test: remove crash marker publication race

.agents/notes/implemented/bug-fix/2026-07-21-semantic-session-checkpoints.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write
-2026-07-21-semantic-session-checkpoints.md: 4bca02fe3893ac39621ed79a000ca8f86db4ff67
-2026-07-21-semantic-session-checkpoints.zh.md: 1f187eb6448a3c9ca6784ec2bddd7295be2706d7
+2026-07-21-semantic-session-checkpoints.md: 0034cde40e5b07bda1573ca39fb7d51816006140
+2026-07-21-semantic-session-checkpoints.zh.md: 3351221d7eeaf1353b4adb0fa4c4dc324ec33da5

.agents/notes/implemented/bug-fix/2026-07-21-semantic-session-checkpoints.md

@@ -26,4 +26,4 @@ Flushing every event or streaming chunk minimizes loss but turns local append an
 
 ## Consequences
 
-Hard-crash recovery retains the complete model request, durable tool intent, and complete settled step at the nearest semantic boundary while allowing partial streaming chunks since the previous boundary to remain lossy. Default CLI, TUI, ACP, Python SDK runtime, headless persistence tests, and JSON-RPC compositions mount the policy with their persistence backend. Unit tests cover ordering, cancellation during a checkpoint, fail-closed behavior, nested dispatch, disposal, and Loader shape; a real child process killed with `SIGKILL` proves request and tool-intent recovery through JSONL, and the shared persistence contract proves both recovery classifications across backends. Keyless ACP snapshots prove both that retry-risk guidance reaches resumed history and the next model turn and that graceful cancellation persists the loop's real closing boundaries.
+Hard-crash recovery retains the complete model request, durable tool intent, and complete settled step at the nearest semantic boundary while allowing partial streaming chunks since the previous boundary to remain lossy. Default CLI, TUI, ACP, Python SDK runtime, headless persistence tests, and JSON-RPC compositions mount the policy with their persistence backend. Unit tests cover ordering, cancellation during a checkpoint, fail-closed behavior, nested dispatch, disposal, and Loader shape; a real child process killed with `SIGKILL` proves request and tool-intent recovery through JSONL, and the shared persistence contract proves both recovery classifications across backends. The crash harness waits for the expected marker contents rather than path existence, so open-before-write visibility cannot trigger the kill early. Keyless ACP snapshots prove both that retry-risk guidance reaches resumed history and the next model turn and that graceful cancellation persists the loop's real closing boundaries.

.agents/notes/implemented/bug-fix/2026-07-21-semantic-session-checkpoints.zh.md

@@ -26,4 +26,4 @@ ACP（Agent Client Protocol）应用在一个有序 Cordis effect 中统一持
 
 ## 后果
 
-发生硬崩溃时，崩溃恢复会在最近的语义边界保留完整的模型请求、持久化的工具意图与完整且已结束的步骤，但允许上一个边界之后的部分流式分片仍可能丢失。默认的 CLI（命令行界面）、TUI、ACP、Python SDK 运行时、headless 持久化测试与 JSON-RPC 组合都会在持久化后端旁加载该策略。单元测试覆盖顺序、检查点期间的取消、失败关闭行为、嵌套分发、dispose（资源释放）与 Loader 形状；一个被 `SIGKILL` 终止的真实子进程通过 JSONL 证明系统可以恢复请求与工具意图，共享持久化契约则证明各后端都支持这两种恢复分类。无密钥 ACP 快照既证明重试风险指引会进入恢复后的历史记录与下一个模型轮次，也证明取消流程正常收尾时，系统会持久化由循环实际生成的闭合边界。
+发生硬崩溃时，崩溃恢复会在最近的语义边界保留完整的模型请求、持久化的工具意图与完整且已结束的步骤，但允许上一个边界之后的部分流式分片仍可能丢失。默认的 CLI（命令行界面）、TUI、ACP、Python SDK 运行时、headless 持久化测试与 JSON-RPC 组合都会在持久化后端旁加载该策略。单元测试覆盖顺序、检查点期间的取消、失败关闭行为、嵌套分发、dispose（资源释放）与 Loader 形状；一个被 `SIGKILL` 终止的真实子进程通过 JSONL 证明系统可以恢复请求与工具意图，共享持久化契约则证明各后端都支持这两种恢复分类。崩溃 harness 会等待预期的标记内容，而不是仅等待路径存在，因此文件在写入前因打开而可见时，不会导致该 harness 提前终止子进程。无密钥 ACP 快照既证明重试风险指引会进入恢复后的历史记录与下一个模型轮次，也证明取消流程正常收尾时，系统会持久化由循环实际生成的闭合边界。

packages/session-persistence/session-checkpoint-policy/tests/crash-recovery.e2e.ts

@@ -1,5 +1,5 @@
 import { spawn } from 'node:child_process'
-import { access, mkdtemp, readFile, rm } from 'node:fs/promises'
+import { mkdtemp, readFile, rm, writeFile } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { fileURLToPath } from 'node:url'
@@ -18,16 +18,21 @@ const sessionId = SessionId('semantic-checkpoint-crash')
 const roots: string[] = []
 const CHILD_FAILPOINT_TIMEOUT_MS = 30_000
 
-async function waitForFile(path: string): Promise<void> {
+async function waitForMarker(path: string, expected: string): Promise<string> {
   const deadline = Date.now() + CHILD_FAILPOINT_TIMEOUT_MS
   for (;;) {
     try {
-      await access(path)
-      return
+      const content = await readFile(path, 'utf8')
+      if (content === expected) return content
+      if (!expected.startsWith(content)) {
+        throw new Error(`crash child wrote unexpected failpoint ${JSON.stringify(content)}`)
+      }
     } catch (error: unknown) {
       if ((error as NodeJS.ErrnoException).code !== 'ENOENT') throw error
     }
-    if (Date.now() >= deadline) throw new Error(`crash child did not reach failpoint ${path}`)
+    if (Date.now() >= deadline) {
+      throw new Error(`crash child did not publish failpoint ${JSON.stringify(expected)} at ${path}`)
+    }
     await new Promise(resolve => setTimeout(resolve, 10))
   }
 }
@@ -36,6 +41,9 @@ async function crashAt(mode: 'request' | 'tool'): Promise<{ root: string; marker
   const root = await mkdtemp(join(tmpdir(), `dsh-semantic-${mode}-`))
   roots.push(root)
   const marker = join(root, 'failpoint')
+  // Keep the open-before-write window deterministic: readiness is marker content, not path existence.
+  await writeFile(marker, '')
+  const expectedMarker = mode === 'request' ? 'request-dispatched' : 'tool-side-effect'
   const child = spawn(process.execPath, ['--import', tsxLoader, childScript, mode, root, marker], {
     cwd: repoRoot,
     env: { ...process.env, TSX_TSCONFIG_PATH: join(repoRoot, 'tsconfig.json') },
@@ -45,8 +53,7 @@ async function crashAt(mode: 'request' | 'tool'): Promise<{ root: string; marker
   child.stderr.setEncoding('utf8')
   child.stderr.on('data', (chunk: string) => { stderr += chunk })
   try {
-    await waitForFile(marker)
-    const markerText = await readFile(marker, 'utf8')
+    const markerText = await waitForMarker(marker, expectedMarker)
     const closed = new Promise<{ code: number | null; signal: NodeJS.Signals | null }>((resolve) => {
       child.once('close', (code, signal) => { resolve({ code, signal }) })
     })