feat: add structured session picker

Cargo.lock

@@ -1477,6 +1477,7 @@ version = "0.1.0"
 dependencies = [
  "agent-client-protocol",
  "libc",
+ "serde",
  "serde_json",
  "tempfile",
  "thiserror 1.0.69",

crates/maestro-acp/Cargo.toml

@@ -10,6 +10,7 @@ description = "ACP client role: one claude-code-acp child per structured session
 [dependencies]
 agent-client-protocol.workspace = true
 libc.workspace = true
+serde.workspace = true
 serde_json.workspace = true
 thiserror.workspace = true
 tokio.workspace = true

crates/maestro-acp/src/lib.rs

@@ -42,13 +42,16 @@ use std::sync::{Arc, Mutex};
 use std::time::Duration;
 
 use agent_client_protocol::schema::v1::{
-    CancelNotification, ClientCapabilities, ContentBlock, FileSystemCapabilities, Implementation,
+    CancelNotification, ClientCapabilities, ConfigOptionUpdate, ContentBlock, CurrentModeUpdate,
-    InitializeRequest, LoadSessionRequest, NewSessionRequest, PromptRequest,
+    FileSystemCapabilities, Implementation, InitializeRequest, PromptRequest,
-    RequestPermissionOutcome, RequestPermissionRequest, RequestPermissionResponse, SessionId,
+    RequestPermissionOutcome, RequestPermissionRequest, RequestPermissionResponse,
-    SessionNotification,
+    SessionConfigKind, SessionConfigOption, SessionConfigOptionCategory, SessionConfigOptionValue,
+    SessionConfigSelectOption, SessionId, SessionModeState, SessionNotification, SessionUpdate,
+    SetSessionConfigOptionRequest, SetSessionModeRequest,
 };
 use agent_client_protocol::schema::ProtocolVersion;
-use agent_client_protocol::{ByteStreams, Client};
+use agent_client_protocol::{ByteStreams, Client, JsonRpcRequest, JsonRpcResponse};
+use serde::{Deserialize, Serialize};
 use tokio::io::AsyncBufReadExt;
 use tokio::sync::{mpsc, oneshot, watch};
 use tokio_util::compat::{TokioAsyncReadCompatExt, TokioAsyncWriteCompatExt};
@@ -78,6 +81,75 @@ pub const TERM_GRACE: Duration = Duration::from_secs(2);
 
 /// Bytes of the child's stderr kept for the failure message.
 const STDERR_TAIL_BYTES: usize = 4096;
+const LEGACY_MODEL_CONFIG_ID: &str = "__maestro_legacy_model";
+const LEGACY_MODE_CONFIG_ID: &str = "__maestro_legacy_mode";
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonRpcRequest)]
+#[request(method = "session/new", response = ExtendedNewSessionResponse)]
+#[serde(rename_all = "camelCase")]
+struct ExtendedNewSessionRequest {
+    cwd: PathBuf,
+    mcp_servers: Vec<serde_json::Value>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonRpcResponse)]
+#[serde(rename_all = "camelCase")]
+struct ExtendedNewSessionResponse {
+    session_id: SessionId,
+    #[serde(default)]
+    modes: Option<SessionModeState>,
+    #[serde(default)]
+    config_options: Option<Vec<SessionConfigOption>>,
+    #[serde(default)]
+    models: Option<LegacyModelState>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonRpcRequest)]
+#[request(method = "session/load", response = ExtendedLoadSessionResponse)]
+#[serde(rename_all = "camelCase")]
+struct ExtendedLoadSessionRequest {
+    session_id: SessionId,
+    cwd: PathBuf,
+    mcp_servers: Vec<serde_json::Value>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonRpcResponse)]
+#[serde(rename_all = "camelCase")]
+struct ExtendedLoadSessionResponse {
+    #[serde(default)]
+    modes: Option<SessionModeState>,
+    #[serde(default)]
+    config_options: Option<Vec<SessionConfigOption>>,
+    #[serde(default)]
+    models: Option<LegacyModelState>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct LegacyModelState {
+    current_model_id: String,
+    available_models: Vec<LegacyModel>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct LegacyModel {
+    model_id: String,
+    name: String,
+    #[serde(default)]
+    description: Option<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonRpcRequest)]
+#[request(method = "session/set_model", response = LegacySetModelResponse)]
+#[serde(rename_all = "camelCase")]
+struct LegacySetModelRequest {
+    session_id: SessionId,
+    model_id: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonRpcResponse)]
+struct LegacySetModelResponse {}
 
 /// What [`spawn`] needs to start one adapter.
 #[derive(Debug, Clone)]
@@ -168,6 +240,11 @@ enum Command {
         turn: u64,
         done: oneshot::Sender<Result<(), String>>,
     },
+    SetConfig {
+        config_id: String,
+        value: SessionConfigOptionValue,
+        done: oneshot::Sender<Result<(), String>>,
+    },
     Close,
 }
 
@@ -301,6 +378,23 @@ impl AcpSession {
         Ok(done_rx)
     }
 
+    /// Change one option advertised by the ACP agent.
+    pub fn set_config(
+        &self,
+        config_id: String,
+        value: SessionConfigOptionValue,
+    ) -> Result<oneshot::Receiver<Result<(), String>>, String> {
+        let (done_tx, done_rx) = oneshot::channel();
+        self.commands
+            .send(Command::SetConfig {
+                config_id,
+                value,
+                done: done_tx,
+            })
+            .map_err(|_| "ACP connection is closed".to_string())?;
+        Ok(done_rx)
+    }
+
     /// End the child: `session/cancel`, wait `cancel_grace`, `SIGTERM`, wait
     /// `term_grace`, `SIGKILL`. Returns once the child has been reaped.
     pub async fn terminate(&self, cancel_grace: Duration, term_grace: Duration) {
@@ -513,6 +607,91 @@ fn client_capabilities() -> ClientCapabilities {
         .terminal(false)
 }
 
+fn advertised_config_options(
+    mut options: Vec<SessionConfigOption>,
+    modes: Option<&SessionModeState>,
+    models: Option<&LegacyModelState>,
+) -> Vec<SessionConfigOption> {
+    let has_model = options
+        .iter()
+        .any(|option| matches!(option.category, Some(SessionConfigOptionCategory::Model)));
+    let has_mode = options
+        .iter()
+        .any(|option| matches!(option.category, Some(SessionConfigOptionCategory::Mode)));
+    if let Some(models) = models.filter(|_| !has_model) {
+        let choices = models
+            .available_models
+            .iter()
+            .map(|model| {
+                let mut option =
+                    SessionConfigSelectOption::new(model.model_id.clone(), &model.name);
+                option.description.clone_from(&model.description);
+                option
+            })
+            .collect::<Vec<_>>();
+        options.push(
+            SessionConfigOption::select(
+                LEGACY_MODEL_CONFIG_ID,
+                "Model",
+                models.current_model_id.clone(),
+                choices,
+            )
+            .category(SessionConfigOptionCategory::Model),
+        );
+    }
+    if let Some(modes) = modes.filter(|_| !has_mode) {
+        let choices = modes
+            .available_modes
+            .iter()
+            .map(|mode| {
+                let mut option = SessionConfigSelectOption::new(mode.id.0.clone(), &mode.name);
+                option.description.clone_from(&mode.description);
+                option
+            })
+            .collect::<Vec<_>>();
+        options.push(
+            SessionConfigOption::select(
+                LEGACY_MODE_CONFIG_ID,
+                "Mode",
+                modes.current_mode_id.0.clone(),
+                choices,
+            )
+            .category(SessionConfigOptionCategory::Mode),
+        );
+    }
+    options
+}
+
+fn replace_config_value(
+    options: &Arc<Mutex<Vec<SessionConfigOption>>>,
+    config_id: &str,
+    value: &SessionConfigOptionValue,
+) -> Vec<SessionConfigOption> {
+    let mut options = options.lock().expect("config options");
+    if let Some(option) = options
+        .iter_mut()
+        .find(|option| option.id.0.as_ref() == config_id)
+    {
+        match (&mut option.kind, value) {
+            (SessionConfigKind::Select(select), SessionConfigOptionValue::ValueId { value }) => {
+                select.current_value = value.clone();
+            }
+            (SessionConfigKind::Boolean(boolean), SessionConfigOptionValue::Boolean { value }) => {
+                boolean.current_value = *value;
+            }
+            _ => {}
+        }
+    }
+    options.clone()
+}
+
+fn config_notification(session_id: &str, options: Vec<SessionConfigOption>) -> SessionNotification {
+    SessionNotification::new(
+        SessionId::new(session_id),
+        SessionUpdate::ConfigOptionUpdate(ConfigOptionUpdate::new(options)),
+    )
+}
+
 async fn run_connection<T>(
     transport: T,
     cwd: PathBuf,
@@ -534,6 +713,7 @@ async fn run_connection<T>(
     // 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 received_updates = updates_tx.clone();
     let result = Client
         .builder()
         .name("maestro")
@@ -544,7 +724,7 @@ async fn run_connection<T>(
                     return Ok(());
                 }
                 // A dropped receiver only means nobody wants updates any more.
-                let _ = updates_tx.send(notification);
+                let _ = received_updates.send(notification);
                 Ok(())
             },
             agent_client_protocol::on_receive_notification!(),
@@ -589,7 +769,7 @@ async fn run_connection<T>(
                     return Ok(());
                 }
             };
-            let session_id = match load_session {
+            let (session_id, modes, initial_options, models) = match load_session {
                 Some(existing) => {
                     if !initialized.agent_capabilities.load_session {
                         let _ = ready_tx.send(Err(ReadyError::Handshake(format!(
@@ -601,7 +781,11 @@ async fn run_connection<T>(
                     let (loaded_tx, loaded_rx) = oneshot::channel();
                     let replaying_done = replaying.clone();
                     if let Err(e) = cx
-                        .send_request(LoadSessionRequest::new(existing.clone(), cwd))
+                        .send_request(ExtendedLoadSessionRequest {
+                            session_id: SessionId::new(existing.as_str()),
+                            cwd,
+                            mcp_servers: vec![],
+                        })
                         .on_receiving_result(move |result| {
                             replaying_done.store(false, Ordering::SeqCst);
                             async move {
@@ -613,8 +797,8 @@ async fn run_connection<T>(
                         let _ = ready_tx.send(Err(ready_error(e)));
                         return Ok(());
                     }
-                    match loaded_rx.await {
+                    let loaded = match loaded_rx.await {
-                        Ok(Ok(_)) => {}
+                        Ok(Ok(loaded)) => loaded,
                         Ok(Err(e)) => {
                             let _ = ready_tx.send(Err(ready_error(e)));
                             return Ok(());
@@ -625,21 +809,48 @@ async fn run_connection<T>(
                             )));
                             return Ok(());
                         }
-                    }
+                    };
-                    existing
+                    (existing, loaded.modes, loaded.config_options.unwrap_or_default(), loaded.models)
                 }
                 None => match cx
-                    .send_request(NewSessionRequest::new(cwd))
+                    .send_request(ExtendedNewSessionRequest {
+                        cwd,
+                        mcp_servers: vec![],
+                    })
                     .block_task()
                     .await
                 {
-                    Ok(created) => created.session_id.0.to_string(),
+                    Ok(created) => (
+                        created.session_id.0.to_string(),
+                        created.modes,
+                        created.config_options.unwrap_or_default(),
+                        created.models,
+                    ),
                     Err(e) => {
                         let _ = ready_tx.send(Err(ready_error(e)));
                         return Ok(());
                     }
                 },
             };
+            let config_options = Arc::new(Mutex::new(advertised_config_options(
+                initial_options,
+                modes.as_ref(),
+                models.as_ref(),
+            )));
+            if let Some(modes) = &modes {
+                let _ = updates_tx.send(SessionNotification::new(
+                    SessionId::new(session_id.as_str()),
+                    SessionUpdate::CurrentModeUpdate(CurrentModeUpdate::new(
+                        modes.current_mode_id.clone(),
+                    )),
+                ));
+            }
+            if !config_options.lock().expect("config options").is_empty() {
+                let _ = updates_tx.send(config_notification(
+                    &session_id,
+                    config_options.lock().expect("config options").clone(),
+                ));
+            }
             let _ = ready_tx.send(Ok(session_id.clone()));
 
             loop {
@@ -689,6 +900,83 @@ async fn run_connection<T>(
                                 }
                             }
                         }
+                        Some(Command::SetConfig { config_id, value, done }) => {
+                            let done = Arc::new(Mutex::new(Some(done)));
+                            let callback_done = done.clone();
+                            let callback_options = config_options.clone();
+                            let callback_updates = updates_tx.clone();
+                            let callback_session = session_id.clone();
+                            let callback_config_id = config_id.clone();
+                            let callback_value = value.clone();
+                            let sent = if config_id == LEGACY_MODEL_CONFIG_ID {
+                                let Some(model_id) = value.as_value_id() else {
+                                    let _ = done.lock().expect("config sender").take()
+                                        .map(|done| done.send(Err("model must be a string value".into())));
+                                    continue;
+                                };
+                                cx.send_request(LegacySetModelRequest {
+                                    session_id: SessionId::new(session_id.as_str()),
+                                    model_id: model_id.0.to_string(),
+                                }).on_receiving_result(move |result| async move {
+                                    if result.is_ok() {
+                                        let options = replace_config_value(&callback_options, &callback_config_id, &callback_value);
+                                        let _ = callback_updates.send(config_notification(&callback_session, options));
+                                    }
+                                    if let Some(done) = callback_done.lock().expect("config sender").take() {
+                                        let _ = done.send(result.map(|_| ()).map_err(|error| error.to_string()));
+                                    }
+                                    Ok(())
+                                })
+                            } else if config_id == LEGACY_MODE_CONFIG_ID {
+                                let Some(mode_id) = value.as_value_id() else {
+                                    let _ = done.lock().expect("config sender").take()
+                                        .map(|done| done.send(Err("mode must be a string value".into())));
+                                    continue;
+                                };
+                                cx.send_request(SetSessionModeRequest::new(
+                                    SessionId::new(session_id.as_str()),
+                                    mode_id.0.to_string(),
+                                )).on_receiving_result(move |result| async move {
+                                    if result.is_ok() {
+                                        let options = replace_config_value(&callback_options, &callback_config_id, &callback_value);
+                                        let _ = callback_updates.send(config_notification(&callback_session, options));
+                                        let _ = callback_updates.send(SessionNotification::new(
+                                            SessionId::new(callback_session.as_str()),
+                                            SessionUpdate::CurrentModeUpdate(CurrentModeUpdate::new(
+                                                callback_value.as_value_id().expect("checked mode value").0.clone(),
+                                            )),
+                                        ));
+                                    }
+                                    if let Some(done) = callback_done.lock().expect("config sender").take() {
+                                        let _ = done.send(result.map(|_| ()).map_err(|error| error.to_string()));
+                                    }
+                                    Ok(())
+                                })
+                            } else {
+                                cx.send_request(SetSessionConfigOptionRequest::new(
+                                    SessionId::new(session_id.as_str()),
+                                    config_id,
+                                    value,
+                                ))
+                                    .on_receiving_result(move |result| async move {
+                                        if let Ok(response) = &result {
+                                            let mut current = callback_options.lock().expect("config options");
+                                            current.retain(|option| option.id.0.as_ref().starts_with("__maestro_legacy_"));
+                                            current.extend(response.config_options.clone());
+                                            let _ = callback_updates.send(config_notification(&callback_session, current.clone()));
+                                        }
+                                        if let Some(done) = callback_done.lock().expect("config sender").take() {
+                                            let _ = done.send(result.map(|_| ()).map_err(|error| error.to_string()));
+                                        }
+                                        Ok(())
+                                    })
+                            };
+                            if let Err(error) = sent {
+                                if let Some(done) = done.lock().expect("config sender").take() {
+                                    let _ = done.send(Err(error.to_string()));
+                                }
+                            }
+                        }
                         Some(Command::Close) | None => break,
                     },
                     _ = cx.incoming_closed() => break,

crates/maestro-acp/tests/fake_acp_agent.py

@@ -36,6 +36,7 @@ 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_SETTINGS=1      advertise legacy model/mode and modern effort options
   FAKE_ACP_PERMISSION_AFTER_CANCEL=1  defer the first prompt's permission
                              callback until a later prompt
 
@@ -78,6 +79,41 @@ prompt_failures = 0
 pending_prompt_id = None
 pending_permission_id = None
 delayed_permission = False
+current_model = "opus"
+current_mode = "default"
+current_effort = "high"
+
+
+def settings_response(include_session=False):
+    result = {}
+    if include_session:
+        result["sessionId"] = session_id
+    if os.environ.get("FAKE_ACP_SETTINGS") == "1":
+        result.update({
+            "models": {
+                "currentModelId": current_model,
+                "availableModels": [
+                    {"modelId": "opus", "name": "Opus"},
+                    {"modelId": "sonnet", "name": "Sonnet"},
+                ],
+            },
+            "modes": {
+                "currentModeId": current_mode,
+                "availableModes": [
+                    {"id": "default", "name": "Default"},
+                    {"id": "plan", "name": "Plan"},
+                ],
+            },
+            "configOptions": [{
+                "id": "effort", "name": "Effort", "category": "thought_level",
+                "type": "select", "currentValue": current_effort,
+                "options": [
+                    {"value": "low", "name": "Low"},
+                    {"value": "high", "name": "High"},
+                ],
+            }],
+        })
+    return result
 
 
 def chunk(text):
@@ -139,7 +175,7 @@ for raw in sys.stdin:
         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({"jsonrpc": "2.0", "id": rid, "result": settings_response(True)})
         send(chunk("hello from fake"))
         if os.environ.get("FAKE_ACP_EXIT_AFTER_NEW") == "1":
             sys.exit(0)
@@ -152,8 +188,18 @@ for raw in sys.stdin:
             continue
         for i in range(int(os.environ.get("FAKE_ACP_LOAD_REPLAY", "0"))):
             send(chunk(f"replayed {i + 1}"))
-        send({"jsonrpc": "2.0", "id": rid, "result": {}})
+        send({"jsonrpc": "2.0", "id": rid, "result": settings_response()})
         send(chunk("hello after load"))
+    elif method == "session/set_model":
+        current_model = params.get("modelId")
+        send({"jsonrpc": "2.0", "id": rid, "result": {}})
+    elif method == "session/set_mode":
+        current_mode = params.get("modeId")
+        send({"jsonrpc": "2.0", "id": rid, "result": {}})
+    elif method == "session/set_config_option":
+        current_effort = params.get("value")
+        send({"jsonrpc": "2.0", "id": rid, "result": {
+            "configOptions": settings_response()["configOptions"]}})
     elif method == "session/cancel":
         if os.environ.get("FAKE_ACP_EMIT_ON_CANCEL") == "1":
             send(chunk("final on cancel"))

crates/maestro-acp/tests/spawn.rs

@@ -180,6 +180,52 @@ async fn session_updates_reach_the_taken_receiver() {
         .await;
 }
 
+#[tokio::test]
+async fn advertised_settings_are_normalized_and_mutable() {
+    let fake = Fake::new();
+    let cwd = TempDir::new().unwrap();
+    let mut config = fake.config(cwd.path());
+    config.env.insert("FAKE_ACP_SETTINGS".into(), "1".into());
+    let session = maestro_acp::spawn(config).await.expect("spawn");
+    let mut updates = session.take_updates().expect("updates");
+
+    let initial = loop {
+        let update = tokio::time::timeout(Duration::from_secs(5), updates.recv())
+            .await
+            .expect("settings update")
+            .expect("channel open");
+        if let SessionUpdate::ConfigOptionUpdate(options) = update.update {
+            break options.config_options;
+        }
+    };
+    assert_eq!(initial.len(), 3);
+    assert!(initial
+        .iter()
+        .any(|option| option.id.0.as_ref() == "effort"));
+    assert!(initial
+        .iter()
+        .any(|option| option.id.0.as_ref() == "__maestro_legacy_model"));
+    assert!(initial
+        .iter()
+        .any(|option| option.id.0.as_ref() == "__maestro_legacy_mode"));
+
+    let changed = session
+        .set_config(
+            "__maestro_legacy_model".into(),
+            maestro_acp::schema::SessionConfigOptionValue::value_id("sonnet"),
+        )
+        .expect("queue model change");
+    changed
+        .await
+        .expect("response delivered")
+        .expect("model changed");
+    fake.wait_for_log("recv session/set_model").await;
+
+    session
+        .terminate(Duration::from_millis(100), Duration::from_secs(2))
+        .await;
+}
+
 #[tokio::test]
 async fn terminate_sends_cancel_then_sigterm() {
     let fake = Fake::new();

crates/maestro-daemon/src/local_api.rs

@@ -21,12 +21,13 @@ use maestro_config::SpawnPreset;
 use maestro_protocol::{
     routes, ApiError, CatalogEvent, CreateSessionRequest, DaemonInfo, GitRoot, NameBatch,
     RenameSessionRequest, ReportActivityRequest, SendInputRequest, Session, SetFocusRequest,
-    StructuredApprovalDecision, StructuredEvent, StructuredPromptRequest, PROTOCOL_VERSION,
+    StructuredApprovalDecision, StructuredConfigRequest, StructuredEvent, StructuredPromptRequest,
+    PROTOCOL_VERSION,
 };
 use serde::Deserialize;
 use uuid::Uuid;
 
-use crate::session::{QueueAcpPrompt, SessionError, SessionManager};
+use crate::session::{QueueAcpPrompt, SessionError, SessionManager, SetAcpConfig};
 use crate::sidecar::EventCursor;
 
 #[derive(Debug, Clone)]
@@ -70,6 +71,7 @@ pub fn router(state: LocalApiState) -> Router {
         .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_CONFIG, post(structured_config))
         .route(
             routes::patterns::STRUCTURED_APPROVAL,
             post(structured_approval),
@@ -472,6 +474,37 @@ async fn structured_cancel(State(s): State<LocalApiState>, Path(id): Path<Uuid>)
     }
 }
 
+async fn structured_config(
+    State(s): State<LocalApiState>,
+    Path(id): Path<Uuid>,
+    Json(body): Json<StructuredConfigRequest>,
+) -> Response {
+    match s
+        .manager
+        .set_acp_config(id, body.config_id, body.value)
+        .await
+    {
+        Ok(SetAcpConfig::Updated) => StatusCode::NO_CONTENT.into_response(),
+        Ok(SetAcpConfig::InvalidValue) => error_response(
+            StatusCode::BAD_REQUEST,
+            "invalid_config_value",
+            "configuration values must be strings or booleans",
+        ),
+        Ok(SetAcpConfig::Unavailable) => error_response(
+            StatusCode::CONFLICT,
+            "not_structured",
+            "session is not a live structured session",
+        ),
+        Ok(SetAcpConfig::Failed(message)) => {
+            error_response(StatusCode::BAD_GATEWAY, "acp_config_failed", &message)
+        }
+        Err(e) => {
+            let info = e.to_error_info();
+            error_response(session_error_status(&info.code), &info.code, &info.message)
+        }
+    }
+}
+
 async fn structured_approval(
     State(s): State<LocalApiState>,
     Path((id, nonce)): Path<(Uuid, String)>,

crates/maestro-daemon/src/projection.rs

@@ -79,6 +79,7 @@ impl Projection {
             SessionUpdate::ConfigOptionUpdate(options) => {
                 let value = to_value(options);
                 self.state.model = model_from_options(&value).or_else(|| self.state.model.clone());
+                self.state.config_options = Some(value);
                 None
             }
             // ACP deliberately adds notification variants over time. Known but
@@ -721,6 +722,10 @@ mod tests {
         assert_eq!(state.context.as_ref().unwrap()["size"], 200);
         assert_eq!(state.mode.as_deref(), Some("plan"));
         assert_eq!(state.model.as_deref(), Some("opus"));
+        assert_eq!(
+            state.config_options.as_ref().unwrap()["configOptions"][0]["currentValue"],
+            "opus"
+        );
         assert_eq!(
             state.plan.as_ref().unwrap()["entries"],
             serde_json::json!([])

crates/maestro-daemon/src/session.rs

@@ -218,6 +218,15 @@ pub enum QueueAcpPrompt {
     Failed(String),
 }
 
+/// Result of changing a live structured session option.
+#[derive(Debug)]
+pub enum SetAcpConfig {
+    Updated,
+    InvalidValue,
+    Unavailable,
+    Failed(String),
+}
+
 impl SessionError {
     pub fn to_error_info(&self) -> ErrorInfo {
         let code = match self {
@@ -850,6 +859,48 @@ impl SessionManager {
         }
     }
 
+    /// Change one option on a live ACP session and wait for the agent to
+    /// acknowledge it. The adapter's returned option set is projected by the
+    /// normal event pump before this request completes.
+    pub async fn set_acp_config(
+        &self,
+        id: Uuid,
+        config_id: String,
+        value: serde_json::Value,
+    ) -> Result<SetAcpConfig, SessionError> {
+        let (acp, stream) = {
+            let sessions = self.inner.sessions.lock().await;
+            let record = sessions.get(&id).ok_or(SessionError::NotFound(id))?;
+            if !record.is_live_structured() {
+                return Ok(SetAcpConfig::Unavailable);
+            }
+            (record.acp.clone(), record.acp_events.clone())
+        };
+        let (Some(acp), Some(stream)) = (acp, stream) else {
+            return Ok(SetAcpConfig::Unavailable);
+        };
+        let value = match value {
+            serde_json::Value::String(value) => {
+                maestro_acp::schema::SessionConfigOptionValue::value_id(value)
+            }
+            serde_json::Value::Bool(value) => {
+                maestro_acp::schema::SessionConfigOptionValue::boolean(value)
+            }
+            _ => return Ok(SetAcpConfig::InvalidValue),
+        };
+        let operation = stream.lock().await.operation.clone();
+        let _operation = operation.lock().await;
+        let done = match acp.set_config(config_id, value) {
+            Ok(done) => done,
+            Err(message) => return Ok(SetAcpConfig::Failed(message)),
+        };
+        match done.await {
+            Ok(Ok(())) => Ok(SetAcpConfig::Updated),
+            Ok(Err(message)) => Ok(SetAcpConfig::Failed(message)),
+            Err(_) => Ok(SetAcpConfig::Failed("ACP connection is closed".into())),
+        }
+    }
+
     /// Cancel an ACP turn and immediately clear its client-facing lifecycle.
     pub async fn cancel_acp_turn(&self, id: Uuid) -> Result<bool, SessionError> {
         let (acp, stream) = {

crates/maestro-protocol/src/lib.rs

@@ -846,6 +846,8 @@ pub struct ReducedState {
     pub model: Option<String>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub mode: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub config_options: Option<Value>,
 }
 
 /// Server messages sent over a structured-session WebSocket.
@@ -871,6 +873,13 @@ pub struct StructuredPromptRequest {
     pub prompt: String,
 }
 
+/// HTTP body for `POST /api/sessions/:id/structured/config`.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct StructuredConfigRequest {
+    pub config_id: String,
+    pub value: Value,
+}
+
 /// Operator decision for a pending ACP permission request.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]

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/config` — change an ACP session option.
+pub fn structured_config(id: Uuid) -> String {
+    format!("{SESSIONS}/{id}/structured/config")
+}
+
 /// `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}")
@@ -109,6 +114,7 @@ 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_CONFIG: &str = "/api/sessions/:id/structured/config";
     pub const STRUCTURED_APPROVAL: &str = "/api/sessions/:id/structured/approvals/:nonce";
 }
 

web/src/api.ts

@@ -12,6 +12,7 @@ import type {
   RecentDirs,
   Session,
   StructuredApprovalDecision,
+  StructuredConfigRequest,
   StructuredPromptRequest,
   Uuid,
 } from "./types.js";
@@ -93,6 +94,21 @@ export async function killSession(id: Uuid, force = false): Promise<void> {
   );
 }
 
+/** Change one option advertised by a live ACP session. */
+export async function setStructuredConfig(
+  id: Uuid,
+  req: StructuredConfigRequest,
+): Promise<void> {
+  await jsonOrError(
+    await fetch(routes.structuredConfig(id), {
+      method: "POST",
+      credentials: "same-origin",
+      headers: { "content-type": "application/json" },
+      body: JSON.stringify(req),
+    }),
+  );
+}
+
 /** Report whether this client's pane is the one currently showing `id` — not
  * merely highlighted in a sidebar. The daemon uses this to clear an
  * `AwaitingInput` glow once the pane has been looked at long enough

web/src/routes.ts

@@ -52,6 +52,11 @@ export function structuredCancel(id: Uuid): string {
   return `${session(id)}/structured/cancel`;
 }
 
+/** `POST /api/sessions/:id/structured/config` — change an ACP session option. */
+export function structuredConfig(id: Uuid): string {
+  return `${session(id)}/structured/config`;
+}
+
 /** `POST /api/sessions/:id/structured/approvals/:nonce` — answer a permission
  * request. */
 export function structuredApproval(id: Uuid, nonce: string): string {

web/src/structured.test.ts

@@ -8,10 +8,16 @@ vi.mock("./api.js", async () => {
     sendStructuredPrompt: vi.fn().mockResolvedValue(undefined),
     cancelStructuredTurn: vi.fn().mockResolvedValue(undefined),
     resolveStructuredApproval: vi.fn().mockResolvedValue(undefined),
+    setStructuredConfig: vi.fn().mockResolvedValue(undefined),
   };
 });
 
-import { cancelStructuredTurn, resolveStructuredApproval, sendStructuredPrompt } from "./api.js";
+import {
+  cancelStructuredTurn,
+  resolveStructuredApproval,
+  sendStructuredPrompt,
+  setStructuredConfig,
+} from "./api.js";
 import { TOGGLE_DRAWER_EVENT } from "./drawer.js";
 import type { CatalogStore } from "./events.js";
 import { createStructuredConnection, type StructuredSocketFactory } from "./structured.js";
@@ -142,6 +148,53 @@ describe("structured connection: data flow", () => {
     conn.dispose();
   });
 
+  it("renders advertised session settings and sends changed values", () => {
+    const ws = new FakeSocket();
+    const conn = mount({ sockets: [ws] });
+    ws.open();
+    ws.emit({
+      type: "reduced_state",
+      state: {
+        ...idleState,
+        config_options: {
+          configOptions: [
+            {
+              id: "model",
+              name: "Model",
+              category: "model",
+              type: "select",
+              currentValue: "opus",
+              options: [
+                { value: "opus", name: "Opus" },
+                { value: "sonnet", name: "Sonnet" },
+              ],
+            },
+            {
+              id: "effort",
+              name: "Effort",
+              category: "thought_level",
+              type: "select",
+              currentValue: "high",
+              options: [{ value: "high", name: "High" }],
+            },
+          ],
+        },
+      },
+    });
+
+    expect(conn.el.querySelector(".structured-config-summary")?.textContent).toBe("Opus · High");
+    (conn.el.querySelector(".structured-config-trigger") as HTMLButtonElement).click();
+    const selects = conn.el.querySelectorAll<HTMLSelectElement>(".structured-config-select");
+    expect(selects).toHaveLength(2);
+    selects[0].value = "sonnet";
+    selects[0].dispatchEvent(new Event("change"));
+    expect(setStructuredConfig).toHaveBeenCalledWith("s1", {
+      config_id: "model",
+      value: "sonnet",
+    });
+    conn.dispose();
+  });
+
   it("applies plan append, patch, and remove without disturbing surrounding rows", () => {
     const ws = new FakeSocket();
     const conn = mount({ sockets: [ws] });

web/src/structured.ts

@@ -10,6 +10,7 @@ import {
   cancelStructuredTurn,
   resolveStructuredApproval,
   sendStructuredPrompt,
+  setStructuredConfig,
   structuredWsUrl,
 } from "./api.js";
 import { requestToggleDrawer } from "./drawer.js";
@@ -19,6 +20,8 @@ import type { PaneConnection } from "./pane.js";
 import { INITIAL_RECONNECT_MS, MAX_RECONNECT_MS } from "./reconnect.js";
 import { buildToolGroup, buildTranscriptRow } from "./structuredRender.js";
 import type {
+  AcpSessionConfigChoice,
+  AcpSessionConfigOption,
   ReducedState,
   StructuredApprovalDecision,
   StructuredEvent,
@@ -69,7 +72,11 @@ export function createStructuredConnection(
     <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>
+      <div class="structured-config" hidden>
+        <button type="button" class="structured-config-trigger" aria-haspopup="true"
+          aria-expanded="false"><span class="structured-config-summary">Session settings</span><span class="structured-config-caret" aria-hidden="true"></span></button>
+        <div class="structured-config-menu" role="group" aria-label="Session settings" hidden></div>
+      </div>
       <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>
@@ -94,7 +101,10 @@ export function createStructuredConnection(
   `;
 
   const stateEl = el.querySelector(".attach-state") as HTMLSpanElement;
-  const pillsEl = el.querySelector(".st-pills") as HTMLSpanElement;
+  const configEl = el.querySelector(".structured-config") as HTMLDivElement;
+  const configTrigger = el.querySelector(".structured-config-trigger") as HTMLButtonElement;
+  const configSummary = el.querySelector(".structured-config-summary") as HTMLSpanElement;
+  const configMenu = el.querySelector(".structured-config-menu") as HTMLDivElement;
   const disconnectBtn = el.querySelector(".disconnect") as HTMLButtonElement;
   const scrollEl = el.querySelector(".structured-scroll") as HTMLDivElement;
   const rowsEl = el.querySelector(".structured-rows") as HTMLDivElement;
@@ -128,6 +138,7 @@ export function createStructuredConnection(
   let state: ReducedState = { turn: idleTurn() };
   let pendingApprovalRowId: string | null = null;
   let availableCommands: AvailableCommand[] = [];
+  let configBusy = false;
   let filteredCommands: AvailableCommand[] = [];
   let activeCommandIndex = -1;
   let submissionGeneration = 0;
@@ -364,11 +375,90 @@ export function createStructuredConnection(
     });
   }
 
-  function renderPills(): void {
+  function sessionConfigOptions(): AcpSessionConfigOption[] {
-    const parts: string[] = [];
+    return state.config_options?.configOptions ?? [];
-    if (state.model) parts.push(state.model);
+  }
-    if (state.mode) parts.push(state.mode);
+
-    pillsEl.textContent = parts.join(" · ");
+  function configChoices(option: AcpSessionConfigOption): AcpSessionConfigChoice[] {
+    return (option.options ?? []).flatMap((choice) =>
+      "options" in choice ? choice.options : [choice],
+    );
+  }
+
+  function currentConfigLabel(option: AcpSessionConfigOption): string {
+    if (typeof option.currentValue === "boolean") return option.currentValue ? "On" : "Off";
+    return configChoices(option).find((choice) => choice.value === option.currentValue)?.name
+      ?? option.currentValue;
+  }
+
+  async function changeConfig(option: AcpSessionConfigOption, value: string | boolean): Promise<void> {
+    configBusy = true;
+    renderConfig();
+    clearError();
+    try {
+      await setStructuredConfig(sessionId, { config_id: option.id, value });
+    } catch (error) {
+      showError(error instanceof Error ? error.message : "Could not change the session setting");
+    } finally {
+      configBusy = false;
+      renderConfig();
+    }
+  }
+
+  function renderConfig(): void {
+    const options = sessionConfigOptions();
+    configEl.hidden = options.length === 0;
+    if (options.length === 0) {
+      configMenu.hidden = true;
+      configTrigger.setAttribute("aria-expanded", "false");
+      return;
+    }
+    const ordered = [...options].sort((a, b) => {
+      const rank = (category?: string | null) =>
+        ["model", "thought_level", "mode", "model_config"].indexOf(category ?? "");
+      const aRank = rank(a.category);
+      const bRank = rank(b.category);
+      return (aRank < 0 ? 99 : aRank) - (bRank < 0 ? 99 : bRank);
+    });
+    configSummary.textContent = ordered.map(currentConfigLabel).join(" · ");
+    configTrigger.title = ordered.map((option) => `${option.name}: ${currentConfigLabel(option)}`).join("\n");
+    configTrigger.disabled = configBusy;
+    configMenu.replaceChildren();
+    for (const option of ordered) {
+      const row = document.createElement("label");
+      row.className = "structured-config-row";
+      const name = document.createElement("span");
+      name.className = "structured-config-name";
+      name.textContent = option.name;
+      row.append(name);
+      if (option.type === "select") {
+        const select = document.createElement("select");
+        select.className = "structured-config-select";
+        select.disabled = configBusy;
+        for (const choice of configChoices(option)) {
+          const item = document.createElement("option");
+          item.value = choice.value;
+          item.textContent = choice.name;
+          item.title = choice.description ?? "";
+          select.append(item);
+        }
+        select.value = String(option.currentValue);
+        select.addEventListener("change", () => void changeConfig(option, select.value));
+        row.append(select);
+      } else if (option.type === "boolean") {
+        const toggle = document.createElement("input");
+        toggle.type = "checkbox";
+        toggle.className = "structured-config-toggle";
+        toggle.checked = option.currentValue === true;
+        toggle.disabled = configBusy;
+        toggle.addEventListener("change", () => void changeConfig(option, toggle.checked));
+        row.append(toggle);
+      } else {
+        continue;
+      }
+      if (option.description) row.title = option.description;
+      configMenu.append(row);
+    }
   }
 
   function renderComposerState(): void {
@@ -403,10 +493,31 @@ export function createStructuredConnection(
         if (prev !== null || newPendingId !== null) rebuildTranscript();
       });
     }
-    renderPills();
+    renderConfig();
     renderComposerState();
   }
 
+  function closeConfigMenu(): void {
+    configMenu.hidden = true;
+    configTrigger.setAttribute("aria-expanded", "false");
+  }
+
+  configTrigger.addEventListener("click", () => {
+    const opening = configMenu.hidden;
+    configMenu.hidden = !opening;
+    configTrigger.setAttribute("aria-expanded", String(opening));
+  });
+  const closeConfigOnOutsidePress = (event: PointerEvent) => {
+    if (!configEl.contains(event.target as Node)) closeConfigMenu();
+  };
+  document.addEventListener("pointerdown", closeConfigOnOutsidePress);
+  configEl.addEventListener("keydown", (event) => {
+    if (event.key === "Escape") {
+      closeConfigMenu();
+      configTrigger.focus();
+    }
+  });
+
   // ---- error banner ----
   let errorEl: HTMLElement | null = null;
   function showError(message: string): void {
@@ -783,6 +894,7 @@ export function createStructuredConnection(
       expandedGroupIds.clear();
       scrollEl.removeEventListener("scroll", onTranscriptScroll);
       scrollEl.removeEventListener("click", onTranscriptClick, true);
+      document.removeEventListener("pointerdown", closeConfigOnOutsidePress);
       el.remove();
     },
   };

web/src/styles.css

@@ -2173,12 +2173,111 @@ input.leaf-rename:focus {
    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 {
+.structured-config {
-  font-size: var(--fs-11);
+  position: relative;
+  flex: 0 1 300px;
+  min-width: 0;
+}
+
+.structured-config-trigger {
+  width: 100%;
+  height: 26px;
+  display: flex;
+  align-items: center;
+  gap: var(--sp-2);
+  padding: 0 var(--sp-2);
+  border: 1px solid var(--border);
+  border-radius: var(--r-2);
+  background: var(--surface-2);
   color: var(--muted);
-  white-space: nowrap;
+  font: 500 var(--fs-11) / 1 var(--font-sans);
+  cursor: pointer;
+}
+
+.structured-config-trigger:hover,
+.structured-config-trigger[aria-expanded="true"] {
+  color: var(--ink);
+  border-color: var(--border-strong);
+  background: var(--surface-3);
+}
+
+.structured-config-trigger:focus-visible,
+.structured-config-select:focus-visible,
+.structured-config-toggle:focus-visible {
+  outline: 2px solid var(--accent);
+  outline-offset: 2px;
+}
+
+.structured-config-summary {
+  min-width: 0;
   overflow: hidden;
   text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.structured-config-caret {
+  width: 6px;
+  height: 6px;
+  flex: 0 0 auto;
+  border-right: 1.5px solid currentColor;
+  border-bottom: 1.5px solid currentColor;
+  transform: translateY(-1px) rotate(45deg);
+}
+
+.structured-config-trigger[aria-expanded="true"] .structured-config-caret {
+  transform: translateY(2px) rotate(225deg);
+}
+
+.structured-config-menu {
+  position: absolute;
+  z-index: 20;
+  top: calc(100% + var(--sp-2));
+  right: 0;
+  width: min(320px, 86vw);
+  padding: var(--sp-2);
+  border: 1px solid var(--border-strong);
+  border-radius: var(--r-2);
+  background: var(--surface);
+  box-shadow: var(--shadow-2);
+}
+
+.structured-config-row {
+  display: grid;
+  grid-template-columns: minmax(80px, 1fr) minmax(0, 1.6fr);
+  align-items: center;
+  gap: var(--sp-3);
+  min-height: 34px;
+  padding: var(--sp-1) var(--sp-2);
+  color: var(--ink);
+  font-size: var(--fs-12);
+}
+
+.structured-config-row + .structured-config-row {
+  border-top: 1px solid var(--border);
+}
+
+.structured-config-name {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.structured-config-select {
+  min-width: 0;
+  height: 28px;
+  padding: 0 var(--sp-2);
+  border: 1px solid var(--border);
+  border-radius: var(--r-1);
+  background: var(--surface-2);
+  color: var(--ink);
+  font: inherit;
+}
+
+.structured-config-toggle {
+  justify-self: end;
+  width: 17px;
+  height: 17px;
+  accent-color: var(--accent);
 }
 
 .structured-body {

web/src/types.ts

@@ -436,6 +436,7 @@ export interface ReducedState {
   context?: AcpUsage | null;
   model?: string | null;
   mode?: string | null;
+  config_options?: { configOptions: AcpSessionConfigOption[] } | null;
 }
 
 /** Server messages on `WS /api/structured/:id`. */
@@ -449,6 +450,33 @@ export interface StructuredPromptRequest {
   prompt: string;
 }
 
+export interface StructuredConfigRequest {
+  config_id: string;
+  value: string | boolean;
+}
+
+export interface AcpSessionConfigChoice {
+  value: string;
+  name: string;
+  description?: string | null;
+}
+
+export interface AcpSessionConfigGroup {
+  group: string;
+  name: string;
+  options: AcpSessionConfigChoice[];
+}
+
+export interface AcpSessionConfigOption {
+  id: string;
+  name: string;
+  description?: string | null;
+  category?: string | null;
+  type: "select" | "boolean" | string;
+  currentValue: string | boolean;
+  options?: Array<AcpSessionConfigChoice | AcpSessionConfigGroup>;
+}
+
 /** `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";