Merge remote-tracking branch 'origin/worktree-cancel-primitive' into worktree-agent-handle

packages/agent-loop/src/agent.ts

@@ -34,6 +34,17 @@ export class ReactLoopAgent implements Agent {
    * leave it set to wrongly drop a later prompt.
    */
   private cancelRequested = false
+  /**
+   * The resolved reason for the pending {@link cancel} (`reason ?? 'cancelled'`),
+   * read by the driver loop's marker branches so a turn dropped in a
+   * marker-only window (pre-step / continuation, where no `AbortController`
+   * carries the reason) ends with the SAME `{kind:'aborted', reason}` the
+   * mid-step abort path produces from `abort.signal.reason`. Without this the
+   * caller's `cancel(reason)` would be silently replaced by the literal
+   * 'cancelled' whenever the cancel landed outside a running step — making the
+   * logged reason race-dependent and the public `reason?` param half-effective.
+   */
+  private cancelReason = 'cancelled'
   private disposed: Promise<void>
   private resolveDisposed!: () => void
   /** Resolves when the driver loop has fully exited (tests/disposal). */
@@ -196,6 +207,10 @@ export class ReactLoopAgent implements Agent {
     // precisely to cover it.
     if (this._status === 'running' || this.currentAbort !== undefined || this.inbox.hasQueued || this.inbox.hasSteering) {
       this.cancelRequested = true
+      // Capture the resolved reason for the marker-only windows (pre-step /
+      // continuation). The mid-step path reads it from abort.signal.reason
+      // below; the marker path reads it via the LoopHandle's cancelReason().
+      this.cancelReason = reason ?? 'cancelled'
     }
     // Drop all pending queued + steering work (un-started prompts never run; the
     // cancelled turn's steering is not re-enqueued). Cleared directly even when
@@ -251,6 +266,7 @@ export class ReactLoopAgent implements Agent {
       disposed: this.disposed,
       isDisposed: () => this._status === 'disposed',
       isCancelled: () => this.cancelRequested,
+      cancelReason: () => this.cancelReason,
       clearCancel: () => { this.cancelRequested = false },
       // Settle whenIdle() waiters WITHOUT a status transition — the pre-step
       // cancel-skip path drops the about-to-run turn and re-parks without ever

packages/agent-loop/src/loop.ts

@@ -116,6 +116,14 @@ export interface LoopHandle {
    * marker governs exactly one cancellation and never leaks to a later prompt.
    */
   isCancelled(): boolean
+  /**
+   * The resolved reason for the pending cancel (`reason ?? 'cancelled'`), read
+   * by the marker branches (pre-step / continuation) so a turn dropped where no
+   * `AbortController` carries the reason still records the caller's
+   * `cancel(reason)` value — matching the mid-step abort path. Only meaningful
+   * when {@link isCancelled} is true.
+   */
+  cancelReason(): string
   /** Clear the cancel marker (called once per iteration after the turn returns). */
   clearCancel(): void
   /**
@@ -396,7 +404,7 @@ async function runTurn(ctx: Context, agent: ReactLoopAgent, handle: LoopHandle,
       // already-appended step/start.
       if (handle.isCancelled()) {
         handle.setAbort(undefined)
-        reason = { kind: 'aborted', reason: 'cancelled' }
+        reason = { kind: 'aborted', reason: handle.cancelReason() }
         closeStep()
         break
       }
@@ -466,7 +474,7 @@ async function runTurn(ctx: Context, agent: ReactLoopAgent, handle: LoopHandle,
       // ends the turn here. cancel() also cleared the steering FIFO, so the
       // override above did not re-arm continuation.
       if (handle.isCancelled()) {
-        reason = { kind: 'aborted', reason: 'cancelled' }
+        reason = { kind: 'aborted', reason: handle.cancelReason() }
         break
       }