v0.1.22 still trapped with BOTH guards silent: the fatal rewind's target is
the ROOT context, which layer 2 exempted. All four prod stacks are the same
collision — a fiber completes its yield-back to main while main's sleep-wake
rewind is still on the stack (maybeStopUnwind → trampoline →
finishContextSwitch → doRewind(root) → unreachable), two "resume main" paths
interleaved in one tick; the 8ms-earlier "index out of bounds" is the wake
side of the same event.
Root entry is legal and constant in healthy flow; only the wake-window
overlap is fatal. So: serialize, don't refuse. The shim marks the
synchronous wake window (Asyncify.__inSleepWake around wakeUp) and DEFERS a
root finishContextSwitch landing inside it by one macrotask
([wx-asyncify] root-entry-deferred beacon, trampoline retry) — an ordering
change only, nothing dropped. Suspension recording happens before the
deferral branch, so the yielding fiber's validity survives the wake chain
nulling currData.
Plus a flight recorder: a 96-entry ring of asyncify/fiber events (sleeps,
wakes, every context switch with ROOT/wake-depth, refusals, deferrals),
silent in normal operation, auto-dumped with full machine state next to the
first trap signature in the console; window.__wxAsyncifyDump() on demand.
The next prod export reads like a black box, not a stack-shape puzzle.
.ci-cache-epoch 3→4 (wasm cache key omits scripts/**).
Local: fiber-resume-park 2/2 (one refusal beacon), timer-park 1/1, sweep 20
passed, web fatal+follow 2/2.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019SE4o46Lnq3hF574FFq8x4
v0.1.21 still trapped with ZERO jump-refused beacons: the fatal swap PASSED
the C++ swap_suspended guard. Mechanism (async/16 round 2): a fresh JS entry
executing while g_current_context still points at a parked fiber gets
attributed to that fiber — fiber_swap writes a fresh, valid-LOOKING foreign
suspension into the parked fiber's struct and re-marks the flag. The flag
lies; the resume rewinds garbage.
This guard tracks truth at the emscripten-fiber layer (handlesleep.js wraps
Fibers.finishContextSwitch):
- valid suspensions = real swap-outs (currData == oldFiber+20 when the
trampoline runs), consumed on rewind;
- internally-parked = an entered slice that ended in a handleSleep park
(currData set, no nextFiber) — quarantined until a GENUINE swap-out,
where genuine means the fiber's pending sleep has resolved
(__pendingSleepContexts), so a laundering write cannot lift it;
- entering a quarantined or suspension-less fiber is REFUSED
([wx-asyncify] fiber-resume-refused, ghost contract).
The ROOT context is exempt from quarantine and refusal: its rewound
continuation runs the whole main loop, whose routine yield park says nothing
about a fiber body — the first build of this guard quarantined main off that
signal and starved every coroutine return (19 collab e2e reds, empty
results). Root = the old side of the first switch ever.
.ci-cache-epoch 2→3: the wasm output cache key omits scripts/**.
Red/green: fiber-resume-park.spec.ts scenario 2 (laundered resume → exactly
one refusal beacon, both coroutines complete); full fiber-heavy sweep green
(21 passed).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019SE4o46Lnq3hF574FFq8x4
The shim has been silently restoring Asyncify.currData across overlapping
parks since it was written — so a prod console dump could never say whether
the #9153 family fired, mislinked, or was bypassed. Rate-limited [wx-asyncify]
reporting, calibrated against the timer-park e2e (2 rounds, 2026-07-31):
- concurrent-park: a FRESH park (state 0) starting while another chain's
currData is live. state-2 entries are NOT reported — every legal resume
re-enters handleSleep while Rewinding (~100/s measured on a healthy run).
- reentrant-state: handleSleep entered mid-unwind (state 1) — never observed;
if it ever fires it IS the bug.
- aliased-wake-live / overlapped-wake: the restore actually repairing —
dangerous (other chain still parked) vs benign (other chain done). The
e2e observed 8 live cross-restores in one run, all survived.
Console.log only, no printf plumbing needed; stacks name the parker
(__asyncjs__wxWasmYieldToBrowser vs _emscripten_sleep etc.).
.ci-cache-epoch 1→2: the wasm output cache key omits scripts/**.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019SE4o46Lnq3hF574FFq8x4
The asyncify single-slot work, executed red-green (full ledger:
docs/features/asyncify-arbiter/redgreen.md; decisions record:
docs/features/async/07-decisions-and-outcome.md):
- tests/apps/standalone/asyncify-races/ + tests/asyncify/ + dedicated
playwright config: 8 scenarios reproducing the KiCad asyncify failure
family with the kicad-faithful startup topology (pre-park fiber swap →
park throw through the live trampoline). Built in 3 variants; the
SHIM_DISABLE_TRAMPOLINE_HEAL / SHIM_DISABLE_HANDLESLEEP ablation builds
keep the historical hang and index-out-of-bounds crash reproducible
forever (mutation-style pins for the existing shims).
- scripts/common/shims/handlesleep.js: catch the "unwind" park sentinel
in the wakeUp path — when main's last pre-park suspension was a sleep,
the main-loop park throw escaped through that sleep's promise reaction
as an uncaught rejection (the calculator/gerbview console errors).
- scripts/common/inject-dyncall-shims.sh: SHIM_DISABLE_* ablation knobs.
- Spec tightening (the acceptance bar): 'uncaught exception: unwind'
tolerance DELETED from pcbnew/eeschema specs; load-pcb gained a hard
clean-console gate over 5 asyncify corruption signatures.
- wxwidgets pointer bump: modal LIFO resolvers, pump resolve-on-error,
sync clipboard IsSupported (014f67e6c1).
Final state: asyncify suite 7/7, wx e2e 291/292 (1 skip), KiCad e2e 40
passed / 2 skipped with ZERO corruption signatures in any log across all
six apps.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The shim bound bare dynCall_* names to JS getWasmTableEntry() calls, bypassing
the asyncify-instrumented dynCall_* wasm trampolines that -sDYNCALLS=1 provides.
That broke Asyncify unwind/rewind through indirect calls -> "indirect call
signature mismatch" (caught every frame in Firefox; fatal renderer crash in
Chrome). Bind the bare names to wasmExports["dynCall_<sig>"] instead.
Result: the PCBnew "select draw lines" e2e is green in Firefox (tool selects and
draws, zero page errors). Dropped the fiber-stabilization block, the shipped
diagnostic block, and the exportCallStack JS hack (all compensated for the wrong
binding); shim shrank 521 -> ~250 lines.
- scripts/common/inject-dyncall-shims.sh: orchestrator only; injected JS extracted
to scripts/common/shims/
- scripts/common/shims/dyncall-binding.js.tmpl: per-signature binding template
- scripts/common/shims/handlesleep.js: nested-Asyncify handleSleep fix (#9153)
- scripts/common/shims/diagnostics.js: logging-only, opt-in via SHIM_DIAGNOSTICS=1
- tests/package.json: add test:kicad:firefox / test:kicad:chrome scripts
Known issue (tracked separately): Chrome still renderer-crashes on the first
coroutine resume. Asyncify.doRewind replays the deep main-context call stack and
exceeds V8's execution-stack limit (Firefox tolerates the same wasm). Proper fix
is JSPI.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
