@@ -11,6 +11,8 @@ import type {
   Projects,
   RecentDirs,
   Session,
+  StructuredApprovalDecision,
+  StructuredPromptRequest,
   Uuid,
 } from "./types.js";
 
@@ -152,4 +154,44 @@ export async function fetchBranches(path: string): Promise<Branches> {
   return jsonOrError(await fetch(url, { credentials: "same-origin" }));
 }
 
-export { eventsWsUrl } from "./routes.js";
+/** Send a prompt to a structured session's ACP turn (#138). `409
+ * turn_in_flight` when one is already active — the caller reflects that from
+ * `ReducedState.turn` instead of racing this call. */
+export async function sendStructuredPrompt(id: Uuid, prompt: string): Promise<void> {
+  await jsonOrError(
+    await fetch(routes.structuredPrompt(id), {
+      method: "POST",
+      credentials: "same-origin",
+      headers: { "content-type": "application/json" },
+      body: JSON.stringify({ prompt } satisfies StructuredPromptRequest),
+    }),
+  );
+}
+
+/** Cancel a structured session's active ACP turn (#138). */
+export async function cancelStructuredTurn(id: Uuid): Promise<void> {
+  await jsonOrError(
+    await fetch(routes.structuredCancel(id), { method: "POST", credentials: "same-origin" }),
+  );
+}
+
+/** Answer a pending ACP permission request (#139). Always resolves once the
+ * session itself is a live structured session — a nonce that is unknown or
+ * already consumed still answers `204` (docs/STRUCTURED-VIEW.md), so two
+ * clients racing the same approval never see this reject. */
+export async function resolveStructuredApproval(
+  id: Uuid,
+  nonce: string,
+  decision: StructuredApprovalDecision,
+): Promise<void> {
+  await jsonOrError(
+    await fetch(routes.structuredApproval(id, nonce), {
+      method: "POST",
+      credentials: "same-origin",
+      headers: { "content-type": "application/json" },
+      body: JSON.stringify(decision),
+    }),
+  );
+}
+
+export { eventsWsUrl, structuredWsUrl } from "./routes.js";

web/src/attach.ts

@@ -4,14 +4,16 @@ import { Terminal } from "@xterm/xterm";
 import "@xterm/xterm/css/xterm.css";
 
 import { attachWsUrl } from "./routes.js";
-import { escapeHtml } from "./html.js";
 import { INITIAL_RECONNECT_MS, MAX_RECONNECT_MS } from "./reconnect.js";
 import { applyModsToChar, cursorSeq, tildeSeq } from "./keys.js";
 import { requestToggleDrawer } from "./drawer.js";
-import { splitCommand, toolIconSvg } from "./toolIcon.js";
+import { paneTitleAttr, paneTitleHtml, type AttachInfo } from "./paneTitle.js";
+import type { PaneConnection } from "./pane.js";
 import type { ClientControl, Uuid } from "./types.js";
 import { WebglPolicy } from "./webglRenderer.js";
 
+export type { AttachInfo } from "./paneTitle.js";
+
 /** One budget for the whole page — see webglRenderer.ts for why contexts are
  *  rationed rather than handed to every connection. */
 const webglPolicy = new WebglPolicy();
@@ -27,25 +29,7 @@ const webglPolicy = new WebglPolicy();
  * session ending) tears the socket down — so switching away and back is
  * instant, with scrollback already in place.
  */
-export interface AttachConnection {
+export interface AttachConnection extends PaneConnection {}
-  readonly sessionId: Uuid;
-  /** The `.attach` element (header + terminal body) to mount into a pane. */
-  readonly el: HTMLElement;
-  /** Becomes the visible view: fit to the pane, focus, sync size.
-   *  `focus: false` mounts without taking the keyboard — what a sidebar
-   *  preview needs, so j/k keeps working while the pane is on screen. */
-  onMount(opts?: { focus?: boolean }): void;
-  /** Parked into the cache: keep streaming, just stop driving focus/resize. */
-  onUnmount(): void;
-  /** Put the keyboard back into this terminal — what leaving the sidebar does. */
-  focusTerminal(): void;
-  /** Type raw bytes straight into the PTY, bypassing the terminal's own key
-   *  handling — the leader's literal Ctrl-K escape hatch
-   *  (docs/COMMAND-BAR.md). */
-  sendInput(data: string): void;
-  /** Fully disconnect: close the WS, dispose the terminal, remove the element. */
-  dispose(): void;
-}
 
 export interface AttachOptions {
   /** Invoked when the user clicks the view's explicit "disconnect" control. */
@@ -59,23 +43,6 @@ export interface AttachOptions {
   shouldReconnect?: (sessionId: Uuid, code: number) => boolean;
 }
 
-/** What the header shows about the session (name / command). Optional — falls
- * back to a short session id when the session isn't known yet. */
-export interface AttachInfo {
-  name: string;
-  command: string;
-}
-
-/** Header echoes the sidebar: the program becomes its tool icon when we have a
- * mark for it and stays as its bare name when we do not. Arguments are
- * dropped, as on the card. */
-function commandFragment(command: string): string {
-  const { tool, program } = splitCommand(command);
-  const icon = tool ? toolIconSvg(tool) : null;
-  const text = icon ? "" : program;
-  return `<span class="at-cmd">${icon ?? ""}${text ? escapeHtml(text) : ""}</span>`;
-}
-
 export function createAttachConnection(
   sessionId: Uuid,
   opts: AttachOptions = {},
@@ -85,15 +52,12 @@ export function createAttachConnection(
   el.className = "attach";
   // Useful identity over a bare UUID: name · command. The full id stays in the
   // tooltip for when you really need it.
-  const titleHtml = info
+  const titleHtml = paneTitleHtml(sessionId, info);
-    ? `<span class="at-name">${escapeHtml(info.name)}</span>` +
+  const titleAttr = paneTitleAttr(sessionId, info);
-      (info.command && info.command !== info.name ? commandFragment(info.command) : "")
-    : `session <span class="sid">${escapeHtml(sessionId.slice(0, 8))}</span>`;
-  const titleAttr = info ? `${info.name} · ${info.command}  (${sessionId})` : sessionId;
   el.innerHTML = `
     <header class="attach-header">
       <button type="button" class="btn btn-ghost btn-icon sessions-btn" aria-label="Show sessions" title="Show sessions">☰</button>
-      <span class="attach-title" title="${escapeHtml(titleAttr)}">${titleHtml}</span>
+      <span class="attach-title" title="${titleAttr}">${titleHtml}</span>
       <span class="attach-state" data-state="connecting">connecting…</span>
       <button class="btn btn-ghost btn-icon disconnect" type="button" aria-label="Disconnect" title="Disconnect this session">⏻</button>
     </header>

web/src/connections.test.ts

@@ -2,28 +2,83 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
 
 import { ConnectionPool } from "./connections.js";
+import { CatalogStore } from "./events.js";
+import type { Session } from "./types.js";
 
 // The pane's own bytes-out path, stubbed: the escape hatch only needs to know
 // the pool reaches the focused connection with them.
 const sent: { id: string; data: string }[] = [];
-vi.mock("./attach.js", () => ({
+const disposed: string[] = [];
-  createAttachConnection: (id: string) => ({
+const mounts: { id: string; focus: boolean | undefined }[] = [];
+function fakeConn(kind: string, id: string) {
+  const el = document.createElement("div");
+  el.tabIndex = -1; // focusable via .focus(), like a real input/terminal
+  el.dataset.kind = kind;
+  el.dataset.session = id;
+  return {
     sessionId: id,
-    el: document.createElement("div"),
+    kind,
-    onMount() {},
+    el,
+    onMount(opts?: { focus?: boolean }) {
+      mounts.push({ id, focus: opts?.focus });
+    },
     onUnmount() {},
     focusTerminal() {},
     sendInput(data: string) {
       sent.push({ id, data });
     },
-    dispose() {},
+    dispose() {
-  }),
+      disposed.push(`${kind}:${id}`);
+    },
+  };
+}
+vi.mock("./attach.js", () => ({
+  createAttachConnection: (id: string) => fakeConn("attach", id),
+}));
+vi.mock("./structured.js", () => ({
+  createStructuredConnection: (id: string) => fakeConn("structured", id),
 }));
 
 afterEach(() => {
   vi.unstubAllGlobals();
+  sent.length = 0;
+  disposed.length = 0;
+  mounts.length = 0;
 });
 
+/** Minimal fixture for the `CatalogState` a `CatalogStore` broadcasts. */
+function session(id: string, view?: "Terminal" | "Structured"): Session {
+  return {
+    id,
+    cwd: "/repo",
+    command: "claude",
+    env: {},
+    metadata: {},
+    status: "Running",
+    created_at: "2026-01-01T00:00:00Z",
+    view,
+  };
+}
+
+/** A `CatalogStore` an id can be pushed into on demand, mirroring
+ *  events.test.ts's own injectable-socket pattern. */
+class FakeCatalogSocket {
+  onmessage: ((ev: { data: string }) => void) | null = null;
+  onopen: (() => void) | null = null;
+  onclose: (() => void) | null = null;
+  onerror: (() => void) | null = null;
+  close(): void {}
+  push(sessions: Session[]): void {
+    this.onmessage?.({ data: JSON.stringify({ type: "Snapshot", sessions }) });
+  }
+}
+function fakeStore(): { store: CatalogStore; socket: FakeCatalogSocket } {
+  const socket = new FakeCatalogSocket();
+  const store = new CatalogStore({ socket: () => socket as unknown as WebSocket });
+  store.start();
+  return { store, socket };
+}
+
 const A = "aaaaaaaa-0000-0000-0000-0000000000ff";
 const B = "bbbbbbbb-0000-0000-0000-0000000000ff";
 
@@ -125,3 +180,203 @@ describe("ConnectionPool.sendToFocused", () => {
     expect(sent).toEqual([]);
   });
 });
+
+// A deep link or restored layout can `mount()` a session before the catalog
+// snapshot names its view — the daemon defaults an absent `view` to
+// `"Terminal"`, but so does an *unknown* session, and only one of those is
+// actually resolved (#140 review).
+describe("ConnectionPool: view resolution races", () => {
+  it("replaces a wrongly-typed connection once the catalog resolves it, without waiting for another mount()", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+
+    pool.mount(A, pane); // no info: deep-link-before-snapshot race
+    expect(disposed).toEqual([]);
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual(["attach:" + A]);
+    // The fresh connection landed in the same pane nothing re-mounted it into.
+    expect(pane.children).toHaveLength(1);
+  });
+
+  it("also repairs a wrongly-typed connection that is parked, not mounted, without evicting its other parked siblings", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const hidden = document.body.lastElementChild as HTMLElement; // this pool's own cache
+    pool.mount(A, document.createElement("div"));
+    pool.mount(B, document.createElement("div"));
+    pool.unmount(A);
+    pool.unmount(B);
+    disposed.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual(["attach:" + A]);
+    // B's own element is still parked — A's repair didn't wipe its siblings
+    // out of the shared hidden cache.
+    expect(hidden.querySelector(`[data-session="${B}"]`)).not.toBeNull();
+    expect((hidden.querySelector(`[data-session="${A}"]`) as HTMLElement | null)?.dataset.kind).toBe("structured");
+  });
+
+  it("does not replace a connection whose resolved view already matches", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    pool.mount(A, pane, { name: "a", command: "claude", view: "Structured" });
+    disposed.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual([]);
+  });
+
+  it("does not downgrade an already-resolved connection when a later mount() call has no info", () => {
+    mockFetch();
+    const pool = new ConnectionPool();
+    const pane = document.createElement("div");
+    pool.mount(A, pane, { name: "a", command: "claude", view: "Structured" });
+    disposed.length = 0;
+
+    pool.mount(A, pane); // e.g. a re-render before the catalog answers again
+
+    expect(disposed).toEqual([]);
+  });
+
+  it("does not treat a session missing from the catalog as Terminal and churn a live connection", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    pool.mount(A, pane, { name: "a", command: "claude", view: "Structured" });
+    disposed.length = 0;
+
+    // `A` is absent from this snapshot — main.ts's own subscription handles
+    // closing the pane; the pool must not race it by "fixing" the view first.
+    socket.push([session(B, "Terminal")]);
+
+    expect(disposed).toEqual([]);
+  });
+
+  it("re-focuses the fresh connection when the keyboard was actually inside the replaced pane", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    document.body.appendChild(pane);
+    pool.mount(A, pane);
+    pool.setFocus(A);
+    (pane.firstElementChild as HTMLElement).focus();
+    expect(document.activeElement).toBe(pane.firstElementChild);
+    mounts.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual(["attach:" + A]);
+    expect(mounts).toEqual([{ id: A, focus: true }]);
+    pane.remove();
+  });
+
+  it("does not steal focus from a same-tab sidebar preview even though focusedId still names the previous pane", () => {
+    // docs/PREVIEW.md: previewing a session already open in the current tab
+    // moves the keyboard into the sidebar without ever calling setFocus, so
+    // `focusedId` keeps naming the pane the operator was in before — but the
+    // DOM disagrees, and the DOM is what must decide.
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    document.body.appendChild(pane);
+    pool.mount(A, pane);
+    pool.setFocus(A);
+    (pane.firstElementChild as HTMLElement).focus();
+
+    const sidebarInput = document.createElement("input");
+    document.body.appendChild(sidebarInput);
+    sidebarInput.focus();
+    expect(document.activeElement).toBe(sidebarInput);
+    mounts.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual(["attach:" + A]);
+    expect(mounts).toEqual([{ id: A, focus: false }]);
+    pane.remove();
+    sidebarInput.remove();
+  });
+
+  it("counts focus on a descendant of the pane's element, not just the element itself", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    document.body.appendChild(pane);
+    pool.mount(A, pane);
+    pool.setFocus(A);
+    const textarea = document.createElement("textarea");
+    (pane.firstElementChild as HTMLElement).appendChild(textarea);
+    textarea.focus();
+    expect(document.activeElement).toBe(textarea);
+    mounts.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(mounts).toEqual([{ id: A, focus: true }]);
+    pane.remove();
+  });
+
+  it("treats document.body (nothing meaningfully focused) as no active descendant", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    document.body.appendChild(pane);
+    pool.mount(A, pane);
+    pool.setFocus(A);
+    (document.activeElement as HTMLElement | null)?.blur();
+    expect(document.activeElement).toBe(document.body);
+    mounts.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(mounts).toEqual([{ id: A, focus: false }]);
+    pane.remove();
+  });
+
+  it("does not steal focus for a merely-visible pane that was never actually focused", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const paneA = document.createElement("div");
+    const paneB = document.createElement("div");
+    pool.mount(A, paneA);
+    pool.mount(B, paneB);
+    pool.setFocus(B); // B is the real keyboard focus; A is only visible
+    mounts.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual(["attach:" + A]);
+    expect(mounts).toEqual([{ id: A, focus: false }]);
+  });
+
+  it("does not focus a parked (unmounted) connection it repairs", () => {
+    mockFetch();
+    const { store, socket } = fakeStore();
+    const pool = new ConnectionPool({ store });
+    const pane = document.createElement("div");
+    pool.mount(A, pane);
+    pool.setFocus(A);
+    pool.unmount(A); // parked — no longer visible, `focusedId` still names it
+    mounts.length = 0;
+
+    socket.push([session(A, "Structured")]);
+
+    expect(disposed).toEqual(["attach:" + A]);
+    expect(mounts).toEqual([]); // parked repair calls onUnmount, never onMount
+  });
+});

web/src/connections.ts

@@ -1,10 +1,10 @@
-import {
+import { createAttachConnection } from "./attach.js";
-  createAttachConnection,
+import type { AttachInfo } from "./paneTitle.js";
-  type AttachConnection,
+import type { PaneConnection } from "./pane.js";
-  type AttachInfo,
+import { createStructuredConnection } from "./structured.js";
-} from "./attach.js";
 import { setSessionFocus } from "./api.js";
-import type { Uuid } from "./types.js";
+import type { CatalogState, CatalogStore } from "./events.js";
+import { sessionName, type SessionView, type Uuid } from "./types.js";
 
 /**
  * How many *parked* (off-screen but still-connected) sessions to keep warm
@@ -16,6 +16,15 @@ import type { Uuid } from "./types.js";
  */
 const MAX_PARKED = 6;
 
+/** A session's view defaults to `"Terminal"` wherever it isn't carried —
+ *  matching the wire default (`SessionView`'s `#[default]`, types.ts). Only
+ *  meaningful once the session itself is known; an altogether-unknown
+ *  session (no `AttachInfo`/`Session` at all) is a distinct, un-resolved
+ *  state callers must check for separately, not "Terminal". */
+function resolveView(view: SessionView | undefined): SessionView {
+  return view ?? "Terminal";
+}
+
 export interface PoolOptions {
   /** Fired when the focused session changes (drives sidebar highlight + HUD). */
   onFocusChange?: (id: Uuid | null) => void;
@@ -27,6 +36,9 @@ export interface PoolOptions {
   onClosed?: (id: Uuid) => void;
   /** Forwarded to each connection: should a dropped socket be retried? */
   shouldReconnect?: (id: Uuid, code: number) => boolean;
+  /** Threaded through to a structured connection so its rail can read live
+   *  worktree/git-status data (#140). Terminal connections don't need it. */
+  store?: CatalogStore;
 }
 
 /**
@@ -40,12 +52,19 @@ export interface PoolOptions {
  */
 export class ConnectionPool {
   /** All live connections. Insertion order doubles as LRU: oldest first. */
-  private readonly cache = new Map<Uuid, AttachConnection>();
+  private readonly cache = new Map<Uuid, PaneConnection>();
+  /** The view each cached connection was actually created for — a deep link
+   *  or a restored layout can `mount()` a session before the catalog
+   *  snapshot names its view, defaulting it to `"Terminal"`; this is what
+   *  lets a later reconciliation notice the resolved view disagrees (#140
+   *  review). */
+  private readonly connViews = new Map<Uuid, SessionView>();
   /** Sessions currently mounted into a visible pane (never evicted). */
   private readonly mounted = new Set<Uuid>();
   private readonly hidden: HTMLElement;
   private focusedId: Uuid | null = null;
   private readonly opts: PoolOptions;
+  private readonly unsubscribeStore?: () => void;
 
   constructor(opts: PoolOptions = {}) {
     this.opts = opts;
@@ -54,6 +73,11 @@ export class ConnectionPool {
     this.hidden.className = "conn-cache";
     this.hidden.setAttribute("aria-hidden", "true");
     document.body.appendChild(this.hidden);
+    // A session `mount()`ed before its catalog entry exists gets a
+    // `"Terminal"` connection by default; once the snapshot actually names
+    // the view, fix any connection that guessed wrong — nothing else
+    // re-`mount()`s an already-open pane just because the catalog updated.
+    this.unsubscribeStore = opts.store?.subscribe((state) => this.reconcileViews(state));
   }
 
   /** The focused session, or null when nothing is focused (welcome pane). */
@@ -77,18 +101,18 @@ export class ConnectionPool {
   mount(id: Uuid, pane: HTMLElement, info?: AttachInfo, opts?: { focus?: boolean }): void {
     let conn = this.cache.get(id);
     if (conn) {
-      this.cache.delete(id);
+      // `info === undefined` means "session not known yet", not "Terminal" —
-      this.cache.set(id, conn);
+      // never downgrade a resolved connection just because a later caller
+      // couldn't resolve the session. Only a *resolved* view that disagrees
+      // with what this connection was built for forces a replace.
+      if (info !== undefined && resolveView(info.view) !== this.connViews.get(id)) {
+        conn = this.replace(id, info);
+      } else {
+        this.cache.delete(id);
+        this.cache.set(id, conn); // LRU refresh
+      }
     } else {
-      conn = createAttachConnection(
+      conn = this.create(id, info);
-        id,
-        {
-          onRequestClose: (sid) => this.opts.onRequestClose?.(sid),
-          onClosed: (sid) => this.opts.onClosed?.(sid),
-          shouldReconnect: (sid, code) => this.opts.shouldReconnect?.(sid, code) ?? false,
-        },
-        info,
-      );
       this.cache.set(id, conn);
     }
     if (conn.el.parentElement !== pane) {
@@ -101,6 +125,71 @@ export class ConnectionPool {
     this.evict();
   }
 
+  private create(id: Uuid, info?: AttachInfo): PaneConnection {
+    const view = resolveView(info?.view);
+    this.connViews.set(id, view);
+    const connOpts = {
+      onRequestClose: (sid: Uuid) => this.opts.onRequestClose?.(sid),
+      onClosed: (sid: Uuid) => this.opts.onClosed?.(sid),
+      shouldReconnect: (sid: Uuid, code: number) => this.opts.shouldReconnect?.(sid, code) ?? false,
+    };
+    return view === "Structured"
+      ? createStructuredConnection(id, connOpts, info, this.opts.store)
+      : createAttachConnection(id, connOpts, info);
+  }
+
+  /** Dispose whatever is cached for `id` and cache a freshly created
+   *  connection in its place. Does not touch the DOM or `mounted` — callers
+   *  place the new element themselves. */
+  private replace(id: Uuid, info?: AttachInfo): PaneConnection {
+    this.cache.get(id)?.dispose();
+    const fresh = this.create(id, info);
+    this.cache.set(id, fresh);
+    return fresh;
+  }
+
+  /** Proactively fix any cached connection whose view no longer matches the
+   *  catalog — the only path that repairs a pane nothing will `mount()`
+   *  again on its own (parked, or mounted but not currently being
+   *  re-rendered by anything else). A session absent from `state` (not yet
+   *  known, or removed) is left alone — that's `main.ts`'s
+   *  `closePane`/eviction concern, not a view mismatch. */
+  private reconcileViews(state: CatalogState): void {
+    for (const id of [...this.cache.keys()]) {
+      const session = state.sessions.get(id);
+      if (session === undefined || resolveView(session.view) === this.connViews.get(id)) continue;
+      const existing = this.cache.get(id)!;
+      const parent = existing.el.parentElement;
+      const wasMounted = this.mounted.has(id);
+      // Capture before anything below touches the DOM: dispose()/el.remove()
+      // detach `existing.el`, and once a focused descendant is detached the
+      // browser moves `document.activeElement` to `<body>` — too late to
+      // tell whether the keyboard was actually in this pane.
+      const hadDomFocus = existing.el.contains(document.activeElement);
+      const info: AttachInfo = { name: sessionName(session), command: session.command, view: session.view };
+      const fresh = this.replace(id, info);
+      existing.el.remove(); // don't rely on dispose() to clear the DOM
+      if (parent && parent !== this.hidden) {
+        parent.replaceChildren(fresh.el);
+      } else {
+        // Parked: `this.hidden` holds every parked connection's element as
+        // siblings — append, never replaceChildren, or they'd all vanish.
+        this.hidden.appendChild(fresh.el);
+      }
+      if (wasMounted) {
+        // `focusedId` names the session the pool was last told to focus —
+        // but a same-tab sidebar preview moves the keyboard into the
+        // sidebar without clearing it (multiview.ts skips `setFocus` while
+        // previewing), so `focusedId` alone can point at a pane the
+        // keyboard already left. Only re-focus when the DOM agrees it
+        // never did.
+        fresh.onMount({ focus: this.focusedId === id && hadDomFocus });
+      } else {
+        fresh.onUnmount();
+      }
+    }
+  }
+
   /** Park `id` back into the hidden cache (still connected) and stop showing it. */
   unmount(id: Uuid): void {
     if (!this.mounted.delete(id)) return;
@@ -177,13 +266,16 @@ export class ConnectionPool {
     if (!conn) return;
     conn.dispose();
     this.cache.delete(id);
+    this.connViews.delete(id);
     this.mounted.delete(id);
     if (this.focusedId === id) this.setFocus(null);
   }
 
   dispose(): void {
+    this.unsubscribeStore?.();
     for (const conn of this.cache.values()) conn.dispose();
     this.cache.clear();
+    this.connViews.clear();
     this.mounted.clear();
     this.hidden.remove();
   }

web/src/main.ts

@@ -172,6 +172,7 @@ const pool = new ConnectionPool({
   onRequestClose: (id) => closePane(id),
   onClosed: (id) => closePane(id),
   shouldReconnect: (id, code) => shouldRetryClose(id, code, store.snapshot().sessions),
+  store,
 });
 
 // Session death used to reach the UI on two uncoordinated channels — the row
@@ -209,7 +210,7 @@ function scheduleSave(): void {
 
 function infoFor(sessionId: string) {
   const s = store.snapshot().sessions.get(sessionId);
-  return s ? { name: sessionName(s), command: s.command } : undefined;
+  return s ? { name: sessionName(s), command: s.command, view: s.view } : undefined;
 }
 
 /** Drive the shell's responsive layout off whether any pane is open. */

web/src/pane.ts

@@ -0,0 +1,26 @@
+// Shared shape a mounted pane connection satisfies, whatever session view is
+// behind it — what ConnectionPool needs to mount/park/dispose a pane without
+// caring whether it holds an xterm attach (attach.ts) or a structured
+// transcript (structured.ts).
+
+import type { Uuid } from "./types.js";
+
+export interface PaneConnection {
+  readonly sessionId: Uuid;
+  /** The element to mount into a pane. */
+  readonly el: HTMLElement;
+  /** Becomes the visible view: fit/focus/sync as the connection needs.
+   *  `focus: false` mounts without taking the keyboard (a sidebar preview). */
+  onMount(opts?: { focus?: boolean }): void;
+  /** Parked into the hidden cache: keep streaming, stop driving focus/sizing. */
+  onUnmount(): void;
+  /** Put the keyboard into this pane's primary input — the terminal for an
+   *  attach connection, the composer for a structured one. */
+  focusTerminal(): void;
+  /** Raw bytes into a PTY, bypassing normal key handling (the leader's
+   *  literal-byte escape hatch, docs/COMMAND-BAR.md). A structured connection
+   *  has no PTY, so this is a no-op there. */
+  sendInput(data: string): void;
+  /** Fully disconnect and remove the element. */
+  dispose(): void;
+}

web/src/paneTitle.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from "vitest";
+
+import { paneTitleAttr, paneTitleHtml } from "./paneTitle.js";
+
+describe("paneTitleHtml", () => {
+  it("falls back to a short session id when there is no info yet", () => {
+    expect(paneTitleHtml("abcdef12-3456-7890-abcd-ef1234567890")).toContain("abcdef12");
+  });
+
+  it("shows the name alone when command matches it", () => {
+    const html = paneTitleHtml("s1", { name: "claude", command: "claude" });
+    expect(html).toContain("claude");
+    expect(html).not.toContain("at-cmd");
+  });
+
+  it("escapes a name that looks like markup", () => {
+    const html = paneTitleHtml("s1", { name: "<img onerror=x>", command: "claude" });
+    expect(html).not.toContain("<img");
+  });
+});
+
+describe("paneTitleAttr", () => {
+  it("escapes the attribute form too", () => {
+    const attr = paneTitleAttr("s1", { name: '"quoted"', command: "claude" });
+    expect(attr).not.toContain('"quoted"');
+    expect(attr).toContain("&quot;quoted&quot;");
+  });
+});

web/src/paneTitle.ts

@@ -0,0 +1,36 @@
+// Pane header title: name/command echoing the sidebar card, shared by the
+// xterm attach view (attach.ts) and the structured transcript view
+// (structured.ts) so both panes read identically.
+
+import { escapeHtml } from "./html.js";
+import { splitCommand, toolIconSvg } from "./toolIcon.js";
+import type { SessionView, Uuid } from "./types.js";
+
+/** What a pane header shows about its session. Falls back to a short session
+ * id when the session isn't known yet. */
+export interface AttachInfo {
+  name: string;
+  command: string;
+  /** Which connection kind to mount (#140). Absent/`"Terminal"` mounts the
+   * xterm attach; `"Structured"` mounts the transcript view. */
+  view?: SessionView;
+}
+
+function commandFragment(command: string): string {
+  const { tool, program } = splitCommand(command);
+  const icon = tool ? toolIconSvg(tool) : null;
+  const text = icon ? "" : program;
+  return `<span class="at-cmd">${icon ?? ""}${text ? escapeHtml(text) : ""}</span>`;
+}
+
+export function paneTitleHtml(sessionId: Uuid, info?: AttachInfo): string {
+  return info
+    ? `<span class="at-name">${escapeHtml(info.name)}</span>` +
+        (info.command && info.command !== info.name ? commandFragment(info.command) : "")
+    : `session <span class="sid">${escapeHtml(sessionId.slice(0, 8))}</span>`;
+}
+
+/** Attribute-safe (`title="..."`) form of the same identity. */
+export function paneTitleAttr(sessionId: Uuid, info?: AttachInfo): string {
+  return escapeHtml(info ? `${info.name} · ${info.command}  (${sessionId})` : sessionId);
+}

web/src/routes.ts

@@ -37,6 +37,27 @@ export function sessionFocus(id: Uuid): string {
   return `${session(id)}/focus`;
 }
 
+/** `WS /api/structured/:id` — transcript/state snapshots and live deltas. */
+export function structured(id: Uuid): string {
+  return `${API_PREFIX}/structured/${encodeURIComponent(id)}`;
+}
+
+/** `POST /api/sessions/:id/structured/prompt` — send an ACP prompt. */
+export function structuredPrompt(id: Uuid): string {
+  return `${session(id)}/structured/prompt`;
+}
+
+/** `POST /api/sessions/:id/structured/cancel` — cancel an ACP turn. */
+export function structuredCancel(id: Uuid): string {
+  return `${session(id)}/structured/cancel`;
+}
+
+/** `POST /api/sessions/:id/structured/approvals/:nonce` — answer a permission
+ * request. */
+export function structuredApproval(id: Uuid, nonce: string): string {
+  return `${session(id)}/structured/approvals/${encodeURIComponent(nonce)}`;
+}
+
 /** Append the `path` query parameter `DIRS` and `GITROOT` accept. */
 export function withPathQuery(route: string, value: string): string {
   return `${route}?${PATH_QUERY}=${encodeURIComponent(value)}`;
@@ -55,3 +76,7 @@ export function eventsWsUrl(): string {
 export function attachWsUrl(id: Uuid): string {
   return `${wsBase()}${attach(id)}`;
 }
+
+export function structuredWsUrl(id: Uuid): string {
+  return `${wsBase()}${structured(id)}`;
+}

web/src/spawnForm.test.ts

@@ -6,6 +6,7 @@ const base: SpawnFormValues = {
   command: "claude",
   cwd: "/home/user/project",
   name: "amber-fox",
+  structuredView: false,
   worktreeEnabled: false,
   worktreeBranch: "",
   worktreeBranchMode: "new",
@@ -25,6 +26,22 @@ describe("buildSpawnRequest", () => {
     expect(res).toEqual({ req: { cwd: base.cwd, command: base.command, metadata: {} } });
   });
 
+  it("requests structured view only for Claude Code", () => {
+    expect(buildSpawnRequest({ ...base, structuredView: true }, null)).toEqual({
+      req: {
+        cwd: base.cwd,
+        command: "claude",
+        metadata: { name: "amber-fox" },
+        view: "Structured",
+      },
+    });
+    expect(
+      buildSpawnRequest({ ...base, command: "opencode", structuredView: true }, null),
+    ).toEqual({
+      req: { cwd: base.cwd, command: "opencode", metadata: { name: "amber-fox" } },
+    });
+  });
+
   it("attaches a trimmed branch when worktree is enabled, and always cleans up", () => {
     const res = buildSpawnRequest(
       { ...base, worktreeEnabled: true, worktreeBranch: "  feat/foo  " },

web/src/spawnForm.ts

@@ -11,6 +11,7 @@ import { attachDirAutocomplete } from "./dirAutocomplete.js";
 import { parentDir } from "./paths.js";
 import { filterProjects, groupProjects, isStale, sortProjects } from "./projectList.js";
 import type { ProjectGroup } from "./projectList.js";
+import { splitCommand } from "./toolIcon.js";
 import { abbreviateCwd } from "./types.js";
 import type { BranchInfo, CreateSessionRequest, Project, Session, SpawnPreset } from "./types.js";
 
@@ -40,6 +41,7 @@ export interface SpawnFormValues {
   command: string;
   cwd: string;
   name: string;
+  structuredView: boolean;
   worktreeEnabled: boolean;
   worktreeBranch: string;
   worktreeBranchEdited: boolean;
@@ -66,6 +68,10 @@ export function buildSpawnRequest(
     metadata,
   };
 
+  if (values.structuredView && splitCommand(values.command).tool === "claude") {
+    req.view = "Structured";
+  }
+
   if (values.worktreeEnabled) {
     const mode = values.worktreeBranchMode ?? "new";
     const branch = values.worktreeBranch.trim();
@@ -153,6 +159,10 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
         <span class="wt-summary"></span>
       </button>
       <div class="wt-collapsible" hidden>
+        <label class="row-inline structured-view" hidden>
+          <input type="checkbox" name="structured_view" />
+          Structured view
+        </label>
         <div class="field wt-step" hidden>
           <span class="field-label">Worktree</span>
           <div class="picker wt-choices"></div>
@@ -203,6 +213,8 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
   const wtChoices = form.querySelector(".wt-choices") as HTMLElement;
   const cwdRawWrap = form.querySelector(".cwd-raw-wrap") as HTMLElement;
   const cwdRaw = form.querySelector(".cwd-raw") as HTMLInputElement;
+  const structuredWrap = form.querySelector(".structured-view") as HTMLElement;
+  const structuredView = form.querySelector("input[name=structured_view]") as HTMLInputElement;
   const wtEnabled = form.querySelector("input[name=worktree_enabled]") as HTMLInputElement;
   const wtToggle = form.querySelector(".wt-toggle") as HTMLButtonElement;
   const wtCollapsible = form.querySelector(".wt-collapsible") as HTMLElement;
@@ -248,6 +260,7 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
       command,
       cwd,
       name: nameInput.value,
+      structuredView: structuredView.checked,
       worktreeEnabled: wtEnabled.checked,
       worktreeBranch: branchValue(),
       worktreeBranchEdited: branchEdited,
@@ -317,6 +330,7 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
     } else {
       command = preset!.command;
     }
+    updateStructuredAvailability();
     for (const tile of cmdTiles.querySelectorAll(".tile")) {
       tile.classList.toggle("is-active", (tile as HTMLElement).dataset.id === id);
     }
@@ -354,10 +368,19 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
   // operator has already touched (#76).
   let commandTouched = false;
 
+  function updateStructuredAvailability(): void {
+    const supported = splitCommand(command).tool === "claude";
+    structuredWrap.hidden = !supported;
+    if (!supported) structuredView.checked = false;
+  }
+
+  structuredView.addEventListener("change", emit);
+
   cmdRaw.addEventListener("input", () => {
     if (selectedPresetId === "custom" || presets.find((p) => p.id === selectedPresetId)?.command === "") {
       commandTouched = true;
       command = cmdRaw.value.trim();
+      updateStructuredAvailability();
       emit();
     }
   });
@@ -844,10 +867,11 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
     if (e.key !== "Enter" || e.defaultPrevented) return;
     const target = e.target as HTMLElement;
 
-    if (target === wtEnabled) {
+    if (target === wtEnabled || target === structuredView) {
       e.preventDefault();
-      wtEnabled.checked = !wtEnabled.checked;
+      const checkbox = target as HTMLInputElement;
-      wtEnabled.dispatchEvent(new Event("change"));
+      checkbox.checked = !checkbox.checked;
+      checkbox.dispatchEvent(new Event("change"));
       return;
     }
 
@@ -885,6 +909,7 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
         command,
         cwd,
         name: nameInput.value,
+        structuredView: structuredView.checked,
         worktreeEnabled: wtEnabled.checked,
         worktreeBranch: branchValue(),
         worktreeBranchEdited: branchEdited,

web/src/spawnFormStructured.test.ts

@@ -0,0 +1,108 @@
+// @vitest-environment happy-dom
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { createSpawnForm, type SpawnFormHandle } from "./spawnForm.js";
+
+function stubApi(): RequestInit[] {
+  const sessionRequests: RequestInit[] = [];
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async (input: RequestInfo | URL, init?: RequestInit) => {
+      const url = String(input);
+      if (url.includes("/api/sessions") && init?.method === "POST") {
+        sessionRequests.push(init);
+        return new Response(JSON.stringify({ id: "s1", command: "claude", cwd: "/srv/work" }), {
+          status: 200,
+        });
+      }
+      if (url.includes("/api/info")) {
+        return new Response(
+          JSON.stringify({ hostname: "h", version: "0", home_dir: "/home/user" }),
+          { status: 200 },
+        );
+      }
+      if (url.includes("/api/names")) {
+        return new Response(JSON.stringify({ names: ["amber-fox"] }), { status: 200 });
+      }
+      return new Response(JSON.stringify([]), { status: 200 });
+    }),
+  );
+  return sessionRequests;
+}
+
+describe("spawn form structured view", () => {
+  let handle: SpawnFormHandle | null = null;
+
+  async function drain(): Promise<void> {
+    for (let i = 0; i < 20; i++) await Promise.resolve();
+  }
+
+  afterEach(async () => {
+    handle?.destroy();
+    handle = null;
+    await drain();
+    vi.unstubAllGlobals();
+  });
+
+  it("is default-off and shown only for the resolved Claude Code command", async () => {
+    stubApi();
+    handle = createSpawnForm({ onSuccess() {} });
+    document.body.appendChild(handle.el);
+    await drain();
+
+    const wrap = handle.el.querySelector<HTMLElement>(".structured-view")!;
+    const checkbox = wrap.querySelector<HTMLInputElement>("input")!;
+    const disclosure = handle.el.querySelector<HTMLElement>(".wt-collapsible")!;
+    expect(disclosure.hidden).toBe(true);
+    handle.el.querySelector<HTMLButtonElement>(".wt-toggle")!.click();
+    expect(disclosure.hidden).toBe(false);
+    expect(wrap.hidden).toBe(false);
+    expect(checkbox.checked).toBe(false);
+
+    handle.el.querySelector<HTMLButtonElement>('[data-id="opencode"]')!.click();
+    expect(wrap.hidden).toBe(true);
+
+    handle.el.querySelector<HTMLButtonElement>('[data-id="claude"]')!.click();
+    expect(wrap.hidden).toBe(false);
+  });
+
+  it("clears a checked value when the command changes away from Claude Code", async () => {
+    stubApi();
+    handle = createSpawnForm({ onSuccess() {} });
+    document.body.appendChild(handle.el);
+    await drain();
+
+    const checkbox = handle.el.querySelector<HTMLInputElement>("input[name=structured_view]")!;
+    checkbox.click();
+    expect(checkbox.checked).toBe(true);
+
+    const custom = handle.el.querySelector<HTMLButtonElement>('[data-id="custom"]')!;
+    custom.click();
+    const command = handle.el.querySelector<HTMLInputElement>(".cmd-raw")!;
+    command.value = "opencode";
+    command.dispatchEvent(new Event("input"));
+
+    expect(checkbox.closest<HTMLElement>(".structured-view")!.hidden).toBe(true);
+    expect(checkbox.checked).toBe(false);
+  });
+
+  it("emits Structured in the submitted request when selected", async () => {
+    const requests = stubApi();
+    handle = createSpawnForm({
+      seed: { cwd: "/srv/work", cwdRawVisible: true, worktreeEnabled: false },
+      onSuccess() {},
+    });
+    document.body.appendChild(handle.el);
+    await drain();
+
+    handle.el.querySelector<HTMLInputElement>("input[name=structured_view]")!.click();
+    handle.el.requestSubmit();
+    await drain();
+
+    expect(requests).toHaveLength(1);
+    expect(JSON.parse(String(requests[0].body))).toMatchObject({
+      command: "claude",
+      view: "Structured",
+    });
+  });
+});

web/src/structured.ts

@@ -0,0 +1,628 @@
+// A single live structured session: a transcript + rail bound to the
+// daemon's `WS /api/structured/:id` (#140). Mirrors attach.ts's contract —
+// decoupled from the UI, streaming whether or not mounted, torn down only by
+// `dispose()` — but the wire is JSON rows, not PTY bytes, and every connect
+// (fresh or reconnect) resends the *whole* transcript rather than resuming a
+// cursor (docs/STRUCTURED-VIEW.md), so a snapshot always replaces state
+// wholesale instead of being merged into what came before.
+
+import {
+  cancelStructuredTurn,
+  resolveStructuredApproval,
+  sendStructuredPrompt,
+  structuredWsUrl,
+} from "./api.js";
+import { requestToggleDrawer } from "./drawer.js";
+import type { CatalogState, CatalogStore } from "./events.js";
+import { paneTitleAttr, paneTitleHtml, type AttachInfo } from "./paneTitle.js";
+import type { PaneConnection } from "./pane.js";
+import { INITIAL_RECONNECT_MS, MAX_RECONNECT_MS } from "./reconnect.js";
+import { buildTranscriptRow, renderRail } from "./structuredRender.js";
+import type {
+  AcpPlan,
+  AcpUsage,
+  ReducedState,
+  Session,
+  StructuredApprovalDecision,
+  StructuredEvent,
+  TranscriptDelta,
+  TranscriptRow,
+  TranscriptRowKind,
+  Uuid,
+} from "./types.js";
+
+export interface StructuredOptions {
+  onRequestClose?: (sessionId: Uuid) => void;
+  onClosed?: (sessionId: Uuid) => void;
+  shouldReconnect?: (sessionId: Uuid, code: number) => boolean;
+}
+
+/** Injectable so tests can drive the socket without a daemon — the same seam
+ *  `CatalogStore` uses (events.ts). */
+export type StructuredSocketFactory = (sessionId: Uuid) => WebSocket;
+
+const idleTurn = (): ReducedState["turn"] => ({
+  responding: false,
+  thinking: false,
+  active_tool_calls: [],
+});
+
+export function createStructuredConnection(
+  sessionId: Uuid,
+  opts: StructuredOptions = {},
+  info?: AttachInfo,
+  store?: CatalogStore,
+  socketFactory: StructuredSocketFactory = (id) => new WebSocket(structuredWsUrl(id)),
+): PaneConnection {
+  const el = document.createElement("div");
+  el.className = "attach structured";
+  el.innerHTML = `
+    <header class="attach-header">
+      <button type="button" class="btn btn-ghost btn-icon sessions-btn" aria-label="Show sessions" title="Show sessions">☰</button>
+      <span class="attach-title" title="${paneTitleAttr(sessionId, info)}">${paneTitleHtml(sessionId, info)}</span>
+      <span class="st-pills"></span>
+      <span class="attach-state" data-state="connecting">connecting…</span>
+      <button class="btn btn-ghost btn-icon disconnect" type="button" aria-label="Disconnect" title="Disconnect this session">⏻</button>
+    </header>
+    <div class="structured-body">
+      <div class="structured-scroll">
+        <div class="structured-rows"></div>
+        <form class="structured-composer">
+          <textarea class="structured-input" rows="1" placeholder="Reply, or / for commands…"></textarea>
+          <button type="submit" class="btn btn-primary structured-send">Send</button>
+          <button type="button" class="btn structured-cancel" hidden>Cancel turn</button>
+        </form>
+      </div>
+      <aside class="structured-rail"></aside>
+    </div>
+  `;
+
+  const stateEl = el.querySelector(".attach-state") as HTMLSpanElement;
+  const pillsEl = el.querySelector(".st-pills") as HTMLSpanElement;
+  const disconnectBtn = el.querySelector(".disconnect") as HTMLButtonElement;
+  const scrollEl = el.querySelector(".structured-scroll") as HTMLDivElement;
+  const rowsEl = el.querySelector(".structured-rows") as HTMLDivElement;
+  const railEl = el.querySelector(".structured-rail") as HTMLElement;
+  const bodyEl = el.querySelector(".structured-body") as HTMLElement;
+  const composerForm = el.querySelector(".structured-composer") as HTMLFormElement;
+  const input = el.querySelector(".structured-input") as HTMLTextAreaElement;
+  const sendBtn = el.querySelector(".structured-send") as HTMLButtonElement;
+  const cancelBtn = el.querySelector(".structured-cancel") as HTMLButtonElement;
+
+  disconnectBtn.addEventListener("click", () => opts.onRequestClose?.(sessionId));
+  // Mobile-only (CSS hides it on desktop, where the sidebar is always in
+  // view): the session list is an off-canvas drawer and this opens it —
+  // same control attach.ts's terminal header carries.
+  (el.querySelector(".sessions-btn") as HTMLElement).addEventListener("click", () =>
+    requestToggleDrawer(),
+  );
+
+  const setConnState = (text: string, kind: "connecting" | "open" | "closed" | "error") => {
+    stateEl.textContent = text;
+    stateEl.dataset.state = kind;
+  };
+
+  // ---- transcript state: mirrors the daemon's own Projection shape (id ->
+  // index, patched in place) so a Patch never needs to search the array. ----
+  let rows: TranscriptRow[] = [];
+  const rowIndex = new Map<string, number>();
+  const rowEls = new Map<string, HTMLElement>();
+  const expandedRowIds = new Set<string>();
+  let state: ReducedState = { turn: idleTurn() };
+  let pendingApprovalRowId: string | null = null;
+  let latestSession: Session | undefined = store?.snapshot().sessions.get(sessionId);
+  let submissionGeneration = 0;
+  let awaitingBeginGeneration: number | null = null;
+  let acceptedSubmission: { generation: number; socketGeneration: number } | null = null;
+  let socketGeneration = 0;
+  let stateSocketGeneration = 0;
+  let disposed = false;
+
+  // Within 64px, wheel and touch imprecision should still count as following.
+  const FOLLOW_BOTTOM_THRESHOLD_PX = 64;
+  let followingBottom = true;
+  let receivedSnapshot = false;
+  let scrollWorkActive = true;
+  let parkedScrollTop: number | null = null;
+  let scrollFrame: number | null = null;
+  let pendingScroll: { top: number; follow: boolean } | null = null;
+
+  function cancelScrollFrame(): void {
+    if (scrollFrame !== null) window.cancelAnimationFrame(scrollFrame);
+    scrollFrame = null;
+    pendingScroll = null;
+  }
+
+  function beginTranscriptLayout(forceBottom = false): void {
+    if (!scrollWorkActive || disposed) return;
+    if (pendingScroll) {
+      if (forceBottom) pendingScroll.follow = true;
+      return;
+    }
+    pendingScroll = {
+      top: scrollEl.scrollTop,
+      follow: forceBottom || followingBottom,
+    };
+  }
+
+  function finishTranscriptLayout(): void {
+    if (!scrollWorkActive || disposed || !pendingScroll || scrollFrame !== null) return;
+    scrollFrame = window.requestAnimationFrame(() => {
+      scrollFrame = null;
+      const pending = pendingScroll;
+      pendingScroll = null;
+      if (!pending || disposed || !scrollWorkActive) return;
+      scrollEl.scrollTop = pending.follow
+        ? Math.max(0, scrollEl.scrollHeight - scrollEl.clientHeight)
+        : pending.top;
+    });
+  }
+
+  function updateTranscriptLayout(update: () => void, forceBottom = false): void {
+    beginTranscriptLayout(forceBottom);
+    update();
+    finishTranscriptLayout();
+  }
+
+  function onTranscriptScroll(): void {
+    const distance = scrollEl.scrollHeight - scrollEl.clientHeight - scrollEl.scrollTop;
+    followingBottom = distance <= FOLLOW_BOTTOM_THRESHOLD_PX;
+    cancelScrollFrame();
+  }
+
+  function onTranscriptClick(event: Event): void {
+    if ((event.target as Element | null)?.closest(".st-tool-head")) beginTranscriptLayout();
+  }
+
+  scrollEl.addEventListener("scroll", onTranscriptScroll);
+  scrollEl.addEventListener("click", onTranscriptClick, true);
+
+  function lastRowIdOfKind(kind: TranscriptRowKind): string | null {
+    for (let i = rows.length - 1; i >= 0; i--) if (rows[i].kind === kind) return rows[i].id;
+    return null;
+  }
+
+  function approvalStateFor(row: TranscriptRow) {
+    if (row.kind !== "approval") return undefined;
+    return {
+      pending: row.id === pendingApprovalRowId,
+      onDecide: (decision: StructuredApprovalDecision) => decide(row.id, decision),
+    };
+  }
+
+  async function decide(rowId: string, decision: StructuredApprovalDecision): Promise<void> {
+    const nonce = state.pending_approval?.nonce;
+    // Already resolved elsewhere between the click and here — the row's
+    // buttons should already be gone, but a stale nonce is a no-op, not an
+    // error (docs/STRUCTURED-VIEW.md: any nonce answers 204). Resolve
+    // quietly: there is nothing for the row to restore.
+    if (!nonce || rowId !== pendingApprovalRowId) return;
+    try {
+      await resolveStructuredApproval(sessionId, nonce, decision);
+    } catch (e: unknown) {
+      // Only propagate the failure — so the row re-enables its buttons — if
+      // this is still the pending approval. If it moved on while the
+      // request was in flight (superseded, cancelled, answered elsewhere),
+      // the state-driven re-render already replaced the row; reviving
+      // buttons on it would be reviving a decision that no longer applies.
+      if (!disposed && rowId === pendingApprovalRowId) {
+        showError(String(e));
+        throw e;
+      }
+    }
+  }
+
+  function buildRowElement(row: TranscriptRow): HTMLElement | null {
+    const el = buildTranscriptRow(
+      row,
+      approvalStateFor(row),
+      expandedRowIds.has(row.id),
+      (expanded) => {
+        if (expanded) expandedRowIds.add(row.id);
+        else expandedRowIds.delete(row.id);
+        finishTranscriptLayout();
+      },
+    );
+    if (!el) return null;
+    if (el.querySelector(".st-tool-head")?.getAttribute("aria-expanded") !== "true") {
+      expandedRowIds.delete(row.id);
+    }
+    return el;
+  }
+
+  function insertRowElement(row: TranscriptRow, el: HTMLElement): void {
+    const index = rowIndex.get(row.id) ?? rows.length - 1;
+    let next: HTMLElement | null = null;
+    for (let i = index + 1; i < rows.length; i++) {
+      next = rowEls.get(rows[i].id) ?? null;
+      if (next) break;
+    }
+    rowEls.set(row.id, el);
+    rowsEl.insertBefore(el, next);
+  }
+
+  function mountRow(row: TranscriptRow): void {
+    const el = buildRowElement(row);
+    if (el) insertRowElement(row, el);
+  }
+
+  function remountRow(row: TranscriptRow): void {
+    const old = rowEls.get(row.id);
+    const oldToolHead = old?.querySelector<HTMLButtonElement>(".st-tool-head") ?? null;
+    const restoreFocus = document.activeElement === oldToolHead;
+    const el = buildRowElement(row);
+    if (!el) {
+      old?.remove();
+      rowEls.delete(row.id);
+      expandedRowIds.delete(row.id);
+      return;
+    }
+    if (old) {
+      rowEls.set(row.id, el);
+      old.replaceWith(el);
+    } else {
+      insertRowElement(row, el);
+    }
+    const newToolHead = el.querySelector<HTMLButtonElement>(".st-tool-head");
+    if (restoreFocus) newToolHead?.focus();
+  }
+
+  function applySnapshot(snapshot: { rows: TranscriptRow[] }): void {
+    const forceBottom = !receivedSnapshot;
+    updateTranscriptLayout(() => {
+      rows = [...snapshot.rows];
+      const expandableIds = new Set(
+        rows.filter((row) => row.kind === "tool_call" || row.kind === "tool_diff").map((row) => row.id),
+      );
+      for (const id of expandedRowIds) if (!expandableIds.has(id)) expandedRowIds.delete(id);
+      rowIndex.clear();
+      rows.forEach((row, i) => rowIndex.set(row.id, i));
+      rowEls.clear();
+      rowsEl.replaceChildren();
+      for (const row of rows) mountRow(row);
+    }, forceBottom);
+    receivedSnapshot = true;
+  }
+
+  function applyDelta(delta: TranscriptDelta | null | undefined): void {
+    if (!delta) return;
+    updateTranscriptLayout(() => {
+      if (delta.type === "append") {
+        rowIndex.set(delta.row.id, rows.length);
+        rows.push(delta.row);
+        mountRow(delta.row);
+      } else if (delta.type === "patch") {
+        const i = rowIndex.get(delta.row.id);
+        if (i === undefined) {
+          rowIndex.set(delta.row.id, rows.length);
+          rows.push(delta.row);
+          mountRow(delta.row);
+        } else {
+          rows[i] = delta.row;
+          remountRow(delta.row);
+        }
+      } else {
+        const i = rowIndex.get(delta.id);
+        if (i === undefined) return;
+        rows.splice(i, 1);
+        expandedRowIds.delete(delta.id);
+        rowIndex.clear();
+        rows.forEach((row, idx) => rowIndex.set(row.id, idx));
+        rowEls.get(delta.id)?.remove();
+        rowEls.delete(delta.id);
+      }
+    });
+  }
+
+  function toolRowCount(): number {
+    return rows.reduce((n, r) => n + (r.kind === "tool_call" || r.kind === "tool_diff" ? 1 : 0), 0);
+  }
+
+  function renderPills(): void {
+    const parts: string[] = [];
+    if (state.model) parts.push(state.model);
+    if (state.mode) parts.push(state.mode);
+    pillsEl.textContent = parts.join(" · ");
+  }
+
+  function renderRailNow(): void {
+    renderRail(railEl, {
+      plan: (state.plan ?? null) as AcpPlan | null,
+      turn: state.turn,
+      toolRowCount: toolRowCount(),
+      usage: (state.usage ?? null) as AcpUsage | null,
+      session: latestSession,
+    });
+  }
+
+  function renderComposerState(): void {
+    const active = state.turn.responding || state.turn.thinking || awaitingBeginGeneration !== null;
+    input.disabled = active;
+    sendBtn.disabled = active;
+    cancelBtn.hidden = !state.turn.responding && !state.turn.thinking;
+  }
+
+  function reconcileAwaitingBegin(): void {
+    if (state.turn.responding || state.turn.thinking) {
+      awaitingBeginGeneration = null;
+    } else if (
+      awaitingBeginGeneration !== null
+      && acceptedSubmission?.generation === awaitingBeginGeneration
+      && stateSocketGeneration > acceptedSubmission.socketGeneration
+    ) {
+      awaitingBeginGeneration = null;
+    }
+  }
+
+  function applyState(next: ReducedState, connectionGeneration: number): void {
+    state = next;
+    stateSocketGeneration = connectionGeneration;
+    reconcileAwaitingBegin();
+    const newPendingId = state.pending_approval ? lastRowIdOfKind("approval") : null;
+    if (newPendingId !== pendingApprovalRowId) {
+      updateTranscriptLayout(() => {
+        const prev = pendingApprovalRowId;
+        pendingApprovalRowId = newPendingId;
+        if (prev !== null && rowIndex.has(prev)) remountRow(rows[rowIndex.get(prev)!]);
+        if (newPendingId !== null) remountRow(rows[rowIndex.get(newPendingId)!]);
+      });
+    }
+    renderPills();
+    renderRailNow();
+    renderComposerState();
+  }
+
+  // ---- error banner ----
+  let errorEl: HTMLElement | null = null;
+  function showError(message: string): void {
+    if (!errorEl) {
+      errorEl = document.createElement("div");
+      errorEl.className = "structured-error";
+      composerForm.insertAdjacentElement("beforebegin", errorEl);
+    }
+    errorEl.textContent = message;
+  }
+  function clearError(): void {
+    errorEl?.remove();
+    errorEl = null;
+  }
+
+  // ---- composer ----
+  function autoResize(): void {
+    updateTranscriptLayout(() => {
+      input.style.height = "auto";
+      input.style.height = `${Math.min(input.scrollHeight, 160)}px`;
+    });
+  }
+  input.addEventListener("input", autoResize);
+  input.addEventListener("keydown", (e) => {
+    if (e.key === "Enter" && !e.shiftKey) {
+      e.preventDefault();
+      composerForm.requestSubmit();
+    }
+  });
+  composerForm.addEventListener("submit", (e) => {
+    e.preventDefault();
+    const text = input.value;
+    if (!text.trim() || input.disabled) return;
+    const generation = ++submissionGeneration;
+    const submissionSocketGeneration = socketGeneration;
+    awaitingBeginGeneration = generation;
+    acceptedSubmission = null;
+    input.value = "";
+    autoResize();
+    clearError();
+    renderComposerState();
+    sendStructuredPrompt(sessionId, text).then(
+      () => {
+        if (
+          disposed
+          || generation !== submissionGeneration
+          || awaitingBeginGeneration !== generation
+        ) return;
+        const acceptanceSocketGeneration = socketGeneration;
+        acceptedSubmission = { generation, socketGeneration: acceptanceSocketGeneration };
+        // A replacement socket may have captured idle before the POST claimed
+        // the prompt. Reconnect again so its snapshot cannot predate the 204.
+        if (acceptanceSocketGeneration > submissionSocketGeneration) reconnectForReconciliation();
+      },
+      (e: unknown) => {
+        if (disposed || generation !== submissionGeneration) return;
+        if (awaitingBeginGeneration === generation) awaitingBeginGeneration = null;
+        if (input.value === "") {
+          input.value = text;
+          autoResize();
+        }
+        showError(String(e));
+        renderComposerState();
+      },
+    );
+  });
+  cancelBtn.addEventListener("click", () => {
+    clearError();
+    cancelStructuredTurn(sessionId).catch((e: unknown) => {
+      if (!disposed) showError(String(e));
+    });
+  });
+
+  // ---- narrow-pane rail collapse (a split pane, not just the viewport) ----
+  const NARROW_BREAKPOINT = 560;
+  const resizeObserver = new ResizeObserver((entries) => {
+    if (disposed) return;
+    const width = entries[0]?.contentRect.width ?? bodyEl.clientWidth;
+    const narrow = width < NARROW_BREAKPOINT;
+    if (bodyEl.classList.contains("st-narrow") === narrow) return;
+    updateTranscriptLayout(() => bodyEl.classList.toggle("st-narrow", narrow));
+  });
+  resizeObserver.observe(bodyEl);
+
+  // ---- live worktree/git-status rail data ----
+  const unsubscribeStore = store?.subscribe((catalog: CatalogState) => {
+    if (disposed) return;
+    latestSession = catalog.sessions.get(sessionId);
+    renderRailNow();
+  });
+
+  // ---- socket lifecycle ----
+  let ws: WebSocket | null = null;
+  let reconnectMs = INITIAL_RECONNECT_MS;
+  let reconnectTimer: number | null = null;
+
+  function cancelReconnect(): void {
+    if (reconnectTimer === null) return;
+    window.clearTimeout(reconnectTimer);
+    reconnectTimer = null;
+  }
+
+  function closeCurrentSocket(): void {
+    const socket = ws;
+    ws = null;
+    if (!socket) return;
+    socket.onopen = null;
+    socket.onmessage = null;
+    socket.onerror = null;
+    socket.onclose = null;
+    try {
+      socket.close();
+    } catch {
+      // ignore
+    }
+  }
+
+  function reconnectForReconciliation(): void {
+    if (disposed) return;
+    cancelReconnect();
+    closeCurrentSocket();
+    setConnState("reconnecting…", "connecting");
+    connect();
+  }
+
+  function connect(): void {
+    if (disposed) return;
+    cancelReconnect();
+    closeCurrentSocket();
+    const connectionGeneration = ++socketGeneration;
+    const socket = socketFactory(sessionId);
+    ws = socket;
+    socket.onopen = () => {
+      if (disposed || ws !== socket) return;
+      reconnectMs = INITIAL_RECONNECT_MS;
+      setConnState("connected", "open");
+    };
+    socket.onmessage = (ev) => {
+      if (disposed || ws !== socket) return;
+      if (typeof ev.data !== "string") return;
+      let msg: StructuredEvent;
+      try {
+        msg = JSON.parse(ev.data) as StructuredEvent;
+      } catch {
+        return; // not a structured event we understand
+      }
+      switch (msg.type) {
+        case "transcript_snapshot":
+          applySnapshot(msg.snapshot);
+          break;
+        case "reduced_state":
+          applyState(msg.state, connectionGeneration);
+          break;
+        case "projection_update":
+          applyDelta(msg.transcript);
+          applyState(msg.state, connectionGeneration);
+          break;
+      }
+    };
+    socket.onerror = () => {
+      if (disposed || ws !== socket) return;
+      setConnState("error", "error");
+    };
+    socket.onclose = (ev) => {
+      if (disposed || ws !== socket) return;
+      ws = null;
+      const reason = ev.reason?.trim();
+      if (ev.code >= 4000 && reason) {
+        setConnState(reason, "error");
+        showError(`cannot attach: ${reason}`);
+        return;
+      }
+      if (opts.shouldReconnect?.(sessionId, ev.code)) {
+        const delay = Math.min(reconnectMs, MAX_RECONNECT_MS);
+        setConnState("reconnecting…", "connecting");
+        reconnectTimer = window.setTimeout(() => {
+          reconnectTimer = null;
+          if (disposed) return;
+          reconnectMs = Math.min(reconnectMs * 2, MAX_RECONNECT_MS);
+          connect();
+        }, delay);
+        return;
+      }
+      setConnState(`closed (${ev.code})`, "closed");
+      opts.onClosed?.(sessionId);
+    };
+  }
+  connect();
+
+  // A pane can be parked again before its deferred focus frame fires (a
+  // preview stepped past it, a split closed it) — the frame must not focus a
+  // hidden textarea out from under whatever the operator moved to since.
+  // `mountToken` is bumped on every mount/unmount so a stale frame can tell
+  // it is no longer the most recent one.
+  let mountToken = 0;
+  let focusFrame: number | null = null;
+
+  function cancelFocusFrame(): void {
+    if (focusFrame !== null) window.cancelAnimationFrame(focusFrame);
+    focusFrame = null;
+  }
+
+  return {
+    sessionId,
+    el,
+    onMount(mountOpts?: { focus?: boolean }) {
+      const focusOnMount = mountOpts?.focus !== false;
+      const token = ++mountToken;
+      scrollWorkActive = true;
+      pendingScroll = {
+        top: parkedScrollTop ?? scrollEl.scrollTop,
+        follow: followingBottom,
+      };
+      parkedScrollTop = null;
+      finishTranscriptLayout();
+      cancelFocusFrame();
+      focusFrame = window.requestAnimationFrame(() => {
+        focusFrame = null;
+        if (disposed || token !== mountToken) return; // parked/remounted since this was scheduled
+        if (focusOnMount && !input.disabled) input.focus();
+      });
+    },
+    onUnmount() {
+      mountToken++;
+      parkedScrollTop = pendingScroll?.top ?? scrollEl.scrollTop;
+      scrollWorkActive = false;
+      cancelScrollFrame();
+      cancelFocusFrame();
+    },
+    focusTerminal() {
+      if (!input.disabled) input.focus();
+    },
+    sendInput() {
+      // No PTY behind a structured session — the leader's literal-byte
+      // escape hatch has nothing to do here.
+    },
+    dispose() {
+      if (disposed) return;
+      disposed = true;
+      mountToken++;
+      scrollWorkActive = false;
+      cancelScrollFrame();
+      cancelFocusFrame();
+      cancelReconnect();
+      resizeObserver.disconnect();
+      unsubscribeStore?.();
+      closeCurrentSocket();
+      expandedRowIds.clear();
+      scrollEl.removeEventListener("scroll", onTranscriptScroll);
+      scrollEl.removeEventListener("click", onTranscriptClick, true);
+      el.remove();
+    },
+  };
+}

web/src/structuredDiff.test.ts

@@ -0,0 +1,187 @@
+import { describe, expect, it } from "vitest";
+
+import { computeDiffLines, diffStats, type DiffLine } from "./structuredDiff.js";
+
+function texts(lines: DiffLine[]): Array<[string, string]> {
+  return lines.map((l) => [l.kind, l.text]);
+}
+
+describe("computeDiffLines", () => {
+  it("renders a brand new file (no oldText) as all additions", () => {
+    const lines = computeDiffLines(null, "a\nb\n");
+    expect(texts(lines)).toEqual([
+      ["add", "a"],
+      ["add", "b"],
+    ]);
+  });
+
+  it("renders a full deletion as all removals", () => {
+    const lines = computeDiffLines("a\nb\n", "");
+    expect(texts(lines)).toEqual([
+      ["del", "a"],
+      ["del", "b"],
+    ]);
+  });
+
+  it("shows a small replace as context around del/add", () => {
+    const lines = computeDiffLines("one\ntwo\nthree\n", "one\ntwx\nthree\n");
+    expect(texts(lines)).toEqual([
+      ["ctx", "one"],
+      ["del", "two"],
+      ["add", "twx"],
+      ["ctx", "three"],
+    ]);
+  });
+
+  it("leaves identical text as pure context, uncollapsed when short", () => {
+    const lines = computeDiffLines("a\nb\nc\n", "a\nb\nc\n");
+    expect(texts(lines)).toEqual([
+      ["ctx", "a"],
+      ["ctx", "b"],
+      ["ctx", "c"],
+    ]);
+  });
+
+  it("handles an insertion without changing surrounding lines", () => {
+    expect(texts(computeDiffLines("a\nc\n", "a\nb\nc\n"))).toEqual([
+      ["ctx", "a"],
+      ["add", "b"],
+      ["ctx", "c"],
+    ]);
+  });
+
+  it("handles a deletion without changing surrounding lines", () => {
+    expect(texts(computeDiffLines("a\nb\nc\n", "a\nc\n"))).toEqual([
+      ["ctx", "a"],
+      ["del", "b"],
+      ["ctx", "c"],
+    ]);
+  });
+
+  it("renders two empty files without invented lines", () => {
+    expect(computeDiffLines("", "")).toEqual([]);
+  });
+
+  it("shows when a final newline is added", () => {
+    expect(texts(computeDiffLines("a", "a\n"))).toEqual([
+      ["del", "a"],
+      ["eof", "\\ No newline at end of file"],
+      ["add", "a"],
+    ]);
+  });
+
+  it("shows when a final newline is removed", () => {
+    expect(texts(computeDiffLines("a\n", "a"))).toEqual([
+      ["del", "a"],
+      ["add", "a"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
+  it("marks an unchanged unterminated final context line", () => {
+    expect(texts(computeDiffLines("a\nb\nc", "a\nX\nc"))).toEqual([
+      ["ctx", "a"],
+      ["del", "b"],
+      ["add", "X"],
+      ["ctx", "c"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
+  it("marks an unterminated new file only once", () => {
+    const lines = computeDiffLines(null, "a");
+    expect(texts(lines)).toEqual([
+      ["add", "a"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+    expect(lines.filter((line) => line.kind === "eof")).toHaveLength(1);
+  });
+
+  it("collapses a long unchanged interior run, keeping 3 lines of context each side", () => {
+    const common = Array.from({ length: 20 }, (_, i) => `line${i}`);
+    const oldText = [...common.slice(0, 10), "OLD", ...common.slice(10)].join("\n");
+    const newText = [...common.slice(0, 10), "NEW", ...common.slice(10)].join("\n");
+    const lines = computeDiffLines(oldText, newText);
+    // The leading run keeps only its last 3 lines (adjacent to the change),
+    // behind a marker for the rest; the trailing run mirrors that.
+    expect(lines[0].kind).toBe("hunk");
+    expect(lines[1]).toEqual({ kind: "ctx", text: "line7" });
+    expect(lines[2]).toEqual({ kind: "ctx", text: "line8" });
+    expect(lines[3]).toEqual({ kind: "ctx", text: "line9" });
+    expect(lines[4].kind).toBe("del");
+    expect(lines[5].kind).toBe("add");
+    expect(lines[6]).toEqual({ kind: "ctx", text: "line10" });
+    expect(lines.filter((l) => l.kind === "hunk")).toHaveLength(2);
+  });
+
+  it("preserves the EOF marker when a long unterminated trailing run collapses", () => {
+    const trailing = Array.from({ length: 10 }, (_, i) => `t${i}`);
+    const oldText = ["OLD", ...trailing].join("\n");
+    const newText = ["NEW", ...trailing].join("\n");
+
+    expect(texts(computeDiffLines(oldText, newText))).toEqual([
+      ["del", "OLD"],
+      ["add", "NEW"],
+      ["ctx", "t0"],
+      ["ctx", "t1"],
+      ["ctx", "t2"],
+      ["hunk", "⋯ 7 unchanged lines ⋯"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
+  it("produces one hunk for the long middle run, none for the short edges", () => {
+    // Edge runs (2 lines) fit within their one-sided 3-line context budget;
+    // only the interior run (10 lines, budgeted 3+3=6) needs to collapse.
+    const middle = Array.from({ length: 10 }, (_, i) => `c${i}`);
+    const oldText = ["lead0", "lead1", "OLD1", ...middle, "OLD2", "trail0", "trail1"].join("\n");
+    const newText = ["lead0", "lead1", "NEW1", ...middle, "NEW2", "trail0", "trail1"].join("\n");
+    const lines = computeDiffLines(oldText, newText);
+    const dels = lines.filter((l) => l.kind === "del").map((l) => l.text);
+    const adds = lines.filter((l) => l.kind === "add").map((l) => l.text);
+    expect(dels).toEqual(["OLD1", "OLD2"]);
+    expect(adds).toEqual(["NEW1", "NEW2"]);
+    expect(lines.filter((l) => l.kind === "hunk")).toHaveLength(1);
+    expect(texts(lines).slice(0, 2)).toEqual([
+      ["ctx", "lead0"],
+      ["ctx", "lead1"],
+    ]);
+    expect(texts(lines).slice(-3)).toEqual([
+      ["ctx", "trail0"],
+      ["ctx", "trail1"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
+  it("handles an old file with no trailing newline", () => {
+    const lines = computeDiffLines("a\nb", "a\nb\nc");
+    expect(texts(lines)).toEqual([
+      ["ctx", "a"],
+      ["del", "b"],
+      ["eof", "\\ No newline at end of file"],
+      ["add", "b"],
+      ["add", "c"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
+  it("falls back to a bounded coarse diff for a pathological changed middle", () => {
+    const oldLines = Array.from({ length: 501 }, (_, index) => `line${index}`);
+    const newLines = [...oldLines.slice(1), oldLines[0]];
+    const lines = computeDiffLines(`${oldLines.join("\n")}\n`, `${newLines.join("\n")}\n`);
+    expect(lines).toHaveLength(1_002);
+    expect(lines.slice(0, 501).every((line) => line.kind === "del")).toBe(true);
+    expect(lines.slice(501).every((line) => line.kind === "add")).toBe(true);
+  });
+});
+
+describe("diffStats", () => {
+  it("counts add/del lines, ignoring context and hunk markers", () => {
+    const lines = computeDiffLines("a\nb\nc\n", "a\nx\ny\nc\n");
+    expect(diffStats(lines)).toEqual({ added: 2, removed: 1 });
+  });
+
+  it("is zero for identical text", () => {
+    expect(diffStats(computeDiffLines("same\n", "same\n"))).toEqual({ added: 0, removed: 0 });
+  });
+});

web/src/structuredDiff.ts

@@ -0,0 +1,167 @@
+// Line-level diff for a `ToolDiff` row's `Diff` content block (#140). ACP
+// hands over full `oldText`/`newText`, not a unified-diff patch, so the
+// coloured hunks the design calls for have to be computed here.
+
+export type DiffLineKind = "add" | "del" | "ctx" | "hunk" | "eof";
+
+export interface DiffLine {
+  kind: DiffLineKind;
+  /** The line's text (a `hunk` line is a human summary, not source text). */
+  text: string;
+}
+
+/** Interior unchanged runs longer than this collapse to a summary line
+ *  flanked by this many lines of real context on each side. */
+const CONTEXT = 3;
+
+/** Bounds the O(n·m) LCS table: above this cell count, the changed middle is
+ *  shown as one coarse del-then-add block instead of a fine-grained diff —
+ *  still correct, just not minimal. */
+const LCS_CELL_LIMIT = 250_000;
+
+interface SourceLine {
+  text: string;
+  terminated: boolean;
+}
+
+function splitLines(text: string): SourceLine[] {
+  if (text === "") return [];
+  const parts = text.split("\n");
+  const hasFinalNewline = text.endsWith("\n");
+  if (hasFinalNewline) parts.pop();
+  return parts.map((line, index) => ({
+    text: line,
+    terminated: index < parts.length - 1 || hasFinalNewline,
+  }));
+}
+
+type Op = { kind: "add" | "del" | "ctx"; line: SourceLine };
+
+function sameLine(a: SourceLine, b: SourceLine): boolean {
+  return a.text === b.text && a.terminated === b.terminated;
+}
+
+/** Longest-common-subsequence diff of two line arrays, already trimmed of any
+ *  shared prefix/suffix by the caller. */
+function lcsDiff(a: SourceLine[], b: SourceLine[]): Op[] {
+  const n = a.length;
+  const m = b.length;
+  if (n === 0) return b.map((line) => ({ kind: "add", line }));
+  if (m === 0) return a.map((line) => ({ kind: "del", line }));
+  if (n * m > LCS_CELL_LIMIT) {
+    return [...a.map((line) => ({ kind: "del" as const, line })), ...b.map((line) => ({ kind: "add" as const, line }))];
+  }
+  // dp[i][j] = length of the LCS of a[i:] and b[j:].
+  const columns = m + 1;
+  const dp = new Uint32Array((n + 1) * columns);
+  for (let i = n - 1; i >= 0; i--) {
+    for (let j = m - 1; j >= 0; j--) {
+      dp[i * columns + j] = sameLine(a[i], b[j])
+        ? dp[(i + 1) * columns + j + 1] + 1
+        : Math.max(dp[(i + 1) * columns + j], dp[i * columns + j + 1]);
+    }
+  }
+  const ops: Op[] = [];
+  let i = 0;
+  let j = 0;
+  while (i < n && j < m) {
+    if (sameLine(a[i], b[j])) {
+      ops.push({ kind: "ctx", line: a[i] });
+      i++;
+      j++;
+    } else if (dp[(i + 1) * columns + j] >= dp[i * columns + j + 1]) {
+      ops.push({ kind: "del", line: a[i] });
+      i++;
+    } else {
+      ops.push({ kind: "add", line: b[j] });
+      j++;
+    }
+  }
+  while (i < n) ops.push({ kind: "del", line: a[i++] });
+  while (j < m) ops.push({ kind: "add", line: b[j++] });
+  return ops;
+}
+
+function diffLines(a: SourceLine[], b: SourceLine[]): Op[] {
+  let pre = 0;
+  while (pre < a.length && pre < b.length && sameLine(a[pre], b[pre])) pre++;
+  let suf = 0;
+  while (
+    suf < a.length - pre &&
+    suf < b.length - pre &&
+    sameLine(a[a.length - 1 - suf], b[b.length - 1 - suf])
+  ) {
+    suf++;
+  }
+  const prefixCtx: Op[] = a.slice(0, pre).map((line) => ({ kind: "ctx", line }));
+  const suffixCtx: Op[] = a.slice(a.length - suf).map((line) => ({ kind: "ctx", line }));
+  const middle = lcsDiff(a.slice(pre, a.length - suf), b.slice(pre, b.length - suf));
+  return [...prefixCtx, ...middle, ...suffixCtx];
+}
+
+/** Collapse a long run of unchanged lines to a summary, keeping up to
+ *  {@link CONTEXT} real lines adjacent to each neighbouring change — same
+ *  shape a unified diff gives a reader, without claiming line numbers this
+ *  module never tracked. A run touching the start/end of the whole diff has
+ *  no change to be adjacent to on that side, so it keeps no context there
+ *  (unless it is the *only* run, i.e. nothing changed at all). */
+function hunk(ops: Op[]): DiffLine[] {
+  const out: DiffLine[] = [];
+  const push = (op: Op) => {
+    out.push({ kind: op.kind, text: op.line.text });
+    if (!op.line.terminated) {
+      out.push({ kind: "eof", text: "\\ No newline at end of file" });
+    }
+  };
+  let i = 0;
+  while (i < ops.length) {
+    if (ops[i].kind !== "ctx") {
+      push(ops[i]);
+      i++;
+      continue;
+    }
+    let j = i;
+    while (j < ops.length && ops[j].kind === "ctx") j++;
+    const run = ops.slice(i, j);
+    const wholeDiff = i === 0 && j === ops.length;
+    const keepHead = wholeDiff || i > 0 ? CONTEXT : 0;
+    const keepTail = wholeDiff || j < ops.length ? CONTEXT : 0;
+    if (run.length <= keepHead + keepTail) {
+      run.forEach(push);
+    } else {
+      if (keepHead) run.slice(0, keepHead).forEach(push);
+      const collapsed = run.slice(keepHead, run.length - keepTail);
+      out.push({
+        kind: "hunk",
+        text: `⋯ ${collapsed.length} unchanged lines ⋯`,
+      });
+      if (collapsed.some((op) => !op.line.terminated)) {
+        out.push({ kind: "eof", text: "\\ No newline at end of file" });
+      }
+      if (keepTail) run.slice(run.length - keepTail).forEach(push);
+    }
+    i = j;
+  }
+  return out;
+}
+
+/** Coloured, hunked diff lines for a `Diff` content block. `oldText` absent
+ *  (a new file) renders every line of `newText` as added. */
+export function computeDiffLines(oldText: string | null | undefined, newText: string): DiffLine[] {
+  const newLines = splitLines(newText);
+  if (oldText == null) return hunk(newLines.map((line) => ({ kind: "add", line })));
+  const ops = diffLines(splitLines(oldText), newLines);
+  return hunk(ops);
+}
+
+/** `+added -removed` counts straight off the diff — real derived data, not a
+ *  fabricated duration or line count. */
+export function diffStats(lines: DiffLine[]): { added: number; removed: number } {
+  let added = 0;
+  let removed = 0;
+  for (const line of lines) {
+    if (line.kind === "add") added++;
+    else if (line.kind === "del") removed++;
+  }
+  return { added, removed };
+}

web/src/structuredRender.test.ts

@@ -0,0 +1,390 @@
+// @vitest-environment happy-dom
+import { describe, expect, it, vi } from "vitest";
+
+import {
+  branchFromWorktreePath,
+  buildTranscriptRow,
+  renderInlineMarkdown,
+  renderRail,
+} from "./structuredRender.js";
+import type { Session, TranscriptRow } from "./types.js";
+
+function row<K extends TranscriptRow["kind"]>(
+  kind: K,
+  data: unknown,
+  id = "r1",
+): TranscriptRow & { kind: K } {
+  return { id, kind, data };
+}
+
+describe("buildTranscriptRow: user/agent/thought", () => {
+  it("renders a user row with the text content and no markdown", () => {
+    const el = buildTranscriptRow(
+      row("user", { content: { type: "text", text: "hi <b>there</b>" } }),
+    );
+    expect(el.className).toContain("st-row-user");
+    expect(el.textContent).toContain("hi <b>there</b>");
+    // never actual markup from user input
+    expect(el.querySelector("b")).toBeNull();
+  });
+
+  it("renders agent prose as paragraphs with inline markdown", () => {
+    const el = buildTranscriptRow(
+      row("agent_text", { content: { type: "text", text: "one **two** `three`\n\nfour" } }),
+    );
+    expect(el.className).toContain("st-row-agent");
+    const ps = el.querySelectorAll("p");
+    expect(ps).toHaveLength(2);
+    expect(ps[0].innerHTML).toContain("<strong>two</strong>");
+    expect(ps[0].innerHTML).toContain("<code>three</code>");
+  });
+
+  it("renders a thought row as plain text", () => {
+    const el = buildTranscriptRow(row("agent_thought", { content: { type: "text", text: "hmm" } }));
+    expect(el.className).toContain("st-row-thought");
+    expect(el.textContent).toBe("hmm");
+  });
+
+  it("falls back to a labelled placeholder for non-text content, never crashing", () => {
+    const el = buildTranscriptRow(row("user", { content: { type: "image" } }));
+    expect(el.textContent).toContain("[image]");
+  });
+
+  it("never clips text: a very long user message is not truncated", () => {
+    const long = "x".repeat(5000);
+    const el = buildTranscriptRow(row("user", { content: { type: "text", text: long } }));
+    expect(el.textContent).toContain(long);
+  });
+});
+
+describe("renderInlineMarkdown", () => {
+  it("escapes raw HTML before applying markdown", () => {
+    expect(renderInlineMarkdown("<script>alert(1)</script>")).not.toContain("<script>");
+  });
+
+  it("does not treat a single asterisk pair meant as bold as nested italics", () => {
+    expect(renderInlineMarkdown("**bold**")).toBe("<strong>bold</strong>");
+  });
+});
+
+describe("buildTranscriptRow: tool calls", () => {
+  it("shows glyph, name, argument and no meta for a completed non-diff call", () => {
+    const el = buildTranscriptRow(
+      row("tool_call", {
+        toolCallId: "t1",
+        title: "Read(src/lib.rs)",
+        kind: "read",
+        status: "completed",
+      }),
+    );
+    const head = el.querySelector(".st-tool-head") as HTMLButtonElement;
+    expect(head.querySelector(".st-tool-name")!.textContent).toBe("Read");
+    expect(head.querySelector(".st-tool-arg")!.textContent).toBe("src/lib.rs");
+    expect(head.querySelector(".st-tool-meta")).toBeNull();
+  });
+
+  it("falls back to the kind label and full title when the title has no Name(arg) shape", () => {
+    const el = buildTranscriptRow(row("tool_call", { title: "does something odd", kind: "execute" }));
+    const head = el.querySelector(".st-tool-head")!;
+    expect(head.querySelector(".st-tool-name")!.textContent).toBe("Execute");
+    expect(head.querySelector(".st-tool-arg")!.textContent).toBe("does something odd");
+  });
+
+  it("shows a running badge for an in-progress call", () => {
+    const el = buildTranscriptRow(row("tool_call", { title: "Bash(sleep 1)", status: "in_progress" }));
+    const meta = el.querySelector(".st-tool-meta")!;
+    expect(meta.textContent).toBe("running");
+    expect(meta.className).toContain("st-tool-meta-running");
+  });
+
+  it("shows a failed badge for a failed call", () => {
+    const el = buildTranscriptRow(row("tool_call", { title: "Bash(false)", status: "failed" }));
+    expect(el.querySelector(".st-tool-meta")!.textContent).toBe("failed");
+  });
+
+  it("starts collapsed and expands its text output on click", () => {
+    const el = buildTranscriptRow(
+      row("tool_call", {
+        title: "Grep(x)",
+        status: "completed",
+        content: [{ type: "content", content: { type: "text", text: "match found" } }],
+      }),
+    );
+    const head = el.querySelector(".st-tool-head") as HTMLButtonElement;
+    const out = el.querySelector(".st-tool-out") as HTMLElement;
+    expect(out.hidden).toBe(true);
+    expect(head.getAttribute("aria-expanded")).toBe("false");
+    head.click();
+    expect(out.hidden).toBe(false);
+    expect(head.getAttribute("aria-expanded")).toBe("true");
+    expect(out.textContent).toContain("match found");
+    head.click();
+    expect(out.hidden).toBe(true);
+  });
+
+  it("does not expand when there is nothing to show", () => {
+    const el = buildTranscriptRow(row("tool_call", { title: "Read(x)", status: "completed" }));
+    const head = el.querySelector(".st-tool-head") as HTMLButtonElement;
+    head.click();
+    expect(head.getAttribute("aria-expanded")).toBe("false");
+  });
+});
+
+describe("buildTranscriptRow: tool diffs", () => {
+  it("shows +added -removed derived from the diff, and renders coloured hunks on expand", () => {
+    const el = buildTranscriptRow(
+      row("tool_diff", {
+        title: "Edit(x.rs)",
+        status: "completed",
+        content: [{ type: "diff", path: "/repo/x.rs", oldText: "a\nb\n", newText: "a\nc\n" }],
+      }),
+    );
+    const meta = el.querySelector(".st-tool-meta")!;
+    expect(meta.textContent).toContain("+1");
+    expect(meta.textContent).toContain("−1");
+    (el.querySelector(".st-tool-head") as HTMLButtonElement).click();
+    const diff = el.querySelector(".st-diff") as HTMLElement;
+    expect(diff).not.toBeNull();
+    expect(diff.querySelector(".st-ln-add")!.textContent).toBe("c");
+    expect(diff.querySelector(".st-ln-del")!.textContent).toBe("b");
+  });
+
+  it("gives the diff its own horizontally-scrolling container", () => {
+    const el = buildTranscriptRow(
+      row("tool_diff", {
+        title: "Edit(x.rs)",
+        content: [{ type: "diff", path: "/repo/x.rs", newText: "new file\n" }],
+      }),
+    );
+    (el.querySelector(".st-tool-head") as HTMLButtonElement).click();
+    // jsdom/happy-dom doesn't compute layout CSS, so assert the class the
+    // stylesheet keys `overflow-x: auto` off, not a computed style.
+    expect(el.querySelector(".st-diff")!.className).toBe("st-diff");
+  });
+
+  it("renders a visible marker for a removed final newline", () => {
+    const el = buildTranscriptRow(
+      row("tool_diff", {
+        title: "Edit(x.rs)",
+        content: [{ type: "diff", path: "/repo/x.rs", oldText: "same\n", newText: "same" }],
+      }),
+    );
+    (el.querySelector(".st-tool-head") as HTMLButtonElement).click();
+    expect(el.querySelector(".st-ln-eof")!.textContent).toBe("\\ No newline at end of file");
+  });
+});
+
+describe("buildTranscriptRow: approval", () => {
+  const approvalRow = (options: Array<{ optionId: string; name: string; kind: string }>) =>
+    row("approval", {
+      sessionId: "s1",
+      toolCall: { toolCallId: "t1", title: "Write outside worktree", locations: [{ path: "/etc/x" }] },
+      options,
+    });
+
+  const allThreeOptions = [
+    { optionId: "a1", name: "Allow once", kind: "allow_once" },
+    { optionId: "a2", name: "Allow always", kind: "allow_always" },
+    { optionId: "r1", name: "Reject once", kind: "reject_once" },
+  ];
+
+  it("shows the three decision buttons only when the request offers all three option kinds", () => {
+    const el = buildTranscriptRow(approvalRow(allThreeOptions), {
+      pending: true,
+      onDecide: () => Promise.resolve(),
+    });
+    const buttons = el.querySelectorAll(".st-approval-acts button");
+    expect(buttons).toHaveLength(3);
+    expect(el.querySelector(".st-approval-path")!.textContent).toBe("/etc/x");
+  });
+
+  it("hides the buttons and shows an answered note once resolved", () => {
+    const el = buildTranscriptRow(approvalRow(allThreeOptions), {
+      pending: false,
+      onDecide: () => Promise.resolve(),
+    });
+    expect(el.querySelector(".st-approval-acts")).toBeNull();
+    expect(el.querySelector(".st-approval-resolved")!.textContent).toBe("answered");
+  });
+
+  it("invokes onDecide with the clicked decision and disables the buttons", () => {
+    const onDecide = vi.fn().mockResolvedValue(undefined);
+    const el = buildTranscriptRow(approvalRow(allThreeOptions), { pending: true, onDecide });
+    const buttons = el.querySelectorAll<HTMLButtonElement>(".st-approval-acts button");
+    buttons[2].click();
+    expect(onDecide).toHaveBeenCalledWith("deny");
+    expect(buttons[0].disabled).toBe(true);
+  });
+
+  it("treats a row with no approval state as not pending, defensively", () => {
+    const el = buildTranscriptRow(approvalRow(allThreeOptions));
+    expect(el.querySelector(".st-approval-acts")).toBeNull();
+  });
+
+  it("omits Allow for session when the request offers no allow_always option", () => {
+    const el = buildTranscriptRow(
+      approvalRow([
+        { optionId: "a1", name: "Allow once", kind: "allow_once" },
+        { optionId: "r1", name: "Reject once", kind: "reject_once" },
+      ]),
+      { pending: true, onDecide: () => Promise.resolve() },
+    );
+    const labels = [...el.querySelectorAll(".st-approval-acts button")].map((b) => b.textContent);
+    expect(labels).toEqual(["Allow once", "Deny"]);
+  });
+
+  it("offers Deny for either reject_once or reject_always, never for neither", () => {
+    const rejectAlwaysOnly = buildTranscriptRow(
+      approvalRow([{ optionId: "r2", name: "Reject always", kind: "reject_always" }]),
+      { pending: true, onDecide: () => Promise.resolve() },
+    );
+    expect([...rejectAlwaysOnly.querySelectorAll(".st-approval-acts button")].map((b) => b.textContent)).toEqual([
+      "Deny",
+    ]);
+  });
+
+  it("shows a 'no decision offered' note instead of an empty action row when nothing matches", () => {
+    const el = buildTranscriptRow(approvalRow([{ optionId: "x", name: "Something else", kind: "allow_once" }]), {
+      pending: true,
+      onDecide: () => Promise.resolve(),
+    });
+    // allow_once is offered, so this specific case still shows a button —
+    // use a kind the client doesn't map to any decision at all.
+    expect(el.querySelectorAll(".st-approval-acts button")).toHaveLength(1);
+
+    const none = buildTranscriptRow(approvalRow([]), { pending: true, onDecide: () => Promise.resolve() });
+    expect(none.querySelector(".st-approval-acts")).toBeNull();
+    expect(none.querySelector(".st-approval-resolved")!.textContent).toBe("no decision offered");
+  });
+
+  it("re-enables the buttons when onDecide rejects", async () => {
+    const onDecide = vi.fn().mockRejectedValue(new Error("network down"));
+    const el = buildTranscriptRow(approvalRow(allThreeOptions), { pending: true, onDecide });
+    const buttons = el.querySelectorAll<HTMLButtonElement>(".st-approval-acts button");
+    buttons[0].click();
+    expect(buttons[0].disabled).toBe(true);
+    await Promise.resolve().then(() => Promise.resolve());
+    expect(buttons[0].disabled).toBe(false);
+    expect(buttons[1].disabled).toBe(false);
+  });
+
+  it("leaves the buttons disabled when onDecide resolves", async () => {
+    const onDecide = vi.fn().mockResolvedValue(undefined);
+    const el = buildTranscriptRow(approvalRow(allThreeOptions), { pending: true, onDecide });
+    const buttons = el.querySelectorAll<HTMLButtonElement>(".st-approval-acts button");
+    buttons[0].click();
+    await Promise.resolve().then(() => Promise.resolve());
+    expect(buttons[0].disabled).toBe(true);
+  });
+});
+
+describe("buildTranscriptRow: notice / unknown kinds", () => {
+  it("renders notice and unknown row kinds safely", () => {
+    expect(buildTranscriptRow(row("notice", { sessionUpdate: "future" }))?.textContent).toBe(
+      "[notice]",
+    );
+    const unknown = { id: "r1", kind: "future_kind", data: {} } as unknown as TranscriptRow;
+    expect(buildTranscriptRow(unknown)?.textContent).toBe("[future_kind]");
+  });
+
+  it("returns no transcript element for a plan row", () => {
+    expect(buildTranscriptRow(row("plan", { entries: [] }))).toBeNull();
+  });
+});
+
+describe("branchFromWorktreePath", () => {
+  it("takes everything after the last /worktrees/ segment", () => {
+    expect(branchFromWorktreePath("/home/n/tea/maestro/worktrees/acp-bridge")).toBe("acp-bridge");
+  });
+
+  it("keeps slashes in a branch name that contains them", () => {
+    expect(branchFromWorktreePath("/repo/worktrees/feature/login")).toBe("feature/login");
+  });
+
+  it("falls back to the basename when there is no /worktrees/ marker", () => {
+    expect(branchFromWorktreePath("/some/other/path")).toBe("path");
+  });
+});
+
+function session(overrides: Partial<Session> = {}): Session {
+  return {
+    id: "s1",
+    cwd: "/repo",
+    command: "claude",
+    env: {},
+    metadata: {},
+    status: "Running",
+    created_at: "2026-01-01T00:00:00Z",
+    ...overrides,
+  };
+}
+
+describe("renderRail", () => {
+  it("omits every section that has nothing to show", () => {
+    const el = document.createElement("div");
+    renderRail(el, {
+      plan: null,
+      turn: { responding: false, thinking: false, active_tool_calls: [] },
+      toolRowCount: 0,
+      usage: null,
+      session: session(),
+    });
+    // Turn always renders (it has a state and a count); the rest are absent.
+    expect(el.querySelectorAll("h3")).toHaveLength(1);
+    expect(el.querySelector("h3")!.textContent).toBe("Turn");
+  });
+
+  it("renders the plan with status marks", () => {
+    const el = document.createElement("div");
+    renderRail(el, {
+      plan: {
+        entries: [
+          { content: "done thing", priority: "high", status: "completed" },
+          { content: "now thing", priority: "high", status: "in_progress" },
+          { content: "later thing", priority: "low", status: "pending" },
+        ],
+      },
+      turn: { responding: false, thinking: false, active_tool_calls: [] },
+      toolRowCount: 0,
+      usage: null,
+      session: session(),
+    });
+    const items = el.querySelectorAll(".st-plan li");
+    expect(items).toHaveLength(3);
+    expect(items[0].className).toBe("st-plan-done");
+    expect(items[1].className).toBe("st-plan-now");
+    expect(items[2].className).toBe("st-plan-todo");
+  });
+
+  it("renders context usage and a meter proportional to used/size", () => {
+    const el = document.createElement("div");
+    renderRail(el, {
+      plan: null,
+      turn: { responding: true, thinking: false, active_tool_calls: ["a"] },
+      toolRowCount: 3,
+      usage: { used: 50_000, size: 200_000 },
+      session: session(),
+    });
+    expect(el.querySelector(".st-meter i")!.getAttribute("style")).toContain("25%");
+  });
+
+  it("renders the worktree section only when the session has one", () => {
+    const el = document.createElement("div");
+    renderRail(el, {
+      plan: null,
+      turn: { responding: false, thinking: false, active_tool_calls: [] },
+      toolRowCount: 0,
+      usage: null,
+      session: session({
+        worktree: { path: "/repo/worktrees/feat/x", base_repo: "/repo" },
+        blocked_work: { uncommitted_files: 2, untracked_files: 1, unpushed_commits: 3 },
+      }),
+    });
+    const headers = [...el.querySelectorAll("h3")].map((h) => h.textContent);
+    expect(headers).toContain("Worktree");
+    const rows = [...el.querySelectorAll(".st-kv-row")].map((r) => r.textContent);
+    expect(rows.some((t) => t?.includes("feat/x"))).toBe(true);
+    expect(rows.some((t) => t?.includes("3"))).toBe(true); // ahead
+    expect(rows.some((t) => t?.includes("dirty") && t.includes("3"))).toBe(true); // 2+1
+  });
+});

web/src/structuredRender.ts

@@ -0,0 +1,553 @@
+// Pure per-row and rail DOM builders for the structured transcript (#140).
+// No socket, no daemon calls — structured.ts owns the connection and calls
+// into here with data already in hand, so every rendering decision here is
+// unit-testable without a WebSocket.
+
+import { escapeHtml } from "./html.js";
+import { computeDiffLines, diffStats } from "./structuredDiff.js";
+import type {
+  AcpContentBlock,
+  AcpPermissionOption,
+  AcpPlan,
+  AcpToolCallContent,
+  AcpToolCallLike,
+  AcpUsage,
+  InTheWay,
+  Session,
+  StructuredApprovalDecision,
+  TranscriptRow,
+} from "./types.js";
+
+// ---------------------------------------------------------------------------
+// row taxonomy
+// ---------------------------------------------------------------------------
+
+/** Glyph shown in a tool row's head, by `ToolKind`. Unrecognised/absent kinds
+ *  fall back to the generic bullet — never a blank glyph column. */
+const KIND_GLYPH: Record<string, string> = {
+  read: "≡",
+  edit: "±",
+  delete: "✕",
+  move: "→",
+  search: "⌕",
+  execute: "$",
+  think: "…",
+  fetch: "⇣",
+  switch_mode: "⇄",
+};
+
+const KIND_LABEL: Record<string, string> = {
+  read: "Read",
+  edit: "Edit",
+  delete: "Delete",
+  move: "Move",
+  search: "Search",
+  execute: "Execute",
+  think: "Think",
+  fetch: "Fetch",
+  switch_mode: "Switch mode",
+};
+
+function toolGlyph(kind: string | undefined): string {
+  return (kind && KIND_GLYPH[kind]) || "•";
+}
+
+function toolKindLabel(kind: string | undefined): string {
+  return (kind && KIND_LABEL[kind]) || "Tool";
+}
+
+/** Split a title into `{label, arg}` when it follows the adapter's own
+ *  `Name(argument)` convention; otherwise the whole title is the arg and the
+ *  tool's `kind` supplies a generic label. Never guesses at a shape the data
+ *  doesn't actually show. */
+function splitToolTitle(
+  title: string | undefined,
+  name: string | null | undefined,
+  kind: string | undefined,
+): { label: string; arg: string } {
+  const label = name ?? toolKindLabel(kind);
+  if (!title) return { label, arg: "" };
+  const m = /^(\S+)\(([\s\S]*)\)$/.exec(title);
+  if (m) return { label: name ?? m[1], arg: m[2] };
+  return { label, arg: title };
+}
+
+function el(tag: string, className?: string): HTMLElement {
+  const node = document.createElement(tag);
+  if (className) node.className = className;
+  return node;
+}
+
+/** Content-block text, or a labelled placeholder for anything that isn't
+ *  text — never dropped silently, never fabricated. */
+function contentBlockText(block: AcpContentBlock | undefined): string {
+  if (!block) return "";
+  switch (block.type) {
+    case "text":
+      return block.text;
+    case "image":
+      return "[image]";
+    case "audio":
+      return "[audio]";
+    case "resource_link":
+      return `[resource: ${block.name ?? block.uri ?? "linked"}]`;
+    case "resource":
+      return "[resource]";
+    default:
+      return "";
+  }
+}
+
+/** A tiny, dependency-free inline renderer: `**bold**`, `*italic*`, and
+ *  `` `code` `` become real markup; everything else stays escaped plain
+ *  text. No block-level markdown (lists, headings) — agent prose is
+ *  paragraphs, not documents. */
+export function renderInlineMarkdown(text: string): string {
+  const escaped = escapeHtml(text);
+  return escaped
+    .replace(/`([^`]+)`/g, "<code>$1</code>")
+    .replace(/\*\*([^*]+)\*\*/g, "<strong>$1</strong>")
+    .replace(/(?<!\*)\*([^*]+)\*(?!\*)/g, "<em>$1</em>");
+}
+
+function renderProse(container: HTMLElement, text: string): void {
+  const paragraphs = text.split(/\n{2,}/);
+  for (const para of paragraphs) {
+    if (!para) continue;
+    const p = document.createElement("p");
+    p.innerHTML = renderInlineMarkdown(para);
+    container.appendChild(p);
+  }
+  if (container.children.length === 0) container.textContent = "";
+}
+
+// ---------------------------------------------------------------------------
+// row builders
+// ---------------------------------------------------------------------------
+
+function buildContentRow(row: TranscriptRow, variant: "user" | "agent" | "thought"): HTMLElement {
+  const data = row.data as { content?: AcpContentBlock; messageId?: string } | undefined;
+  const text = contentBlockText(data?.content);
+  const wrap = el("div", `st-row st-row-${variant}`);
+  const body = el("div", "st-body");
+  if (variant === "user") {
+    const who = el("div", "st-who");
+    who.textContent = "You";
+    body.appendChild(who);
+    const line = el("div", "st-user-text");
+    line.textContent = text;
+    body.appendChild(line);
+  } else if (variant === "agent") {
+    renderProse(body, text);
+  } else {
+    body.textContent = text;
+  }
+  wrap.appendChild(body);
+  return wrap;
+}
+
+function buildDiffBlock(diff: { path: string; oldText?: string | null; newText: string }): HTMLElement {
+  const wrap = el("div", "st-diff-block");
+  const label = el("div", "st-diff-path");
+  label.textContent = diff.path;
+  label.title = diff.path;
+  wrap.appendChild(label);
+  const scroller = el("div", "st-diff");
+  const pre = document.createElement("pre");
+  for (const line of computeDiffLines(diff.oldText, diff.newText)) {
+    const span = document.createElement("span");
+    span.className = `st-ln st-ln-${line.kind}`;
+    span.textContent = line.text;
+    pre.appendChild(span);
+    pre.appendChild(document.createTextNode("\n"));
+  }
+  scroller.appendChild(pre);
+  wrap.appendChild(scroller);
+  return wrap;
+}
+
+/** `+added -removed` across every diff block in a tool call's content —
+ *  real derived data, never a fabricated duration. */
+function toolDiffMeta(content: AcpToolCallContent[]): string {
+  let added = 0;
+  let removed = 0;
+  for (const block of content) {
+    if (block.type !== "diff") continue;
+    const stats = diffStats(computeDiffLines(block.oldText, block.newText));
+    added += stats.added;
+    removed += stats.removed;
+  }
+  return `+${added} −${removed}`;
+}
+
+function statusMeta(status: string | undefined, hasDiff: boolean): { text: string; kind: string } | null {
+  if (status === "in_progress") return { text: "running", kind: "running" };
+  if (status === "failed") return { text: "failed", kind: "failed" };
+  if (status === "pending" && !hasDiff) return { text: "pending", kind: "pending" };
+  return null;
+}
+
+function buildToolRow(
+  row: TranscriptRow,
+  expanded: boolean,
+  onExpandedChange?: (expanded: boolean) => void,
+): HTMLElement {
+  const tool = (row.data ?? {}) as AcpToolCallLike;
+  const content = tool.content ?? [];
+  const hasDiff = content.some((c) => c.type === "diff");
+  const { label, arg } = splitToolTitle(tool.title, tool.name, tool.kind);
+
+  const wrap = el("div", "st-row st-row-tool");
+  const card = el("div", "st-tool");
+  wrap.appendChild(card);
+
+  const head = document.createElement("button");
+  head.type = "button";
+  head.className = "st-tool-head";
+  head.setAttribute("aria-expanded", "false");
+
+  const glyph = el("span", "st-tool-glyph");
+  glyph.textContent = toolGlyph(tool.kind);
+  glyph.setAttribute("aria-hidden", "true");
+  const name = el("span", "st-tool-name");
+  name.textContent = label;
+  const argEl = el("span", "st-tool-arg");
+  argEl.textContent = arg;
+  argEl.title = arg;
+  head.append(glyph, name, argEl);
+
+  const metaParts: string[] = [];
+  if (hasDiff) metaParts.push(toolDiffMeta(content));
+  const meta = statusMeta(tool.status, hasDiff);
+  if (meta) metaParts.push(meta.text);
+  if (metaParts.length > 0) {
+    const metaEl = el("span", "st-tool-meta");
+    if (meta) metaEl.classList.add(`st-tool-meta-${meta.kind}`);
+    metaEl.textContent = metaParts.join(" · ");
+    head.appendChild(metaEl);
+  }
+  card.appendChild(head);
+
+  const out = el("div", "st-tool-out");
+  out.hidden = true;
+  let outBuilt = false;
+  const buildOut = () => {
+    if (outBuilt) return;
+    outBuilt = true;
+    const texts = content
+      .filter((c): c is Extract<AcpToolCallContent, { type: "content" }> => c.type === "content")
+      .map((c) => contentBlockText(c.content))
+      .filter(Boolean);
+    if (texts.length > 0) {
+      const textPanel = el("div", "st-tool-text");
+      textPanel.textContent = texts.join("\n");
+      out.appendChild(textPanel);
+    }
+    for (const block of content) {
+      if (block.type === "diff") out.appendChild(buildDiffBlock(block));
+      if (block.type === "terminal") {
+        const note = el("div", "st-tool-text");
+        note.textContent = "[embedded terminal]";
+        out.appendChild(note);
+      }
+    }
+    if (out.children.length === 0) out.hidden = true;
+  };
+  card.appendChild(out);
+
+  const setExpanded = (nextExpanded: boolean) => {
+    if (nextExpanded) buildOut();
+    if (out.children.length === 0) nextExpanded = false;
+    head.setAttribute("aria-expanded", String(nextExpanded));
+    out.hidden = !nextExpanded;
+  };
+  head.addEventListener("click", () => {
+    setExpanded(head.getAttribute("aria-expanded") !== "true");
+    onExpandedChange?.(head.getAttribute("aria-expanded") === "true");
+  });
+  setExpanded(expanded);
+
+  return wrap;
+}
+
+function buildPlainRow(row: TranscriptRow): HTMLElement {
+  const wrap = el("div", "st-row st-row-notice");
+  const body = el("div", "st-body");
+  body.textContent = `[${row.kind}]`;
+  wrap.appendChild(body);
+  return wrap;
+}
+
+export interface ApprovalRowState {
+  pending: boolean;
+  /** Resolves once the decision has been submitted; rejects when the POST
+   *  failed and this approval is still the one awaiting a decision, so the
+   *  caller knows to restore its controls. Never rejects for a stale click
+   *  (the approval already moved on) — there is nothing to restore then. */
+  onDecide: (decision: StructuredApprovalDecision) => Promise<void>;
+}
+
+/** Which decisions a permission request actually backs, by the
+ *  `PermissionOptionKind` values it offers (docs/STRUCTURED-VIEW.md's
+ *  "Decision mapping"). A decision with no matching option resolves
+ *  `Cancelled` server-side regardless of what the client sent — offering its
+ *  button would let the operator "allow" something that silently no-ops. */
+function offeredDecisions(options: AcpPermissionOption[]): StructuredApprovalDecision[] {
+  const kinds = new Set(options.map((o) => o.kind));
+  const decisions: StructuredApprovalDecision[] = [];
+  if (kinds.has("allow_once")) decisions.push("allow_once");
+  if (kinds.has("allow_always")) decisions.push("allow_for_session");
+  if (kinds.has("reject_once") || kinds.has("reject_always")) decisions.push("deny");
+  return decisions;
+}
+
+function buildApprovalRow(row: TranscriptRow, approval: ApprovalRowState): HTMLElement {
+  const request = (row.data ?? {}) as { toolCall?: AcpToolCallLike; options?: AcpPermissionOption[] };
+  const toolCall = request.toolCall ?? {};
+  const wrap = el("div", "st-row st-row-approval");
+  const card = el("div", "st-approval");
+  wrap.appendChild(card);
+
+  const title = el("div", "st-approval-title");
+  title.innerHTML = `<span aria-hidden="true">⚠</span> permission requested`;
+  card.appendChild(title);
+
+  const what = el("div", "st-approval-what");
+  what.textContent = toolCall.title ?? toolKindLabel(toolCall.kind);
+  card.appendChild(what);
+
+  const path = toolCall.locations?.[0]?.path;
+  if (path) {
+    const pathEl = el("div", "st-approval-path");
+    pathEl.textContent = path;
+    card.appendChild(pathEl);
+  }
+
+  if (approval.pending) {
+    const acts = el("div", "st-approval-acts");
+    const mk = (label: string, decision: StructuredApprovalDecision, cls: string) => {
+      const btn = document.createElement("button");
+      btn.type = "button";
+      btn.className = cls ? `act ${cls}` : "act";
+      btn.textContent = label;
+      btn.addEventListener("click", () => {
+        const buttons = [...acts.querySelectorAll<HTMLButtonElement>("button")];
+        buttons.forEach((b) => (b.disabled = true));
+        approval.onDecide(decision).catch(() => {
+          // Rejects only when this approval is still pending (see
+          // ApprovalRowState) — restore the controls so the operator can
+          // retry; the error itself is surfaced by the connection.
+          buttons.forEach((b) => (b.disabled = false));
+        });
+      });
+      return btn;
+    };
+    const offered = offeredDecisions(request.options ?? []);
+    const specs: [StructuredApprovalDecision, string, string][] = [
+      ["allow_once", "Allow once", "primary"],
+      ["allow_for_session", "Allow for session", ""],
+      ["deny", "Deny", "deny"],
+    ];
+    for (const [decision, label, cls] of specs) {
+      if (offered.includes(decision)) acts.appendChild(mk(label, decision, cls));
+    }
+    if (acts.children.length > 0) {
+      card.appendChild(acts);
+    } else {
+      const none = el("div", "st-approval-resolved");
+      none.textContent = "no decision offered";
+      card.appendChild(none);
+    }
+  } else {
+    const resolved = el("div", "st-approval-resolved");
+    resolved.textContent = "answered";
+    card.appendChild(resolved);
+  }
+
+  return wrap;
+}
+
+/** Build the DOM for one transcript row, or `null` for a plan shown only in
+ *  the rail. `approval` is consulted only for an `approval` row; tool
+ *  expansion is supplied and reported explicitly. */
+export function buildTranscriptRow(
+  row: TranscriptRow & { kind: "plan" },
+  approval?: ApprovalRowState,
+  toolExpanded?: boolean,
+  onToolExpandedChange?: (expanded: boolean) => void,
+): null;
+export function buildTranscriptRow(
+  row: TranscriptRow & { kind: Exclude<TranscriptRow["kind"], "plan"> },
+  approval?: ApprovalRowState,
+  toolExpanded?: boolean,
+  onToolExpandedChange?: (expanded: boolean) => void,
+): HTMLElement;
+export function buildTranscriptRow(
+  row: TranscriptRow,
+  approval?: ApprovalRowState,
+  toolExpanded?: boolean,
+  onToolExpandedChange?: (expanded: boolean) => void,
+): HTMLElement | null;
+export function buildTranscriptRow(
+  row: TranscriptRow,
+  approval?: ApprovalRowState,
+  toolExpanded = false,
+  onToolExpandedChange?: (expanded: boolean) => void,
+): HTMLElement | null {
+  let built: HTMLElement;
+  switch (row.kind) {
+    case "user":
+      built = buildContentRow(row, "user");
+      break;
+    case "agent_text":
+      built = buildContentRow(row, "agent");
+      break;
+    case "agent_thought":
+      built = buildContentRow(row, "thought");
+      break;
+    case "tool_call":
+    case "tool_diff":
+      built = buildToolRow(row, toolExpanded, onToolExpandedChange);
+      break;
+    case "approval":
+      built = buildApprovalRow(row, approval ?? { pending: false, onDecide: () => Promise.resolve() });
+      break;
+    case "plan":
+      return null;
+    default:
+      built = buildPlainRow(row);
+      break;
+  }
+  built.dataset.rowId = row.id;
+  return built;
+}
+
+// ---------------------------------------------------------------------------
+// rail
+// ---------------------------------------------------------------------------
+
+const PLAN_MARK: Record<string, string> = { completed: "✓", in_progress: "▸", pending: "·" };
+const PLAN_CLASS: Record<string, string> = { completed: "done", in_progress: "now", pending: "todo" };
+
+function renderPlanSection(plan: AcpPlan | null | undefined): HTMLElement | null {
+  if (!plan || plan.entries.length === 0) return null;
+  const section = el("div", "st-rail-section");
+  const h = document.createElement("h3");
+  h.textContent = "Plan";
+  section.appendChild(h);
+  const list = document.createElement("ul");
+  list.className = "st-plan";
+  for (const entry of plan.entries) {
+    const li = document.createElement("li");
+    li.className = `st-plan-${PLAN_CLASS[entry.status] ?? "todo"}`;
+    li.setAttribute("aria-label", `${entry.status.replace("_", " ")}: ${entry.content}`);
+    const mark = el("span", "st-plan-mark");
+    mark.textContent = PLAN_MARK[entry.status] ?? "·";
+    mark.setAttribute("aria-hidden", "true");
+    const text = document.createElement("span");
+    text.textContent = entry.content;
+    li.append(mark, text);
+    list.appendChild(li);
+  }
+  section.appendChild(list);
+  return section;
+}
+
+function kv(label: string, value: string): HTMLElement {
+  const row = el("div", "st-kv-row");
+  const k = el("span", "st-kv-k");
+  k.textContent = label;
+  const v = el("span", "st-kv-v");
+  v.textContent = value;
+  row.append(k, v);
+  return row;
+}
+
+function renderTurnSection(
+  turn: { responding: boolean; thinking: boolean; active_tool_calls: string[] },
+  toolRowCount: number,
+  usage: AcpUsage | null | undefined,
+): HTMLElement {
+  const section = el("div", "st-rail-section");
+  const h = document.createElement("h3");
+  h.textContent = "Turn";
+  section.appendChild(h);
+  const box = el("div", "st-kv");
+  const activity = turn.thinking ? "thinking" : turn.responding ? "responding" : "idle";
+  box.appendChild(kv("state", activity));
+  box.appendChild(kv("active tools", String(turn.active_tool_calls.length)));
+  box.appendChild(kv("tool calls", String(toolRowCount)));
+  if (usage?.cost) box.appendChild(kv("cost", `$${usage.cost.amount.toFixed(2)}`));
+  section.appendChild(box);
+  return section;
+}
+
+function renderContextSection(usage: AcpUsage | null | undefined): HTMLElement | null {
+  if (!usage) return null;
+  const section = el("div", "st-rail-section");
+  const h = document.createElement("h3");
+  h.textContent = "Context";
+  section.appendChild(h);
+  const box = el("div", "st-kv");
+  box.appendChild(kv("used", formatTokenCount(usage.used)));
+  box.appendChild(kv("window", formatTokenCount(usage.size)));
+  section.appendChild(box);
+  const meter = el("div", "st-meter");
+  const fill = el("i");
+  const pct = usage.size > 0 ? Math.min(100, (usage.used / usage.size) * 100) : 0;
+  fill.style.width = `${pct}%`;
+  meter.appendChild(fill);
+  section.appendChild(meter);
+  return section;
+}
+
+function formatTokenCount(n: number): string {
+  return n >= 1000 ? `${(n / 1000).toFixed(1)}k` : String(n);
+}
+
+/** `SessionWorktree.path` is `<repo>/worktrees/<branch>` (docs/WORKTREES.md);
+ *  the branch is not carried anywhere else on the wire, so derive it here. */
+export function branchFromWorktreePath(path: string): string {
+  const marker = "/worktrees/";
+  const i = path.indexOf(marker);
+  if (i >= 0) return path.slice(i + marker.length);
+  return path.split("/").filter(Boolean).pop() ?? path;
+}
+
+function renderWorktreeSection(session: Session | undefined): HTMLElement | null {
+  const worktree = session?.worktree;
+  if (!worktree) return null;
+  const section = el("div", "st-rail-section");
+  const h = document.createElement("h3");
+  h.textContent = "Worktree";
+  section.appendChild(h);
+  const box = el("div", "st-kv");
+  box.appendChild(kv("branch", branchFromWorktreePath(worktree.path)));
+  const blocked: InTheWay | null | undefined = session?.blocked_work;
+  box.appendChild(kv("ahead", String(blocked?.unpushed_commits ?? 0)));
+  const dirty = (blocked?.uncommitted_files ?? 0) + (blocked?.untracked_files ?? 0);
+  box.appendChild(kv("dirty", String(dirty)));
+  section.appendChild(box);
+  return section;
+}
+
+export interface RailContext {
+  plan: AcpPlan | null | undefined;
+  turn: { responding: boolean; thinking: boolean; active_tool_calls: string[] };
+  toolRowCount: number;
+  usage: AcpUsage | null | undefined;
+  session: Session | undefined;
+}
+
+/** Rebuild the rail wholesale from the latest state — rails are small, so a
+ *  full rebuild per update is simpler and cheap enough that no incremental
+ *  patching is worth the complexity. */
+export function renderRail(container: HTMLElement, ctx: RailContext): void {
+  const sections = [
+    renderPlanSection(ctx.plan),
+    renderTurnSection(ctx.turn, ctx.toolRowCount, ctx.usage),
+    renderContextSection(ctx.usage),
+    renderWorktreeSection(ctx.session),
+  ].filter((s): s is HTMLElement => s !== null);
+  container.replaceChildren(...sections);
+}

web/src/styles.css

@@ -2165,6 +2165,510 @@ input.leaf-rename:focus {
   border-color: var(--accent-strong);
 }
 
+/* ---------- structured view (#140) ----------
+   `.attach.structured` reuses `.attach`'s flex column, `.attach-header` and
+   `.attach-state` verbatim (attach.ts and structured.ts share paneTitle.ts's
+   header markup) — only the body differs: a transcript column + rail grid
+   instead of an xterm surface. Hierarchy is deliberate: the approval is the
+   only lifted, card-like element on the page; everything else is either a
+   tinted block (user), plain text (agent), or a thin bordered row (tool). */
+
+.st-pills {
+  font-size: var(--fs-11);
+  color: var(--muted);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.structured-body {
+  flex: 1 1 auto;
+  min-height: 0;
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) 232px;
+}
+
+.structured-body.st-narrow {
+  grid-template-columns: minmax(0, 1fr);
+  grid-template-rows: minmax(0, 1fr) auto;
+}
+
+.structured-body.st-narrow .structured-rail {
+  border-left: 0;
+  border-top: 1px solid var(--border);
+  max-height: 40%;
+}
+
+.structured-scroll {
+  min-width: 0;
+  overflow-y: auto;
+  display: flex;
+  flex-direction: column;
+}
+
+.structured-rows {
+  padding: var(--sp-3) var(--sp-3) 0;
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-3);
+  min-width: 0;
+}
+
+.structured-rail {
+  border-left: 1px solid var(--border);
+  background: var(--surface-2);
+  padding: var(--sp-3);
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-5);
+  min-width: 0;
+  overflow-y: auto;
+}
+
+.structured-rail h3 {
+  margin: 0 0 var(--sp-2);
+  font-size: var(--fs-11);
+  letter-spacing: 0.12em;
+  text-transform: uppercase;
+  color: var(--faint);
+  font-weight: 500;
+}
+
+.st-plan {
+  list-style: none;
+  margin: 0;
+  padding: 0;
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-2);
+}
+
+.st-plan li {
+  display: flex;
+  gap: var(--sp-2);
+  font-size: var(--fs-12);
+  line-height: 1.4;
+}
+
+.st-plan-mark {
+  flex: 0 0 auto;
+  width: 12px;
+  text-align: center;
+}
+
+.st-plan-done {
+  color: var(--faint);
+}
+
+.st-plan-now {
+  color: var(--ink);
+}
+
+.st-plan-now .st-plan-mark,
+.st-plan-done .st-plan-mark {
+  color: var(--live);
+}
+
+.st-plan-todo {
+  color: var(--muted);
+}
+
+.st-plan-todo .st-plan-mark {
+  color: var(--border-strong);
+}
+
+.st-kv {
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-2);
+  font-size: var(--fs-12);
+}
+
+.st-kv-row {
+  display: flex;
+  justify-content: space-between;
+  gap: var(--sp-2);
+}
+
+.st-kv-k {
+  color: var(--faint);
+}
+
+.st-kv-v {
+  color: var(--ink);
+  font-variant-numeric: tabular-nums;
+}
+
+.st-meter {
+  height: 4px;
+  background: var(--surface-3);
+  border-radius: var(--r-1);
+  overflow: hidden;
+  margin-top: var(--sp-2);
+}
+
+.st-meter i {
+  display: block;
+  height: 100%;
+  background: var(--live);
+}
+
+/* every transcript row carries its own layout; none of them are cards */
+.st-row {
+  display: flex;
+  gap: var(--sp-3);
+  min-width: 0;
+}
+
+.st-body {
+  min-width: 0;
+}
+
+/* user turn: the only tinted block besides the approval — an accent rail,
+   never a full border, so it still reads lighter than the approval card. */
+.st-row-user {
+  border-left: 2px solid var(--accent);
+  background: var(--surface-2);
+  padding: var(--sp-3);
+}
+
+.st-who {
+  font-size: var(--fs-11);
+  letter-spacing: 0.1em;
+  text-transform: uppercase;
+  color: var(--faint);
+  margin-bottom: var(--sp-1);
+}
+
+.st-user-text {
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+}
+
+/* agent prose: no card, no background — plain text is the point */
+.st-row-agent .st-body p {
+  margin: 0 0 var(--sp-2);
+  overflow-wrap: anywhere;
+}
+
+.st-row-agent .st-body p:last-child {
+  margin-bottom: 0;
+}
+
+.st-row-agent code {
+  background: var(--surface-2);
+  border: 1px solid var(--border);
+  border-radius: var(--r-1);
+  padding: 0 3px;
+  font-size: 0.92em;
+}
+
+.st-row-thought {
+  color: var(--faint);
+  font-style: italic;
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+}
+
+.st-row-notice {
+  color: var(--faint);
+  font-size: var(--fs-12);
+}
+
+/* tool rows: bordered, compact, deliberately not lifted */
+.st-tool {
+  border: 1px solid var(--border);
+  border-radius: var(--r-2);
+  min-width: 0;
+}
+
+.st-tool-head {
+  appearance: none;
+  width: 100%;
+  border: 0;
+  background: transparent;
+  color: inherit;
+  font: inherit;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  gap: var(--sp-2);
+  padding: var(--sp-2) var(--sp-3);
+  min-width: 0;
+}
+
+.st-tool-head:hover {
+  background: var(--surface-2);
+}
+
+.st-tool-glyph {
+  width: 16px;
+  flex: 0 0 auto;
+  text-align: center;
+  color: var(--faint);
+}
+
+.st-tool-name {
+  font-weight: 500;
+  flex: 0 0 auto;
+}
+
+.st-tool-arg {
+  color: var(--muted);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  min-width: 0;
+  text-align: left;
+}
+
+.st-tool-meta {
+  margin-left: auto;
+  flex: 0 0 auto;
+  font-size: var(--fs-11);
+  color: var(--faint);
+  font-variant-numeric: tabular-nums;
+}
+
+.st-tool-meta-running {
+  color: var(--live);
+}
+
+.st-tool-meta-failed {
+  color: var(--danger);
+}
+
+.st-tool-out {
+  border-top: 1px solid var(--border);
+  padding: var(--sp-2) var(--sp-3);
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-2);
+}
+
+/* `display: flex` above outranks the UA sheet's `[hidden]` (same pitfall as
+   `.wt-step`/`.raw-wrap`) — restate it explicitly. */
+.st-tool-out[hidden] {
+  display: none;
+}
+
+.st-tool-text {
+  font-size: var(--fs-12);
+  color: var(--muted);
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+  overflow-x: auto;
+}
+
+.st-diff-block {
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-1);
+}
+
+.st-diff-path {
+  font-size: var(--fs-11);
+  color: var(--muted);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+/* the diff gets its own horizontal scroller, independent of the page */
+.st-diff {
+  font-size: var(--fs-12);
+  overflow-x: auto;
+  border: 1px solid var(--border);
+  border-radius: var(--r-1);
+}
+
+.st-diff pre {
+  margin: 0;
+}
+
+.st-ln {
+  display: block;
+  white-space: pre;
+  padding: 0 var(--sp-3);
+}
+
+.st-ln-add {
+  background: color-mix(in oklab, var(--live) 14%, transparent);
+}
+
+.st-ln-del {
+  background: var(--danger-tint);
+}
+
+.st-ln-ctx {
+  color: var(--muted);
+}
+
+.st-ln-hunk {
+  color: var(--faint);
+  background: var(--surface-2);
+}
+
+.st-ln-eof {
+  color: var(--faint);
+  font-style: italic;
+}
+
+/* the one lifted, card-like element on the surface: the only thing the
+   operator owes a decision on */
+.st-approval {
+  border: 1px solid var(--warn);
+  border-left-width: 3px;
+  border-radius: var(--r-2);
+  background: color-mix(in oklab, var(--warn) 12%, var(--surface));
+  box-shadow: var(--shadow-1);
+  padding: var(--sp-3);
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-2);
+  min-width: 0;
+}
+
+.st-approval-title {
+  color: var(--warn);
+  font-size: var(--fs-11);
+  letter-spacing: 0.1em;
+  text-transform: uppercase;
+  display: flex;
+  align-items: center;
+  gap: var(--sp-2);
+}
+
+.st-approval-what {
+  color: var(--ink);
+}
+
+.st-approval-path {
+  background: var(--surface);
+  border: 1px solid var(--border);
+  border-radius: var(--r-1);
+  padding: var(--sp-2);
+  font-size: var(--fs-12);
+  overflow-x: auto;
+  white-space: pre;
+}
+
+.st-approval-acts {
+  display: flex;
+  gap: var(--sp-2);
+  flex-wrap: wrap;
+}
+
+.st-approval-resolved {
+  font-size: var(--fs-11);
+  color: var(--faint);
+}
+
+.act {
+  appearance: none;
+  font: inherit;
+  font-size: var(--fs-12);
+  height: 26px;
+  padding: 0 var(--sp-3);
+  border-radius: var(--r-2);
+  border: 1px solid var(--border-strong);
+  background: var(--surface);
+  color: var(--ink);
+  cursor: pointer;
+  transition:
+    transform var(--dur-fast) var(--ease-out),
+    background var(--dur-fast) var(--ease-out);
+}
+
+.act:hover {
+  background: var(--surface-3);
+}
+
+.act:active {
+  transform: translateY(1px);
+}
+
+.act:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.act.primary {
+  background: var(--accent);
+  color: var(--accent-ink);
+  border-color: var(--accent);
+  font-weight: 500;
+}
+
+.act.deny {
+  color: var(--danger);
+  border-color: color-mix(in oklab, var(--danger) 40%, transparent);
+}
+
+.act.deny:hover {
+  background: var(--danger-tint);
+  border-color: var(--danger);
+}
+
+/* composer: sticky at the bottom of the scrolling transcript column */
+.structured-composer {
+  position: sticky;
+  bottom: 0;
+  margin-top: var(--sp-3);
+  padding: var(--sp-3);
+  border-top: 1px solid var(--border);
+  background: var(--surface);
+  display: flex;
+  align-items: flex-end;
+  gap: var(--sp-2);
+}
+
+.structured-input {
+  flex: 1 1 auto;
+  min-width: 0;
+  max-height: 160px;
+  resize: none;
+  padding: var(--sp-2) var(--sp-3);
+  border: 1px solid var(--border-strong);
+  border-radius: var(--r-2);
+  background: var(--bg);
+  color: var(--ink);
+  font-family: var(--font-mono);
+  font-size: var(--fs-13);
+}
+
+.structured-input:focus {
+  outline: none;
+  border-color: var(--accent);
+  box-shadow: 0 0 0 3px var(--accent-tint);
+}
+
+.structured-input:disabled {
+  color: var(--faint);
+  background: var(--surface-2);
+}
+
+/* `.btn` sets `display: inline-flex`, which outranks the UA sheet's
+   `[hidden]` — restate it explicitly (same pitfall as `.st-tool-out`). */
+.structured-cancel[hidden] {
+  display: none;
+}
+
+.structured-error {
+  margin: 0 var(--sp-3);
+  padding: var(--sp-2) var(--sp-3);
+  background: var(--danger-tint);
+  color: var(--danger);
+  font-size: var(--fs-12);
+  border-radius: var(--r-2);
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .act {
+    transition-duration: 0.01ms;
+  }
+}
+
 /* ---------- modal ---------- */
 
 .modal-backdrop {

web/src/toolIcon.test.ts

@@ -1,5 +1,12 @@
 import { describe, expect, it } from "vitest";
 import { splitCommand, toolIconSvg } from "./toolIcon.js";
+import commandResolutionFixture from "../../fixtures/command-resolution.json";
+
+interface CommandResolutionCase {
+  command: string;
+  program: string;
+  tool: string | null;
+}
 
 describe("tool icons on the command fragment (docs/SIDEBAR.md)", () => {
   it("recognises the agents and shells sessions are spawned with", () => {
@@ -46,6 +53,14 @@ describe("tool icons on the command fragment (docs/SIDEBAR.md)", () => {
     expect(splitCommand("").tool).toBeNull();
   });
 
+  it("resolves every case in the shared command-resolution fixture (#199)", () => {
+    const cases = commandResolutionFixture.cases as CommandResolutionCase[];
+    expect(cases.length).toBeGreaterThan(0);
+    for (const { command, program, tool } of cases) {
+      expect(splitCommand(command), command).toEqual({ tool, program });
+    }
+  });
+
   it("gives every recognised tool a labelled mark", () => {
     for (const tool of ["claude", "codex", "opencode", "gemini", "aider", "cursor", "pi", "shell"]) {
       const svg = toolIconSvg(tool);

web/src/toolIcon.ts

@@ -9,10 +9,11 @@
  * as text, so the fragment never renders a mark that stands for the wrong tool.
  */
 
-/** Command wrappers that run another program: the tool is what follows. */
+/** Program name (already basenamed and lowercased) → icon id.
-const WRAPPERS = new Set(["sudo", "env", "npx", "bunx", "uvx", "pnpm", "yarn", "command"]);
+ *
-
+ * `claude-code-acp` — the daemon's actual structured-session child — is
-/** Program name (already basenamed and lowercased) → icon id. */
+ * deliberately absent: the daemon launches it directly and ignores the
+ * session's command, so it is never itself a valid user-facing launch form. */
 const BY_PROGRAM: Record<string, string> = {
   claude: "claude",
   "claude-code": "claude",
@@ -53,39 +54,443 @@ export interface CommandParts {
   program: string;
 }
 
-/** Split a command line into the tool its icon stands for and the program name.
+/** Split a command line into the tool its icon stands for and the program
+ * name — basenamed and stripped of its arguments. Leading `FOO=bar`
+ * assignments and wrapper forms (`sudo`, `env -i`, `npx`, `pnpm dlx`, …) are
+ * looked through, and quoting/escaping is honoured (never evaluated — no
+ * `$var`/`` `cmd` ``/`$(cmd)` expansion). A command a shell would need real
+ * grammar for (pipelines, `&&`/`;`, redirections, substitution, an
+ * unterminated quote) falls back to the naive first word rather than
+ * guessing through it (#199). Mirrors the Rust `command_program`/
+ * `command_tool` in `crates/maestro-protocol/src/display.rs`.
  *
  * `claude --resume` → `{tool: "claude", program: "claude"}`; an unrecognised
  * `hx src/` keeps `hx` as the program with no tool. */
 export function splitCommand(command: string): CommandParts {
-  const words = command.trim().split(/\s+/).filter(Boolean);
+  const words = tokenize(command);
-  let i = 0;
+  if (words === null) {
-  // Leading `FOO=bar` assignments and wrappers stand in front of the real
+    const program = legacyFirstWord(command);
-  // program; `pnpm dlx x` / `yarn dlx x` need one more word skipped.
+    return { tool: null, program };
-  while (i < words.length) {
-    const word = words[i];
-    if (/^[A-Za-z_][A-Za-z0-9_]*=/.test(word)) {
-      i += 1;
-      continue;
-    }
-    const wrapper = basename(word).toLowerCase();
-    if (WRAPPERS.has(wrapper)) {
-      i += 1;
-      if ((wrapper === "pnpm" || wrapper === "yarn") && words[i] === "dlx") i += 1;
-      continue;
-    }
-    break;
   }
+  const i = programIndex(words);
   if (i >= words.length) return { tool: null, program: command.trim() };
-  const program = basename(words[i]);
+  const program = basename(words[i].text);
   return { tool: BY_PROGRAM[program.toLowerCase()] ?? null, program };
 }
 
+/** The naive "first whitespace word, basenamed" reading used only when
+ * {@link tokenize} rejects the line outright — still something sane to
+ * show, never a wrapper/tool match to act on. */
+function legacyFirstWord(command: string): string {
+  const first = command.trim().split(/\s+/).filter(Boolean)[0];
+  return first === undefined ? command.trim() : basename(first);
+}
+
+/** One token from {@link tokenize}: its dequoted text, and — when both the
+ * name and `=` were entirely unquoted/unescaped in the source — the index of
+ * the name. Quoting or escaping either (`"FOO"=1`, `F\OO=1`, `FOO\=1`)
+ * makes the word an executable named `FOO=1`; quoting/escaping only the value
+ * preserves the assignment, matching Bash's assignment-word grammar (#199). */
+interface Word {
+  text: string;
+  plainEq: number | null;
+}
+
+/** `FOO=bar`, the shell's own prefix for one command's environment —
+ * recognised only when the `=` came from plain, unquoted/unescaped source
+ * text (#199). */
+function isEnvAssignment(word: Word): boolean {
+  if (word.plainEq === null) return false;
+  return /^[A-Za-z_][A-Za-z0-9_]*$/.test(word.text.slice(0, word.plainEq));
+}
+
+/** Walk `words` past leading `FOO=bar` assignments and known wrapper forms
+ * (interleaved in any order/count) to the index of the actual program. An
+ * assignment run is only consumed at the very start of the line or right
+ * after a wrapper whose own semantics accept one there ({@link Wrapper.acceptsAssignment}) —
+ * `command FOO=1 claude` and `nohup FOO=1 claude` stop at `FOO=1` rather than
+ * skipping to `claude`, since `command`/`nohup` just exec their next argument
+ * as the program, they don't setenv from an assignment-shaped one (#199). */
+function programIndex(words: Word[]): number {
+  const texts = words.map((w) => w.text);
+  let i = 0;
+  let assignmentAllowed = true;
+  for (;;) {
+    if (assignmentAllowed) {
+      while (i < words.length && isEnvAssignment(words[i])) {
+        i += 1;
+      }
+    }
+    if (i >= words.length) break;
+    const wrapper = basename(texts[i]).toLowerCase();
+    const w = WRAPPER_RESOLVERS[wrapper];
+    if (!w) break;
+    const next = w.resolve(texts, i);
+    // Not a form of the wrapper we recognise (an unknown option, or — for
+    // `pnpm`/`yarn`/`bun` — no `dlx`/`x` subcommand behind it): the wrapper
+    // word itself is the program, not a launcher.
+    if (next === null || next <= i) break;
+    i = next;
+    assignmentAllowed = w.acceptsAssignment;
+  }
+  return i;
+}
+
 function basename(word: string): string {
   const cut = word.lastIndexOf("/");
   return cut >= 0 ? word.slice(cut + 1) : word;
 }
 
+/** Word-split `command` the way a shell would (honouring `'…'`, `"…"` and
+ * `\` quoting/escaping — POSIX quote *removal*, not evaluation) and return
+ * `null` the moment it needs real shell grammar this resolver doesn't
+ * attempt: a pipeline/list operator (`|`, `&`, `;`, `<`, `>`), a subshell or
+ * substitution (`(`, `)`, `` ` ``, `$(`), an unescaped newline (a command
+ * separator, like `;` — #199), or an unterminated quote/escape. Never
+ * expands `$var`/`` `cmd` ``/`$(cmd)` — a bare `$` is kept literal. A
+ * backslash immediately before a newline, quoted or not, is a line
+ * continuation: removed entirely rather than embedding the newline or
+ * ending the word (#199). */
+function tokenize(command: string): Word[] | null {
+  const words: Word[] = [];
+  let current = "";
+  let hasCurrent = false;
+  let plainEq: number | null = null;
+  let assignmentNameIsPlain = true;
+  let i = 0;
+  const n = command.length;
+
+  while (i < n) {
+    const c = command[i];
+    if (c === " " || c === "\t" || c === "\r") {
+      if (hasCurrent) {
+        words.push({ text: current, plainEq });
+        current = "";
+        hasCurrent = false;
+        plainEq = null;
+        assignmentNameIsPlain = true;
+      }
+      i += 1;
+    } else if (c === "\n") {
+      return null;
+    } else if ("|&;<>()`".includes(c)) {
+      return null;
+    } else if (c === "$" && command[i + 1] === "(") {
+      return null;
+    } else if (c === "'") {
+      hasCurrent = true;
+      if (plainEq === null) assignmentNameIsPlain = false;
+      i += 1;
+      const close = command.indexOf("'", i);
+      if (close === -1) return null; // unterminated single quote
+      current += command.slice(i, close);
+      i = close + 1;
+    } else if (c === '"') {
+      hasCurrent = true;
+      if (plainEq === null) assignmentNameIsPlain = false;
+      i += 1;
+      for (;;) {
+        if (i >= n) return null; // unterminated double quote
+        const c2 = command[i];
+        if (c2 === '"') {
+          i += 1;
+          break;
+        }
+        if (c2 === "\\") {
+          const escaped = command[i + 1];
+          if (escaped === undefined) return null; // trailing backslash
+          if (escaped === "\n") {
+            i += 2; // line continuation, removed entirely
+            continue;
+          }
+          current += '"\\$`'.includes(escaped) ? escaped : "\\" + escaped;
+          i += 2;
+        } else {
+          current += c2;
+          i += 1;
+        }
+      }
+    } else if (c === "\\") {
+      const escaped = command[i + 1];
+      if (escaped === undefined) return null; // trailing backslash
+      if (escaped === "\n") {
+        i += 2; // line continuation, removed entirely
+        continue;
+      }
+      hasCurrent = true;
+      if (plainEq === null) assignmentNameIsPlain = false;
+      current += escaped;
+      i += 2;
+    } else {
+      hasCurrent = true;
+      if (c === "=" && plainEq === null && assignmentNameIsPlain) {
+        plainEq = current.length;
+      }
+      current += c;
+      i += 1;
+    }
+  }
+  if (hasCurrent) words.push({ text: current, plainEq });
+  return words;
+}
+
+/** A wrapper's known `-`/`--` options: which take no value, and which
+ * consume either a following word or a `--flag=value` as theirs. A
+ * `-`-prefixed word this table doesn't know halts resolution rather than
+ * guessing past it (#199) — callers read that as {@link consumeOptions}
+ * returning `null`. */
+interface OptionTable {
+  flags: Set<string>;
+  valued: Set<string>;
+  /** Whether this wrapper's short options may be combined (`-iv`) or take
+   * an attached value (`-uroot`), the way real getopt-based tools do
+   * (#199). JS-toolchain wrappers (`npx`, `pnpm`, `yarn`, bun's `x`/`dlx`)
+   * don't get this — guessing at bundling they don't actually support
+   * would resolve through options they'd reject outright. */
+  bundlesShortOptions: boolean;
+}
+
+/** `-iv` (bundled boolean short flags) or `-uroot` (a valued short option
+ * with its value attached) — getopt's traditional short-option forms.
+ * `false` the moment a character isn't a short option this table knows, or
+ * a valued one ends the word with no attached value left to be its operand
+ * (#199: rejected rather than guessed to come from the next word instead). */
+function matchesShortCluster(opts: OptionTable, word: string): boolean {
+  let idx = 1;
+  while (idx < word.length) {
+    const short = "-" + word[idx];
+    if (opts.flags.has(short)) {
+      idx += 1;
+      continue;
+    }
+    if (opts.valued.has(short)) {
+      return idx + 1 < word.length;
+    }
+    return false;
+  }
+  return true;
+}
+
+/** Consume `opts`'s options starting at `words[i]`, returning the index just
+ * past them (which may equal `i` if there are none) — or `null` on an
+ * option this table doesn't recognise, or a valued option missing its
+ * operand. */
+function consumeOptions(opts: OptionTable, words: string[], i: number): number | null {
+  for (;;) {
+    const word = words[i];
+    if (word === undefined) return i;
+    if (word === "--") return i + 1;
+    if (word === "-" || !word.startsWith("-")) return i;
+    const eq = word.indexOf("=");
+    if (eq >= 0) {
+      if (opts.valued.has(word.slice(0, eq)) && word.slice(eq + 1).length > 0) {
+        i += 1;
+        continue;
+      }
+      return null;
+    }
+    if (opts.flags.has(word)) {
+      i += 1;
+      continue;
+    }
+    if (opts.valued.has(word)) {
+      const value = words[i + 1];
+      if (value === undefined || value.length === 0 || value.startsWith("-")) return null;
+      i += 2;
+      continue;
+    }
+    if (
+      opts.bundlesShortOptions &&
+      !word.startsWith("--") &&
+      word.length > 2 &&
+      matchesShortCluster(opts, word)
+    ) {
+      i += 1;
+      continue;
+    }
+    return null;
+  }
+}
+
+const NO_OPTIONS: OptionTable = { flags: new Set(), valued: new Set(), bundlesShortOptions: false };
+
+const ENV_OPTS: OptionTable = {
+  flags: new Set(["-i", "--ignore-environment", "-0", "--null", "-v", "--debug"]),
+  valued: new Set(["-u", "--unset", "-C", "--chdir"]),
+  bundlesShortOptions: true,
+};
+
+const SUDO_OPTS: OptionTable = {
+  flags: new Set([
+    "-i",
+    "--login",
+    "-n",
+    "--non-interactive",
+    "-E",
+    "--preserve-env",
+    "-H",
+    "--set-home",
+    "-A",
+    "--askpass",
+    "-b",
+    "--background",
+    "-k",
+    "--reset-timestamp",
+    "-K",
+    "--remove-timestamp",
+    "-S",
+    "--stdin",
+  ]),
+  valued: new Set(["-u", "--user", "-g", "--group"]),
+  bundlesShortOptions: true,
+};
+
+/** `-v`/`-V` only print what would run — they never execute it — so
+ * resolving through them would claim a program runs that `command` never
+ * launches (#199). Only `-p`, which still executes normally, is safe to
+ * look through. */
+const COMMAND_BUILTIN_OPTS: OptionTable = {
+  flags: new Set(["-p"]),
+  valued: new Set(),
+  bundlesShortOptions: true,
+};
+
+/** The bash *keyword* `time` only ever parses `-p` (POSIX output format);
+ * `-o`/`-v`/`-a`/`-f`/`--verbose`/... belong to the external GNU
+ * `/usr/bin/time`, a different program a bare `time` word doesn't
+ * necessarily name. Assuming them here would be guessing which `time`
+ * resolves (#199). */
+function resolveTime(words: string[], i: number): number | null {
+  let next = i + 1;
+  if (words[next] === "-p") next += 1;
+  if (words[next] === "--") next += 1;
+  const command = words[next];
+  return command?.startsWith("-") ? null : next;
+}
+
+/** `-c`/`--call` embeds a whole shell command string rather than naming the
+ * program positionally — resolving past it would mean guessing at a
+ * program buried inside that string, so it's left unrecognised and
+ * resolution stops at `npx` (#199). */
+const NPX_OPTS: OptionTable = {
+  flags: new Set(["-y", "--yes", "--no", "-q", "--quiet", "--ignore-existing"]),
+  valued: new Set(["-p", "--package", "--shell"]),
+  bundlesShortOptions: false,
+};
+
+const PNPM_OPTS: OptionTable = {
+  flags: new Set(["--silent", "-s", "--stream", "--aggregate-output", "--no-progress"]),
+  // `--package`/`--package=value` is documented in this pre-`dlx` position
+  // (`pnpm --package=x dlx y`), alongside the identical flag `dlx` itself
+  // also accepts (`PNPM_DLX_OPTS`).
+  valued: new Set(["-C", "--dir", "--filter", "--package"]),
+  bundlesShortOptions: false,
+};
+
+const YARN_OPTS: OptionTable = {
+  flags: new Set(["--silent", "-s", "--no-progress", "--non-interactive"]),
+  valued: new Set(["--cwd"]),
+  bundlesShortOptions: false,
+};
+
+const PNPM_DLX_OPTS: OptionTable = {
+  flags: new Set(["-s", "--silent"]),
+  valued: new Set(["--package"]),
+  bundlesShortOptions: false,
+};
+
+const YARN_DLX_OPTS: OptionTable = {
+  flags: new Set(["-q", "--quiet"]),
+  valued: new Set(["-p", "--package"]),
+  bundlesShortOptions: false,
+};
+
+const BUN_X_OPTS: OptionTable = {
+  flags: new Set(["--bun", "--no-install", "--verbose", "--silent"]),
+  valued: new Set(["-p", "--package"]),
+  bundlesShortOptions: false,
+};
+
+/** `pnpm`/`yarn` only look through to the package behind an explicit `dlx`
+ * — without it, the next word is a `package.json` script name, not a
+ * package to run (#199: `pnpm claude` is not `pnpm dlx claude`). `dlx`
+ * itself takes launcher-specific options too, consumed before the executable. */
+function resolveDlx(
+  opts: OptionTable,
+  dlxOpts: OptionTable,
+  words: string[],
+  i: number,
+): number | null {
+  const j = consumeOptions(opts, words, i + 1);
+  if (j === null) return null;
+  if (words[j] !== "dlx") return null;
+  return consumeOptions(dlxOpts, words, j + 1);
+}
+
+/** `bun x <pkg>` is bun's `dlx`/`npx` equivalent; `bun run <script>` is not
+ * (the same package-script ambiguity as bare `pnpm`/`yarn`), so only an `x`
+ * subcommand is looked through. `--bun` (`BUN_X_OPTS`) may follow it before
+ * the executable. */
+function resolveBun(words: string[], i: number): number | null {
+  if (words[i + 1] !== "x") return null;
+  return consumeOptions(BUN_X_OPTS, words, i + 2);
+}
+
+/** A resolver for one wrapper form: given the tokenized command and the
+ * index of the wrapper word itself, the index of the word after it (past
+ * its options and any subcommand it requires), or `null` if this occurrence
+ * isn't a form we resolve through. */
+type WrapperResolver = (words: string[], i: number) => number | null;
+
+/** One recognised wrapper form: how to walk past it, and whether an
+ * assignment word is a valid follow-on once it's been walked past. */
+interface Wrapper {
+  resolve: WrapperResolver;
+  /** `true` only for wrappers that themselves interpret a following
+   * `FOO=bar` as an environment assignment for the command they launch
+   * (`env`, `sudo`), or a shell keyword that restarts the assignment-prefix
+   * grammar for a brand new simple command (`time`). Every other wrapper here
+   * is a plain executable that execs its next argument as the program
+   * outright — an assignment-shaped one names a program literally called
+   * `FOO=1`, not an env var (#199). */
+  acceptsAssignment: boolean;
+}
+
+const WRAPPER_RESOLVERS: Record<string, Wrapper> = {
+  env: { resolve: (words, i) => consumeOptions(ENV_OPTS, words, i + 1), acceptsAssignment: true },
+  sudo: {
+    resolve: (words, i) => consumeOptions(SUDO_OPTS, words, i + 1),
+    acceptsAssignment: true,
+  },
+  command: {
+    resolve: (words, i) => consumeOptions(COMMAND_BUILTIN_OPTS, words, i + 1),
+    acceptsAssignment: false,
+  },
+  nohup: {
+    resolve: (words, i) => consumeOptions(NO_OPTIONS, words, i + 1),
+    acceptsAssignment: false,
+  },
+  time: { resolve: resolveTime, acceptsAssignment: true },
+  npx: {
+    resolve: (words, i) => consumeOptions(NPX_OPTS, words, i + 1),
+    acceptsAssignment: false,
+  },
+  pnpm: {
+    resolve: (words, i) => resolveDlx(PNPM_OPTS, PNPM_DLX_OPTS, words, i),
+    acceptsAssignment: false,
+  },
+  yarn: {
+    resolve: (words, i) => resolveDlx(YARN_OPTS, YARN_DLX_OPTS, words, i),
+    acceptsAssignment: false,
+  },
+  bun: { resolve: resolveBun, acceptsAssignment: false },
+  bunx: {
+    resolve: (words, i) => consumeOptions(BUN_X_OPTS, words, i + 1),
+    acceptsAssignment: false,
+  },
+  uvx: { resolve: (_words, i) => i + 1, acceptsAssignment: false },
+};
+
 /** Anthropic's burst: tapered rays around a centre, long ones on the axes. */
 function burst(): string {
   const rays = Array.from({ length: 8 }, (_, k) => {

web/src/types.ts

@@ -60,8 +60,15 @@ export interface Session {
    * `session/new` (#134). Only a `Structured` session whose handshake
    * succeeded has one; a respawn passes it to `session/load` (#135). */
   acp_session_id?: string | null;
+  /** Terminal (PTY bytes) or structured (ACP rows) (#133). Fixed at spawn and
+   * immutable for the session's life. Defaults to `"Terminal"` on the wire, so
+   * absent means terminal. */
+  view?: SessionView;
 }
 
+/** A session's process shape (#133): mirrors `maestro_protocol::SessionView`. */
+export type SessionView = "Terminal" | "Structured";
+
 /** A session's daemon-created worktree (`SessionWorktree` on the wire). */
 export interface SessionWorktree {
   path: string;
@@ -269,6 +276,7 @@ export interface CreateSessionRequest {
   env?: Record<string, string>;
   metadata?: Record<string, unknown>;
   worktree?: WorktreeSpec;
+  view?: SessionView;
 }
 
 export type CatalogEvent =
@@ -367,6 +375,189 @@ export function abbreviateCwd(cwd: string, home?: string): string {
   return cwd;
 }
 
+// ---------------------------------------------------------------------------
+// Structured-session projections (#133/#140). Mirror of
+// `maestro_protocol`'s "Structured-session projections" section. `data`,
+// `ReducedState.plan/usage/context/pending_approval` and every `Acp*` type
+// below are the daemon's opaque ACP payloads (`serde_json::Value` on the
+// wire) — shaped to `claude-code-acp`'s ACP v1 schema, not covered by
+// maestro-protocol's own compatibility guarantee. Treat every field as
+// optional and degrade gracefully rather than trust this shape exactly.
+// ---------------------------------------------------------------------------
+
+/** `maestro_protocol::TranscriptRowKind`, snake_case on the wire. */
+export type TranscriptRowKind =
+  | "user"
+  | "agent_text"
+  | "agent_thought"
+  | "tool_call"
+  | "tool_diff"
+  | "approval"
+  | "plan"
+  | "notice";
+
+/** One row of a structured session's transcript. */
+export interface TranscriptRow {
+  id: string;
+  kind: TranscriptRowKind;
+  data: unknown;
+}
+
+/** The complete transcript at a durable event-log position (`WS
+ * /api/structured/:id`'s first message, and every replay page). */
+export interface TranscriptSnapshot {
+  cursor: number;
+  rows: TranscriptRow[];
+}
+
+/** A change to one transcript row, addressed by `id`. */
+export type TranscriptDelta =
+  | { type: "append"; row: TranscriptRow }
+  | { type: "patch"; row: TranscriptRow }
+  | { type: "remove"; id: string };
+
+/** Per-turn indicators derived from the ACP stream — read verbatim, never
+ * re-derived client-side (docs/STRUCTURED-VIEW.md). */
+export interface TurnState {
+  responding: boolean;
+  thinking: boolean;
+  active_tool_calls: string[];
+}
+
+/** A whole-session view derived from ACP notifications. `plan`/`usage`/
+ * `context`/`pending_approval` are opaque ACP JSON — see the module note
+ * above. `pending_approval` is `{nonce, request: AcpRequestPermissionRequest}`
+ * while a permission request is live, absent otherwise. */
+export interface ReducedState {
+  turn: TurnState;
+  pending_approval?: { nonce: string; request: AcpRequestPermissionRequest } | null;
+  plan?: AcpPlan | null;
+  usage?: AcpUsage | null;
+  context?: AcpUsage | null;
+  model?: string | null;
+  mode?: string | null;
+}
+
+/** Server messages on `WS /api/structured/:id`. */
+export type StructuredEvent =
+  | { type: "transcript_snapshot"; snapshot: TranscriptSnapshot }
+  | { type: "reduced_state"; state: ReducedState }
+  | { type: "projection_update"; transcript?: TranscriptDelta | null; state: ReducedState };
+
+/** `POST /api/sessions/:id/structured/prompt` body. */
+export interface StructuredPromptRequest {
+  prompt: string;
+}
+
+/** `POST /api/sessions/:id/structured/approvals/:nonce` body — a bare JSON
+ * string (a bracketless Rust enum), not `{decision: ...}`. */
+export type StructuredApprovalDecision = "allow_once" | "allow_for_session" | "deny";
+
+// ---- ACP v1 payload shapes (agent-client-protocol schema, camelCase) ----
+
+/** `ContentBlock`. Only `text` is common in practice; the rest degrade to a
+ * generic placeholder rather than being dropped silently. */
+export type AcpContentBlock =
+  | { type: "text"; text: string }
+  | { type: "image"; mimeType?: string }
+  | { type: "audio"; mimeType?: string }
+  | { type: "resource_link"; uri?: string; name?: string }
+  | { type: "resource"; resource?: unknown };
+
+/** `ContentChunk` — the payload of a `User`/`AgentText`/`AgentThought` row. */
+export interface AcpContentChunk {
+  content: AcpContentBlock;
+  messageId?: string | null;
+}
+
+/** `ToolKind`, snake_case on the wire. */
+export type AcpToolKind =
+  | "read"
+  | "edit"
+  | "delete"
+  | "move"
+  | "search"
+  | "execute"
+  | "think"
+  | "fetch"
+  | "switch_mode"
+  | "other";
+
+/** `ToolCallStatus`, snake_case on the wire. */
+export type AcpToolCallStatus = "pending" | "in_progress" | "completed" | "failed";
+
+/** `Diff` — a file modification. `oldText` absent means a new file. */
+export interface AcpDiff {
+  path: string;
+  oldText?: string | null;
+  newText: string;
+}
+
+/** `ToolCallContent`. */
+export type AcpToolCallContent =
+  | { type: "content"; content: AcpContentBlock }
+  | ({ type: "diff" } & AcpDiff)
+  | { type: "terminal"; terminalId?: string };
+
+export interface AcpToolCallLocation {
+  path: string;
+  line?: number | null;
+}
+
+/** `ToolCall` (a `ToolCall`/`ToolDiff` row's `data`) and, loosely, the
+ * flattened `ToolCallUpdate` an approval's `toolCall` field carries — the
+ * two share every field below, just with different subsets required. */
+export interface AcpToolCallLike {
+  toolCallId?: string;
+  title?: string;
+  /** Unstable ACP capability; absent when the adapter doesn't send one. */
+  name?: string | null;
+  kind?: AcpToolKind;
+  status?: AcpToolCallStatus;
+  content?: AcpToolCallContent[];
+  locations?: AcpToolCallLocation[];
+  rawInput?: unknown;
+  rawOutput?: unknown;
+}
+
+/** `PlanEntryPriority` / `PlanEntryStatus`, snake_case on the wire. */
+export type AcpPlanPriority = "high" | "medium" | "low";
+export type AcpPlanEntryStatus = "pending" | "in_progress" | "completed";
+
+export interface AcpPlanEntry {
+  content: string;
+  priority: AcpPlanPriority;
+  status: AcpPlanEntryStatus;
+}
+
+/** `Plan` — `ReducedState.plan`. */
+export interface AcpPlan {
+  entries: AcpPlanEntry[];
+}
+
+/** `UsageUpdate` — `ReducedState.usage`/`.context` (the daemon folds one
+ * update into both fields). */
+export interface AcpUsage {
+  used: number;
+  size: number;
+  cost?: { amount: number; currency: string } | null;
+}
+
+export interface AcpPermissionOption {
+  optionId: string;
+  name: string;
+  kind: "allow_once" | "allow_always" | "reject_once" | "reject_always";
+}
+
+/** `RequestPermissionRequest`, serialized without its nonce (the nonce lives
+ * only in `ReducedState.pending_approval.nonce`) — an `Approval` row's `data`,
+ * and `ReducedState.pending_approval.request`. */
+export interface AcpRequestPermissionRequest {
+  sessionId: string;
+  toolCall: AcpToolCallLike;
+  options: AcpPermissionOption[];
+}
+
 /** `~/git.naps.pt/naps62/maestro` → `~/g/n/maestro`: keep the last segment
  * verbatim, collapse every earlier one to its first character. Two-or-fewer
  * segments are left alone (nothing to gain). Returns escaped HTML with the