fix(session): decide working/idle from the pane, not the composer redraw

Every working Claude session reported `status: "idle"` about two seconds
into its turn. Measured on live workers: two sessions mid-tool-call at 13
and 17 minutes both read `idle` while their panes showed
`✻ Actualizing… (13m 23s · ↓ 47.5k tokens)`.

Two things had drifted apart:

1. The working indicator changed. Claude animates the glyph through
   `· ✢ ✳ ∗ ✻ ✽` and randomizes the gerund per turn, so neither
   SPINNER_PATTERN (braille, no longer drawn) nor the keyword list
   (Thinking/Writing/Reading/Running) matches a turn anymore.
2. A `❯` sighting is not the end of a turn. Claude redraws the composer
   roughly once a second all the way through one, and that redraw armed
   the "2s later, call it idle" timer.

Matching the new status line in the STREAM does not fix it either: tmux
ships partial repaints, so the complete line reached the PTY about once
every 20 seconds while the `❯` arrived every second.

So the decision moves off the stream:

- An unbroken run of repaints marks a turn as started. Sampled once a
  second for 12s over six live sessions, the two working ones produced
  output in 12/12 windows and the four idle ones in 0/12. Pure helpers in
  session-activity.ts carry the thresholds.
- Idle now needs the pane to go quiet AND the screen to agree.
  `_confirmIdle()` asks tmux what is rendered (new `capturePaneText()`,
  one plain `capture-pane`, floored at 1.5s per session and only ever at
  a transition) and re-checks every 5s while the screen still shows work.
  A turn can sit silent for tens of seconds inside one tool call, so
  silence alone proves nothing.
- The same screen check vetoes keystroke echo, which is a steady stream
  of repaints too but is not work.

CLAUDE_WORKING_LINE_PATTERN matches the `… (elapsed)` shape rather than
the glyph, because the FINISHED line (`✻ Cooked for 2m 49s`) carries the
same glyph and would otherwise pin a session at working forever.

Claude mode only. An external CLI has no `❯`, so nothing would arm the
confirmation and such a session would latch busy.

respawn-patterns.hasWorkingPattern() had the same blind spot (its gerund
list cannot see "Actualizing"), so it takes the pattern as an extra
signal. That can only make respawn less eager, never more.

Idle now lands about 3 to 5 seconds after a turn ends instead of 2
seconds into one. Verified end to end against a live worker, sampled
against the CLI's own "esc to interrupt" footer as independent ground
truth: busy for all 25s of a turn, idle 3s after it ended.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/mux-interface.ts

@@ -274,4 +274,13 @@ export interface TerminalMultiplexer extends EventEmitter {
    * Pass `{ fullHistory: true }` to capture the entire scrollback (COD-47).
    */
   captureActivePaneBuffer?(muxName: string, opts?: PaneCaptureOptions): string | null;
+
+  /**
+   * Plain text of the visible frame: no styles, no cursor query, no repaint
+   * reconstruction. Deliberately cheaper than `capturePaneBuffer` because idle
+   * detection calls it on a timer: it only needs to read what the CLI is
+   * currently rendering, never to replay it into an xterm. Returns null when the
+   * pane cannot be read.
+   */
+  capturePaneText?(muxName: string, paneTarget?: string): string | null;
 }

src/respawn-patterns.ts

@@ -8,7 +8,7 @@
  * @module respawn-patterns
  */
 
-import { TOKEN_PATTERN } from './utils/index.js';
+import { TOKEN_PATTERN, CLAUDE_WORKING_LINE_PATTERN } from './utils/index.js';
 
 // ========== Constants ==========
 
@@ -108,7 +108,12 @@ export function isCompletionMessage(data: string): boolean {
  * @returns True if any working pattern is found in the window
  */
 export function hasWorkingPattern(window: string): boolean {
-  return WORKING_PATTERNS.some((pattern) => window.includes(pattern));
+  // Current Claude randomizes the gerund ("Actualizing…", "Finagling…"), so the
+  // list above catches only a fraction of turns. The live status line's own shape
+  // (`… (13m 23s · ↓ 47.5k tokens)`) is what identifies the rest. Kept as an
+  // extra signal rather than a replacement: this window is RAW terminal data, and
+  // a partial repaint can split the line across chunks.
+  return CLAUDE_WORKING_LINE_PATTERN.test(window) || WORKING_PATTERNS.some((pattern) => window.includes(pattern));
 }
 
 /**

src/session-activity.ts

@@ -0,0 +1,93 @@
+/**
+ * @fileoverview Pure working/idle heuristics for a Claude interactive pane.
+ *
+ * Split out of `session.ts` so the thresholds and the state math are unit
+ * testable without a PTY (same reasoning as `session-order.ts` /
+ * `usage-limit-patterns.ts`).
+ *
+ * **Why activity and not the status line.** Claude Code's working indicator is
+ * `✻ Actualizing… (13m 23s · ↓ 47.5k tokens)`, where the glyph animates through
+ * `· ✢ ✳ ∗ ✻ ✽` and the gerund is randomized per turn. Neither the braille
+ * spinner (`SPINNER_PATTERN`) nor the old keyword list (`Thinking|Writing|
+ * Reading|Running`) matches any of that, so the pane looked idle for a whole
+ * turn. Matching the new line does not rescue the stream either: tmux ships
+ * PARTIAL repaints, so measured on a live worker the complete line reached the
+ * PTY roughly once every 20 seconds, while the composer's `❯` (which is what
+ * ARMS idle detection) arrived every single second.
+ *
+ * What is left is the one thing measured to separate the two states cleanly: a
+ * working pane repaints, an idle pane emits nothing at all. Sampled once per
+ * second for 12s across six live sessions, the two working ones produced output
+ * in 12/12 windows and the four idle ones in 0/12.
+ */
+
+/**
+ * A gap longer than this ends a run of continuous output. Claude repaints at
+ * least once a second while working, so this leaves generous headroom.
+ */
+export const ACTIVITY_GAP_MS = 2000;
+
+/**
+ * Continuous output for this long means the pane is working. Long enough that a
+ * one-off repaint (an update-check line, a rotating tip) cannot reach it.
+ */
+export const WORKING_STREAK_MS = 2000;
+
+/**
+ * Silence for this long is what confirms the pane really went idle. Must stay
+ * above ACTIVITY_GAP_MS, or a pause between two repaints of one turn would
+ * read as the end of the turn.
+ */
+export const IDLE_SILENCE_MS = 2500;
+
+/** How often a pending idle confirmation re-checks a pane that is still noisy. */
+export const IDLE_RECHECK_MS = 500;
+
+/**
+ * Floor between two pane probes for one session. The probe shells out to tmux,
+ * so this is what keeps a screenful of busy sessions from turning idle detection
+ * into a subprocess storm.
+ */
+export const PANE_PROBE_MIN_INTERVAL_MS = 1500;
+
+/**
+ * How long to wait before looking again at a pane the probe just called working.
+ * Claude can sit silent for tens of seconds inside one tool call, so this is the
+ * cadence that carries a long quiet turn, so it is deliberately slow.
+ */
+export const PANE_PROBE_RECHECK_MS = 5000;
+
+/** An unbroken run of PTY output. */
+export interface ActivityStreak {
+  /** When this run began. */
+  startedAt: number;
+  /** The most recent chunk in it. */
+  lastAt: number;
+}
+
+/**
+ * Fold one output chunk into the current streak, starting a new one when the
+ * pane has been quiet longer than `gapMs`.
+ */
+export function trackActivityStreak(
+  streak: ActivityStreak | null,
+  now: number,
+  gapMs: number = ACTIVITY_GAP_MS
+): ActivityStreak {
+  if (!streak || now - streak.lastAt > gapMs) return { startedAt: now, lastAt: now };
+  return { startedAt: streak.startedAt, lastAt: now };
+}
+
+/**
+ * True once a streak has been running long enough to mean work rather than a
+ * single repaint. Measured on the streak's own span (`lastAt - startedAt`), not
+ * against the caller's clock, so a stale streak cannot age into a true.
+ */
+export function isSustainedActivity(streak: ActivityStreak | null, streakMs: number = WORKING_STREAK_MS): boolean {
+  return !!streak && streak.lastAt - streak.startedAt >= streakMs;
+}
+
+/** True when the pane has produced nothing for long enough to call it idle. */
+export function isPaneQuiet(lastActivityAt: number, now: number, silenceMs: number = IDLE_SILENCE_MS): boolean {
+  return now - lastActivityAt >= silenceMs;
+}

src/session.ts

@@ -59,11 +59,21 @@ import type { TerminalMultiplexer, MuxSession } from './mux-interface.js';
 import { TaskTracker, type BackgroundTask } from './task-tracker.js';
 import { RalphTracker } from './ralph-tracker.js';
 import { BashToolParser } from './bash-tool-parser.js';
+import {
+  trackActivityStreak,
+  isSustainedActivity,
+  isPaneQuiet,
+  IDLE_RECHECK_MS,
+  PANE_PROBE_MIN_INTERVAL_MS,
+  PANE_PROBE_RECHECK_MS,
+  type ActivityStreak,
+} from './session-activity.js';
 import {
   BufferAccumulator,
   ANSI_ESCAPE_PATTERN_FULL,
   TOKEN_PATTERN,
   SPINNER_PATTERN,
+  CLAUDE_WORKING_LINE_PATTERN,
   MAX_SESSION_TOKENS,
   execPattern,
   getClaudeCliVersion,
@@ -376,6 +386,9 @@ export class Session extends EventEmitter {
   private _lastPromptTime: number = 0;
   private activityTimeout: NodeJS.Timeout | null = null;
   private _awaitingIdleConfirmation: boolean = false; // Prevents timeout reset during idle detection
+  private _activityStreak: ActivityStreak | null = null; // Unbroken run of PTY repaints (working detection)
+  private _lastPaneProbeAt = 0; // Throttle for the tmux screen probe
+  private _lastPaneProbeWorking: boolean | null = null; // Its last verdict (null = could not read)
   private _trustDialogAccepted: boolean = false; // Prevents repeated trust dialog auto-accept
   private _taskTracker: TaskTracker;
 
@@ -1753,44 +1766,7 @@ export class Session extends EventEmitter {
       }
 
       // === Idle/working detection runs on every chunk (latency-sensitive) ===
-      // Detect if Claude is working or at prompt
-      // The prompt line contains "❯" when waiting for input
-      if (data.includes('❯') || data.includes('\u276f')) {
-        // Only start a new timeout if we're not already awaiting idle confirmation
-        // This prevents status bar redraws (which include ❯) from resetting the timer
-        if (!this._awaitingIdleConfirmation) {
-          if (this.activityTimeout) clearTimeout(this.activityTimeout);
-          this._awaitingIdleConfirmation = true;
-          this.activityTimeout = setTimeout(() => {
-            this._awaitingIdleConfirmation = false;
-            // Emit idle if either:
-            // 1. Claude was working and is now at prompt (normal case)
-            // 2. Session just started and is ready (status is 'busy' but _isWorking is false)
-            const wasWorking = this._isWorking;
-            const isInitialReady = this._status === 'busy' && !this._isWorking;
-            if (wasWorking || isInitialReady) {
-              this._isWorking = false;
-              this._status = 'idle';
-              this._lastPromptTime = Date.now();
-              this.emit('idle');
-            }
-          }, IDLE_DETECTION_DELAY_MS);
-        }
-      }
-
-      // Detect when Claude starts working (thinking, writing, etc)
-      // Fast path: check spinner characters on raw data (Unicode, never in ANSI sequences)
-      const hasSpinner = SPINNER_PATTERN.test(data);
-      if (hasSpinner) {
-        if (!this._isWorking) {
-          this._isWorking = true;
-          this._status = 'busy';
-          this.emit('working');
-          this._autoOps.notifyWorking();
-        }
-        this._awaitingIdleConfirmation = false;
-        if (this.activityTimeout) clearTimeout(this.activityTimeout);
-      }
+      this._detectInteractiveActivity(data);
 
       // === Expensive processing (ANSI strip, Ralph, bash parser) is throttled ===
       // Instead of running regex-heavy parsers on every PTY chunk, we accumulate
@@ -1839,6 +1815,7 @@ export class Session extends EventEmitter {
       this._pid = null;
       this._status = 'idle';
       this._awaitingIdleConfirmation = false;
+      this._activityStreak = null;
       // Clear all timers to prevent memory leaks
       if (this.activityTimeout) {
         clearTimeout(this.activityTimeout);
@@ -1894,6 +1871,134 @@ export class Session extends EventEmitter {
     return this._respawnBlocked;
   }
 
+  /**
+   * Per-chunk working/idle detection for an interactive pane. Split out of the
+   * PTY `onData` handler so it can be unit tested without spawning one.
+   *
+   * @param data raw PTY chunk, ANSI included
+   */
+  private _detectInteractiveActivity(data: string): void {
+    // The prompt line contains "❯" when Claude is waiting for input. It only ARMS
+    // the check and is NOT evidence the turn ended: Claude redraws the composer
+    // about once a second all the way through a turn, which is exactly how a
+    // working session used to flip to idle two seconds in. _confirmIdle() waits
+    // for the pane to actually go quiet before believing it.
+    if (data.includes('❯')) {
+      // Only start a new timeout if we're not already awaiting idle confirmation.
+      // This prevents status bar redraws (which include the prompt) from resetting it.
+      if (!this._awaitingIdleConfirmation) {
+        if (this.activityTimeout) clearTimeout(this.activityTimeout);
+        this._awaitingIdleConfirmation = true;
+        this.activityTimeout = setTimeout(() => this._confirmIdle(), IDLE_DETECTION_DELAY_MS);
+      }
+    }
+
+    // Detect when Claude starts working (thinking, writing, etc).
+    // Fast path: spinner characters on raw data (Unicode, never inside ANSI sequences).
+    if (SPINNER_PATTERN.test(data)) this._markWorking();
+
+    // Activity fallback: current Claude Code animates `✻ Actualizing…` instead of a
+    // braille spinner, so the fast path above misses entire turns, and matching the
+    // new status line does not rescue it either (tmux repaints partially, so the
+    // complete line reaches the PTY only every few tens of seconds). An unbroken run
+    // of repaints is the signal that survives. See session-activity.ts for the
+    // measurement. Claude only: an external CLI's TUI has no ❯, so nothing would
+    // ever arm the idle confirmation and such a session would latch busy forever.
+    if (!isExternalCliMode(this.mode)) {
+      this._activityStreak = trackActivityStreak(this._activityStreak, Date.now());
+      // A streak is the TRIGGER to look, not the verdict: typing into the composer
+      // also produces a steady stream of repaints. The screen settles it, and only
+      // an explicit "no working line" vetoes; a probe that cannot read the pane
+      // (null) leaves the streak in charge.
+      if (!this._isWorking && isSustainedActivity(this._activityStreak) && this._probePaneWorking() !== false) {
+        this._markWorking();
+      }
+    }
+  }
+
+  /**
+   * Ask the pane what it is rendering right now.
+   *
+   * The PTY stream cannot answer this on its own: measured on a live worker,
+   * Claude repaints roughly once a second for most of a turn but can then sit
+   * completely silent for tens of seconds inside a single tool call, while the
+   * `✻ Elucidating… (39s · ↓ 2.0k tokens)` line stays on screen the whole time.
+   * Silence therefore proves nothing, and the rendered frame is the only cheap
+   * source that is right in both directions.
+   *
+   * Costs one `capture-pane`, floored at PANE_PROBE_MIN_INTERVAL_MS per session
+   * and only ever called at a transition, never on the output hot path.
+   *
+   * @returns true/false when the screen could be read, null when it could not
+   *   (no mux, capture failed, tests). Callers must treat null as "no evidence"
+   *   and fall back to their stream heuristics.
+   */
+  private _probePaneWorking(): boolean | null {
+    if (!this._mux || !this._muxSession) return null;
+    const now = Date.now();
+    if (now - this._lastPaneProbeAt < PANE_PROBE_MIN_INTERVAL_MS) return this._lastPaneProbeWorking;
+    this._lastPaneProbeAt = now;
+    const text = this._mux.capturePaneText?.(this._muxSession.muxName) ?? null;
+    this._lastPaneProbeWorking = text === null ? null : CLAUDE_WORKING_LINE_PATTERN.test(text);
+    return this._lastPaneProbeWorking;
+  }
+
+  /**
+   * Mark the pane as working. Idempotent: `working` is emitted on the transition
+   * only, so the per-chunk detectors can all call it freely.
+   *
+   * Deliberately does NOT cancel a pending idle confirmation. That confirmation
+   * is what eventually notices the turn ended, and it already refuses to fire
+   * while the pane is noisy, and cancelling it here would leave a session that
+   * finished during a lull with nothing armed to ever call it idle.
+   */
+  private _markWorking(): void {
+    if (this._isWorking) return;
+    this._isWorking = true;
+    this._status = 'busy';
+    this.emit('working');
+    this._autoOps.notifyWorking();
+  }
+
+  /**
+   * Decide whether the armed idle confirmation is real.
+   *
+   * A ❯ sighting alone means nothing (Claude redraws the composer through the
+   * whole turn), so the pane must ALSO have gone quiet. While output is still
+   * flowing the check re-arms instead of concluding. That loop is a timestamp
+   * compare every IDLE_RECHECK_MS and ends the moment the pane falls silent.
+   */
+  private _confirmIdle(): void {
+    if (this._isStopped) {
+      this._awaitingIdleConfirmation = false;
+      return;
+    }
+    if (!isPaneQuiet(this._lastActivityAt, Date.now())) {
+      this.activityTimeout = setTimeout(() => this._confirmIdle(), IDLE_RECHECK_MS);
+      return; // stays _awaitingIdleConfirmation, so ❯ redraws do not pile up timers
+    }
+    // Quiet is necessary but NOT sufficient: a turn can go silent mid-tool-call.
+    // Ask the screen before concluding, and keep asking on a slow cadence.
+    if (this._probePaneWorking() === true) {
+      this._markWorking();
+      this.activityTimeout = setTimeout(() => this._confirmIdle(), PANE_PROBE_RECHECK_MS);
+      return;
+    }
+    this._awaitingIdleConfirmation = false;
+    this.activityTimeout = null;
+    // Emit idle if either:
+    // 1. Claude was working and is now at prompt (normal case)
+    // 2. Session just started and is ready (status is 'busy' but _isWorking is false)
+    const wasWorking = this._isWorking;
+    const isInitialReady = this._status === 'busy' && !this._isWorking;
+    if (wasWorking || isInitialReady) {
+      this._isWorking = false;
+      this._status = 'idle';
+      this._lastPromptTime = Date.now();
+      this.emit('idle');
+    }
+  }
+
   /**
    * Process expensive parsers (ANSI strip, Ralph, bash tool, token, CLI info, task descriptions).
    * Called on a throttled schedule (every EXPENSIVE_PROCESS_INTERVAL_MS) instead of on every
@@ -1944,22 +2049,22 @@ export class Session extends EventEmitter {
       this.parseTaskDescriptionsFromTerminalData(getCleanData());
     }
 
-    // Work keyword detection (text-based, needs clean data)
-    // Only check if spinner didn't already trigger working state
+    // Work detection (text-based, needs clean data: the status line is coloured,
+    // so raw data has escape sequences between the `…` and the elapsed timer).
+    // Only check if a faster path didn't already trigger working state.
     if (!this._isWorking) {
       const cleanData = getCleanData();
       if (
+        CLAUDE_WORKING_LINE_PATTERN.test(cleanData) ||
+        // Legacy gerunds. Current Claude randomizes the word ("Actualizing…",
+        // "Finagling…"), so these catch only a fraction of turns; the pattern
+        // above and the activity streak carry the rest.
         cleanData.includes('Thinking') ||
         cleanData.includes('Writing') ||
         cleanData.includes('Reading') ||
         cleanData.includes('Running')
       ) {
-        this._isWorking = true;
-        this._status = 'busy';
-        this.emit('working');
-        this._autoOps.notifyWorking();
-        this._awaitingIdleConfirmation = false;
-        if (this.activityTimeout) clearTimeout(this.activityTimeout);
+        this._markWorking();
       }
     }
   }

src/tmux-manager.ts

@@ -3144,6 +3144,30 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
    *   Used for full page reloads so the user gets back their scroll history.
    *   Caveat: lines tmux has already evicted past its history-limit are gone.
    */
+  /**
+   * Plain visible-frame text for the working/idle probe (see `session.ts`).
+   *
+   * One `capture-pane` and nothing else: no `-e` styles, no `display-message`
+   * cursor query, no repaint reconstruction: this feeds a regex, not a
+   * terminal. Returns null in tests (no tmux) so callers fall back to their
+   * stream heuristics rather than reading an empty screen as "not working".
+   */
+  capturePaneText(muxName: string, paneTarget?: string): string | null {
+    if (IS_TEST_MODE) return null;
+    const target = resolveTmuxPaneTarget(muxName, paneTarget);
+    if (!target) return null;
+    try {
+      return execSync(`${this.tmux()} capture-pane -p -t ${shellescape(target)}`, {
+        encoding: 'utf-8',
+        timeout: EXEC_TIMEOUT_MS,
+      });
+    } catch {
+      // A dead/renamed pane is an ordinary outcome here, not an error worth logging
+      // on a timer; the caller treats null as "no evidence either way".
+      return null;
+    }
+  }
+
   capturePaneBuffer(muxName: string, paneTarget?: string, opts?: PaneCaptureOptions): string | null {
     if (IS_TEST_MODE) return '';
     const target = resolveTmuxPaneTarget(muxName, paneTarget);

src/utils/index.ts

@@ -17,6 +17,7 @@ export {
   ANSI_ESCAPE_PATTERN_SIMPLE,
   TOKEN_PATTERN,
   SPINNER_PATTERN,
+  CLAUDE_WORKING_LINE_PATTERN,
   stripAnsi,
   SAFE_PATH_PATTERN,
   execPattern,

src/utils/regex-patterns.ts

@@ -60,6 +60,24 @@ export function stripAnsi(text: string): string {
  */
 export const SPINNER_PATTERN = /[⠋⠙⠹⠸⠼⠴⠦⠧]/;
 
+/**
+ * Claude Code's live working status line, e.g.
+ *   `✻ Actualizing… (13m 23s · ↓ 47.5k tokens)`
+ *   `✽ Herding… (3s · esc to interrupt)`
+ *
+ * Matched on the ELLIPSIS + elapsed timer, never on the leading glyph: the
+ * animation cycles through `· ✢ ✳ ∗ ✻ ✽` (two of those are ordinary punctuation)
+ * and the gerund is randomized per turn, while the finished line (`✻ Cooked for
+ * 2m 49s`) carries the same glyph with no `…` and no parenthesis. Feed this
+ * ANSI-STRIPPED data: tmux colours the timer separately, so the raw stream has
+ * escape sequences sitting between the `…` and the `(`.
+ *
+ * A sighting is proof the pane is working; its ABSENCE proves nothing, because
+ * tmux repaints partially and the whole line reaches the PTY only occasionally
+ * (see `session-activity.ts` for what carries the idle decision instead).
+ */
+export const CLAUDE_WORKING_LINE_PATTERN = /…\s*\((?:\d+h\s+)?(?:\d+m\s+)?\d+s\b|esc to interrupt/;
+
 export const SAFE_PATH_PATTERN = /^[\p{L}\p{N}_/\-. ~]+$/u;
 
 /**