[CI] Reduce payload resolution during run polling

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

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[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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Click here to learn what changesets are, and how to add one.

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

[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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Click here to learn what changesets are, and how to add one.

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

[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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Click here to learn what changesets are, and how to add one.

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

[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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Click here to learn what changesets are, and how to add one.

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

[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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Click here to learn what changesets are, and how to add one.

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

[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd

[karthikscale3]

Poll run metadata without resolving payload refs, then fetch output or error data once the run reaches a terminal state.
Validated with the core run tests and typecheck.

[vercel]

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 8:25pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 19, 2026 8:25pm
example-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-astro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-express-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-fastify-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-hono-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nestjs-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nitro-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-nuxt-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-python-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-sveltekit-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workbench-vite-workflow	Ready	Preview	Aug 19, 2026 8:25pm
workflow-docs	Ready	Preview, v0	Aug 19, 2026 8:25pm
workflow-swc-playground	Ready	Preview	Aug 19, 2026 8:25pm
workflow-tarballs	Ready	Preview	Aug 19, 2026 8:25pm
workflow-web	Ready	Preview	Aug 19, 2026 8:25pm

[github-actions]

📊 Workflow Benchmarks

commit d0f90db · Wed, 19 Aug 2026 20:43:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1307 (+395%) 🔻	1566 🔴 (+41%) 🔻	1581 🔴 (+37%) 🔻	1707 🔴 (+19%) 🔻	30
TTFS	stream	221 (-78%) 💚	1396 🔴 (+31%) 🔻	1440 🔴 (+33%) 🔻	1520 🔴 (+37%) 🔻	30
TTFS	hook + stream	581 (-54%) 💚	1872 🔴 (+35%) 🔻	1947 🔴 (+35%) 🔻	2033 🔴 (+24%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	1437 (+28%) 🔻	3057 (+114%) 🔻	3059 (+33%) 🔻	4477 (+87%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	5928 (+23%) 🔻	11711 (+49%) 🔻	13212 (+54%) 🔻	17949 (+104%) 🔻	10
STSO	1020 steps (inline)	141 (+2.2%)	183 (-24%) 💚	207 (-27%) 💚	381 (-22%) 💚	1019
WO	1020 steps	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	185899 (-20%) 💚	1
CRTT	first chunk (pooled)	123 (+48%) 🔻	185 (+49%) 🔻	468 (+174%) 🔻	602 (+206%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	165 (+68%)	168 (+12%)	214 (-48%)	390 (-61%)	123 (-51%)	10
size sweep (100/s, 160B-12KB)	162 (+47%)	179 (+22%)	218 (-25%)	460 (-16%)	136 (+16%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	468 (+277%)	207 (+40%)	304 (+27%)	635 (-20%)	300 (-25%)	3
replay eve-gpt-5.6-sol-2000t (1x)	185 (+53%)	171 (+1%)	433 (+69%)	4168 (+470%)	2277 (+240%)	2
replay eve-gpt-5.6-sol-2000t (2x)	364 (+279%)	237 (+25%)	325 (+23%)	1158 (+89%)	660 (+112%)	3

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

1020 steps (inline)

Cumulative STSO time: main 233199ms → this run 184427ms (Δ -48772ms, -21%)

 100-150 ms ┃ main 6 this 17 +11
150-200 ms ████████░░░░░░░░░░░░░░░┃ main 283 this 874 +591
200-250 ms ██┃███████████ main 523 this 94 -429
250-300 ms ┃███ main 144 this 14 -130
300-350 ms ┃ main 34 this 8 -26
350-400 ms ┃ main 11 this 3 -8
400-450 ms ┃ main 3 this 2 -1
450-500 ms ┃ main 7 this 2 -5
500-550 ms ┃ main 3 this 2 -1
550-600 ms ┃ main 0 this 1 +1
600-650 ms ┃ main 2 this 1 -1
800-850 ms ┃ main 1 this 0 -1
850-900 ms ┃ main 0 this 1 +1
950-1000 ms ┃ main 2 this 0 -2

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

variant RTT 1ms→5s+ avg p50 p90 p99 n
control ······▂█▁···· 144.9 (±0%) 139 (+30%) 214 (-48%) 390 (-61%) 3000
sweep ······▁█▂···· 151.3 (+21%) 140 (+28%) 218 (-25%) 460 (-16%) 3000
gw 1x ·····▁▂█▃▁··· 165.6 (+27%) 143 (+34%) 304 (+27%) 635 (-20%) 5295
eve 1x ······▂█▂▁▁▁· 252.2 (+86%) 131 (+26%) 433 (+69%) 4168 (+470%) 5186
eve 2x ······▁█▄▁▁·· 208.7 (+40%) 167 (+24%) 325 (+23%) 1158 (+89%) 7779

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

control █▃▃▃▃▄▂▃▁▁ 132–175ms
sweep █▄▂▁▁▂▃▂▃▁ 135–204ms
gw 1x █▃▁▂▂▁▂▁▂▁ 132–312ms
eve 1x █▄▁▁▁▁▁▁▁▁ 132–947ms
eve 2x ▃▂█▂▁▁▂▃▂▂ 143–431ms

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

sweep ▇█▃▄▅▁▇ 151–152ms

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

control ▁▄█▅▅▇▅█▄▄ 33–53ms
sweep ▁█▆▅▅▇▆▆▇▆ 38–71ms
gw 1x █▂▁▁▂▂▂▁▂▁ 41–75ms
eve 1x █▃▁▂▂▂▁▁▁▁ 24–63ms
eve 2x ▆▃█▁▂▂▂▃▂▄ 24–41ms

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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

🧪 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.

• cross-file step error preserves message and function names in stack (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 20:27:52Z · abandoned wrun_01M0DVA2E709NA6RTRS18CZ7J0

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3474	0	738	4212
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	156	0	0	156
✅ 🌐 Cross-language Conformance	9	0	128	137
✅ vercel-multi-region	27	0	0	27
Total	15096	0	2540	17636

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
✅ nuxt-quickjs	128	0	28
✅ python-node	8	0	148
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ 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

[changeset-bot]

⚠️ No Changeset found

Latest commit: d0f90db

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[VaguelySerious]

Great catch! LGTM assuming CI passes

[github-actions]

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

Full trace: world-sim.txt

[github-actions]

No backport to stable for 78a531a (AI decision).

This is a performance optimization: run polling now reads metadata with resolveData: 'none' and only fetches full payloads once the run reaches a terminal state. The existing behavior is correct — it just resolves payload refs more often than necessary — so there is no user-visible defect, crash, or unbounded-resource problem being fixed, and the accompanying test changes only assert the new call pattern. Maintenance-line users gain no stability from the change, so it should stay on main.

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

78a531a0881742276dbc9e6b6ac9fbdc502e33bd