Merge remote-tracking branch 'origin/master' into fix/subagent-depth-budget

# Conflicts:
#	examples/acp-agent/tests/acp.snapshot.ts

packages/support/acp-snapshot/src/harness.ts

@@ -37,11 +37,10 @@ export type { AgentUnderTest } from './launcher.ts'
  * (random) session id into a `{{sessionId}}` variable that later steps
  * reference, since a committed file cannot know the id in advance.
  *
- * `promptAndCancel` sends a prompt WITHOUT awaiting its response, waits until
- * the client observes the first streamed `agent_message_chunk` (so the emitted
- * frames deterministically precede the cancellation), then cancels the turn —
- * the only way to exercise a cancel deterministically (a plain `prompt` step
- * awaits the response, which a cancel/hang scenario would block on forever).
+ * `promptAndCancel` starts a prompt without awaiting completion, waits until
+ * the client observes the selected update (`agent_message_chunk` by default),
+ * then cancels and awaits completion. A named `waitForToolCallUpdate` keeps the
+ * step open for a terminal tool update that may follow the prompt response.
  */
 export type InputStep =
   | { op: 'initialize'; terminalOutput?: boolean }
@@ -49,7 +48,12 @@ export type InputStep =
   | { op: 'newSessionExpectError'; additionalDirectories?: string[] }
   | { op: 'prompt'; text: string }
   | { op: 'promptExpectError'; text: string }
-  | { op: 'promptAndCancel'; text: string }
+  | {
+    op: 'promptAndCancel'
+    text: string
+    afterUpdate?: 'agent_message_chunk' | 'tool_call'
+    waitForToolCallUpdate?: string
+  }
   | { op: 'cancel' }
   | { op: 'setConfigOption'; configId: string; value: string }
   | { op: 'setConfigOptionExpectError'; configId: string; value: string }
@@ -342,17 +346,19 @@ async function runStep(
     case 'promptAndCancel': {
       const sessionId = getSessionId()
       if (sessionId === undefined) throw new Error('snapshot-harness: promptAndCancel before newSession')
-      // Dispatch the prompt WITHOUT awaiting (a hang fixture never resolves on
-      // its own). To pin frame order deterministically, wait until the client
-      // has OBSERVED the hang's streamed agent_message_chunk before cancelling —
-      // so those update frames always precede the cancelled prompt response in
-      // the transcript (without this, the late chunk and the response race).
-      // Then cancel and await the prompt, which the bridge settles as
-      // `cancelled` once the abort propagates.
+      // Dispatch without awaiting because the fixture does not settle on its
+      // own. Waiting for the selected update pins it before cancellation and
+      // the cancelled prompt response in the transcript.
       const promptDone = client.prompt({ sessionId, prompt: [{ type: 'text', text: step.text }] })
-      await waitForUpdate(u => u.sessionUpdate === 'agent_message_chunk')
+      const afterUpdate = step.afterUpdate ?? 'agent_message_chunk'
+      await waitForUpdate(u => u.sessionUpdate === afterUpdate)
+      // Arm this before cancellation so a fast tool drain cannot outrun the waiter.
+      const toolCallUpdateDone = step.waitForToolCallUpdate === undefined
+        ? undefined
+        : waitForUpdate(u => u.sessionUpdate === 'tool_call_update' && u.toolCallId === step.waitForToolCallUpdate)
       await client.cancel({ sessionId })
       await promptDone
+      if (toolCallUpdateDone !== undefined) await toolCallUpdateDone
       return
     }
     case 'cancel': {

packages/support/acp-snapshot/tests/fixtures/fake-acp-agent.ts

@@ -33,6 +33,10 @@ interface Behavior {
   rejectExtraDirs?: boolean
   /** How `session/prompt` settles: a clean response, a JSON-RPC error, or a hang until `session/cancel`. */
   prompt?: 'respond' | 'error' | 'hang-until-cancel'
+  /** Emit a tool call instead of a message chunk before parking a cancellable prompt. */
+  cancelAtToolCall?: boolean
+  /** Emit the parked tool call's terminal update after answering cancellation. */
+  cancelToolCallUpdate?: boolean
   /** Before responding to a prompt, send a `session/request_permission` request and echo its outcome as a chunk. */
   permissionProbe?: boolean
   /** Echo the `DSH_SNAPSHOT_*` env the harness set as a chunk (spec-side env-plumbing assertions). */
@@ -126,7 +130,23 @@ async function handlePrompt(id: number | string): Promise<void> {
       params: { sessionId, update: { sessionUpdate: 'agent_thought_chunk', content: { type: 'text', text: 'mulling' } } },
     })
   }
-  chunk('thinking about it')
+  if (behavior.cancelAtToolCall === true) {
+    send({
+      method: 'session/update',
+      params: {
+        sessionId,
+        update: {
+          sessionUpdate: 'tool_call',
+          toolCallId: 'call_fake_1',
+          title: 'fake tool',
+          kind: 'execute',
+          status: 'in_progress',
+        },
+      },
+    })
+  } else {
+    chunk('thinking about it')
+  }
   if (behavior.echoEnv === true) {
     chunk(`env:${JSON.stringify({
       mode: process.env.DSH_SNAPSHOT,
@@ -229,6 +249,19 @@ function handleFrame(frame: Record<string, unknown>): void {
         const parked = parkedPromptId
         parkedPromptId = null
         respond(parked, { stopReason: 'cancelled' })
+        if (behavior.cancelToolCallUpdate === true) {
+          send({
+            method: 'session/update',
+            params: {
+              sessionId,
+              update: {
+                sessionUpdate: 'tool_call_update',
+                toolCallId: 'call_fake_1',
+                status: 'failed',
+              },
+            },
+          })
+        }
       }
       return
     default:

packages/support/acp-snapshot/tests/harness.spec.ts

@@ -334,6 +334,28 @@ describe('runScenario', () => {
     expect(result.rawStdout.indexOf('thinking about it')).toBeLessThan(result.rawStdout.indexOf('cancelled'))
   })
 
+  it('promptAndCancel can bracket cancellation with tool-call updates', { timeout: 20_000 }, async () => {
+    const { fixtureFile } = await scenario({
+      prompt: 'hang-until-cancel',
+      cancelAtToolCall: true,
+      cancelToolCallUpdate: true,
+    })
+    const result = await runScenario(
+      {
+        steps: [...boot, {
+          op: 'promptAndCancel',
+          text: 'hang',
+          afterUpdate: 'tool_call',
+          waitForToolCallUpdate: 'call_fake_1',
+        }],
+      },
+      { agent: AGENT, mode: 'replay', fixtureFile },
+    )
+    expect(result.rawStdout).toContain('"sessionUpdate":"tool_call"')
+    expect(result.rawStdout.indexOf('"sessionUpdate":"tool_call"')).toBeLessThan(result.rawStdout.indexOf('cancelled'))
+    expect(result.rawStdout.indexOf('cancelled')).toBeLessThan(result.rawStdout.indexOf('"sessionUpdate":"tool_call_update"'))
+  })
+
   it('promptExpectError swallows a model-error response as the expected outcome', { timeout: 20_000 }, async () => {
     const { fixtureFile } = await scenario({ prompt: 'error' })
     const result = await runScenario(

packages/support/invariants/src/scoped-events.generated.ts

@@ -30,10 +30,12 @@ const scopedSubjectResolvers = Object.freeze({
   'agent/created': adapt<'agent/created'>(args => args[0]),
   'agent/disposed': adapt<'agent/disposed'>(args => args[0]),
   'agent/error': adapt<'agent/error'>(args => args[0]),
+  'agent/post-step': adapt<'agent/post-step'>(args => args[0]),
   'agent/pre-step': adapt<'agent/pre-step'>(args => args[0]),
   'agent/prompt-submit': adapt<'agent/prompt-submit'>(args => args[0]),
   'agent/queued': adapt<'agent/queued'>(args => args[0]),
   'agent/request': adapt<'agent/request'>(args => args[0]),
+  'agent/request-error': adapt<'agent/request-error'>(args => args[0]),
   'agent/session-prefix': adapt<'agent/session-prefix'>(args => args[0]),
   'agent/session-start': adapt<'agent/session-start'>(args => args[0]),
   'agent/status': adapt<'agent/status'>(args => args[0]),

packages/support/invariants/tests/invariants.spec.ts

@@ -814,7 +814,7 @@ describe('scoped-dispatch invariants', () => {
       ['agent/status', [agent, 'idle']],
       ['agent/queued', [agent, [], { source: { kind: 'user' }, steering: false }]],
       ['agent/session-start', [agent, 'startup']],
-      ['agent/pre-step', [agent, 1, 1, '', new AbortController().signal]],
+      ['agent/pre-step', [agent, 1, 1, new AbortController().signal]],
       ['agent/prompt-submit', [agent, [], { kind: 'user' }, () => Promise.resolve({ kind: 'allow' })]],
       ['agent/request', [agent, 1, 1, { model: 'm' }, () => Promise.resolve({ model: 'm' })]],
       ['agent/session-prefix', [agent, [], new AbortController().signal, () => Promise.resolve([])]],