Review findings on the CPython backend: a child that never reads fd 3 leaves
the reply pipe full forever, so the drain loop waits on 'drain' while every
call frame it keeps sending resolves a binding and queues another reply —
the backlog (and the binding results it pins) would grow until the wall
clock. sendReply now caps the pending backlog at MAX_PENDING_REPLIES and
settles the run as worker-exit past it, mirroring the frame cap; a child
flooding calls against a binding that never settles would otherwise bypass
that cap (pendingReplies grows only after the await), so the dispatcher
counts in-flight binding calls before dispatch and releases the slot in the
async body's finally, capping outstanding closures at the same bound. The
drain also compacts its consumed prefix (replyQueue.splice(0, head)) once
head reaches the bound, so a drain that stays alive without emptying cannot
grow the backing store linearly with cumulative throughput.
The completion-value meter counted lone surrogates with
_SURROGATE.findall(folded), materializing one single-character string per
surrogate: a surrogate-dense value near the budget (millions of surrogates,
each serializing to six bytes) allocated millions of objects before the meter
returned, defeating the meter's counting-without-building contract. The count
is now the length difference between folded and the without string the meter
already computes; a standalone equivalence check confirms it matches findall
across lone-high, lone-low, paired, astral, and mixed cases.
validateBindings read namespace.global/errorClass.name/memberNameProperty
several times and retained the original errorClass object for the boot
frame, whose JSON.stringify re-read it after validation: a stateful getter
could throw or change between the two stages, turning the seam-misuse
rejection into a worker-exit or injecting an unvalidated name. Each field is
now read once into a plain value and the bindings map stores a plain
{ name, memberNameProperty } copy, so validation and the boot frame see
identical values.
Regression tests: a hostile child floods 5000 sequential valid calls without
reading fd 3 and the run settles worker-exit with the reply-queue message
before maxWallMs; a 3,000,000-surrogate completion succeeds at an
18,000,002-byte budget and reports output-limit one byte under; a 5000-call
flood against a never-settling binding settles worker-exit with the
call-backlog message; getter-backed namespace metadata that throws or
changes on a second read boots and runs with each field read exactly once; a
two-wave flood whose replies exceed the writable high-water mark drives the
drain past the compaction bound mid-delivery and verifies all 1524 replies
arrive. README Known Limitations gains the reply-backlog and call-backlog
bounds (en/zh, pairing re-recorded); a new Agent Note registers the findings.
Review findings on the CPython backend: an explicit pythonBin path bypassed
the load-time checks (missing/non-executable/directory paths surfaced only
as a run-time worker-exit); a throwing binding member accessor escaped the
fd-3 data callback and terminated the host; the reply drain waited on
'drain' alone, so a pipe destroyed under the wait hung forever; and two
staging-leak assertions diffed a global tmpdir that parallel workers can
perturb.
resolvePythonBin now applies the same accessSync(X_OK) + isFile check to
explicit paths (resolved against the host CWD), and the load error message
distinguishes 'is not an executable regular file' from 'does not resolve on
PATH'. validateBindings snapshots callables into a plain record during run()'s
synchronous validation, turning an accessor throw into the seam-misuse
rejection and fixing the key set the boot frame and dispatch share. The reply
drain waits on drain/close/error together and short-circuits on
proto.destroyed. The staging-leak assertions check the exact paths this test
file staged (recorded by the mocked mkdtempSync) instead of a tmpdir diff.
docs(code-runtime-python): add the alternatives section to the hardening note
docs(config-catalog): refresh the code-runtime-python Config source line
test(code-runtime-python): cover the async spawn-error worker-exit path
The review's final wording items: the portable-identifier note's Scope said the
backend 'has since shipped' without noting it is experimental/private; the
RESERVED_WORDS JSDoc said backends 'ship for both languages'. Both now name the
TypeScript backend as released and the CPython backend as experimental and
private. The package README also records that the truncation-marker text and
tempdir prefix keep the pre-rename short names (byte-anchored by tests,
independent of the npm name).
The review's move-follow-ups: the Windows test exclude now points at
packages/experimental/code-runtime-python (the constructor throws by design on
Windows, so the suite must stay excluded); the invariant companion and
@module annotations use the new npm name; the truncation marker text and
tmpdir prefix stay as-is (tests anchor them); the package JSDoc and READMEs no
longer call the private experimental backend 'published'/'shipped'; the
code-runtime README row describes the package as protocol AND runtime; the
fd-3 note records the package's experimental location.
The CPython code runtime's complete public contract is experimental, so it
moves to packages/experimental per the experimental-packages rules: npm name
@deepseek-ai/dsh-experimental-code-runtime-python, private: true, no
publishConfig. All references updated (code-runtime READMEs, config-catalog
and module-graph regenerated with zh alignment, tsconfig paths, doc-standard
and workspace-constraints scripts, the fd-3 and settlement Agent Notes, and
the package README links); md-links and translation pairing pass, and the
suite still runs green.
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