fix(core): QuickJS - quiet expected inline step contention by AndrewBarba · Pull Request #4266 · vercel/workflow

AndrewBarba · 2026-09-19T15:33:55Z

Description

Concurrent QuickJS wakeups can reach the same fresh inline step and print a warning even when execution succeeds. Record this expected overlap at debug level while retaining warnings for recovery and background-step contention. The single-flight guard still runs one body and makes competing invocations wait for it to settle.

Closes #4265. This is an independent, narrower fix related to #4254: current main already bypasses single-flight for fresh Node claims after #3568, and this PR preserves that behavior. In particular, it does not wrap a failed pre-claim in single-flight, which can suppress the actual owner. There are no changes to step ownership, retries, or execution dispatch.

How did you test your changes?

pnpm --filter @workflow/core... build and pnpm --filter @workflow/core build — passed.
pnpm --filter @workflow/core typecheck — passed.
pnpm --filter @workflow/core test — 2,590 passed, 3 expected-failure cases, 1 skipped; 123 test files passed.
A new QuickJS entrypoint regression drives two overlapping invocations through the real single-flight guard and logger, verifying one execution, silent default logging, and waiting for settlement. Removing the caller's debug argument makes this test fail; restoring it passes.
Helper coverage checks default recovery warnings, opt-in debug diagnostics with run/step IDs, and settlement after both success and failure. Existing pre-claimed ownership tests also pass.
pnpm exec biome check packages/core/src/runtime/step-single-flight.ts packages/core/src/runtime/step-single-flight.test.ts packages/core/src/runtime/quickjs-entrypoint.ts packages/core/src/runtime/quickjs-entrypoint-contention.test.ts — passed with seven existing warnings in the QuickJS entrypoint.
node scripts/check-changesets.mjs — passed.

PR Checklist - Required to merge

📦 pnpm changeset was run to create a changelog for this PR
- Patch release for @workflow/core.
🔒 DCO sign-off passes (git commit --signoff)
📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete

Signed-off-by: Andrew Barba <barba@hey.com>

changeset-bot · 2026-09-19T15:33:58Z

🦋 Changeset detected

Latest commit: ff3decc

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@workflow/core	Patch
@workflow/builders	Patch
@workflow/cli	Patch
@workflow/next	Patch
@workflow/nitro	Patch
@workflow/vitest	Patch
@workflow/web-shared	Patch
@workflow/web	Patch
workflow	Patch
@workflow/world-testing	Patch
@workflow/astro	Patch
@workflow/nest	Patch
@workflow/rollup	Patch
@workflow/sveltekit	Patch
@workflow/vite	Patch
@workflow/nuxt	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

vercel · 2026-09-19T15:34:02Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
example-nextjs-workflow-turbopack	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
example-nextjs-workflow-webpack	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
example-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-astro-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-express-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-fastify-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-hono-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-nestjs-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-nitro-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-nuxt-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-python-workflow	Building	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-sveltekit-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-tanstack-start-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workbench-vite-workflow	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workflow-docs	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workflow-swc-playground	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workflow-tarballs	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC
workflow-web	Ready	Preview, v0	Sep 21, 2026 5:05pm UTC

github-actions · 2026-09-19T15:34:10Z

🧪 E2E Test Results

✅ All tests passed

⚠️ Flaky E2E Tests (passed on retry)

These tests failed at least once and passed on a retry. A recurring entry here is a real race worth investigating.

applies prepareCall before streaming (nextjs-webpack · vercel-prod / vercel / node / production)
webhook route with invalid token (astro · local-dev / local / node / stable)

🛠 Infra Events (absorbed by the harness)

Platform anomalies the e2e harness detected and worked around (e.g. a run the queue never picked up, replaced by a fresh run). Clustered timestamps indicate a backend blip; a steady drip indicates a platform issue worth escalating.

cold-start-warmup · suite warmup (tanstack-start) · at 17:07:35Z · abandoned wrun_01M32EYDJPKFK5M5412Q1976GX · (+2 more)
run-pickup-stall · hookCleanupTestWorkflow - hook token reuse after workflow completion (nextjs-webpack) · at 17:14:04Z · abandoned wrun_01M32FBAMKECEV4GFB6T1FJ2DD

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3670	731	4401
✅ 💻 Local Development	4014	550	4564
✅ 📦 Local Production	4014	550	4564
✅ 🐘 Local Postgres	4014	550	4564
✅ 🪟 Windows	324	2	326
✅ 🌐 Cross-language Conformance	68	76	144
✅ vercel-http-transport	825	153	978
✅ vercel-multi-region	27	0	27
✅ vercel-ws-transport	559	93	652
Total	17515	2705	20220

Details by Category

✅ ▲ Vercel Production

App	Passed	Skipped
✅ astro-node	133	30
✅ astro-quickjs	133	30
✅ example-node	133	30
✅ example-quickjs	133	30
✅ express-node	133	30
✅ express-quickjs	133	30
✅ fastify-node	133	30
✅ fastify-quickjs	133	30
✅ hono-node	133	30
✅ hono-quickjs	133	30
✅ nest-node	133	30
✅ nest-quickjs	133	30
✅ nextjs-turbopack-node	160	3
✅ nextjs-turbopack-quickjs	160	3
✅ nextjs-webpack-node	160	3
✅ nextjs-webpack-quickjs	160	3
✅ nitro-node	133	30
✅ nitro-quickjs	133	30
✅ nuxt-node	133	30
✅ nuxt-quickjs	133	30
✅ python-node	66	97
✅ sveltekit-node	152	11
✅ sveltekit-quickjs	152	11
✅ tanstack-start-node	133	30
✅ tanstack-start-quickjs	133	30
✅ vite-node	133	30
✅ vite-quickjs	133	30

✅ 💻 Local Development

App	Passed	Skipped
✅ astro-stable-node	134	29
✅ astro-stable-quickjs	134	29
✅ express-stable-node	134	29
✅ express-stable-quickjs	134	29
✅ fastify-stable-node	134	29
✅ fastify-stable-quickjs	134	29
✅ hono-stable-node	134	29
✅ hono-stable-quickjs	134	29
✅ nest-stable-node	134	29
✅ nest-stable-quickjs	134	29
✅ nextjs-turbopack-canary-node	162	1
✅ nextjs-turbopack-canary-quickjs	162	1
✅ nextjs-turbopack-stable-node	162	1
✅ nextjs-turbopack-stable-quickjs	162	1
✅ nextjs-webpack-canary-node	162	1
✅ nextjs-webpack-canary-quickjs	162	1
✅ nextjs-webpack-stable-node	162	1
✅ nextjs-webpack-stable-quickjs	162	1
✅ nitro-stable-node	134	29
✅ nitro-stable-quickjs	134	29
✅ nuxt-stable-node	134	29
✅ nuxt-stable-quickjs	134	29
✅ sveltekit-stable-node	153	10
✅ sveltekit-stable-quickjs	153	10
✅ tanstack-start-node	134	29
✅ tanstack-start-quickjs	134	29
✅ vite-stable-node	134	29
✅ vite-stable-quickjs	134	29

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	134	29
✅ astro-stable-quickjs	134	29
✅ express-stable-node	134	29
✅ express-stable-quickjs	134	29
✅ fastify-stable-node	134	29
✅ fastify-stable-quickjs	134	29
✅ hono-stable-node	134	29
✅ hono-stable-quickjs	134	29
✅ nest-stable-node	134	29
✅ nest-stable-quickjs	134	29
✅ nextjs-turbopack-canary-node	162	1
✅ nextjs-turbopack-canary-quickjs	162	1
✅ nextjs-turbopack-stable-node	162	1
✅ nextjs-turbopack-stable-quickjs	162	1
✅ nextjs-webpack-canary-node	162	1
✅ nextjs-webpack-canary-quickjs	162	1
✅ nextjs-webpack-stable-node	162	1
✅ nextjs-webpack-stable-quickjs	162	1
✅ nitro-stable-node	134	29
✅ nitro-stable-quickjs	134	29
✅ nuxt-stable-node	134	29
✅ nuxt-stable-quickjs	134	29
✅ sveltekit-stable-node	153	10
✅ sveltekit-stable-quickjs	153	10
✅ tanstack-start-node	134	29
✅ tanstack-start-quickjs	134	29
✅ vite-stable-node	134	29
✅ vite-stable-quickjs	134	29

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	134	29
✅ astro-stable-quickjs	134	29
✅ express-stable-node	134	29
✅ express-stable-quickjs	134	29
✅ fastify-stable-node	134	29
✅ fastify-stable-quickjs	134	29
✅ hono-stable-node	134	29
✅ hono-stable-quickjs	134	29
✅ nest-stable-node	134	29
✅ nest-stable-quickjs	134	29
✅ nextjs-turbopack-canary-node	162	1
✅ nextjs-turbopack-canary-quickjs	162	1
✅ nextjs-turbopack-stable-node	162	1
✅ nextjs-turbopack-stable-quickjs	162	1
✅ nextjs-webpack-canary-node	162	1
✅ nextjs-webpack-canary-quickjs	162	1
✅ nextjs-webpack-stable-node	162	1
✅ nextjs-webpack-stable-quickjs	162	1
✅ nitro-stable-node	134	29
✅ nitro-stable-quickjs	134	29
✅ nuxt-stable-node	134	29
✅ nuxt-stable-quickjs	134	29
✅ sveltekit-stable-node	153	10
✅ sveltekit-stable-quickjs	153	10
✅ tanstack-start-node	134	29
✅ tanstack-start-quickjs	134	29
✅ vite-stable-node	134	29
✅ vite-stable-quickjs	134	29

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	162	0	1
✅ nextjs-turbopack-quickjs	162	0	1

✅ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
✅ python	68	0	76

✅ vercel-http-transport

App	Passed	Skipped
✅ example	133	30
✅ express	133	30
✅ hono	133	30
✅ nextjs-turbopack	160	3
✅ nitro	133	30
✅ vite	133	30

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Skipped
✅ example	133	30
✅ express	133	30
✅ nextjs-turbopack	160	3
✅ vite	133	30

📋 View full workflow run

github-actions · 2026-09-19T15:34:47Z

📊 Workflow Benchmarks

commit ff3decc · Mon, 21 Sep 2026 17:28:40 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	2130 (+42%) 🔻	2216 🔴 (+31%) 🔻	2257 🔴 (+30%) 🔻	2373 🔴 (+25%) 🔻	30
TTFS	stream	162 (+3.8%)	2241 🔴 (+33%) 🔻	2331 🔴 (+37%) 🔻	2423 🔴 (+41%) 🔻	30
TTFS	hook + stream	595 (-2.9%)	2630 🔴 (+27%) 🔻	2677 🔴 (+25%) 🔻	3015 🔴 (+33%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	533 (+1.5%)	944 (+39%) 🔻	976 (+37%) 🔻	2688 (+29%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	1753 (±0%)	3776 (+37%) 🔻	5784 (+98%) 🔻	10211 (+21%) 🔻	10
STSO	1020 steps (inline)	131 (+5.6%)	173 (+19%) 🔻	193 (+18%) 🔻	280 (+19%) 🔻	1019
WO	1020 steps	172051 (+17%) 🔻	172051 (+17%) 🔻	172051 (+17%) 🔻	172051 (+17%) 🔻	1
CRTT	first chunk (pooled)	74 (+16%) 🔻	128 (-13%)	148 (-53%) 💚	433 (-9.2%)	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	93 (-10%)	217 (-45%)	471 (-14%)	1406 (+58%)	180 (-48%)	10
size sweep (100/s, 160B-12KB)	123 (+3%)	218 (-75%)	275 (-74%)	402 (-81%)	222 (-30%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	103 (-14%)	192 (-72%)	247 (-88%)	602 (-85%)	399 (-20%)	3
replay eve-gpt-5.6-sol-2000t (1x)	104 (-36%)	189 (-22%)	255 (-31%)	712 (+3%)	659 (±0%)	2
replay eve-gpt-5.6-sol-2000t (2x)	96 (-24%)	313 (-65%)	389 (-64%)	853 (-37%)	353 (-53%)	3

📈 STSO distribution vs main (inline / queue-hop histograms)

1020 steps (inline)

Cumulative STSO time: main 146805ms → this run 171782ms (Δ +24977ms, +17%)

100-150 ms  ██┃████████████████████   main 812  this  99  -713
150-200 ms  █████░░░░░░░░░░░░░░░░░░┃  main 183  this 842  +659
200-250 ms  █┃                        main  18  this  56   +38
250-300 ms  ┃                         main   4  this  15   +11
300-350 ms  ┃                         main   2  this   4    +2
350-400 ms  ┃                         main   0  this   1    +1
400-450 ms  ┃                         main   0  this   1    +1
500-550 ms  ┃                         main   0  this   1    +1

📈 CRTT drill-down vs main (RTT distributions & profiles)

variant  RTT 1ms→5s+             avg         p50         p90          p99     n
control  ······▁█▃▁▁··  209.2 (-10%)  154 (-14%)  471 (-14%)  1406 (+58%)  3000
sweep    ······▁█▃····  169.6 (-58%)  154 (-27%)  275 (-74%)   402 (-81%)  3000
gw 1x    ······▁█▂▁···  161.9 (-55%)   147 (-1%)  247 (-88%)   602 (-85%)  5295
eve 1x   ······▂█▂▁···   170.6 (-9%)   144 (+4%)  255 (-31%)    712 (+3%)  5186
eve 2x   ······▁██▁▁··  230.6 (-47%)  189 (-19%)  389 (-64%)   853 (-37%)  7779

RTT over stream progress (avg per tenth of stream, bars scaled min→max):

control  ▂█▄▄▃▃▆▅▂▁  166–275ms
sweep    ██▄▃▃▂▆▁▁▄  147–198ms
gw 1x    ▆▆▁▂█▃▁▅▃▁  144–193ms
eve 1x   ▂▁▁▂▁▁▄█▅▁  143–249ms
eve 2x   ▃▁▃▂▁▃▂▆█▂  171–377ms

RTT by chunk size (avg per log size bin, ~160B → ~12KB serialized, bars scaled min→max):

sweep  ▁█▄▅▆▆▄  168–171ms

Delivery jitter over stream progress (avg positive CDV per tenth of stream, bars scaled min→max):

control  █▄▅▁▁▃▆▆▂▃  40–74ms
sweep    ██▇▄▂▂▆▁▄▇  61–81ms
gw 1x    ▅▅▁▁█▂▂▅▃▂  43–58ms
eve 1x   ▆▆▁▇▅▅▇█▆▆  25–35ms
eve 2x   █▇▃▃▄▄▃▁▆▇  28–40ms

📜 Previous results (1)

`4ed138f`

Sat, 19 Sep 2026 16:02:58 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	299 (-80%) 💚	2164 🔴 (+19%) 🔻	2178 🔴 (+17%) 🔻	2283 🔴 (+2.6%)	30
TTFS	stream	212 (-2.3%)	2161 🔴 (+23%) 🔻	2184 🔴 (+21%) 🔻	2212 🔴 (+14%)	30
TTFS	hook + stream	588 (-70%) 💚	2586 🔴 (+25%) 🔻	2628 🔴 (+21%) 🔻	2787 🔴 (+15%)	30
Fan-out TTFS	Promise.all(100 steps)	389 (-9.7%)	807 (-17%) 💚	955 (-56%) 💚	6734 (+209%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2900 (+29%) 🔻	4178 (-49%) 💚	4534 (-46%) 💚	14378 (+61%) 🔻	10
STSO	1020 steps (inline)	128 (+1.6%)	150 (-3.8%)	168 (-2.3%)	262 (-9.0%)	1019
WO	1020 steps	153708 (-2.0%)	153708 (-2.0%)	153708 (-2.0%)	153708 (-2.0%)	1
CRTT	first chunk (pooled)	67 (+1.5%)	103 (-25%) 💚	152 (-6.7%)	529 (+146%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	82.5 (-35%)	176 (-39%)	314 (-22%)	897 (+41%)	159 (-34%)	10
size sweep (100/s, 160B-12KB)	94 (-14%)	216 (-35%)	356 (-28%)	580 (-22%)	198 (-32%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	95 (+2%)	142 (-51%)	168 (-54%)	318 (-55%)	175 (-64%)	3
replay eve-gpt-5.6-sol-2000t (1x)	97.5 (-26%)	135 (-81%)	167 (-90%)	326 (-92%)	380 (-82%)	2
replay eve-gpt-5.6-sol-2000t (2x)	152 (+18%)	209 (-65%)	303 (-67%)	596 (-59%)	261 (-71%)	3

ℹ️ Metric definitions & methodology

_{Streams: first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach.}

_{The collapsed STSO distribution section above buckets every step gap, split inline (same warm process — pure framework overhead) vs queue-hop (fresh process — dispatch, reinit, replay). █ = main, ┃ = this run, ░ = fill.}

_{The collapsed CRTT drill-down: per-variant RTT histograms (fixed log bins, · = empty) and mean RTT/positive-CDV profile lines over stream progress and chunk size. Histograms, avgs, and profiles merge exactly across runs; p50–p99 are percentile-of-percentiles. Per-index rows live in the artifacts.}

_{Best/P75/P90/P99 deltas compare against the most recent benchmark run on main at the time of this run. 🔻 flags a delta worse than +15%, 💚 one better than −15%.}

_{Metrics — TTFS: time to first step body (in-deployment start() → first step body) · Fan-out TTFS: fan-out time to first step (in-deployment start() → first of the parallel step bodies to complete) · Fan-out TTLS: fan-out time to last step (in-deployment start() → last of the parallel step bodies to complete, i.e. when the Promise.all resolves) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · CRTT: chunk round-trip time (per-chunk write → read latency, one clock domain: deployment → stream backend → same deployment) · CDV: chunk delay variation / delivery jitter (inter-arrival gap minus inter-write gap per seq-adjacent pair; skew-free; the row is each run's MAX positive value, so one stall moves it)}

_{Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · Promise.all(100 steps): 100 trivial no-op steps started together in a single Promise.all; Fan-out TTFS is the first of them to complete and Fan-out TTLS the last, both from the in-deployment clientStart, so their gap is the spread the runtime adds across the fan-out · paced control (100/s, 60B): the control: 300 tiny (~60B) deltas metronome-paced at 100/s — zero workload structure, so it reads the transport floor and flush cadence, and disambiguates transport-wide vs workload-specific when a replay row moves · size sweep (100/s, 160B-12KB): same pacing as the control with deltas padded in rotation across seven log-spaced sizes (~160B–12KB) — rotation decouples size from stream position, so it isolates whether chunk size causes latency · replay gateway-gpt-5.4-nano-2000t (1x): raw provider SSE cadence captured at the AI gateway boundary (gpt-5.4-nano, the most popular gateway model; per-token deltas p50 208B = the modal production chunk size), replayed exactly as measured — the typical customer's workload; its CDV is the typical customer's real delivery jitter · replay eve-gpt-5.6-sol-2000t (1x): a captured eve turn (gpt-5.6-sol, the most-used demanding eve model; ~2000 output tokens = production p50 turn length) replayed exactly as measured — eve's envelope protocol re-ships the cumulative message so sizes ramp 142B→13KB; the demanding outlier tenant's reality · replay eve-gpt-5.6-sol-2000t (2x): the same eve capture at 2x — the headroom/stress row; real fast-tier models emit the same chunk sizes at proportionally higher rate, so time compression is a faithful speed model · first chunk (pooled): every run's seq-0 RTT pooled across all stream scenarios — the first chunk precedes any workload differentiation, so pooling samples one shared stream-open path with exact percentiles}

_{Replay cadences (semantic sha256) — eve-gpt-5.6-sol-2000t eaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t 6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600}

_{All timestamps are deployment-side; runs are triggered in-deployment, so the CI runner and api.vercel.com sit outside every measured window. TTFS = start() → first step body (includes dispatch + any cold start); Fan-out TTFS/TTLS = first/last step completion of one Promise.all from the same anchor (the gap is the runtime’s fan-out spread); STSO/WO between step bodies; CRTT inside the workflow (excludes the api.vercel.com read path).}

_{Cold starts stay in the numbers (real bursty-workload latency, inflates P75+); Best is the warm floor.}

github-actions · 2026-09-19T15:37:45Z

Framework	Flow route	Step reg.	Framework output
hono	251.1 KiB (±0)	93.5 KiB (±0)	1.90 MiB (+22 B)
nextjs-turbopack	258.5 KiB (±0)	426 B (±0)	903.0 KiB (+7 B)

About these numbers

Sizes are gzip; parentheses show the change against main.
Flow route and Step reg. gate this job, on raw bytes rather than the gzip shown, at max(2%, 50.0 KiB). Framework output is informational.

ff3decc · run

github-actions · 2026-09-19T15:37:50Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 42 total

fence=per-spec

scenario	outcome	events	virt	replay
✅ `smoke-no-steps`	completed	3	0ms	ok
✅ `smoke-one-step`	completed	6	0ms	ok
✅ `hook-at-step-started`	completed	12	0ms	ok
✅ `hook-at-step-completed`	completed	12	0ms	ok
✅ `hook-at-hook-created`	completed	12	0ms	ok
✅ `deadline-hook-wins`	completed	7	1.0h	ok
✅ `deadline-expires`	completed	7	1.0h	ok
✅ `step-vs-timer-early-settlement`	completed	8	1.0h	ok
✅ `long-sleep`	completed	11	30.0d	ok
✅ `hook-never-arrives`	stalled	3	0ms	skipped
✅ `step-retries-twice`	completed	10	2.0s	ok
✅ `parallel-steps`	completed	9	0ms	ok
✅ `hook-on-execution-state`	completed	12	0ms	ok
✅ `peek-hook-before-branch`	completed	12	0ms	ok
✅ `peek-hook-after-branch`	completed	12	0ms	ok
✅ `peek-hook-at-registration`	completed	12	0ms	ok
✅ `race-hook-before-probe`	completed	12	0ms	ok
✅ `race-hook-after-probe`	completed	12	0ms	ok
✅ `race-duplicate-delivery`	completed	13	0ms	ok
✅ `attr-hook-before-step`	completed	11	0ms	ok
✅ `attr-hook-after-step`	completed	11	0ms	ok
✅ `attr-from-step-body`	completed	13	0ms	ok
✅ `fork-hook-after-timeout`	completed	14	1.0m	ok
✅ `fork-hook-before-timeout`	completed	14	1.0m	ok
✅ `count-hook-after-timeout`	completed	17	1.0m	ok
✅ `count-hook-before-timeout`	completed	20	1.0m	ok
✅ `stale-read-step-count-fork`	completed	20	1.0m	ok
✅ `stale-read-equal-step-counts`	completed	14	1.0m	ok
✅ `step-vs-step-fork`	completed	12	0ms	ok
✅ `step-vs-step-fork-fenced`	completed	12	0ms	ok
✅ `fence-catches-benign-direction`	completed	12	5ms	ok
✅ `in-flight-before-decision`	completed	17	1.0m	ok
❌ `in-flight-before-decision-counted`	completed	17	1.0m	ok
✅ `in-flight-after-decision`	completed	19	2.0m	ok
✅ `stale-read-step-count-fork-fenced`	completed	20	1.0m	ok
✅ `fork-hook-wins`	completed	13	1.0m	ok
✅ `fork-timeout-wins`	completed	13	1.0m	ok
✅ `unclaimed-payload-under-fork`	completed	17	1.0m	ok
✅ `claimed-payload-under-fork`	completed	17	1.0m	ok
✅ `writers-independent-step-bodies`	completed	12	0ms	ok
✅ `writers-scripted-tempo`	completed	12	0ms	ok
✅ `cancel-mid-step`	cancelled	7	0ms	skipped

Full trace: world-sim.txt

Co-authored-by: Peter Wielander <mittgfu@gmail.com> Signed-off-by: Andrew Barba <barba@hey.com>

github-actions · 2026-09-21T18:22:52Z

No backport to stable for 101d347 (AI decision).

This is a log-noise fix to the QuickJS entrypoint's inline-step single-flight guard, but that code does not exist on stable: git ls-tree origin/stable -- packages/core/src/runtime/quickjs-entrypoint.ts packages/core/src/runtime/step-single-flight.ts returns nothing, and the stable runtime directory contains no QuickJS or single-flight modules at all. There is no behavior on the maintenance line for this fix to correct, and the change would not apply.

To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:

101d3472f6f150f0900713b4340c95d422ed673c

fix(core): QuickJS - quiet expected inline step contention

4ed138f

Signed-off-by: Andrew Barba <barba@hey.com>

AndrewBarba requested a review from a team as a code owner September 19, 2026 15:34

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core: normal fresh inline wake races emit misleading in-flight step warnings #4265

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VaguelySerious approved these changes Sep 19, 2026

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Comment thread .changeset/dull-hands-teach.md Resolved

VaguelySerious mentioned this pull request Sep 20, 2026

fix(builders): fail the build when the flow bundle still needs require() #4268

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Merge branch 'main' into barba/quiet-inline-step-contention

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Update .changeset/dull-hands-teach.md

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Co-authored-by: Peter Wielander <mittgfu@gmail.com> Signed-off-by: Andrew Barba <barba@hey.com>

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AndrewBarba merged commit 101d347 into main Sep 21, 2026
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AndrewBarba deleted the barba/quiet-inline-step-contention branch September 21, 2026 18:21

github-actions Bot mentioned this pull request Sep 21, 2026

Version Packages (beta) #4283

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This was referenced Sep 21, 2026

Version Packages (beta) Jokacar10/jkworkflow#548

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Version Packages ben-vargas/workflow#104

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prha mentioned this pull request Sep 22, 2026

fix(eve): quiet expected workflow contention warnings vercel/eve#3608

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AndrewBarba mentioned this pull request Sep 30, 2026

core: queued step delivery that races a fresh inline claim logs an in-flight warning #4545

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fix(core): QuickJS - quiet expected inline step contention - #4266

fix(core): QuickJS - quiet expected inline step contention#4266
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AndrewBarba commented Sep 19, 2026

Description

How did you test your changes?

PR Checklist - Required to merge

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🧪 E2E Test Results

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📊 Workflow Benchmarks

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