[probe] Post-outage E2E baseline by shalabhc · Pull Request #3752 · vercel/workflow

shalabhc · 2026-08-23T00:06:06Z

Not for merge — measurement only

Comment-only change to packages/core/e2e/e2e.test.ts, purely to trigger a full E2E run against current main now that the queue-service incident is over.

A docs or README change would not work: detect-ci-scope classifies docs/, *.md and .changeset/ as a runtime fast path and skips the E2E jobs entirely. A comment in a source file is inert but keeps the full suite in scope.

Why

Main's failure rate over the incident window:

commit	E2E jobs failing
`7e48e7b4`	2 / 19
`71bc027a`	26 / 27
`bf9de1cd`	27 / 27
`3c0d60be` (current)	3 / 27

The 26–27/27 window was the queue-service incident, not a code regression — confirmed by both commits suspected at the time still being present in HEAD while the rate returned to baseline.

The last measurement at 3c0d60be (3/27) partly overlapped the incident's tail, so it is not a trustworthy healthy-state baseline. This run establishes one.

What to read from it

The pre-incident residual was the sleep/wait stall: runs reaching wait_created with no wait_completed, Status: running, timeouts rather than assertion failures, concentrated in outputStream* plus python - node.

Same cluster, similar rate → the stall is independent of the incident and remains the open defect.
Clean → the stall was an artefact of a degraded queue all along, and the earlier investigation was chasing incident noise.
Different cluster → something new, worth separating from the old thread.

Check the run diagnostics either way: a stall shows Status: running with a stale last event, which is distinguishable from a run that merely completed slowly.

Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>

changeset-bot · 2026-08-23T00:06:11Z

⚠️ No Changeset found

Latest commit: 1eafb5c

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vercel · 2026-08-23T00:06:12Z

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 23, 2026 12:09am
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 23, 2026 12:09am
example-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-astro-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-express-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-fastify-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-hono-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-nestjs-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-nitro-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-nuxt-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-python-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workbench-vite-workflow	Ready	Preview, v0	Aug 23, 2026 12:09am
workflow-docs	Ready	Preview, v0	Aug 23, 2026 12:09am
workflow-swc-playground	Ready	Preview, v0	Aug 23, 2026 12:09am
workflow-tarballs	Ready	Preview, v0	Aug 23, 2026 12:09am
workflow-web	Ready	Preview, v0	Aug 23, 2026 12:09am

github-actions · 2026-08-23T00:06:22Z

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

promiseAllWorkflow | wrun_41M0NZ3NJC0GS1R9H0QJH3FQ2K | 🔍 observability
sleepingWorkflow | wrun_41M0NZ4D9E0GKQ5BK38D8FXHW9 | 🔍 observability
parallelSleepWorkflow | wrun_41M0NZ4DM10GHY2SY0PA39DHWC | 🔍 observability
nullByteWorkflow | wrun_41M0NZ4PGR0GR373P0Z2DSECAY | 🔍 observability
cancelRun - cancelling a running workflow | wrun_41M0NZ9EXW0GPXZ8FNHJFD5AV9 | 🔍 observability
cancelRun via CLI - cancelling a running workflow | wrun_41M0NZ9GFV0GNM65C5P66YM05T | 🔍 observability
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0NZ9QR50GG08K5RKD40W5GQ | 🔍 observability
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0NZA97F0GVNN4FV558N0K3W | 🔍 observability

💻 Local Development (1 failed)

vite-stable-node (1 failed):

sleepWinsRaceWorkflow | wrun_41M0NZ4FQR0GPRTVHMB4SQD67C

🪟 Windows (1 failed)

nextjs-turbopack-quickjs (1 failed):

cancelRun via CLI - cancelling a running workflow | wrun_41M0NZ9GFV0GNM65C5P66YM05T

🌐 Cross-language Conformance (9 failed)

python (9 failed):

deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0NZEGHDHMP77CBAH44EH5B1
promiseAllWorkflow | wrun_41M0NZ3NJC0GS1R9H0QJH3FQ2K
sleepingWorkflow | wrun_41M0NZ4D9E0GKQ5BK38D8FXHW9
parallelSleepWorkflow | wrun_41M0NZ4DM10GHY2SY0PA39DHWC
nullByteWorkflow | wrun_41M0NZ4PGR0GR373P0Z2DSECAY
cancelRun - cancelling a running workflow | wrun_41M0NZ9EXW0GPXZ8FNHJFD5AV9
cancelRun via CLI - cancelling a running workflow | wrun_41M0NZ9GFV0GNM65C5P66YM05T
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0NZ9QR50GG08K5RKD40W5GQ
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0NZA97F0GVNN4FV558N0K3W

⚠️ 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 (express)
sleepWinsRaceWorkflow (tanstack-start)

🛠 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.

33 infra events

cold-start-warmup · suite warmup (python) · at 00:09:27Z · abandoned wrun_41M0NZ35D00GTAWVGVD08QEX0M · (+7 more)
run-pickup-stall · promiseAllWorkflow (python) · at 00:09:44Z · abandoned wrun_41M0NZ6T8K0GQZSR1DC482ZKS3
run-pickup-stall · parallelSleepWorkflow (python) · at 00:09:44Z · abandoned wrun_41M0NZ6T8T0GQ1CX5RNRBWFMDZ
run-pickup-stall · nullByteWorkflow (python) · at 00:09:44Z · abandoned wrun_41M0NZ6T8X0GKWCQKC0D0CY0E8
run-pickup-stall · sleepingWorkflow (python) · at 00:09:44Z · abandoned wrun_41M0NZ6T8T0GQ1CX5RNRBWFMDY
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 00:09:44Z · abandoned wrun_41M0NZ6TNZ0GKVVF2TWKKCD08G
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 00:10:17Z · abandoned wrun_41M0NZ7TFX0GMX80P5XQ0T3PNF
run-pickup-stall · sleepingWorkflow (python) · at 00:10:44Z · abandoned wrun_41M0NZ8NW20GYWA7816C21DZAE
run-pickup-stall · promiseAllWorkflow (python) · at 00:10:44Z · abandoned wrun_41M0NZ8NV70GVYP6MBKNT4Q0DP
run-pickup-stall · nullByteWorkflow (python) · at 00:10:45Z · abandoned wrun_41M0NZ8NYP0GHYBYM71JZPDZH2
run-pickup-stall · parallelSleepWorkflow (python) · at 00:10:45Z · abandoned wrun_41M0NZ8NVY0GYM4HH05QY53WGQ
cold-start-warmup · suite warmup (tanstack-start) · at 00:11:26Z · abandoned wrun_01M0NZ9KG8XGYZASSEFJ49HWEM
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 00:11:35Z · abandoned wrun_41M0NZ8TA80GK9QHWRBEAHFG9Z
cold-start-warmup · suite warmup (python) · at 00:12:24Z · abandoned wrun_01M0NZ8J3K0VER2S8TWR1ZD90P · (+7 more)
run-pickup-stall · sleepingWorkflow (python) · at 00:12:39Z · abandoned wrun_01M0NZC78R6KFGSC6N4PHXK2RN
run-pickup-stall · promiseAllWorkflow (python) · at 00:12:39Z · abandoned wrun_01M0NZC78M79948VQCH798JYJ1
run-pickup-stall · parallelSleepWorkflow (python) · at 00:12:39Z · abandoned wrun_01M0NZC78S3BMXB0PV778P91QZ
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 00:12:39Z · abandoned wrun_01M0NZC78KQD10V0N1BATFDYPH
run-pickup-stall · nullByteWorkflow (python) · at 00:12:39Z · abandoned wrun_01M0NZC78V8DZ9ACJNFVQJNRZ0
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 00:13:16Z · abandoned wrun_41M0NZBJ6T0GYS8R4737BGT7C3
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 00:13:17Z · abandoned wrun_41M0NZBDQS0GPKBX5AN2N32Q3P
run-pickup-stall · parallelSleepWorkflow (python) · at 00:13:39Z · abandoned wrun_01M0NZE1WA0XAS1G7J1DFY264B
run-pickup-stall · sleepingWorkflow (python) · at 00:13:39Z · abandoned wrun_01M0NZE1WB4KZM792GXCBRMSZ4
run-pickup-stall · promiseAllWorkflow (python) · at 00:13:39Z · abandoned wrun_01M0NZE1W7ZXFHV6A53QMEAE51
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 00:13:39Z · abandoned wrun_01M0NZE1W5PMATD2799QWC3KQX
run-pickup-stall · nullByteWorkflow (python) · at 00:13:39Z · abandoned wrun_01M0NZE1WG5JNAH8NJM9RDTW4P
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 00:14:39Z · abandoned wrun_01M0NZFWFQAY0147KQJCXJXKDD
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 00:14:39Z · abandoned wrun_01M0NZFWG02NEJ5TZ33VSNS03X
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 00:14:39Z · abandoned wrun_01M0NZFWFWKV0MTR5YTT0JTY03
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 00:15:09Z · abandoned wrun_01M0NZGSV8A14CCCJC4WRC6D81
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 00:15:09Z · abandoned wrun_01M0NZGSVEJRYFG9DEB1XWD0G8
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 00:15:39Z · abandoned wrun_01M0NZHQ33E0F4386THN82X6DC
run-pickup-stall · plainModuleDoneHook resumed via plain API route (o2flow shape) (nextjs-webpack) · at 00:17:04Z · abandoned wrun_01M0NZMA9EKG2GACX1NVJBMYRT

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
❌ 💻 Local Development	3921	1	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
❌ 🪟 Windows	319	1	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17051	19	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

❌ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
❌ vite-stable-node	133	1	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

❌ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
❌ nextjs-turbopack-quickjs	159	1	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Skipped
✅ example	132	28
✅ express	132	28
✅ hono	132	28
✅ nextjs-turbopack	157	3
✅ nitro	132	28
✅ vite	132	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Skipped
✅ example	132	28
✅ express	132	28
✅ nextjs-turbopack	157	3
✅ vite	132	28

📋 View full workflow run

github-actions · 2026-08-23T00:06:27Z

📊 Workflow Benchmarks

commit 1eafb5c · Sun, 23 Aug 2026 00:23:04 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	409 (-59%) 💚	1371 🔴 (+24%) 🔻	1409 🔴 (+22%) 🔻	1782 🔴 (+42%) 🔻	30
TTFS	stream	436 (-38%) 💚	1372 🔴 (+25%) 🔻	1396 🔴 (+26%) 🔻	1453 🔴 (+13%)	30
TTFS	hook + stream	1216 (-11%)	1661 🔴 (+13%)	1745 🔴 (+16%) 🔻	1911 🔴 (+20%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	557 (-14%)	899 (-47%) 💚	1914 (+7.0%)	2113 (+8.6%)	10
Fan-out TTLS	Promise.all(100 steps)	1991 (+3.1%)	2556 (-20%) 💚	3915 (+19%) 🔻	8173 (-3.6%)	10
STSO	1020 steps (inline)	101 (-3.8%)	130 (-12%)	150 (-11%)	198 (-9.2%)	1019
WO	1020 steps	130669 (-11%)	130669 (-11%)	130669 (-11%)	130669 (-11%)	1
CRTT	first chunk (pooled)	90 (+2.3%)	125 (+0.8%)	177 (-8.3%)	2600 (+319%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	97.5 (-13%)	118 (-9%)	207 (-2%)	401 (-47%)	134 (-6%)	10
size sweep (100/s, 160B-12KB)	98.5 (-12%)	113 (-20%)	148 (-21%)	488 (-57%)	111 (-19%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	125 (+2%)	119 (-82%)	171 (-95%)	559 (-88%)	437 (+101%)	3
replay eve-gpt-5.6-sol-2000t (1x)	1381 (+1070%)	118 (-12%)	237 (+40%)	2536 (+635%)	1579 (+504%)	2
replay eve-gpt-5.6-sol-2000t (2x)	114 (-7%)	152 (-17%)	209 (-21%)	460 (-17%)	250 (+10%)	3

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

1020 steps (inline)

Cumulative STSO time: main 147417ms → this run 130385ms (Δ -17032ms, -12%)

100-150 ms  █████████████████████░░┃  main 785  this 913  +128
150-200 ms  ██┃███                    main 216  this  96  -120
200-250 ms  ┃                         main  14  this   9    -5
250-300 ms  ┃                         main   4  this   0    -4
400-450 ms  ┃                         main   0  this   1    +1

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

variant  RTT 1ms→5s+             avg         p50         p90           p99     n
control  ······█▆▁····  104.2 (-13%)   94 (-11%)   207 (-2%)    401 (-47%)  3000
sweep    ·····▁█▄▁▁···    100 (-19%)   89 (-19%)  148 (-21%)    488 (-57%)  3000
gw 1x    ·····▁█▅▁▁···  109.7 (-67%)    92 (-9%)  171 (-95%)    559 (-88%)  5295
eve 1x   ·····▁█▄▁▁▁▁·  151.5 (+37%)    89 (-2%)  237 (+40%)  2536 (+635%)  5186
eve 2x   ·····▁▆█▂▁···  124.1 (-11%)  108 (-16%)  209 (-21%)    460 (-17%)  7779

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

control  ▆█▃▃▃▄▅▂▁▅  94–119ms
sweep    ▆▅▃▃▂▆▂█▆▁  84–117ms
gw 1x    ▂▁▄▁▆█▂▃▁▂  96–142ms
eve 1x   ▁▂▁▁█▁▁▁▁▁  92–550ms
eve 2x   ▇▂▆▅▄▆██▄▁  98–143ms

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

sweep  ▆▅▇█▄▁▁  98–102ms

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

control  ▅█▅▆▂▇▂▃▁▄  26–36ms
sweep    ▆█▄▅▃▅▃▅▄▁  32–41ms
gw 1x    ▃▄▆▁█▆▇▄▂▃  25–35ms
eve 1x   ▂▄▂▃█▁▃▂▂▃  18–39ms
eve 2x   █▄▅▄▆█▇▁▂▆  17–22ms

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 · 2026-08-23T00:09:48Z

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

[probe] Post-outage E2E baseline

1eafb5c

Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>

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[probe] Post-outage E2E baseline - #3752

[probe] Post-outage E2E baseline#3752
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shalabhc commented Aug 23, 2026

Not for merge — measurement only

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🧪 E2E Test Results

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

💻 Local Development (1 failed)

🪟 Windows (1 failed)

🌐 Cross-language Conformance (9 failed)

⚠️ Flaky E2E Tests (passed on retry)

🛠 Infra Events (absorbed by the harness)

E2E Test Summary

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📊 Workflow Benchmarks

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Sim World

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