[e2e] Re-enable concurrent execution of the e2e suite by alangenfeld · Pull Request #3658 · vercel/workflow

alangenfeld · 2026-08-19T14:39:17Z

Summary & Motivation

Serial execution was the dominant wall-clock cost per matrix entry (~22 of 24 minutes on the Vercel lanes), and the blockers that forced it in 78048e0 are fixed.

Per-test harness state (name, tracked runs, skip) binds through AsyncLocalStorage instead of module globals, so a failing test dumps its own diagnostics and a mid-body conformance gate skips the right test. The suite's test is a createTaskCollector wrapper that delegates to the enclosing suite's collector, which is both how the binding gets a direct call stack to the handler and how describe.concurrent inheritance reaches each test.
Each lane ends with a load summary — test and CLI child counts, peak concurrency of each, median test wall time, CLI share of summed test time, ten slowest tests — since under concurrency the question is where per-test latency went, not pass/fail.
maxConcurrency is tunable via WORKFLOW_E2E_MAX_CONCURRENCY, default unchanged at 5. Higher values starve CLI children on lanes that also host the app and Postgres.
RACE_WINNER_MAX_DURATION_MS goes 5s → 8s; queue latency under concurrency pushed observed winner durations to ~6.5s, still far below the 10s loser.

A test that genuinely cannot share a deployment can opt out with test.sequential.

Builds on VaguelySerious's investigation in #2083.

Test Plan

Added a unit test for interleaved per-test attribution; five consecutive full-matrix CI runs at maxConcurrency=5 were green (162/162) with Vercel-prod lanes at 5-7 min against 22-25 min serial and median test time unchanged, and a maxConcurrency=8 probe established 5 as the value safe on every lane type.

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vercel · 2026-08-19T14:39:25Z

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview	Aug 19, 2026 5:45pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 5:45pm
example-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 5:45pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 5:45pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 5:45pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 5:45pm
workflow-web	Ready	Preview	Aug 19, 2026 5:45pm

Serial execution has been the dominant wall-clock cost per matrix entry since concurrency was disabled before conf (78048e0): ~128 tests at ~22 of 24 minutes on the Vercel lanes, and lately the slowest lane cannot finish under its 30-minute job timeout on a slow runner day at all. #2083 measured the concurrent suite at ~3x job wall-clock (4-5x on the vitest phase) and identified what broke; its blockers are now fixed: world-local writeExclusive is atomic (write-then-link), abort-fetch tests are hermetic (#3618), the fibonacci tree fits the scheduler (#3619), and source-map assertions are positive-only (#3620). What this change adds is concurrency-safe per-test attribution. The harness tracked runs and test names in module globals reset by a beforeEach - under concurrency every test clobbered every other's state, so a failing test dumped an unrelated sibling's diagnostics. vitest's getCurrentTest() cannot substitute: it is a plain module variable, wrong after any await. Instead an auto fixture - the one place that receives the test's own context unambiguously - binds a per-test state (name, tracked runs, the test's own skip) via AsyncLocalStorage around each test body, and trackRun / recordInfraEvent / requireFixture read it ambiently with no call-site changes. The conformance gates skip through the bound state's skip, so a mid-body requireFixture skips the right test. Sequential suites (dev, agent, region) keep setupRunTracking's module-global fallback. Full suite passes 137/137 concurrently against a local dev server in under 2 minutes. A test that genuinely cannot share a deployment can opt out with test.sequential. Builds on VaguelySerious's investigation in #2083. Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

CI on the first concurrent run caught the fixture design failing in the one place skip-correctness is load-bearing: vitest resolves fixtures in a separate async context, so an AsyncLocalStorage store bound around use() never reaches the test body. Every ambient read silently fell to the module fallback - conformance-gated tests on the Python lane ran instead of skipping and hard-failed on fixtures missing from the manifest ('declared in e2e-conformance.json but not in the deployed manifest'). The suite's test is now built with createTaskCollector, mirroring vitest's own argument normalization, and the wrapper binds the state around the handler call itself - a direct call stack, so propagation is guaranteed rather than assumed. Validated by a collector-pattern ALS experiment (per-test store after awaits, mid-body skip targets self, each/skip/todo chains), a conformance-file simulation reproducing the Python failure shape (fixture-missing tests now skip with the right note), and a 137/137 concurrent local run. Also raises RACE_WINNER_MAX_DURATION_MS 5s -> 8s: the winner takes 1s, the loser 10s, and the bound only has to sit clearly below the loser - concurrent-suite queue latency pushed observed winner durations to ~6.5s on loaded local-dev lanes (vite, first concurrent CI run), so 5s flaked without catching anything 8s misses. Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

github-actions · 2026-08-19T15:05:34Z

📊 Workflow Benchmarks

commit c35ea2c · Wed, 19 Aug 2026 18:18:12 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1380 (+381%) 🔻	1517 🔴 (+30%) 🔻	1557 🔴 (+16%) 🔻	1624 🔴 (+3.9%)	30
TTFS	stream	311 (+65%) 🔻	1510 🔴 (+35%) 🔻	1575 🔴 (+38%) 🔻	1913 🔴 (+64%) 🔻	30
TTFS	hook + stream	1625 (+25%) 🔻	1970 🔴 (+43%) 🔻	2048 🔴 (+45%) 🔻	2524 🔴 (+47%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1152 (+4.3%)	2804 (+22%) 🔻	3163 (+14%)	3207 (+16%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5366 (+1.6%)	8639 (+30%) 🔻	10891 (+58%) 🔻	19609 (+149%) 🔻	10
STSO	1020 steps (inline)	117 (-11%)	164 (-38%) 💚	190 (-38%) 💚	365 (-28%) 💚	1019
WO	1020 steps	166506 (-33%) 💚	166506 (-33%) 💚	166506 (-33%) 💚	166506 (-33%) 💚	1
CRTT	first chunk (pooled)	112 (+33%) 🔻	186 (+46%) 🔻	300 (-4.8%)	436 (-30%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	172 (+52%)	176 (+7%)	254 (+9%)	457 (-2%)	159 (-1%)	10
size sweep (100/s, 160B-12KB)	149 (+39%)	165 (+7%)	324 (+15%)	518 (-24%)	151 (-6%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	126 (+13%)	158 (-43%)	240 (-67%)	719 (-52%)	353 (-41%)	3
replay eve-gpt-5.6-sol-2000t (1x)	135 (-14%)	146 (+4%)	186 (-3%)	743 (+18%)	523 (+7%)	2
replay eve-gpt-5.6-sol-2000t (2x)	138 (-73%)	247 (-39%)	355 (-87%)	729 (-83%)	569 (-6%)	3

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

1020 steps (inline)

Cumulative STSO time: main 247209ms → this run 164994ms (Δ -82215ms, -33%)

100-150 ms  █░░░░░░░░░░░░░░░░░░░░░░┃  main   6  this 474  +468
150-200 ms  ██████████░░░░░░░░░░░░┃   main 205  this 464  +259
200-250 ms  █┃██████████████████████  main 481  this  45  -436
250-300 ms  ┃██████████               main 217  this  15  -202
300-350 ms  ┃██                       main  58  this   7   -51
350-400 ms  ┃                         main  20  this   8   -12
400-450 ms  ┃                         main  12  this   3    -9
450-500 ms  ┃                         main   9  this   1    -8
500-550 ms  ┃                         main   4  this   1    -3
550-600 ms  ┃                         main   2  this   0    -2
600-650 ms  ┃                         main   4  this   1    -3
850-900 ms  ┃                         main   1  this   0    -1

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

variant  RTT 1ms→5s+             avg         p50         p90         p99     n
control  ······▂█▂····  148.6 (+19%)  137 (+27%)   254 (+9%)   457 (-2%)  3000
sweep    ······▃█▂▁···  145.5 (+10%)  129 (+15%)  324 (+15%)  518 (-24%)  3000
gw 1x    ·····▁▄█▁▁···  132.2 (-25%)   116 (+5%)  240 (-67%)  719 (-52%)  5295
eve 1x   ·····▁▅█▁▁···   133.2 (+7%)   113 (+5%)   186 (-3%)  743 (+18%)  5186
eve 2x   ·····▁▂█▃▁···  173.2 (-55%)  139 (-19%)  355 (-87%)  729 (-83%)  7779

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

control  █▄▃▂▄▂▄▁▁▂  131–192ms
sweep    ▇▃▂▁▃▃▄█▂▂  124–181ms
gw 1x    ▃█▄▂▂▄▁▂▃▄  110–178ms
eve 1x   ▂▃█▃▁▂▅▄▃█  101–182ms
eve 2x   █▁▂▂▁▄▅▅▄▅  127–257ms

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

sweep  █▆▃▁▄▅█  142–148ms

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

control  ▁▇▆▅▇▄█▄▆▄  27–47ms
sweep    ▁▆▆▆█▇▇▇▅▄  31–61ms
gw 1x    ▄▆▄▁▄█▃▄▃▅  32–45ms
eve 1x   ▄▆▆▇▁▄█▆▃█  20–29ms
eve 2x   █▁▃▂▃▅▃▁▄▅  18–35ms

📜 Previous results (2)

`c35ea2c`

Wed, 19 Aug 2026 17:11:18 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1255 (+337%) 🔻	1314 🔴 (+13%)	1358 🔴 (+1.4%)	1383 🔴 (-12%)	30
TTFS	stream	241 (+28%) 🔻	1334 🔴 (+20%) 🔻	1399 🔴 (+23%) 🔻	1681 🔴 (+44%) 🔻	30
TTFS	hook + stream	367 (-72%) 💚	1748 🔴 (+27%) 🔻	1778 🔴 (+26%) 🔻	1952 🔴 (+14%)	30
Fan-out TTFS	Promise.all(100 steps)	1392 (+26%) 🔻	2936 (+28%) 🔻	3132 (+13%)	3151 (+14%)	10
Fan-out TTLS	Promise.all(100 steps)	5963 (+13%)	7084 (+6.4%)	7237 (+5.1%)	8436 (+7.0%)	10
STSO	1020 steps (inline)	111 (-16%) 💚	272 (+3.4%)	320 (+5.3%)	495 (-2.0%)	1019
WO	1020 steps	245809 (-1.1%)	245809 (-1.1%)	245809 (-1.1%)	245809 (-1.1%)	1
CRTT	first chunk (pooled)	98 (+17%) 🔻	169 (+33%) 🔻	398 (+26%) 🔻	824 (+31%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	135 (+19%)	434 (+163%)	618 (+166%)	1102 (+137%)	617 (+287%)	10
size sweep (100/s, 160B-12KB)	149 (+39%)	344 (+123%)	540 (+92%)	1044 (+54%)	288 (+79%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	127 (+13%)	169 (-39%)	290 (-60%)	750 (-50%)	524 (-13%)	3
replay eve-gpt-5.6-sol-2000t (1x)	206 (+32%)	151 (+8%)	246 (+28%)	501 (-20%)	380 (-22%)	2
replay eve-gpt-5.6-sol-2000t (2x)	153 (-70%)	191 (-53%)	315 (-89%)	676 (-84%)	444 (-27%)	3

`f437a21`

Wed, 19 Aug 2026 15:26:31 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1341 (+367%) 🔻	1586 🔴 (+36%) 🔻	1690 🔴 (+26%) 🔻	1885 🔴 (+21%) 🔻	30
TTFS	stream	362 (+92%) 🔻	1460 🔴 (+31%) 🔻	1538 🔴 (+35%) 🔻	1747 🔴 (+49%) 🔻	30
TTFS	hook + stream	1593 (+22%) 🔻	1872 🔴 (+36%) 🔻	1946 🔴 (+38%) 🔻	2005 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1248 (+13%)	2227 (-3.2%)	2780 (+0.5%)	3913 (+41%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5426 (+2.7%)	11957 (+80%) 🔻	22902 (+233%) 🔻	24329 (+209%) 🔻	10
STSO	1020 steps (inline)	111 (-16%) 💚	164 (-38%) 💚	187 (-38%) 💚	285 (-44%) 💚	1019
WO	1020 steps	159883 (-36%) 💚	159883 (-36%) 💚	159883 (-36%) 💚	159883 (-36%) 💚	1
CRTT	first chunk (pooled)	96 (+14%)	204 (+61%) 🔻	341 (+8.3%)	765 (+22%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	141 (+25%)	184 (+12%)	398 (+72%)	735 (+58%)	152 (-5%)	10
size sweep (100/s, 160B-12KB)	168 (+57%)	155 (+1%)	206 (-27%)	408 (-40%)	126 (-22%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	316 (+182%)	167 (-40%)	225 (-69%)	429 (-71%)	293 (-51%)	3
replay eve-gpt-5.6-sol-2000t (1x)	161 (+3%)	166 (+19%)	217 (+13%)	556 (-11%)	270 (-45%)	2
replay eve-gpt-5.6-sol-2000t (2x)	162 (-68%)	201 (-50%)	264 (-91%)	537 (-87%)	177 (-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 · 2026-08-19T15:06:25Z

🧪 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.

cancelRun via CLI - cancelling a running workflow (astro)
cancelRun via CLI - cancelling a running workflow (vite)
deploymentId: 'latest' is a no-op in non-Vercel worlds (nitro)
hookGetConflictThenStepParallelWorkflow - hook.getConflict() continuation step runs alongside other steps (nextjs-webpack)

🛠 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 18:14:32Z · abandoned wrun_01M0DKNYTD6N9KWDRTEMB63XWM
run-pickup-stall · hookGetConflictWorkflow - hook.getConflict() resolves with the conflicting run when token is already registered (nuxt) · at 18:15:38Z · abandoned wrun_01M0DKRB1H8KCG69A7VFN9V5XN

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3474	738	4212
✅ 💻 Local Development	3810	558	4368
✅ 📦 Local Production	3810	558	4368
✅ 🐘 Local Postgres	3810	558	4368
✅ 🪟 Windows	312	0	312
✅ 🌐 Cross-language Conformance	9	128	137
✅ vercel-multi-region	27	0	27
Total	15252	2540	17792

Details by Category

✅ ▲ Vercel Production

App	Passed	Skipped
✅ astro-node	128	28
✅ astro-quickjs	128	28
✅ example-node	128	28
✅ example-quickjs	128	28
✅ express-node	128	28
✅ express-quickjs	128	28
✅ fastify-node	128	28
✅ fastify-quickjs	128	28
✅ hono-node	128	28
✅ hono-quickjs	128	28
✅ nest-node	128	28
✅ nest-quickjs	128	28
✅ nextjs-turbopack-node	153	3
✅ nextjs-turbopack-quickjs	153	3
✅ nextjs-webpack-node	153	3
✅ nextjs-webpack-quickjs	153	3
✅ nitro-node	128	28
✅ nitro-quickjs	128	28
✅ nuxt-node	128	28
✅ nuxt-quickjs	128	28
✅ python-node	8	148
✅ sveltekit-node	147	9
✅ sveltekit-quickjs	147	9
✅ tanstack-start-node	128	28
✅ tanstack-start-quickjs	128	28
✅ vite-node	128	28
✅ vite-quickjs	128	28

✅ 💻 Local Development

App	Passed	Skipped
✅ astro-stable-node	130	26
✅ astro-stable-quickjs	130	26
✅ express-stable-node	130	26
✅ express-stable-quickjs	130	26
✅ fastify-stable-node	130	26
✅ fastify-stable-quickjs	130	26
✅ hono-stable-node	130	26
✅ hono-stable-quickjs	130	26
✅ nest-stable-node	130	26
✅ nest-stable-quickjs	130	26
✅ nextjs-turbopack-canary-node	137	19
✅ nextjs-turbopack-canary-quickjs	137	19
✅ nextjs-turbopack-stable-node	156	0
✅ nextjs-turbopack-stable-quickjs	156	0
✅ nextjs-webpack-canary-node	137	19
✅ nextjs-webpack-canary-quickjs	137	19
✅ nextjs-webpack-stable-node	156	0
✅ nextjs-webpack-stable-quickjs	156	0
✅ nitro-stable-node	130	26
✅ nitro-stable-quickjs	130	26
✅ nuxt-stable-node	130	26
✅ nuxt-stable-quickjs	130	26
✅ sveltekit-stable-node	149	7
✅ sveltekit-stable-quickjs	149	7
✅ tanstack-start-node	130	26
✅ tanstack-start-quickjs	130	26
✅ vite-stable-node	130	26
✅ vite-stable-quickjs	130	26

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	130	26
✅ astro-stable-quickjs	130	26
✅ express-stable-node	130	26
✅ express-stable-quickjs	130	26
✅ fastify-stable-node	130	26
✅ fastify-stable-quickjs	130	26
✅ hono-stable-node	130	26
✅ hono-stable-quickjs	130	26
✅ nest-stable-node	130	26
✅ nest-stable-quickjs	130	26
✅ nextjs-turbopack-canary-node	137	19
✅ nextjs-turbopack-canary-quickjs	137	19
✅ nextjs-turbopack-stable-node	156	0
✅ nextjs-turbopack-stable-quickjs	156	0
✅ nextjs-webpack-canary-node	137	19
✅ nextjs-webpack-canary-quickjs	137	19
✅ nextjs-webpack-stable-node	156	0
✅ nextjs-webpack-stable-quickjs	156	0
✅ nitro-stable-node	130	26
✅ nitro-stable-quickjs	130	26
✅ nuxt-stable-node	130	26
✅ nuxt-stable-quickjs	130	26
✅ sveltekit-stable-node	149	7
✅ sveltekit-stable-quickjs	149	7
✅ tanstack-start-node	130	26
✅ tanstack-start-quickjs	130	26
✅ vite-stable-node	130	26
✅ vite-stable-quickjs	130	26

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	130	26
✅ astro-stable-quickjs	130	26
✅ express-stable-node	130	26
✅ express-stable-quickjs	130	26
✅ fastify-stable-node	130	26
✅ fastify-stable-quickjs	130	26
✅ hono-stable-node	130	26
✅ hono-stable-quickjs	130	26
✅ nest-stable-node	130	26
✅ nest-stable-quickjs	130	26
✅ nextjs-turbopack-canary-node	137	19
✅ nextjs-turbopack-canary-quickjs	137	19
✅ nextjs-turbopack-stable-node	156	0
✅ nextjs-turbopack-stable-quickjs	156	0
✅ nextjs-webpack-canary-node	137	19
✅ nextjs-webpack-canary-quickjs	137	19
✅ nextjs-webpack-stable-node	156	0
✅ nextjs-webpack-stable-quickjs	156	0
✅ nitro-stable-node	130	26
✅ nitro-stable-quickjs	130	26
✅ nuxt-stable-node	130	26
✅ nuxt-stable-quickjs	130	26
✅ sveltekit-stable-node	149	7
✅ sveltekit-stable-quickjs	149	7
✅ tanstack-start-node	130	26
✅ tanstack-start-quickjs	130	26
✅ vite-stable-node	130	26
✅ vite-stable-quickjs	130	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	156	0	0
✅ nextjs-turbopack-quickjs	156	0	0

✅ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
✅ python	9	0	128

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

📋 View full workflow run

github-actions · 2026-08-19T15:08:56Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 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
✅ `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

The previous commit's collector called getCurrentSuite().task() directly, which skips the suite collector's Object.assign({}, suiteOptions, options) - the merge that carries describe.concurrent onto each test. The suite therefore still ran sequentially, and CI proved it: every Vercel Prod lane matched the serial baseline minute-for-minute (nextjs-turbopack quickjs 25m vs 25m), so a fully green run said nothing about concurrency. The same slowdown showed up locally as a full-suite run taking 6m15s where the earlier concurrent one took 1m58s, which I had misread as server slowness. The collector now wraps the handler and hands the call to getCurrentSuite().test.fn - exactly what vitest's own top-level test does - so suite-option inheritance is vitest's code path again, while the wrapper still owns the handler call stack that makes the AsyncLocalStorage binding reach the test body. Verified with an experiment asserting both properties at once: four 300ms tests plus a 600ms observer finish in 602ms (1800ms if sequential), max-in-flight > 1, and each test still reads its own store after awaits. Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

The previous commit added the counters and the summary but left the call sites out of the handler wrapper and afterAll, so nothing was collected and no summary printed. Caught by review. Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

alangenfeld added 2 commits August 19, 2026 10:04

alangenfeld force-pushed the alangenfeld/e2e-concurrent-v2 branch from 0556953 to f437a21 Compare August 19, 2026 15:05

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VaguelySerious mentioned this pull request Aug 19, 2026

Batch: pre-claim inline steps in the same batch #3568

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Comment thread packages/core/e2e/e2e.test.ts

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[e2e] Re-enable concurrent execution of the e2e suite - #3658

[e2e] Re-enable concurrent execution of the e2e suite#3658
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🧪 E2E Test Results

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