fix(runtime): close teardown gaps and simplify framing

.agents/notes/implemented/feature/2026-06-15-code-mode.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 .agents/notes/implemented/feature/2026-06-15-code-mode.md
-2026-06-15-code-mode.md: b0778b2c9a8dfce8f786faccf6cc47f477c6b7c0
-2026-06-15-code-mode.zh.md: 437692eac3fc6740e0f1d4dd9001130fd6dd448a
+2026-06-15-code-mode.md: 1be25f5b145e50d8fe391d22910b71d85181582e
+2026-06-15-code-mode.zh.md: a4e8fbbd339899937c4f39091b4befbbb78ec347

.agents/notes/implemented/feature/2026-06-15-code-mode.md

@@ -79,7 +79,7 @@ Requests contain every runtime input; implementations own validated timeout and
 5. **Enforce independent budgets.** `computeMs` meters worker busy time, allowing slow awaited tools without excusing a hot loop. `maxWallMs` bounds total elapsed time, including unresolved waits. `maxOutputBytes` bounds only the combined serialized outer logs, completion, or diagnostic; intermediate binding values have no byte cap. Expiry, cancellation, and completion terminate the worker, and heap exits or outer overflow are explicit failures.
 6. **Dispose to quiescence**: the service's own disposal terminates in-flight workers and *awaits* their exits before resolving, per [defensive patterns](../../../../docs/defensive-patterns.md).
 
-`@deepseek-ai/dsh-code-runtime-subprocess` preserves those program, binding, output, and worker-budget semantics across a filesystem/subprocess execution world. It writes a dependency-free runner below `ctx.subprocess.runtimeRoot`, resolves Node through the provider, and carries binding traffic over bounded base64 JSON frames on raw pipes. The heap-bounded worker rejects expanded completion wires before MessagePort transfer; terminal settlement asks the launcher to reap its controller and keeps process-group escalation armed until `waitForExit()` confirms whole-tree quiescence. The [portable execution-world decision](../architecture/2026-07-28-portable-execution-world-consumers.md) owns why this generic backend replaces provider-specific Code Runtime packages; `dsh-code-runtime-worker` remains the single-process and single-file-distribution path.
+`@deepseek-ai/dsh-code-runtime-subprocess` preserves those program, binding, output, and worker-budget semantics across a filesystem/subprocess execution world. It writes a dependency-free runner below `ctx.subprocess.runtimeRoot`, resolves Node through the provider, and carries binding traffic over bounded newline-delimited UTF-8 JSON frames on raw pipes. The heap-bounded worker rejects expanded completion wires before MessagePort transfer; terminal settlement asks the launcher to reap its controller and keeps process-group escalation armed until `waitForExit()` confirms whole-tree quiescence. The [portable execution-world decision](../architecture/2026-07-28-portable-execution-world-consumers.md) owns why this generic backend replaces provider-specific Code Runtime packages; `dsh-code-runtime-worker` remains the single-process and single-file-distribution path.
 
 ### Trust posture
 

.agents/notes/implemented/feature/2026-06-15-code-mode.zh.md

@@ -79,7 +79,7 @@ Cloudflare 的 [Code Mode](https://blog.cloudflare.com/code-mode/) 提出了一
 5. **强制独立预算。** `computeMs` 计量 worker 忙碌时间，允许慢速的 awaited 工具而不放过热循环。`maxWallMs` 约束总经过时间，包括未解析的等待。`maxOutputBytes` 只约束序列化后的外层日志、完成值或诊断的组合；中间绑定值没有字节数上限。到期、取消和完成都终止 worker，堆退出或外层溢出会作为显式失败报告。
 6. **dispose 至完全停稳**：服务自身的 dispose（资源释放）终止进行中的 worker 并*等待*其退出后再 resolve，遵循[防御性模式](../../../../docs/defensive-patterns.md)。
 
-`@deepseek-ai/dsh-code-runtime-subprocess` 在文件系统／子进程执行环境中保持相同的程序、绑定、输出与 worker 预算语义。它在 `ctx.subprocess.runtimeRoot` 下写入一个无依赖 runner，通过提供方解析 Node，并在原始管道上使用有界 base64 JSON 帧承载绑定通信。受堆上限约束的 worker 会在通过 MessagePort 传输前拒绝展开后的完成值 wire；终态结算会请求 launcher 回收其 controller，并让进程组升级终止机制保持待命，直至 `waitForExit()` 确认整棵进程树完全停稳。[可移植执行环境决策](../architecture/2026-07-28-portable-execution-world-consumers.md)说明为何这个通用后端会取代提供方专用的 Code Runtime 包；`dsh-code-runtime-worker` 仍用于单进程和单文件发行版。
+`@deepseek-ai/dsh-code-runtime-subprocess` 在文件系统／子进程执行环境中保持相同的程序、绑定、输出与 worker 预算语义。它在 `ctx.subprocess.runtimeRoot` 下写入一个无依赖 runner，通过提供方解析 Node，并在原始管道上使用有界的、以换行符分隔的 UTF-8 JSON 帧承载绑定通信。受堆上限约束的 worker 会在通过 MessagePort 传输前拒绝展开后的完成值 wire；终态结算会请求 launcher 回收其 controller，并让进程组升级终止机制保持待命，直至 `waitForExit()` 确认整棵进程树完全停稳。[可移植执行环境决策](../architecture/2026-07-28-portable-execution-world-consumers.md)说明为何这个通用后端会取代提供方专用的 Code Runtime 包；`dsh-code-runtime-worker` 仍用于单进程和单文件发行版。
 
 ### 信任姿态