feat(maestro): mirror activity_since and Error state in web types

crates/maestro-cli/src/sessions.rs

@@ -108,6 +108,7 @@ fn print_session_table(out: &mut impl Write, sessions: &[Session], info: &Daemon
             ActivityState::Active => "active",
             ActivityState::Idle => "idle",
             ActivityState::AwaitingInput => "awaiting",
+            ActivityState::Error => "error",
         };
         // Show the live foreground command alongside the spawn command when
         // the daemon has observed one that differs (NAP-340).
@@ -176,6 +177,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
             current_cwd: None,
             blocked_work: None,
         }

crates/maestro-daemon/src/session.rs

@@ -353,6 +353,7 @@ impl SessionManager {
             foreground: None,
             activity: ActivityState::Active,
             last_activity_at: Utc::now(),
+            activity_since: chrono::Utc::now(),
 
             current_cwd: None,
             // The watcher fills this in on its first blocked-work pass; a
@@ -572,6 +573,7 @@ impl SessionManager {
                     foreground: None,
                     activity: ActivityState::Idle,
                     last_activity_at: Utc::now(),
+                    activity_since: chrono::Utc::now(),
 
                     current_cwd: None,
                     blocked_work: None,

crates/maestro-daemon/tests/sidecar.rs

@@ -27,6 +27,7 @@ fn sample(id: Uuid) -> Session {
         foreground: None,
         activity: Default::default(),
         last_activity_at: chrono::Utc::now(),
+        activity_since: chrono::Utc::now(),
         current_cwd: Some(PathBuf::from("/tmp/work/crates")),
         blocked_work: None,
     }

crates/maestro-protocol/src/lib.rs

@@ -80,6 +80,13 @@ pub struct Session {
     /// from daemons that predate the field.
     #[serde(default = "epoch")]
     pub last_activity_at: DateTime<Utc>,
+    /// Wall-clock time at which the session entered its current
+    /// [`ActivityState`] (#102) — how long it has been `Active`, `Idle` or
+    /// `AwaitingInput`. Distinct from [`Self::last_activity_at`], which only
+    /// tracks the last observed PTY output. Populated by #104; defaults to the
+    /// Unix epoch on payloads from daemons that predate the field.
+    #[serde(default = "epoch")]
+    pub activity_since: DateTime<Utc>,
     /// The pane's *current* working directory (`#{pane_current_path}`) — distinct
     /// from [`Session::cwd`], the directory it was spawned in. The activity
     /// watcher refreshes it as the user `cd`s around; it drives the web UI's
@@ -119,6 +126,9 @@ pub enum ActivityState {
     Idle,
     /// Blocked on a `read()` from the pty — waiting on the user.
     AwaitingInput,
+    /// The agent running in the session reported a failure (#102). Never
+    /// inferred by the daemon; only set when an agent reports it (#105).
+    Error,
 }
 
 /// Optional worktree request attached to a `CreateSessionRequest`.
@@ -537,6 +547,9 @@ mod tests {
             last_activity_at: DateTime::parse_from_rfc3339("2026-05-24T12:05:00Z")
                 .unwrap()
                 .with_timezone(&Utc),
+            activity_since: DateTime::parse_from_rfc3339("2026-05-24T12:04:30Z")
+                .unwrap()
+                .with_timezone(&Utc),
             current_cwd: Some(PathBuf::from("/home/naps62/projects/maestro/crates")),
             blocked_work: None,
         }
@@ -588,6 +601,35 @@ mod tests {
         );
     }
 
+    #[test]
+    fn activity_since_defaults_to_epoch_on_legacy_payload() {
+        // A daemon predating #102 omits `activity_since`; it must deserialize
+        // to the forward-compat default rather than failing, and a present
+        // value round-trips.
+        let json = serde_json::json!({
+            "id": Uuid::from_u128(1),
+            "cwd": "/tmp",
+            "command": "bash",
+            "status": "Running",
+            "created_at": "2026-05-24T12:00:00Z"
+        });
+        let s: Session = serde_json::from_value(json).unwrap();
+        assert_eq!(s.activity_since, epoch());
+
+        let full = sample_session();
+        assert_eq!(full, round_trip(&full));
+    }
+
+    // #102: nothing infers `Error`; only #105's agent-reported failure sets it.
+    #[test]
+    fn error_activity_state_serializes_pascal_case_and_idle_stays_default() {
+        assert_eq!(
+            serde_json::to_value(ActivityState::Error).unwrap(),
+            serde_json::json!("Error")
+        );
+        assert_eq!(ActivityState::default(), ActivityState::Idle);
+    }
+
     #[test]
     fn activity_state_serializes_pascal_case_and_defaults_idle() {
         assert_eq!(

crates/maestro-testing/src/lib.rs

@@ -42,6 +42,7 @@ pub fn session(id: Uuid, cwd: &str, command: &str) -> Session {
         foreground: None,
         activity: Default::default(),
         last_activity_at: Utc::now(),
+        activity_since: chrono::Utc::now(),
         current_cwd: None,
         blocked_work: None,
     }

crates/maestro-tui/src/app.rs

@@ -1127,6 +1127,7 @@ mod tests {
                 foreground: None,
                 activity: Default::default(),
                 last_activity_at: Utc::now(),
+                activity_since: chrono::Utc::now(),
                 current_cwd: None,
                 blocked_work: None,
             }],
@@ -1644,6 +1645,7 @@ mod tests {
                 foreground: None,
                 activity: Default::default(),
                 last_activity_at: chrono::Utc::now(),
+                activity_since: chrono::Utc::now(),
 
                 current_cwd: None,
                 blocked_work: None,

crates/maestro-tui/src/catalog.rs

@@ -194,6 +194,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
             current_cwd: None,
             blocked_work: None,
         }

crates/maestro-tui/src/sidebar.rs

@@ -105,6 +105,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
             current_cwd: None,
             blocked_work: None,
         }
@@ -228,6 +229,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
 
             current_cwd: None,
             blocked_work: None,

web/src/types.ts

@@ -9,8 +9,9 @@ export type IsoTimestamp = string;
 export type SessionStatus = "Running" | "Dead";
 
 /** Daemon-inferred activity dimension, orthogonal to `SessionStatus` (NAP-340).
- * Absent on payloads from daemons that predate the field. */
-export type ActivityState = "Active" | "Idle" | "AwaitingInput";
+ * Absent on payloads from daemons that predate the field. `Error` is only set
+ * when an agent reports failure (#105); the daemon never infers it. */
+export type ActivityState = "Active" | "Idle" | "AwaitingInput" | "Error";
 
 export interface Session {
   id: Uuid;
@@ -27,6 +28,11 @@ export interface Session {
   activity?: ActivityState;
   /** Wall-clock of the most recent observed PTY output (NAP-340). */
   last_activity_at?: IsoTimestamp;
+  /** Wall-clock of when the session entered its current `activity` state
+   * (#102) — distinct from `last_activity_at`, which only tracks PTY output.
+   * Defaults to the Unix epoch on payloads from daemons that predate the
+   * field. */
+  activity_since?: IsoTimestamp;
   /** The pane's *current* working directory, as the daemon's activity watcher
    * observed it (`#{pane_current_path}`) — distinct from `cwd` (the spawn dir).
    * Drives the directory-based session tree. Absent until first observed. */