fix(session): close checkpoint cancellation races

This commit is contained in:
Yichen Jiang
2026-07-21 17:58:34 +08:00
parent f1e0410a5d
commit 380a94febb
15 changed files with 136 additions and 49 deletions

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@@ -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: b672375a177964589ef4a3bf3661d66a2086d0d0
2026-07-21-semantic-session-checkpoints.zh.md: eedb4df471b17d42fad9b8f1c35f6139b9abe470
2026-07-21-semantic-session-checkpoints.md: 3dc2699a1a48274ede8e5f9abde0302d5bebeda4
2026-07-21-semantic-session-checkpoints.zh.md: 0d5adccf4f582286894d0f1404f1d4523ec80f74

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@@ -14,7 +14,9 @@ Persistence buffered every synchronous `session/event` until the loop's final tu
Persistence and checkpoint scheduling remain separate Cordis plugins. A backend makes requested `session/flush` boundaries durable but does not choose them; loading it without this policy is valid and retains the loop's coarser checkpoints. First-party persisted apps and runtimes explicitly mount both, while a specialized deployment may intentionally omit or replace the policy. Registration order governs whether events appended by other `agent/post-step` listeners join this checkpoint; the loop-owned assistant message and ordered results always precede the event.
Checkpoint failure is fail-closed at effect boundaries. A rejected request checkpoint prevents adapter dispatch; a rejected tool checkpoint becomes an error result without invoking the tool body; a rejected post-step checkpoint stops continuation before another model request. Persistence serialization continues to belong to the coordinator, so concurrent tool checkpoints cannot duplicate event sequences.
Checkpoint failure and cancellation are fail-closed at effect boundaries. A rejected request checkpoint prevents adapter dispatch; a rejected tool checkpoint becomes an error result without invoking the tool body. If cancellation lands while the tool checkpoint is pending, the policy rechecks the signal and returns the canonical `ABORTED` result before dispatch. A rejected post-step checkpoint stops continuation before another model request. Persistence serialization continues to belong to the coordinator, so concurrent tool checkpoints cannot duplicate event sequences.
The ACP app owns its bridge, checkpoint policy, and persistence backend in one ordered Cordis effect. Cordis unloads sibling plugin effects concurrently, so independent mounts would let persistence detach while bridge teardown was still closing an interrupted turn. The composite lifecycle unloads the bridge first, waits for its agents to quiesce and flush the real `step/end` and `turn/end`, then removes checkpoint scheduling and persistence. If connection disposal follows an effective `session/cancel` while post-step persistence is pending, the loop preserves the earlier `aborted` reason instead of replacing it with `disposed`.
Crash repair distinguishes durable evidence. An assistant tool request without a `tool/call` becomes `TOOL_NOT_STARTED` and may be retried if still needed. A durable `tool/call` without a result becomes `TOOL_OUTCOME_UNKNOWN`; its model-visible result permits retry only for read-only or idempotent operations and directs the model to verify external state or ask the user before deciding about side-effecting work. A provider that supports idempotency keys can receive the stable `callId`, but the Harness does not claim generic exactly-once effects.
@@ -24,4 +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, 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. A keyless ACP snapshot loads a seeded unknown-outcome session through the shipped ACP example and proves that the retry-risk guidance reaches both resumed history and the next model turn.
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.

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@@ -14,7 +14,9 @@ Status: implemented
持久化与检查点调度仍是相互独立的 Cordis 插件。后端使请求的 `session/flush` 边界持久化,但不选择边界;只加载后端而不加载本策略仍是有效组合,并保留循环提供的较粗检查点。第一方持久化应用与运行时会显式加载两者,专用部署则可以有意省略或替换本策略。注册顺序决定其他 `agent/post-step` 监听器追加的事件是否会纳入本检查点;循环自身记录的助手消息与有序结果始终先于该事件。
检查点失败在副作用边界上采取失败关闭策略。请求检查点被拒绝时,系统不会分发给适配器;工具检查点被拒绝时,系统会返回错误结果,不调用工具主体步骤后检查点被拒绝时,系统会在发起下一个模型请求前停止继续执行。持久化写入的串行化仍由协调器负责,因此并发的工具检查点不会产生重复的事件序号。
检查点失败与取消在副作用边界上采取失败关闭策略。请求检查点被拒绝时,系统不会分发给适配器;工具检查点被拒绝时,系统会返回错误结果,不调用工具主体。如果在工具检查点等待期间收到取消,策略会重新检查信号,并在分发前返回标准的 `ABORTED` 结果。步骤后检查点被拒绝时,系统会在发起下一个模型请求前停止继续执行。持久化写入的串行化仍由协调器负责,因此并发的工具检查点不会产生重复的事件序号。
ACPAgent Client Protocol应用在一个有序 Cordis effect 中统一持有其桥接层、检查点策略与持久化后端。Cordis 会并发卸载同级插件的 effect如果分别加载桥接层仍在为被中断的轮次收尾时持久化后端就可能已经卸载。组合生命周期会先卸载桥接层等待其各 agent 达到静止,并刷新真实的 `step/end``turn/end`,再移除检查点调度与持久化。如果在步骤后持久化仍在等待时,连接释放发生在已生效的 `session/cancel` 之后,循环会保留先前的 `aborted` 原因,而不会将其替换为 `disposed`
崩溃修复会区分持久化证据。如果模型发出了工具请求,却没有 `tool/call`,系统会将其标记为 `TOOL_NOT_STARTED`;如果仍有需要,可以重试。如果持久化的 `tool/call` 没有结果,系统会将其标记为 `TOOL_OUTCOME_UNKNOWN`;对应的模型可见结果只允许重试只读或幂等操作,并指示模型在决定是否重试有副作用的工作前,先验证外部状态或询问用户。支持幂等键的模型提供方可以获取稳定的 `callId`,但 Harness 不承诺通用的副作用恰好执行一次保证。
@@ -24,4 +26,4 @@ Status: implemented
## 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、ACPAgent Client Protocol、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、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。一项无密钥 ACP 快照通过已交付的 ACP 示例加载预置的结果未知会话,并证明重试风险指引会同时出现在恢复后的历史记录与下一个模型轮次
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