test(acp-snapshot): skip POSIX-cancel scenarios on Windows

The cancel-tool-calls scenario cancels a live bash call, which relies on
POSIX detached-process-group termination; bash has no Windows process-tree
kill yet (deferred with the Bash execution domain), so the hung call times
the scenario out on the native Windows snapshot lane.

Add a posixOnly scenario declaration that skips the run test on win32
while the fixture guards keep covering committed files on every platform,
and mark cancel-tool-calls with it.

examples/acp-agent/tests/acp.snapshot.ts

@@ -111,7 +111,9 @@ const SCENARIOS: Scenario[] = [
     configPath: WORKSPACE_CONTEXT_CONFIG,
   },
   { name: 'cancel', hasModelTurn: true, recorded: false, overridden: true },
-  { name: 'cancel-tool-calls', hasModelTurn: true, recorded: false, overridden: true },
+  // Cancelling a live bash call relies on POSIX process-group termination;
+  // Windows bash process-tree kill is deferred with the Bash execution domain.
+  { name: 'cancel-tool-calls', hasModelTurn: true, recorded: false, overridden: true, posixOnly: true },
   { name: 'subagent-spawn', hasModelTurn: true, recorded: true },
   { name: 'subagent-multi', hasModelTurn: true, recorded: true },
   { name: 'subagent-fork', hasModelTurn: true, recorded: true },

packages/support/acp-snapshot/README.md

@@ -38,7 +38,7 @@ defineAcpSnapshotSuite({
 
 A scenario booting a differently-composed tree sets its own `configPath` (an overlay whose basename still ends in `cordis.yml`, so the bin's replay swap finds the sibling `*cordis.snapshot.yml`) and, when that composition changes the request header, its own `headerClass` with its own pinning scenario — the acp-agent example's Code Mode and filesystem scenarios are templates. Each pinning directory stores the normalized full prompt sequence in generated `system-prompt.golden.md` and the corresponding full tool-schema sequence in generated `tool-schemas.golden.json`; `session.jsonl` stores `"system":"{{system}}","tools":"{{tools}}"` while retaining config, reason, and any model-visible prefix. A pin with legitimate mid-run header changes declares `expectedHeaderChanges`, which fixes the length of both sidecar sequences.
 
-Every scenario compares `stdout.golden.jsonl` with cwd-rooted separators canonicalized to `/`. On Windows, `pinsNativeWindowsStdout` additionally compares the complete `stdout.golden.windows.jsonl` after the shared golden and requires that sidecar exactly when enabled.
+Every scenario compares `stdout.golden.jsonl` with cwd-rooted separators canonicalized to `/`. On Windows, `pinsNativeWindowsStdout` additionally compares the complete `stdout.golden.windows.jsonl` after the shared golden and requires that sidecar exactly when enabled. A scenario whose driven behavior needs POSIX process semantics (e.g. cancelling a live bash call kills a detached process group) declares `posixOnly`, which skips its run test on Windows while the fixture guards keep covering its committed files everywhere.
 
 The example also ships a `cordis.snapshot.yml` replay overlay next to its `cordis.yml` (the bin swaps them under `DSH_SNAPSHOT=replay` — [single-source replay config RFC](../../../docs/rfc/implemented/testing/2026-07-04-single-source-acp-replay-config.md)); replay fixtures are served by [`dsh-llm-replay`](../llm-replay/README.md), which this package points at via the `DSH_SNAPSHOT_*` env vars it sets on the child. `pnpm run test:snapshot:record` calls the live LLM and rewrites the recorded scenarios' model fixtures; `pnpm run test:snapshot:refresh` stays keyless, runs the replay overlay, and rewrites stdout, comparable session-log goldens, and each pin's prompt and tool-schema sidecars from the committed model scripts. Fixture roles, record/replay/refresh semantics, and scenario-table fields are documented on `Scenario` and in the [snapshot RFC](../../../docs/rfc/implemented/testing/2026-06-19-acp-snapshot-tests.md).
 

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

@@ -111,6 +111,32 @@ export interface Scenario {
    * exactly when the option is set.
    */
   pinsNativeWindowsStdout?: boolean
+  /**
+   * Whether the driven behavior needs POSIX process semantics the harness
+   * cannot exercise on Windows (e.g. cancelling a live bash tool call kills a
+   * detached process group). The scenario's run test is skipped on Windows;
+   * its fixtures stay guarded on every platform.
+   */
+  posixOnly?: boolean
+}
+
+/**
+ * Whether a scenario's run test is skipped for this mode and host: record mode
+ * skips authored (non-`recorded`) scenarios, and {@link Scenario.posixOnly}
+ * scenarios skip on Windows.
+ *
+ * @param scenario The scenario whose run test is being registered.
+ * @param recording Whether the suite runs in record mode.
+ * @param platform The running Node platform, injectable for unit coverage.
+ * @returns True when the scenario's run test must not execute.
+ */
+export function scenarioSkipped(
+  scenario: Scenario,
+  recording: boolean,
+  platform: NodeJS.Platform = process.platform,
+): boolean {
+  if (recording && !scenario.recorded) return true
+  return scenario.posixOnly === true && platform === 'win32'
 }
 
 /** One stdout golden selected for a platform run. */
@@ -499,8 +525,9 @@ export function defineAcpSnapshotSuite(options: SnapshotSuiteOptions): void {
   scenarioSuite('snapshot scenarios', () => {
     for (const scenario of scenarios) {
       // In RECORD mode, only re-run the `recorded` (live-API) scenarios; the `authored` ones
-      // (sidecar-driven errors/cancel) are never re-recorded.
+      // (sidecar-driven errors/cancel) are never re-recorded. `posixOnly` scenarios skip on
-      it.skipIf(RECORDING && !scenario.recorded)(`snapshot: ${scenario.name} matches the goldens`, async ({ expect }) => {
+      // Windows, where their process semantics cannot be driven.
+      it.skipIf(scenarioSkipped(scenario, RECORDING))(`snapshot: ${scenario.name} matches the goldens`, async ({ expect }) => {
         const dir = join(snapshotsDir, scenario.name)
         const input = JSON.parse(await readFile(join(dir, 'input.json'), 'utf8')) as InputScript
         const overrideFile = join(dir, 'replay.override.json')

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

@@ -15,6 +15,7 @@ import {
   normalizedToolSchemas,
   parseToolSchemasSnapshot,
   refreshFixtureReplacements,
+  scenarioSkipped,
   sessionFixtureNames,
   restorePinnedToolSchemas,
   stabilizeRefreshLog,
@@ -256,6 +257,23 @@ describe('stdoutGoldenVariants', () => {
   })
 })
 
+describe('scenarioSkipped', () => {
+  const authored: Scenario = { name: 'authored', hasModelTurn: true, recorded: false }
+  const posix: Scenario = { name: 'posix-cancel', hasModelTurn: true, recorded: false, posixOnly: true }
+
+  it('skips authored scenarios only while recording', () => {
+    expect(scenarioSkipped(authored, true, 'linux')).toBe(true)
+    expect(scenarioSkipped(authored, false, 'linux')).toBe(false)
+  })
+
+  it('skips posixOnly scenarios on Windows and nowhere else', () => {
+    expect(scenarioSkipped(posix, false, 'win32')).toBe(true)
+    expect(scenarioSkipped(posix, false, 'linux')).toBe(false)
+    expect(scenarioSkipped(posix, false, 'darwin')).toBe(false)
+    expect(scenarioSkipped(authored, false, 'win32')).toBe(false)
+  })
+})
+
 describe('fixtureContext', () => {
   it('reads the fixture header id and cwd', () => {
     const ctx = fixtureContext('{"type":"session","id":"abc","cwd":"/rec"}\n{"type":"turn/start"}\n')