fix(code-runtime-python): bind the _done_with_value entry name and correct the residual documentation

Addresses the review's registration-text accuracy findings:
- _run binds _done_with_value into a local (done_with_value_bound) before the
  program runs, closing the __main__._done_with_value = boom success-rewrite
  vector; a regression test rebinds it and returns a legitimate value, asserting
  the success survives.
- README (en + zh): the CPU-recheck bullet now states the recheck runs
  unconditionally after the program returns (a pre-return overrun dies there as
  a timeout) and the false-success window is only a trap-SIGXCPU program that
  passes the recheck and overruns during the settlement flush/encode; the
  encoder-deps residual rationale is replaced with the actual one (bash-equivalent
  trust, verdict still delivered via the send_done fallback frame) and names the
  now-bound entry; the t.join() deadlock bullet fixes the subject/object (the
  main coroutine joins the worker, blocking the pump's main event loop).
- The portable-identifier-seam architecture note no longer claims the Python
  backend does not exist.
- Settlement note (en + zh) registers the entry-name binding and the new test.
- All pairings re-recorded; corpus-wide verify-translation-pairing passes 1004.

.agents/notes/implemented/architecture/2026-07-31-code-runtime-portable-identifier-seam.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/architecture/2026-07-31-code-runtime-portable-identifier-seam.md
-2026-07-31-code-runtime-portable-identifier-seam.md: 2011b0f6bc8209e628227ddf486aa1143a63688a
-2026-07-31-code-runtime-portable-identifier-seam.zh.md: 36af33366d004fedc6b1077a937d6519de743638
+2026-07-31-code-runtime-portable-identifier-seam.md: d44de2c5331951b4755bf3e6e3e602011ec4f57e
+2026-07-31-code-runtime-portable-identifier-seam.zh.md: 4c9269d10031944207dda38049f591bc0db77d90

.agents/notes/implemented/architecture/2026-07-31-code-runtime-portable-identifier-seam.md

@@ -25,7 +25,7 @@ The constants live in the Service Definition even though the worker is the only
 
 ## Scope
 
-This decision delivers only the Service Definition extension and the worker's adoption of it. The `py-types` renderer and PTC mode language dispatch are owned by the [language-dispatch note](../feature/2026-07-31-ptc-language-dispatch.md); a Python backend does not exist yet. The Service Definition README keeps its worker-only wording for that reason: linking to a `dsh-code-runtime-python` README that does not exist would break the dead-link gate.
+This decision defines the Service Definition extension and its adoption by the worker-thread and CPython subprocess backends. The `py-types` renderer and PTC mode language dispatch are owned by the [language-dispatch note](../feature/2026-07-31-ptc-language-dispatch.md).
 
 `RESERVED_BINDING_GLOBALS` encodes the Python bootstrap's concrete design ahead of the backend itself: it seeds exactly `__builtins__`/`__name__` and wraps the program under `__dsh_main__`. A Python backend that seeds any additional module global (`__doc__`, `__loader__`, `__spec__`, `__file__`, `__package__`, …) MUST widen this set in the same change, exactly as adding a language widens `PORTABLE_RESERVED_WORDS` — a name the bootstrap seeds but the set omits is the portability split this contract exists to prevent.
 

.agents/notes/implemented/architecture/2026-07-31-code-runtime-portable-identifier-seam.zh.md

@@ -25,7 +25,7 @@ Service Definition 同时把可移植标识符子集收窄为 `[A-Za-z_][A-Za-z0
 
 ## Scope
 
-本决策只交付 Service Definition 扩展与 worker 对它的采用。`py-types` 渲染器与 PTC mode 的语言分发归[语言分发 note](../feature/2026-07-31-ptc-language-dispatch.zh.md) 所有；Python 后端尚不存在。Service Definition README 因此保留仅描述 worker 的措辞：链接到一个不存在的 `dsh-code-runtime-python` README 会破坏死链 gate。
+本决策定义 Service Definition 扩展，以及 worker-thread 与 CPython 子进程后端对它的采用。`py-types` 渲染器与 PTC mode 的语言分发归[语言分发 note](../feature/2026-07-31-ptc-language-dispatch.zh.md)所有。
 
 `RESERVED_BINDING_GLOBALS` 先于后端本身编码了 Python bootstrap 的具体设计：它恰好 seed `__builtins__`/`__name__`，并把程序包装在 `__dsh_main__` 之下。任何 seed 额外模块 global（`__doc__`、`__loader__`、`__spec__`、`__file__`、`__package__` 等）的 Python 后端必须在同一改动中扩宽此集合，正如新增一门语言即扩宽 `PORTABLE_RESERVED_WORDS`——bootstrap 会 seed 却不在集合中的名称，正是本约定要防止的可移植性分裂。
 

.agents/notes/implemented/bug-fix/2026-07-31-code-runtime-python-settlement-fixes.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/bug-fix/2026-07-31-code-runtime-python-settlement-fixes.md
-2026-07-31-code-runtime-python-settlement-fixes.md: c24ae8ae9f8d16b30281ded3b470dcdfc4c9f10a
-2026-07-31-code-runtime-python-settlement-fixes.zh.md: 628c367aaca7c03844e0eb5b5b98201f3dee0d1e
+2026-07-31-code-runtime-python-settlement-fixes.md: e1c6b8edd36a4580167c2b808d6400a4e4814fa7
+2026-07-31-code-runtime-python-settlement-fixes.zh.md: 638c8b71ebf25c91fda59af7bc4b1d6b1141d699

.agents/notes/implemented/bug-fix/2026-07-31-code-runtime-python-settlement-fixes.md

@@ -74,7 +74,7 @@ One residual write-path copy is fixed alongside, independent of the config gate:
 
 ### The completion value and error are pre-encoded at their validation point
 
-In [`py/bootstrap.py`](../../../../packages/code-runtime/code-runtime-python/py/bootstrap.py), `_done_with_value` now returns the whole terminal frame as a PRE-ENCODED JSON string on the success path: the admitted value is serialized once here, at the validation point inside `_run`'s `try`, as `'{"type": "done", "value": ' + _encode_json_plain(value) + "}"`. The program can keep mutating a returned list/dict from a daemon thread or signal handler after it returns, so a second traversal held at a later point would be a TOCTOU — a concurrent mutation into a non-JSON type would let that later encode throw outside the settlement handler and downgrade a settled run host-side to `worker-exit`. Serializing once, inside the `try` that wraps this call, closes the window: if a concurrent mutation makes the encode throw, the exception handler classifies it as an `exception`, and once the string is produced the frame is written verbatim with no further touching of the live value. `_done_with_value` also binds `_check_done_value` and `_encode_json_plain` as DEF-TIME default arguments, so a `__main__` rebind of those two names after model execution cannot rewrite a legitimate success into an `exception`; a rebind of a transitive dep the encoder reaches (`_dump_scalar`, `io`) can still, which is registered as an accepted residual in the package README.
+In [`py/bootstrap.py`](../../../../packages/code-runtime/code-runtime-python/py/bootstrap.py), `_done_with_value` now returns the whole terminal frame as a PRE-ENCODED JSON string on the success path: the admitted value is serialized once here, at the validation point inside `_run`'s `try`, as `'{"type": "done", "value": ' + _encode_json_plain(value) + "}"`. The program can keep mutating a returned list/dict from a daemon thread or signal handler after it returns, so a second traversal held at a later point would be a TOCTOU — a concurrent mutation into a non-JSON type would let that later encode throw outside the settlement handler and downgrade a settled run host-side to `worker-exit`. Serializing once, inside the `try` that wraps this call, closes the window: if a concurrent mutation makes the encode throw, the exception handler classifies it as an `exception`, and once the string is produced the frame is written verbatim with no further touching of the live value. `_run` binds the `_done_with_value` ENTRY NAME into a local (`done_with_value_bound`) before the program runs, and `_done_with_value` itself binds `_check_done_value` and `_encode_json_plain` as DEF-TIME default arguments — so a `__main__` rebind of the entry name or those two names after model execution cannot rewrite a legitimate success into an `exception`. A rebind of a transitive dep the encoder reaches (`_dump_scalar`, `io`) can still, which is registered as an accepted residual in the package README.
 
 `send_done` (a local function inside `_run`) writes the pre-encoded string through a BOUND `channel.write_encoded`, and encodes a dict error frame through a bound `_encode_json_plain` before writing it — it never calls `channel.send_sync`, whose body re-resolves `self.write_encoded` and the module-level `_encode_json_plain` at call time. `_encode_json_plain` and `channel.write_encoded` are bound into locals before the program runs, for the same reason `flush_out`/`flush_err`/`safe_model_traceback` are: the program runs as `__main__`, so `import __main__; __main__.ProtocolChannel.send_sync = boom` or `__main__._encode_json_plain = boom` would otherwise re-resolve the send/encode to a rebranded callable at call time and, when that replacement raises, skip the `done` frame and downgrade a settled verdict to a host-side `worker-exit`.
 
@@ -98,7 +98,7 @@ In [`py/bootstrap.py`](../../../../packages/code-runtime/code-runtime-python/py/
 
 - `tests/boot-write-failure.spec.ts` mocks `spawn` so the fd-3 pipe throws on the boot write — the one path a real subprocess cannot be coerced into — and asserts `run()` resolves a `worker-exit` rather than rejecting. A sibling case makes the mocked `spawn` throw SYNCHRONOUSLY and asserts `run()` still resolves a `worker-exit` and removes its staging directory, keyed off the exact bootstrap path the mocked `spawn` received in its argv so a sibling worker's concurrent staging cannot flake it. Both are isolated in this spec so the real-subprocess suite is untouched.
 - `tests/residual-detach.spec.ts` unit-tests `detachResidual`: the carried copy equals the residual, owns a backing store sized to its own length (fixture kept above Node's Buffer pool threshold), and does not share the source frame's `ArrayBuffer`.
-- `tests/runtime.spec.ts` — the output-cap case asserts the `ceiling - envelope` bound (268435392) and its message. A daemon-thread case drives four threads emitting unterminated writes through settlement's flush. A native-write case writes 200 KiB with no newline via `os.write` under a raised `maxLogBytes` and asserts it reads back as EXACTLY one log entry (proving stray output is aggregated by line, not split at pipe-chunk boundaries); a companion writes `b"one\ntwo\nthree"` and asserts three entries (proving real newlines still delimit). A newline-free-flood case writes 2 MiB under a 4 KiB `maxLogBytes` and asserts the capture ends at the truncation marker and stays under budget (proving the residual is bounded by the ledger, not buffered whole); a NUL-flood companion writes 4000 newline-free NULs under the same budget and asserts truncation (proving the residual is charged by SERIALIZED cost, ~6× raw, measured without allocating the escaped copy); an illegal-UTF-8 case paces single-byte `\xff` writes under a 3072-byte budget with `Buffer.concat` wrapped to measure the peak merged buffer, asserting it stays under 2048 (charged at the U+FFFD width 3 the residual flushes near 1024 raw bytes; a raw-byte undercount would let it reach ~3072, so the bound discriminates); a CESU-8/overlong case paces the structurally-well-formed but illegal `ED A0 80` one byte at a time and asserts the same peak bound (charged at the true 9 per sequence it flushes early; charging the structural width 3 triples the peak, so reverting the per-lead range check turns it red); a broken-multibyte case writes a 3-byte lead then a fresh ASCII byte in separate chunks and asserts both a captured `A` and a U+FFFD (exercising `accrueStrayCost`'s cross-chunk broken-sequence branch); a post-truncation case writes a 108-byte payload (under the smallest PIPE_BUF, so one atomic write) whose first line exhausts a 64-byte budget and asserts the second line is dropped (exercising the post-truncation admit no-op in one `data` callback, no v8-ignore); a short-escape case writes a line mixing a tab, quote, backslash, a `\uXXXX` control, a multibyte character, and ASCII, asserting it round-trips verbatim (exercising every branch of `jsonStringCostUpTo`); a reassembly case writes a payload spanning every valid multibyte lead class (E0-range, plain 3-byte, F0, and F4) past the pipe buffer and asserts it round-trips with no U+FFFD (exercising `accrueStrayCost`'s per-lead ranges and cross-chunk reassembly); a lone-surrogate case forges an fd-3 `log` frame flooding 1000 `\ud800` escapes under a 4 KiB budget and asserts truncation (the count sits in the window where charging 3 bytes would admit and 6 bytes truncates, proving the surrogate is charged its full escaped width); a stray-sealing case paces 60000 single-byte newline-free `os.write(1, …)` calls under a raised budget with `Buffer.concat` wrapped to measure copy volume, asserting the trickle coalesces to one entry and the cumulative copy stays under a measured 256 KiB threshold (the sealed shape copies ~120 KB, the re-merge shape ~538 KB, so reverting the seal to a re-merge turns the assertion red — proving the fragment list seals into blocks past `MAX_PENDING_CHUNKS`). A closeDeadline-flush case has the leader write a newline-free diagnostic then spawn a `setsid` orphan holding the pipes open, and asserts the diagnostic survives in `logs` (proving the residual is flushed before the deadline destroys the streams). The same-group reap case spawns a SIGTERM-ignoring same-group descendant that releases the pipes and bumps a heartbeat file; the test asserts the heartbeat STOPS after the grace-window SIGKILL — an assertion robust whether the killed descendant is reaped or lingers as a zombie, so it holds where PID 1 does not wait() orphans. A dispose-after-resolve case asserts `dispose()` of a completed run with a same-group survivor returns only after the survivor stops executing (proving the run stays in `live` until its group is reaped), with an `expect(afterDispose).toBeGreaterThan(0)` guard so the frozen-heartbeat assertion cannot pass vacuously when the file was never written. A deadline case busy-blocks the event loop past both timers and asserts the survivor's heartbeat freezes (proving the poll's deadline arm sends SIGKILL itself rather than cancelling the unfired escalation). The cross-loop case runs a binding from a worker thread's own `asyncio.run` loop while the main coroutine yields with `await asyncio.sleep`, asserting the reply round-trips instead of timing out; a companion case abandons a thread's call so its loop closes, then answers it before a later binding — asserting the pump survives the closed-loop `call_soon_threadsafe` (host-gated ordering makes it deterministic, fail-before hangs the later binding to the wall clock). The inherited-soft-limit case runs the interpreter through a `ulimit -S -t` wrapper that sets a CPU soft limit below `cpuSeconds` and asserts the applieLine truncated
+- `tests/runtime.spec.ts` — the output-cap case asserts the `ceiling - envelope` bound (268435392) and its message. A daemon-thread case drives four threads emitting unterminated writes through settlement's flush. A native-write case writes 200 KiB with no newline via `os.write` under a raised `maxLogBytes` and asserts it reads back as EXACTLY one log entry (proving stray output is aggregated by line, not split at pipe-chunk boundaries); a companion writes `b"one\ntwo\nthree"` and asserts three entries (proving real newlines still delimit). A newline-free-flood case writes 2 MiB under a 4 KiB `maxLogBytes` and asserts the capture ends at the truncation marker and stays under budget (proving the residual is bounded by the ledger, not buffered whole); a NUL-flood companion writes 4000 newline-free NULs under the same budget and asserts truncation (proving the residual is charged by SERIALIZED cost, ~6× raw, measured without allocating the escaped copy); an illegal-UTF-8 case paces single-byte `\xff` writes under a 3072-byte budget with `Buffer.concat` wrapped to measure the peak merged buffer, asserting it stays under 2048 (charged at the U+FFFD width 3 the residual flushes near 1024 raw bytes; a raw-byte undercount would let it reach ~3072, so the bound discriminates); a CESU-8/overlong case paces the structurally-well-formed but illegal `ED A0 80` one byte at a time and asserts the same peak bound (charged at the true 9 per sequence it flushes early; charging the structural width 3 triples the peak, so reverting the per-lead range check turns it red); a broken-multibyte case writes a 3-byte lead then a fresh ASCII byte in separate chunks and asserts both a captured `A` and a U+FFFD (exercising `accrueStrayCost`'s cross-chunk broken-sequence branch); a post-truncation case writes a 108-byte payload (under the smallest PIPE_BUF, so one atomic write) whose first line exhausts a 64-byte budget and asserts the second line is dropped (exercising the post-truncation admit no-op in one `data` callback, no v8-ignore); a short-escape case writes a line mixing a tab, quote, backslash, a `\uXXXX` control, a multibyte character, and ASCII, asserting it round-trips verbatim (exercising every branch of `jsonStringCostUpTo`); a reassembly case writes a payload spanning every valid multibyte lead class (E0-range, plain 3-byte, F0, and F4) past the pipe buffer and asserts it round-trips with no U+FFFD (exercising `accrueStrayCost`'s per-lead ranges and cross-chunk reassembly); a lone-surrogate case forges an fd-3 `log` frame flooding 1000 `\ud800` escapes under a 4 KiB budget and asserts truncation (the count sits in the window where charging 3 bytes would admit and 6 bytes truncates, proving the surrogate is charged its full escaped width); a stray-sealing case paces 60000 single-byte newline-free `os.write(1, …)` calls under a raised budget with `Buffer.concat` wrapped to measure copy volume, asserting the trickle coalesces to one entry and the cumulative copy stays under a measured 256 KiB threshold (the sealed shape copies ~120 KB, the re-merge shape ~538 KB, so reverting the seal to a re-merge turns the assertion red — proving the fragment list seals into blocks past `MAX_PENDING_CHUNKS`). A closeDeadline-flush case has the leader write a newline-free diagnostic then spawn a `setsid` orphan holding the pipes open, and asserts the diagnostic survives in `logs` (proving the residual is flushed before the deadline destroys the streams). The same-group reap case spawns a SIGTERM-ignoring same-group descendant that releases the pipes and bumps a heartbeat file; the test asserts the heartbeat STOPS after the grace-window SIGKILL — an assertion robust whether the killed descendant is reaped or lingers as a zombie, so it holds where PID 1 does not wait() orphans. A dispose-after-resolve case asserts `dispose()` of a completed run with a same-group survivor returns only after the survivor stops executing (proving the run stays in `live` until its group is reaped), with an `expect(afterDispose).toBeGreaterThan(0)` guard so the frozen-heartbeat assertion cannot pass vacuously when the file was never written. A deadline case busy-blocks the event loop past both timers and asserts the survivor's heartbeat freezes (proving the poll's deadline arm sends SIGKILL itself rather than cancelling the unfired escalation). The cross-loop case runs a binding from a worker thread's own `asyncio.run` loop while the main coroutine yields with `await asyncio.sleep`, asserting the reply round-trips instead of timing out; a companion case abandons a thread's call so its loop closes, then answers it before a later binding — asserting the pump survives the closed-loop `call_soon_threadsafe` (host-gated ordering makes it deterministic, fail-before hangs the later binding to the wall clock). The inherited-soft-limit case runs the interpreter through a `ulimit -S -t` wrapper that sets a CPU soft limit below `cpuSeconds` and asserts the applieLine truncated
 
 ## Alternatives considered
 

.agents/notes/implemented/bug-fix/2026-07-31-code-runtime-python-settlement-fixes.zh.md

@@ -74,7 +74,7 @@ Status: implemented
 
 ### 完成值与错误在其校验点处预编码
 
-在 [`py/bootstrap.py`](../../../../packages/code-runtime/code-runtime-python/py/bootstrap.py) 中，`_done_with_value` 现在会在成功路径上把整个终止帧作为一个已预编码的 JSON 字符串返回：被准入的值在这里、在 `_run` 的 `try` 之内的校验点处恰好序列化一次，即 `'{"type": "done", "value": ' + _encode_json_plain(value) + "}"`。程序在返回之后仍可能从 daemon 线程或信号处理器继续变异它返回的 list／dict，因此在一个更晚的点上做第二次遍历会构成一次 TOCTOU——如果一次变异让一个并发变异的后续编码在结算处理器之外抛出，就会把一次已结算的运行在宿主侧降级成 `worker-exit`。在这里、在包裹该调用的 `try` 之内恰好序列化一次，就关上了这个窗口：如果一次并发变异导致编码抛出，异常处理器会把它如实分类为 `exception`；一旦字符串产生出来，该帧就会被逐字写走、不再触碰任何活对象。`_done_with_value` 还把 `_check_done_value` 与 `_encode_json_plain` 绑定为 def 期默认参数，因此模型执行后对这两个名字的 `__main__` 重绑无法把一个合法成功改写为 `exception`；但编码器到达的一个传递依赖（`_dump_scalar`、`io`）重绑仍可，这在包 README 中被登记为已接受残余。
+在 [`py/bootstrap.py`](../../../../packages/code-runtime/code-runtime-python/py/bootstrap.py) 中，`_done_with_value` 现在会在成功路径上把整个终止帧作为一个已预编码的 JSON 字符串返回：被准入的值在这里、在 `_run` 的 `try` 之内的校验点处恰好序列化一次，即 `'{"type": "done", "value": ' + _encode_json_plain(value) + "}"`。程序在返回之后仍可能从 daemon 线程或信号处理器继续变异它返回的 list／dict，因此在一个更晚的点上做第二次遍历会构成一次 TOCTOU——如果一次变异让一个并发变异的后续编码在结算处理器之外抛出，就会把一次已结算的运行在宿主侧降级成 `worker-exit`。在这里、在包裹该调用的 `try` 之内恰好序列化一次，就关上了这个窗口：如果一次并发变异导致编码抛出，异常处理器会把它如实分类为 `exception`；一旦字符串产生出来，该帧就会被逐字写走、不再触碰任何活对象。`_run` 在程序运行前把 `_done_with_value` 的入口名绑成局部（`done_with_value_bound`），而 `_done_with_value` 自身把 `_check_done_value` 与 `_encode_json_plain` 绑定为 def 期默认参数——因此模型执行后对入口名或这两个名字的 `__main__` 重绑无法把一个合法成功改写为 `exception`；但编码器到达的一个传递依赖（`_dump_scalar`、`io`）重绑仍可，这在包 README 中被登记为已接受残余。
 
 `send_done`（`_run` 内部的一个局部函数）通过绑定的 `channel.write_encoded` 写出已预编码的字符串，并在写之前用绑定的 `_encode_json_plain` 编码一个 dict 错误帧——它绝不经 `channel.send_sync`，因为后者的函数体会在调用时刻重新解析 `self.write_encoded` 和模块级的 `_encode_json_plain`。`_encode_json_plain` 与 `channel.write_encoded` 在程序运行前就被绑定进局部变量，理由与 `flush_out`／`flush_err`／`safe_model_traceback` 被绑定相同：程序以 `__main__` 运行，因此 `import __main__; __main__.ProtocolChannel.send_sync = boom` 或 `__main__._encode_json_plain = boom` 本会在调用时刻把发送／编码重新解析成被替换的可调用对象，当该替换抛出时跳过 `done` 帧、把已结算的结论降级成宿主侧的 `worker-exit`。
 
@@ -98,7 +98,7 @@ Status: implemented
 
 - `tests/boot-write-failure.spec.ts` 对 `spawn` 做 mock，使 fd-3 管道在引导写入时抛出异常（这是真实子进程无法被迫进入的唯一路径），并断言 `run()` resolve 出一个 `worker-exit` 而非 reject。一个同级用例让被 mock 的 `spawn` 同步抛出，并断言 `run()` 仍然 resolve 出一个 `worker-exit`，且会移除它的暂存目录——以被 mock 的 `spawn` 在其 argv 中收到的确切引导路径为准，因此一个同级 worker 的并发暂存不会让它变得不稳定。两者都被隔离在这个 spec 中，因此真实子进程测试套件不受影响。
 - `tests/residual-detach.spec.ts` 对 `detachResidual` 做单元测试：向前传递的副本与残余数据相等、拥有一个大小与其自身长度一致的底层存储（fixture 保持在 Node 的 Buffer 池阈值之上），并且不与源帧的 `ArrayBuffer` 共享。
-- `tests/runtime.spec.ts`：output-cap 用例断言 `ceiling - envelope` 上界（268435392）及其消息。一个 daemon 线程用例驱动四个线程穿过结算的 flush 发出未结束的写入。一个 native-write 用例在抬高后的 `maxLogBytes` 之下，通过 `os.write` 写入 200 KiB 且不含换行符，断言它回读时恰好是一条日志条目（证明散逸输出是按行聚合的，而不是在管道分片边界处被切开）；一个配套用例写入 `b"one\ntwo\nthree"`，断言得到三条条目（证明真正的换行符仍然起分隔作用）。一个 newline-free-flood 用例在一个 4 KiB 的 `maxLogBytes` 之下写入 2 MiB，断言捕获终止于截断标记且保持在预算之内（证明残余数据受账本约束，而不是被整体缓冲）；一个 NUL-flood 配套用例在同一预算之下写入 4000 个不含换行符的 NUL，断言发生截断（证明残余数据是按序列化开销计费的，约为原始的 6 倍，且在度量时不分配转义后的副本）；一个 illegal-UTF-8 用例在一个 3072 字节的预算之下控速发出单字节 `\xff` 写入，并对 `Buffer.concat` 做包装以度量峰值合并缓冲区，断言它保持在 2048 之下（按 U+FFFD 宽度 3 计费时残余数据在约 1024 原始字节处冲刷；一次原始字节的少计会让它达到约 3072，因此该界限具有区分力）；一个 CESU-8/overlong 用例把结构良构但非法的 `ED A0 80` 一次一个字节地控速发出，断言同样的峰值界限（按每序列真实的 9 计费时它提前冲刷；按结构宽度 3 计费会使峰值增至三倍，因此把逐前导字节范围检查回退会使它变红）；一个 broken-multibyte 用例在分开的分片里先写入一个 3 字节的前导字节、再写入一个新的 ASCII 字节，断言同时捕获到一个 `A` 和一个 U+FFFD（覆盖 `accrueStrayCost` 的跨分片断裂序列分支）；一个 post-truncation 用例写入一个 108 字节的载荷（小于最小的 PIPE_BUF，因此是一次原子写入），其首行耗尽一个 64 字节的预算，断言第二行被丢弃（覆盖单次 `data` 回调中的截断后准入空操作，无需 v8-ignore）；一个 short-escape 用例写入一行混合了制表符、引号、反斜杠、一个 `\uXXXX` 控制字符、一个多字节字符和 ASCII 的内容，断言它原样完成往返（覆盖 `jsonStringCostUpTo` 的每一条分支）；一个 reassembly 用例写入一个跨越每个合法多字节前导字节类别（E0 范围、普通 3 字节、F0 和 F4）、越过管道缓冲区的载荷，断言它原样完成往返且不含 U+FFFD（覆盖 `accrueStrayCost` 的逐前导字节范围与跨分片重组）；一个 lone-surrogate 用例在一个 4 KiB 预算之下伪造一个以 1000 个 `\ud800` 转义洪泛的 fd-3 `log` 帧，断言发生截断（该计数正落在计 3 字节会放行、计 6 字节则截断的窗口内，证明该代理项是按其完整转义宽度计费的）；一个 stray-sealing 用例在抬高后的预算之下控速发出 60000 次单字节、不含换行符的 `os.write(1, …)` 调用，并对 `Buffer.concat` 做包装以度量复制量，断言这股细流合并为一条条目、且累积复制量保持在一个实测的 256 KiB 阈值之下（封存后的形态复制约 120 KB，重新合并的形态复制约 538 KB，因此把封存回退成重新合并会使该断言变红——证明分片列表在越过 `MAX_PENDING_CHUNKS` 后封存为块）。一个 closeDeadline-flush 用例让 leader 写入一段不含换行符的诊断，随后 spawn 一个持有管道不放的 `setsid` 孤儿进程，断言该诊断在 `logs` 中存留下来（证明残余数据在截止时间销毁流之前被冲刷）。same-group 回收用例 spawn 一个忽略 SIGTERM 的同进程组后代，它释放管道并递增一个心跳文件；该测试断言在宽限窗口的 SIGKILL 之后心跳停止：无论被杀死的后代是被回收还是作为僵尸进程滞留，这个断言都成立，因此它在 PID 1 不 wait() 孤儿进程的环境下同样成立。一个 dispose-after-resolve 用例断言，对一个已完成、且存在同进程组存活者的运行调用 `dispose()`，只有在该存活者停止执行之后才返回（证明该运行会一直留在 `live` 中，直到它的进程组被回收），并带有一个 `expect(afterDispose).toBeGreaterThan(0)` 守卫，使得当心跳文件从未被写入时，冻结心跳的断言不会被空洞地通过。一个 deadline 用例忙阻塞事件循环越过两个定时器，断言该存活者的心跳冻结（证明轮询的截止时间分支自身发送 SIGKILL，而不是取消尚未触发的升级）。cross-loop 用例在主协程通过 `await asyncio.sleep` 让出时，从一个工作线程自己的 `asyncio.run` 事件循环运行一个绑定，断言该回复完成往返而不是超时；一个配套用例放弃某个线程的调用，使其事件循环关闭，Line truncated
+- `tests/runtime.spec.ts`：output-cap 用例断言 `ceiling - envelope` 上界（268435392）及其消息。一个 daemon 线程用例驱动四个线程穿过结算的 flush 发出未结束的写入。一个 native-write 用例在抬高后的 `maxLogBytes` 之下，通过 `os.write` 写入 200 KiB 且不含换行符，断言它回读时恰好是一条日志条目（证明散逸输出是按行聚合的，而不是在管道分片边界处被切开）；一个配套用例写入 `b"one\ntwo\nthree"`，断言得到三条条目（证明真正的换行符仍然起分隔作用）。一个 newline-free-flood 用例在一个 4 KiB 的 `maxLogBytes` 之下写入 2 MiB，断言捕获终止于截断标记且保持在预算之内（证明残余数据受账本约束，而不是被整体缓冲）；一个 NUL-flood 配套用例在同一预算之下写入 4000 个不含换行符的 NUL，断言发生截断（证明残余数据是按序列化开销计费的，约为原始的 6 倍，且在度量时不分配转义后的副本）；一个 illegal-UTF-8 用例在一个 3072 字节的预算之下控速发出单字节 `\xff` 写入，并对 `Buffer.concat` 做包装以度量峰值合并缓冲区，断言它保持在 2048 之下（按 U+FFFD 宽度 3 计费时残余数据在约 1024 原始字节处冲刷；一次原始字节的少计会让它达到约 3072，因此该界限具有区分力）；一个 CESU-8/overlong 用例把结构良构但非法的 `ED A0 80` 一次一个字节地控速发出，断言同样的峰值界限（按每序列真实的 9 计费时它提前冲刷；按结构宽度 3 计费会使峰值增至三倍，因此把逐前导字节范围检查回退会使它变红）；一个 broken-multibyte 用例在分开的分片里先写入一个 3 字节的前导字节、再写入一个新的 ASCII 字节，断言同时捕获到一个 `A` 和一个 U+FFFD（覆盖 `accrueStrayCost` 的跨分片断裂序列分支）；一个 post-truncation 用例写入一个 108 字节的载荷（小于最小的 PIPE_BUF，因此是一次原子写入），其首行耗尽一个 64 字节的预算，断言第二行被丢弃（覆盖单次 `data` 回调中的截断后准入空操作，无需 v8-ignore）；一个 short-escape 用例写入一行混合了制表符、引号、反斜杠、一个 `\uXXXX` 控制字符、一个多字节字符和 ASCII 的内容，断言它原样完成往返（覆盖 `jsonStringCostUpTo` 的每一条分支）；一个 reassembly 用例写入一个跨越每个合法多字节前导字节类别（E0 范围、普通 3 字节、F0 和 F4）、越过管道缓冲区的载荷，断言它原样完成往返且不含 U+FFFD（覆盖 `accrueStrayCost` 的逐前导字节范围与跨分片重组）；一个 lone-surrogate 用例在一个 4 KiB 预算之下伪造一个以 1000 个 `\ud800` 转义洪泛的 fd-3 `log` 帧，断言发生截断（该计数正落在计 3 字节会放行、计 6 字节则截断的窗口内，证明该代理项是按其完整转义宽度计费的）；一个 stray-sealing 用例在抬高后的预算之下控速发出 60000 次单字节、不含换行符的 `os.write(1, …)` 调用，并对 `Buffer.concat` 做包装以度量复制量，断言这股细流合并为一条条目、且累积复制量保持在一个实测的 256 KiB 阈值之下（封存后的形态复制约 120 KB，重新合并的形态复制约 538 KB，因此把封存回退成重新合并会使该断言变红——证明分片列表在越过 `MAX_PENDING_CHUNKS` 后封存为块）。一个 closeDeadline-flush 用例让 leader 写入一段不含换行符的诊断，随后 spawn 一个持有管道不放的 `setsid` 孤儿进程，断言该诊断在 `logs` 中存留下来（证明残余数据在截止时间销毁流之前被冲刷）。same-group 回收用例 spawn 一个忽略 SIGTERM 的同进程组后代，它释放管道并递增一个心跳文件；该测试断言在宽限窗口的 SIGKILL 之后心跳停止：无论被杀死的后代是被回收还是作为僵尸进程滞留，这个断言都成立，因此它在 PID 1 不 wait() 孤儿进程的环境下同样成立。一个 dispose-after-resolve 用例断言，对一个已完成、且存在同进程组存活者的运行调用 `dispose()`，只有在该存活者停止执行之后才返回（证明该运行会一直留在 `live` 中，直到它的进程组被回收），并带有一个 `expect(afterDispose).toBeGreaterThan(0)` 守卫，使得当心跳文件从未被写入时，冻结心跳的断言不会被空洞地通过。一个 deadline 用例忙阻塞事件循环越过两个定时器，断言该存活者的心跳冻结（证明轮询的截止时间分支自身发送 SIGKILL，而不是取消尚未触发的升级）。cross-loop 用例在主协程通过 `await asyncio.sleep` 让出时，从一个工作线程自己的 `asyncio.run` 事件循环运行一个绑定，断言该回复完成往返而不是超时；一个配套用例放弃某个线程的调用，使其事件循环关闭，Line truncated
 
 ## Alternatives considered
 

packages/code-runtime/code-runtime-python/README.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 packages/code-runtime/code-runtime-python/README.md
-README.md: f976b050992863cc8586b5415d9c36cfe193229e
-README.zh.md: 608ac28ecab35f90d9a9d6582e15a24fa4e78c10
+README.md: 3522c7726460b10f0366c56566336465a76491c5
+README.zh.md: 95984cf1ae3677aff4a5c4565bed87a57701d086

packages/code-runtime/code-runtime-python/README.md

@@ -39,7 +39,7 @@ No direct invalidation; the named consumer owns any request-prefix changes.
 - **A descendant that calls `setsid()` / `start_new_session=True` escapes teardown.** Termination signals the child's process group with `kill(-pid)`; a descendant that moves itself into a fresh session is no longer in that group and no signal reaches it. If it also releases the inherited stdout/stderr/fd-3 pipes, the leader's `close` still settles the run, and after the `closeDeadline` bound the fiber goes quiescent while that orphan keeps running. This is the containment boundary, not a security one — model code has bash-equivalent trust, and a bash tool can `setsid` away just the same. Reaching such an orphan would require tracking every descendant pid (as the bash-local backend's process-inspector does) and is deferred; the process-group teardown reaps everything that stays in the group.
 - **A combined log-and-value peak is not modelled by the load gate.** Each budget is checked against `addressSpaceMb` on its own. A model daemon thread that keeps writing while the completion value is metered and framed can refill the log pending toward `maxLogBytes` during that window, so the two peaks add in a way no gate admits or rejects. A gate over `(maxLogBytes + maxValueBytes)` was considered and deferred: its discriminating case cannot be scheduled deterministically under `RLIMIT_AS`, so the gate would only prove its own arithmetic. When the combined peak is reached the run dies as `worker-exit` -- containment holds and only the failure classification is degraded.
 - **A 1-second dual-limit `ulimit -t 1` CPU overrun is reported as `worker-exit`, not a timeout.** When the host starts under a hard CPU limit equal to the soft (`ulimit -t N` sets both) and that limit is 1, `_clamped` cannot lower the soft to 0, so the kernel SIGKILLs the busy loop in the same tick and SIGXCPU is never delivered. The host classifies a CPU overrun only on `signal === 'SIGXCPU'`, so the overrun is reported as `worker-exit`. For a dual limit of 2 or more the soft is lowered by one unit, SIGXCPU fires, and the run is a timeout. Containment holds in both cases; only the classification is degraded.
-- **A program that traps SIGXCPU can exceed the soft CPU limit during settlement encoding and still report success.** The settlement CPU recheck runs before the completion value is flushed and encoded; a program that traps SIGXCPU (soft limit) and keeps burning past it through the build-and-encode window returns a result before `die_if_cpu_exhausted` re-checks, so the run reports success. Containment holds — the hard limit (soft + 1s) and the wall clock still bound it — and only the classification is degraded. The CPU recheck does not run mid-encode because doing so would have to meter the encode itself, and the encode is the path the budget already bounds.
-- **The encoder's direct dependencies resolve at call time.** `_encode_json_plain` reaches `_dump_scalar`/`_dump_string`/`json` via module-global lookup, so a program running as `__main__` that rebinds one of those names (e.g. `__main__._dump_scalar = boom`) after returning a legitimate value can make the encode throw and downgrade a success to `exception`. The value path's top-level `_check_done_value`/`_encode_json_plain` are bound as def-time defaults, but their transitive deps are not; this is an accepted residual for the same reason the analogous `_dump_*` helpers are not rebound in practice.
+- **A program that traps SIGXCPU can exceed the soft CPU limit during settlement encoding and still report success.** The settlement CPU recheck (`die_if_cpu_exhausted`) runs unconditionally after the program returns and before the log flush and completion encode; a program that exceeded the soft limit before returning is caught there and dies on the re-delivered SIGXCPU, classified as a timeout. The only false-success window is a program that PASSES the recheck and then, with SIGXCPU trapped, exceeds the soft limit during the settlement flush/encode window. A post-encode recheck is not done because it would charge the settlement encode's own CPU to the program, misclassifying a legitimate near-limit program. Containment holds — the hard limit (soft + 1s) and the wall clock still bound it — and only the classification is degraded.
+- **The encoder's direct dependencies resolve at call time.** `_encode_json_plain` reaches `_dump_scalar`/`_dump_string`/`json` via module-global lookup, so a program running as `__main__` that rebinds one of those names (e.g. `__main__._dump_scalar = boom`) after returning a legitimate value can make the encode throw and downgrade a success to `exception`. The value path's entry name (`_done_with_value`) is bound into `_run` locals and its top-level `_check_done_value`/`_encode_json_plain` are def-time defaults, but the encoder's transitive deps (`_dump_scalar`/`_dump_string`/`json`) still resolve at call time. This is an accepted residual: under the bash-equivalent trust model a rebind here only harms the model's own run, and the verdict still reaches the host — `send_done`'s fixed fallback frame delivers a done frame even when the error-path encode/write throws.
 - **A wide binding REPLY expands host-side state per member.** Resolutions cross through `snapshotJsonValue` in [`@deepseek-ai/dsh-session`](../../core/session/README.md), whose `walkJsonValue` pushes one task frame per member, and binding resolution carries no seam-level byte cap. A legitimate reply of several million elements can therefore exhaust the host heap. The property belongs to that shared walk, not to this backend -- the worker-thread backend consumes the same function -- so the fix belongs in `packages/core/session` where every consumer benefits.
-- **A cross-thread binding that the program joins with a synchronous `t.join()` can deadlock.** This is specific to the `process` isolation backend: the reply pump runs on the child's main event loop, so a worker thread that joins the main coroutine with `t.join()` blocks the loop the pump needs to deliver the binding's reply, and `await` never resumes until the wall clock. The worker-thread backend does not share this structure, so the fix belongs here, not in `packages/core/session`.
+- **A cross-thread binding that the program joins with a synchronous `t.join()` can deadlock.** This is specific to the `process` isolation backend: the reply pump runs on the child's main event loop, so when the program's main coroutine calls `t.join()` on a worker thread that is still awaiting a binding reply, the join blocks the main thread's event loop — the loop the pump needs to deliver that reply — and the worker's `await` never resumes until the wall clock. The worker-thread backend does not share this structure, so the fix belongs here, not in `packages/core/session`.

packages/code-runtime/code-runtime-python/README.zh.md

@@ -39,7 +39,7 @@ host 与 CPython 子进程在子进程的 fd 3 上交换一个无版本号的 JS
 - **调用 `setsid()` ／ `start_new_session=True` 的后代会逃出 teardown。** 终止是用 `kill(-pid)` 向子进程的进程组发信号；一个把自己移入新会话的后代已不在该进程组内，任何信号都到不了它。若它同时释放了继承而来的 stdout／stderr／fd-3 管道，leader 的 `close` 仍会结算该次运行，在 `closeDeadline` 到界之后 fiber 变为完全停稳，而那个孤儿仍在运行。这是 containment 边界，而非安全边界——模型代码具有等同 bash 的信任级别，一个 bash 工具同样能 `setsid` 逃逸。要够到这样的孤儿需要追踪每一个后代 pid（如 bash-local 后端的 process-inspector 所做），此项已推迟；进程组 teardown 会回收所有留在组内的进程。
 - **日志与完成值的叠加峰值未被加载门建模。** 每项预算都是各自对照 `addressSpaceMb` 检查的。模型的 daemon 线程可以在完成值被计量并分帧的窗口内持续写入、把日志 pending 重填到接近 `maxLogBytes`，于是两个峰值以任何门都不曾放行也不曾拒绝的方式相加。对 `(maxLogBytes + maxValueBytes)` 设门的方案经评估后推迟：它的判别用例无法在 `RLIMIT_AS` 之下确定性地构造出来，因此该门只能证明自己的算术。叠加峰值被触及时该次运行死为 `worker-exit`——containment 仍然成立，只是失败分类失真。
 - **1 秒双限 `ulimit -t 1` 下的 CPU 超限会被报告为 `worker-exit`，而非超时。** 当宿主在一个硬 CPU 限制等于软限制（`ulimit -t N` 同时设置两者）且该限制为 1 的环境下启动时，`_clamped` 无法把软限制降到 0，因此内核在同一 tick 直接 SIGKILL 忙循环，SIGXCPU 永不送达。宿主只在 `signal === 'SIGXCPU'` 时把 CPU 超限分类为超时，因此该超限被报告为 `worker-exit`。当双限为 2 或更大时，软限制会被降低一个单位，SIGXCPU 触发，该次运行成为超时。两种情况 containment 都成立；只是分类被降级。
-- **一个 trap SIGXCPU 的程序可以在结算编码期间超过软 CPU 限制并仍报告成功。** 结算时的 CPU 复查在完成值被 flush 与编码之前运行；一个 trap SIGXCPU（软限制）并在构建与编码窗口内继续燃烧 CPU 的程序会在 `die_if_cpu_exhausted` 复查之前返回结果，因此该次运行报告成功。containment 成立——硬限制（软限制 + 1s）与墙钟仍会约束它——只是分类被降级。CPU 复查不在编码中途运行，因为那必须计量编码本身，而编码正是预算已经约束的路径。
-- **编码器的直接依赖在调用时解析。** `_encode_json_plain` 通过模块全局查找到达 `_dump_scalar`/`_dump_string`/`json`，因此以 `__main__` 运行的程序在返回合法值后重绑这些名字之一（例如 `__main__._dump_scalar = boom`）可以让编码抛出、把成功降级为 `exception`。值路径顶层的 `_check_done_value`/`_encode_json_plain` 被绑定为 def 期默认值，但其传递依赖没有；这是已接受的残余，原因与对应的 `_dump_*` 辅助函数在实践中不被重绑相同。
+- **一个 trap SIGXCPU 的程序可以在结算编码期间超过软 CPU 限制并仍报告成功。** 结算时的 CPU 复查（`die_if_cpu_exhausted`）在程序返回后、日志 flush 与完成值编码之前无条件运行；一个在返回前已超过软限制的程序会在这里死于重投递的 SIGXCPU，被归类为超时。唯一的误报窗口是一个通过复查后、trap 住 SIGXCPU 并在结算 flush/编码窗口内越过软限制的程序。不做编码后复查，是因为那会把结算编码自身消耗的 CPU 记到程序头上、误分类一个合法的近限程序。containment 成立——硬限制（软限制 + 1s）与墙钟仍会约束它——只是分类被降级。
+- **编码器的直接依赖在调用时解析。** `_encode_json_plain` 通过模块全局查找到达 `_dump_scalar`/`_dump_string`/`json`，因此以 `__main__` 运行的程序在返回合法值后重绑这些名字之一（例如 `__main__._dump_scalar = boom`）可以让编码抛出、把成功降级为 `exception`。值路径的入口名（`_done_with_value`）被绑定进 `_run` 局部、其顶层的 `_check_done_value`/`_encode_json_plain` 是 def 期默认值，但编码器的传递依赖（`_dump_scalar`/`_dump_string`/`json`）仍在调用时解析。这是已接受的残余：在 bash-equivalent 信任模型下，这里的重绑只会伤害模型自身的运行，且判决仍必达宿主——`send_done` 的固定兜底帧即使在错误路径编码/写入抛出时也能送达一帧 done。
 - **宽 binding 回复会按成员展开宿主侧状态。** 回复经由 [`@deepseek-ai/dsh-session`](../../core/session/README.zh.md) 的 `snapshotJsonValue` 穿越，其 `walkJsonValue` 为每个成员压入一个任务帧，而 binding 回复在 seam 层没有字节上限。因此一个数百万元素的合法回复可以耗尽宿主堆。该性质属于那个共享遍历，而不属于本后端——worker-thread 后端消费同一个函数——所以修复应落在 `packages/core/session`，让所有消费方一并受益。
-- **程序用同步的 `t.join()` 连接一个跨线程 binding 会死锁。** 这是 `process` 隔离后端特有的：回复泵运行在子进程的主事件循环上，因此一个用 `t.join()` 阻塞主协程的 worker 线程会卡住泵投递该 binding 回复所需的循环，`await` 直到墙钟才会恢复。worker-thread 后端不共享此结构，所以修复应落在这里，而非 `packages/core/session`。
+- **程序用同步的 `t.join()` 连接一个跨线程 binding 会死锁。** 这是 `process` 隔离后端特有的：回复泵运行在子进程的主事件循环上，因此当程序的主协程对一个仍在等待 binding 回复的 worker 线程调用 `t.join()` 时，join 会阻塞承载泵的主线程事件循环——正是泵投递该回复所需的循环——该 worker 的 `await` 直到墙钟才会恢复。worker-thread 后端不共享此结构，所以修复应落在这里，而非 `packages/core/session`。

packages/code-runtime/code-runtime-python/py/bootstrap.py

@@ -997,6 +997,14 @@ async def _run(channel: ProtocolChannel) -> None:
     # bound above.
     encode_plain_bound = _encode_json_plain
     write_encoded_bound = channel.write_encoded
+    # The completion-frame builder is bound into a LOCAL here, before the
+    # program runs: `done = _done_with_value(...)` below sits after the program
+    # (which is `__main__`) may have rebound `__main__._done_with_value`, so a
+    # module-global lookup at call time would let a one-line rebind rewrite a
+    # legitimate success into an `exception`. Binding it (with its own def-time
+    # default-captured `_check_done_value`/`_encode_json_plain`) makes the entry
+    # name immune.
+    done_with_value_bound = _done_with_value
     # The fallback primitives are bound into LOCALS here, before the program
     # runs, so `send_done`'s except arm does not read module globals at call
     # time. This bootstrap is `__main__`, so `__main__._os_write = boom` (or
@@ -1068,7 +1076,7 @@ async def _run(channel: ProtocolChannel) -> None:
         # the value frame's peak stands alone against the address space.
         flush_out()
         flush_err()
-        done = _done_with_value(value, max_value_bytes)
+        done = done_with_value_bound(value, max_value_bytes)
     except _BaseException as exc:  # noqa: BLE001 -- report every failure to host; `_BaseException` is a pre-program local, not a rebindable module global
         done = {
             "type": "done",

packages/code-runtime/code-runtime-python/tests/runtime.spec.ts

@@ -3145,6 +3145,29 @@ describe('PythonCodeRuntime — hostile peer', () => {
     expect(result.value).toBe('released')
   }, 15_000)
 
+  it('keeps a successful completion when _done_with_value is rebound', async () => {
+    // `_run` calls `_done_with_value(value, max_value_bytes)` after the program
+    // returns. The name is a module global, and this bootstrap IS `__main__`, so
+    // `__main__._done_with_value = boom` as a program statement would otherwise
+    // be resolved at call time and a legitimate success would be rewritten into
+    // an `exception`. `_run` now binds `done_with_value_bound = _done_with_value`
+    // before the program runs, so the entry name is immune; the run must still
+    // report the success value.
+    const { runtime } = await setup({ maxWallMs: 10_000 })
+    const result = await runtime.run({
+      program: [
+        'import __main__',
+        'def boom(*a, **k):',
+        '    raise RuntimeError("hijacked")',
+        '__main__._done_with_value = boom',
+        'return 1',
+      ].join('\n'),
+      bindings: [],
+    })
+    expect(result.error).toBeUndefined()
+    expect(result.value).toBe(1)
+  }, 15_000)
+
   it('round-trips an exactly representable large integer through a binding echo', async () => {
     // The reply serializer must print BigInt digits for a beyond-safe
     // integral double: String(2**60) emits a rounded form, and the child