checkDoneValue cannot bound object width sublinearly: JS has no lazy own-key
iterator (for...in materializes the key set), and done.value is already
JSON.parse'd before the check runs, so the frame's width is paid upstream. The
genuine width bound is the host's fixed 256 MiB fd-3 receive buffer (a later
stack layer). Reword the JSDoc and branch comments to claim only what holds —
the traversal caps the INCREMENTAL allocation the check would add (escaped
strings, enqueued children, per-key stringify) and refuses over-budget before
those secondary allocations — and drop the mid-count micro-check that JS cannot
honor. Replace the Proxy test (whose ownKeys allocated a 2M array, proving
nothing) with assertions that an over-budget string/array/object is refused
before its escaped copy or child enqueue.
The object branch counted every own key before applying the size bound, so a
forged done.value with millions of keys and a small cap forced an O(frame)
walk — contradicting the O(cap) guarantee the comment promised and able to
block the host event loop. Bail mid-count the instant the running minimum
encoding (braces + 4 bytes/entry + commas) crosses maxBytes, and drop the now
-redundant post-count check the loop subsumes. Add a Proxy-based test proving
a 2M-key object enumerates fewer than 1000 keys under a 64-byte cap.
Also correct the checkDoneValue JSDoc: per-scalar byte length is measured via
scalarJson (exact BigInt digits for beyond-safe integers), not JSON.stringify.
- Drop a CALL frame whose id is negative zero: it passes Number.isFinite but
the reply re-serializes it as `0`, colliding with a real call id `0`. The
honest child never issues `-0`.
- Document that validateChildFrame preserves a forged done frame's value and
error together on purpose, so consumers must check error before value.
- Cover the log-frame `truncated` rebuild branch: assert a literal-true flag
rides along and any other value (1, string, false) is dropped, closing the
protocol.ts branch the coverage gate flagged.
- Correct encodeJsonPlain's JSDoc: it matches compact JSON.stringify EXCEPT on
a beyond-safe-range integral double, where it emits the exact BigInt digits
(`...846976`) rather than the rounded `...847000` — the divergence the
"emits exact digits" test pins.
- Declare py/protocol.py's `global`-bearing frames (Namespace, CallMessage)
with functional TypedDict syntax so they carry the real wire key instead of
a `global_` attribute the wire never sends, and split optional-field messages
(Namespace/LogMessage/DoneMessage) into a required base plus a total=False
subclass so `type` and other required fields cannot be dropped. Widen
HostToChild to include the boot and run frames the host sends before replies.
- Reword the mirror e2e's py/ directory assertion to describe the source-tree
layout it actually checks.
Introduce @deepseek-ai/dsh-code-runtime-python with the versionless
JSON-lines protocol between the Node host and the CPython subprocess:
the host-side hostile-frame codec (validateChildFrame, encodeJsonPlain,
checkDoneValue, hasUnsafeIntegerToken, hasNonLosslessNumber,
logTruncationMarker) and the Python-side wire-vocabulary mirror
(py/protocol.py).
This is the protocol layer of the code-runtime-python stack, split from
#436 and based on the multi-language seam extension. The PythonCodeRuntime
implementation and its Python JSON codec land in the backend-core PR on
top of this branch.
Ship the minimal buildable package skeleton (package.json, tsconfig,
tsdown, barrel index, invariant companion, bilingual README) because the
workspace-constraint, coverage, and invariant-topology gates require the
package to exist and build the moment its directory does; the backend-core
PR extends those files rather than creating them.
Align py/protocol.py with src/protocol.ts (the round-12 review of #436
found LogMessage.truncated, DoneMessage.error.kind, and Namespace.errorClass
stale) and guard the two runtime-executed surfaces (PROTOCOL_FD and the log
truncation marker) with a real-python3 cross-language mirror e2e test.
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