Fix process transport internal promise hardening - #109
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Repair T21/P1 by removing awaits of module-owned InternalPromise values. Internal continuations now register through the module-captured promiseThen instead of awaiting observable promise objects. This closes the async_hooks prototype-reparenting attack reproduced on Node 24.12.0: - async_hooks init hook observes InternalPromise resources - hook applies setPrototypeOf(resource, Promise.prototype) - hook applies preventExtensions(resource) - Promise.prototype is hostile/mutated - unmodified main can hang past the exchange deadline - this candidate settles without ordinary then lookup Deliberate behaviour change: A faulted platform termination strategy now settles as ESCALATION_FAILED instead of leaving the exchange pending with an unhandled rejection. T22 correction: T22 is NOT_REPRODUCIBLE. Probe-side definitions use REAL_DEFINE and bypass countedDefineProperty, so they do not inflate the counters. Settlement-time counters are retained as defensive hardening, not as a defect repair. Carried but not fixed: settle() -> cleanup() -> removeAllEvents(child) hostile-handle fault path is pre-existing in main and remains a separate finding. No feature wiring: src/adapters/** remains unimported and unexported. No caller, export, routing, or runtime path to invokeAgentProcess is introduced. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MRxUE54XK17eWaYPeGYsVx
📝 WalkthroughWalkthroughThe process transport replaces internal async settlement with callback-based continuations through captured Promise intrinsics. POSIX and Windows termination paths use guarded escalation and cleanup. Tests add reparented Promise hardening probes and stricter termination invariants. ChangesProcess termination and settlement
Priority: ⬇️ Low Estimated code review effort: 4 (Complex) | ~60 minutes Change: Bug fix Sequence Diagram(s)sequenceDiagram
participant ProcessTransport
participant terminate
participant ChildProcess
participant waitForExit
ProcessTransport->>terminate: start platform termination
terminate->>ChildProcess: send termination signal
terminate->>waitForExit: wait for bounded exit
waitForExit-->>terminate: report settlement
terminate->>ChildProcess: escalate when still running
terminate-->>ProcessTransport: report scope or failure
Merge Risk: 🔵 Low · up to A hostile taskkill handle can leave listeners installed, but the current operation still completes. The localized cleanup fix is recommended before merge. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches📝 Generate docstrings
🧪 Generate unit tests (beta)
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In `@src/adapters/process-transport.ts`:
- Line 699: Update runTaskkill around waitForExit and whenSettled so waitForExit
construction is guarded separately: if it throws while reading child exit state,
invoke the existing finish cleanup path and preserve the reap total, rather than
relying on the current catch that only resolves false. Do not wrap whenSettled
in an outer catch that could invoke done twice; retain normal settlement
callbacks for successfully constructed waits.
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`waitForExit` observes `exitCode` and `signalCode` before it has a promise to hand back, so a hostile accessor faults before `whenSettled` runs and therefore before `finish` is attached to anything. The reap then skipped clearing the listeners and rearming the spawn-failure absorber, and never called `done`; the caller's own catch resolved false but performed none of that cleanup. Constructing the wait under its own guard and ending through the same `finish` keeps the reap total: listeners cleared, absorber rearmed, `done` called exactly once. Only the construction is guarded — a catch around the whole registration would also catch a throw from `finish` and call it a second time. Addresses the CodeRabbit Minor finding on PR #109. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MRxUE54XK17eWaYPeGYsVx
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The captured `Promise.prototype.then` resolves a species constructor before it
registers anything: it reads `constructor` off the promise and `@@species` off
whatever that yields. On a reparented, sealed instance both reads reach
attacker-controlled objects, so the intrinsic can throw with no continuation
installed and nothing that will ever report.
Reporting that through the same callback a rejection uses said the operation had
failed, when the operation was in fact still running and simply unreachable. On
an ordinary POSIX timeout a child that ignored SIGTERM could then reach
ESCALATION_FAILED without SIGKILL ever being sent and without the retained local
pipe ends being released.
`whenSettled` now answers with a boolean — registered, or not — and calls nothing
when registration failed, so each caller runs its own synchronous fallback
without risking a second settlement. Synchronous is the only fallback worth
having: the same hostile `@@species` defeats every later registration too.
Per call site, on registration failure:
- reapUnprotectedHelper finish once, the ending every other route takes
- terminatePosix one direct-child SIGKILL, settle DIRECT_CHILD_ONLY
- terminatePosix escalate settle the scope already earned
- terminateWindows settle the scope already earned; an inconclusive
taskkill degrades to the direct child
- terminate settle DIRECT_CHILD_ONLY; nothing further may be claimed
- releaseUnprotectedChild the faulted-attempt ending: guarded signal, cleanup
- runTermination ESCALATION_FAILED, local pipe ends released, settle
No process group is targeted on any fallback path, so the ratified PID-reuse
position stands and T4 is not reopened.
Also corrects the stale claim that `Symbol.species` is unreachable. It is not
consulted on the `await` route, but nothing takes that route any more.
Addresses the Codex P1 finding on PR #109.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MRxUE54XK17eWaYPeGYsVx
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PR #109 MERGE DECISION RECORD — species-coverage limitation This records the current merge-decision limitation for PR #109 head The Codex P1 repair in The repair rests on:
LIMITATION: The end-to-end runtime reproduction with hostile Additional recorded points:
This comment is a durable PR record. It does not edit code, resolve threads, alter branches, or authorize feature wiring. |
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Registering a continuation is synchronous, and so is the fallback when registration fails, so an already-aborted signal can run an entire termination lifecycle — settlement and cleanup() included — before the dispatch returns. The deadline was armed after that point, which made it a ref'd timer created past the cleanup that was supposed to release it. Nothing cancelled it, so a completed invocation could hold the host for up to MAX_TIMEOUT_MS. Arming it first leaves cleanup() authoritative over every resource the exchange owns, whenever it runs, and makes the dispatch the last statement of the executor so nothing follows a point where the exchange may already be over. This is the class, not the witness. A `settled` guard at the scheduling site would have restored correctness there and left the next statement appended after the dispatch exposed to the same hazard. The ordering is asserted structurally in both directions: the deadline is armed before the dispatch, and nothing but closing braces follows the dispatch. WF2 Option A, establish-then-activate. Addresses the Codex P1 finding on PR #109. The property it protects — synchronous settlement during initialization is reachable — was introduced by e32639e, the T21 repair, not by the fallback it was reported against. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MRxUE54XK17eWaYPeGYsVx
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1. Summary
Repairs T21 / P1 carried from #108 by preventing
async_hooksprototypereparenting from routing internal waits through hostile
Promise.prototypestate.
2. Baseline
main@46929a7aec2bbc9dab08dd5f7506c261eb18e0e33. Changed files
src/adapters/process-transport.tstests/adapters/process-transport.test.tstests/adapters/transport-invariants.test.ts4. T21 reproduction
Reproduced on Node 24.12.0. An
async_hooksinithook observes eachInternalPromiseresource inside the allocation that produced it, while it isstill extensible, and applies both:
setPrototypeOf(resource, Promise.prototype)— removing the owned prototypethat answered the recognition test
preventExtensions(resource)— making the own-property fallback impossiblepaired with a mutated
Promise.prototype. Both of the transport's answers aregone at once, the awaited value is assimilated as a plain thenable through the
mutated
then, and athenthat installs no continuation leaves the exchangesuspended past its own deadline.
Against unmodified
main:Against this PR:
Two new probe modes carry this as a regression test:
hardening-persistent-reparented-ctor-thenandtimeout-persistent-reparented-ctor-then.5. Mechanism — option 2
No
awaitof a module-ownedInternalPromiseremains. Continuations registerthrough the module-captured
promiseThenvia a newwhenSettledhelper, whichreads the promise's internal state: no
constructorlookup, nothenlookup,and nothing a prototype change or a seal can reach. This is the idiom the
taskkill reaper already used in one place, generalised to all 11 former
awaitsites.
No new object type. No public contract change. No feature wiring.
whenSettled's contract now states explicitly that it does not catch throwsfrom
onValue— a continuation runs from a promise job, outside everylexically enclosing
try— so every continuation touching the child handlecarries its own guard.
6. T22 correction
T22 is NOT_REPRODUCIBLE. The earlier triage classified it CURRENT by
confirming the absence of the proposed fix rather than the presence of the
defect.
protectLikeRepairand theOwnedPromiseprototype setup both callREAL_DEFINE— the intrinsic captured beforecountedDefinePropertyisinstalled over
Object.defineProperty— so they bypass the counter entirely.Measured on the sealed mode:
PROTECTION_ATTEMPTS3 =..._AT_SETTLEMENT3 andPROTECTION_FAILURES2 =..._AT_SETTLEMENT2. The controls contributed zero.The settlement-time counters are retained as defensive hardening, not a defect
repair: they make the assertion attributable by construction rather than by
the incidental fact that probe controls use the captured intrinsic, and that
assertion is the one guarding the mechanism this PR rewrites.
7. Deliberate behaviour change
A faulted platform termination strategy now settles as
ESCALATION_FAILEDinstead of leaving the exchange pending with an unhandled rejection nothing
awaited. Nothing stronger is claimed — a strategy that faulted proved nothing
about the child, which is exactly what that scope says.
8.
whenSettledcontinuation audit — 10 sitesreapUnprotectedHelper->finishtry/absorb infinish;done()always reachedterminatePosixgracefulescalate, which guardsterminatePosixescalateescalate'stry->failterminateWindowskillDirectAndSettletry->failterminateWindowsawaitTreeExittry->failterminateWindowsrunTaskkillcontinuationterminatereleaseUnprotectedChildattemptCleanupx3;clearEventsKeepingAbsorberreturns rather than throwsrunTerminationclose waittry/absorb ->settle()runTerminationafterTermination/onTerminationFaultfinishTermination'stry->settle()No continuation reads the handle without a guard.
9.
terminateWindowsstructural invarianttransport-invariants.test.tsgainsreaches every handle-observing wait through a guarded step, asserting thatkillDirectAndSettleandawaitTreeExiteach open atrybefore reachingwaitForExitand route faultsto
fail, and that therunTaskkillcontinuation delegates rather thaninlining the wait.
Why structural rather than a runtime reproduction. The blocker is not the
platform gate —
process.platformis read at call time and is spoofable by aprobe that owns its process. It is the
taskkilldependency plus read-countdeterminism: reaching
awaitTreeExitneedsrunTaskkillto reportconclusively, which needs a real helper exiting 0 or 128 (
resolveTaskkillvalidates the path string and never stats it, so a bogus path yields a spawn
error and takes the degraded path instead), and an accessor faulting on a
later read than the one the strategy opens with — a counter spanning two
ChildProcess.prototype-sharing handles and a live helper. Such a probe wouldtest the probe more than the transport.
The invariant was proven to fail without the fix: restoring the inline shape
yields
expected 'runTaskkill(taskkill, pid),...' to contain 'awaitTreeExit();'.Known minor brittleness, offered for review: the invariant anchors on
const <step> = (): void => {, which freezes declaration syntax as well as thename. Matching on the step name alone would survive an arrow-to-declaration
refactor.
10. Separate carried finding
settle()->cleanup()->removeAllEvents(child)can throw on a hostilehandle and leave the exchange unresolved. Same hang class, but it lives in the
exchange's core settlement path rather than the promise-protection mechanism, it
is pre-existing in
main, and it is not fixed here. Recorded, not repaired.11. Binding condition
Per #108 (comment) —
this PR does not wire a caller.
src/adapters/**remains unimported andunexported: no importer outside the adapters slice, no entry in
src/index.ts,no caller, export, routing, or runtime path to
invokeAgentProcess. RepairingT21 is the prerequisite that condition names; satisfying it is not the same as
lifting it, and wiring remains a separate decision.
12. Verification
Node 24.12.0:
npm run typecheckPASSnpm run lintPASSnpm run buildPASSnpm run testPASSnpm run verify(composite) PASSTests: 2831 passed, 45 skipped, 0 failed at head
544c106(mainis 2826;+2 T21 reproductions, +3 structural invariants). No pre-existing test changed
status. CI on
544c106:verifyPASS,windows-owner-helperPASS.13. Non-actions
14. Final WF2 / carried records
14.1 Species-hostile end-to-end reproduction — limitation
The Codex P1 repairs rest on structural invariants plus a standalone Node
24.12.0 mechanism probe. The end-to-end runtime reproduction with a hostile
Symbol.speciesis NOT staged, and no coverage of it is claimed.Reason: the embedded probe's
installHostileConstructordeliberately leavesspecies resolving to the intrinsic so its own captured-intrinsic instrumentation
keeps working. Breaking species would disable the instrument along with the
subject.
14.2 S9 — carried finding, not repaired
reflectApply(writableEnd, stdin, …)during initialization is unguarded. Asynchronous throw escapes the executor, rejects the exchange promise with a
non-
AgentExchangevalue, and bypassescleanup()entirely — listeners stayattached and the child keeps running.
Same invariant class as the repairs in this PR, different mechanism (throw
rather than settle). Pre-existing in
main, verified byte-identical. Notrepaired here. Only a broader cleanup-owns-creation design (DDR Option C) would
close it.
14.3
settle()→cleanup()→removeAllEvents(child)— carried findingcleanup()can throw on a hostile handle, leaving the exchange unresolved.Pre-existing in
main, in the exchange's core settlement path rather than thepromise-protection mechanism. Recorded, not repaired here.
14.4 T22 correction
T22 is corrected to NOT_REPRODUCIBLE. Probe-side definitions call
REAL_DEFINE, the intrinsic captured beforecountedDefinePropertyisinstalled, so they never inflated the counters — measured:
PROTECTION_ATTEMPTS3 =
..._AT_SETTLEMENT3,PROTECTION_FAILURES2 =..._AT_SETTLEMENT2.The settlement-time counters remain as defensive hardening, not a defect
repair.
14.5 Binding condition — NOT lifted
This PR repairs the prerequisite named by the binding comment on #108, but it
does not authorize wiring.
src/adapters/**remains unimported andunexported; no caller, export, routing, or runtime path to
invokeAgentProcessis introduced. Future wiring remains a separate Commander/human gate.
14.6 WF2 Option A record
T21 → setup-vs-operation → deadline-after-synchronous-settlement.
544c106arms the deadline before the pending-abort dispatch, socleanup()is authoritative over every resource the exchange owns.dispatch and that the dispatch is the final statement of the executor.
reachable — was introduced by
e32639e, the T21 repair, not by the fallbackthe finding was reported against.
(retire/rebuild/relayer), not another WF2 patch cycle.
14.7 WF3 signal and narrowed claim
A fourth same-family CURRENT finding landed on the post-Option-A head:
Codex P2, thread
PRRT_kwDOTzqfcs6iVPKE, "Cancel the abandoned grace waitbefore settling."
WF3 signalled. No further patch cycle is authorized in this PR.
NARROWED CLAIM. This PR repairs T21 and materially improves liveness on
hostile paths. It does NOT establish:
That invariant remains open.
The residual is a CLASS, not one instance — helper-created timers armed
before a continuation is registered, and abandoned when registration fails.
Known members:
process-transport.ts:647waitForExitgrace timerprocess-transport.ts:847runTaskkilltimerprocess-transport.ts:855runTaskkillreapTimerprocess-transport.ts:1509awaitClosewaiterBound:
MAX_GRACE_MS— 60 seconds.Consequence: inert callback, no wrong exchange outcome, bounded
liveness/resource leak.
ORIGIN: the class entered at
e32639e, the T21 repair — not at5731d00.whenSettled'scatchalready abandoned the armed helper promisewith no continuation registered.
DDR correction: the DDR's finite-closure argument was falsified. It
enumerated
invokeAgentProcessinitialization only, while the invariant itclaimed to close covers every resource the exchange owns.
Comparison against
main: under the same attackmainhangs forever;this PR settles and may leak a bounded timer. The residual is strictly better
than the status quo it replaces.
14.8 Expanded binding condition
The binding condition is expanded.
Wiring a caller to
invokeAgentProcessnow additionally requires closing theowned-resource residual class recorded in 14.7 — in addition to the previous
T21/T22 prerequisite.
src/adapters/**remains unimported and unexported. No caller, export, routing,or runtime path to
invokeAgentProcessis introduced by this PR. Future wiringremains a separate Commander/human gate.
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