feat(streams): add WebSocket writer lifecycle

[alangenfeld]

Summary & Motivation

Implements the client half of workflow-stream-ws/v1 behind the existing default-off WORKFLOW_STREAMS_TRANSPORT=ws gate, populating the createWriteSession seam only when opted in.

• Writes and closes are serialized over one socket per writer lifetime; groups above the v1 per-request chunk cap are split without resetting writer-local sequence.
• Any failure before the upgrade is accepted (declined upgrade, proxy, load error, a dispatch that beats the handshake) falls back to HTTP for the rest of the writer's life.
• Once a write is on the socket, a missing or uncorrelatable reply poisons the session rather than replaying over HTTP, since a duplicate append cannot be ruled out.
• Idle clean closes reconnect with the same writer id, capped at three attempts so a draining server can't hot-loop.
• The handshake gets a workflow.stream.ws.connect span and each frame a synthesized http POST span, so per-event tracing survives the non-fetch transport.

Test Plan

New unit tests cover the lifecycle, fallback, and poisoning paths; 598 @workflow/world-vercel tests plus package build/typecheck and workspace lint/format pass. Root build/typecheck couldn't run locally (missing Rust toolchain for the unrelated @workflow/swc-plugin).

[changeset-bot]

🦋 Changeset detected

Latest commit: ab87b64

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

This PR includes changesets to release 17 packages

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

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

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[vercel]

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 10:14pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 10:14pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 10:14pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 10:14pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 10:14pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 10:14pm

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

🐘 Local Postgres (1 failed)

astro-stable-node (1 failed):

• cancelRun via CLI - cancelling a running workflow | wrun_41M102F1NH0GJ7WFHZN61P2TST

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M102M66CV3WYDVVHMEVDQXHD
• promiseAllWorkflow | wrun_41M10291WF0GP9JM79H3271Y0J
• sleepingWorkflow | wrun_41M1029Q040GYQZP1YX3WXHK77
• parallelSleepWorkflow | wrun_41M1029RYD0GR44TQX9C1HHSQN
• nullByteWorkflow | wrun_41M1029ZK40GR828P83Q2C14BK
• cancelRun - cancelling a running workflow | wrun_41M102EWVG0GXFZ0BSA4ZB8SD3
• cancelRun via CLI - cancelling a running workflow | wrun_41M102F1NH0GJ7WFHZN61P2TST
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M102F3EF0GQPJ15XJYPCY0CZ
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M102FNX10GWMX3JBYE2F8QWZ

⚠️ 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.

• addTenWorkflow (hono)
• cancelRun via CLI - cancelling a running workflow (nextjs-webpack)
• deploymentId: 'latest' is a no-op in non-Vercel worlds (nuxt)
• RetryableError respects custom retryAfter delay (sveltekit)
• RetryableError respects custom retryAfter delay (vite)

🛠 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.

19 infra events

• cold-start-warmup · suite warmup (tanstack-start) · at 22:19:12Z · abandoned wrun_01M102EZ34QJTNN9S9KVH8EKDE
• cold-start-warmup · suite warmup (python) · at 22:20:20Z · abandoned wrun_01M102E7R9P9PE6WCX2MM8C30V · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 22:20:35Z · abandoned wrun_01M102HWWVDEWWZ51EHYRM5TXS
• run-pickup-stall · promiseAllWorkflow (python) · at 22:20:35Z · abandoned wrun_01M102HWWVDEWWZ51EHYRM5TXT
• run-pickup-stall · parallelSleepWorkflow (python) · at 22:20:35Z · abandoned wrun_01M102HWX3Z2FPETABQAK45BRV
• run-pickup-stall · sleepingWorkflow (python) · at 22:20:35Z · abandoned wrun_01M102HWX1VY4TJGKYW31PCQMB
• run-pickup-stall · nullByteWorkflow (python) · at 22:20:35Z · abandoned wrun_01M102HWX5P89C2F52QTGQPY4G
• run-pickup-stall · sleepingWorkflow (python) · at 22:21:35Z · abandoned wrun_01M102KQGR316KYSWE65BPMBCR
• run-pickup-stall · promiseAllWorkflow (python) · at 22:21:35Z · abandoned wrun_01M102KQGNGR9W92Z9075AJTT0
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 22:21:35Z · abandoned wrun_01M102KQGXG05FGSNJM36DZ80C
• run-pickup-stall · parallelSleepWorkflow (python) · at 22:21:35Z · abandoned wrun_01M102KQGZ0712F9N007MTJ034
• run-pickup-stall · nullByteWorkflow (python) · at 22:21:35Z · abandoned wrun_01M102KQH1B8JMBYSGHST3GXWW
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 22:22:35Z · abandoned wrun_01M102NJ4CPFEVRFTAP7Q9JCXT
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 22:22:35Z · abandoned wrun_01M102NJ4SQHMJNCX67FWHD1YP
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 22:22:35Z · abandoned wrun_01M102NJ4M19JBS6XT5MDK1TGC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 22:23:05Z · abandoned wrun_01M102PFFQ0WC2AP9EVJE13Q9W
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 22:23:05Z · abandoned wrun_01M102PFG1YCN2ZGYRGD4Q2FE8
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 22:23:35Z · abandoned wrun_01M102QCQWTCHA92P2112Q4MQ1
• run-pickup-stall · hookCleanupTestWorkflow - hook token reuse after workflow completion (nextjs-webpack) · at 22:24:09Z · abandoned wrun_01M102RDS41XQ6PBEXS75CFCCK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	3570	0	590	4160
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
❌ 🐘 Local Postgres	3921	1	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17052	10	2626	19688

Details by Category

✅ ▲ Vercel Production

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

✅ 💻 Local Development

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

✅ 📦 Local Production

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

❌ 🐘 Local Postgres

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

✅ 🪟 Windows

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

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

commit ab87b64 · Wed, 26 Aug 2026 22:30:08 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	291 (-39%) 💚	1274 🔴 (+18%) 🔻	1313 🔴 (+17%) 🔻	1370 🔴 (-7.1%)	30
TTFS	stream	175 (-82%) 💚	1277 🔴 (+22%) 🔻	1305 🔴 (+20%) 🔻	1497 🔴 (+12%)	30
TTFS	hook + stream	396 (-11%)	1507 🔴 (+17%) 🔻	1537 🔴 (+8.0%)	5581 🔴 (+13%)	30
Fan-out TTFS	Promise.all(100 steps)	524 (+9.2%)	861 (+19%) 🔻	1741 (+123%) 🔻	1807 (-63%) 💚	10
Fan-out TTLS	Promise.all(100 steps)	1903 (+10%)	2369 (-20%) 💚	3189 (-34%) 💚	8142 (-22%) 💚	10
STSO	1020 steps (inline)	68 (-36%) 💚	123 (-6.8%)	138 (-8.0%)	194 (-4.0%)	1019
WO	1020 steps	123430 (-8.1%)	123430 (-8.1%)	123430 (-8.1%)	123430 (-8.1%)	1
CRTT	first chunk (pooled)	84 (-4.5%)	121 (-6.9%)	147 (-28%) 💚	177 (-25%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	97 (-13%)	115 (-22%)	159 (-44%)	306 (-60%)	123 (-43%)	10
size sweep (100/s, 160B-12KB)	102 (-11%)	116 (-29%)	151 (-55%)	503 (-14%)	104 (-57%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	99 (-17%)	109 (-13%)	132 (-25%)	449 (-19%)	133 (-65%)	3
replay eve-gpt-5.6-sol-2000t (1x)	104 (-38%)	112 (-23%)	148 (-30%)	593 (-7%)	348 (-34%)	2
replay eve-gpt-5.6-sol-2000t (2x)	111 (-18%)	150 (-22%)	186 (-37%)	367 (-48%)	238 (-16%)	3

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

1020 steps (inline)

Cumulative STSO time: main 134112ms → this run 123206ms (Δ -10906ms, -8%)

 50-100 ms  ┃                         main   0  this   3    +3
100-150 ms  ███████████████████████┃  main 917  this 973   +56
150-200 ms  ┃█                        main  91  this  33   -58
200-250 ms  ┃                         main   6  this   6    +0
250-300 ms  ┃                         main   2  this   1    -1
300-350 ms  ┃                         main   1  this   2    +1
350-400 ms  ┃                         main   1  this   1    +0
900-950 ms  ┃                         main   1  this   0    -1

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

variant  RTT 1ms→5s+             avg         p50         p90         p99     n
control  ······██▁····  103.1 (-20%)    99 (-4%)  159 (-44%)  306 (-60%)  3000
sweep    ······██▁▁···  105.9 (-21%)    98 (-9%)  151 (-55%)  503 (-14%)  3000
gw 1x    ·····▁█▅▁▁···   98.5 (-10%)    93 (-6%)  132 (-25%)  449 (-19%)  5295
eve 1x   ·····▁█▅▁▁···    103 (-19%)   90 (-13%)  148 (-30%)   593 (-7%)  5186
eve 2x   ·····▁▇█▁····  118.3 (-25%)  104 (-17%)  186 (-37%)  367 (-48%)  7779

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

control  ▇▃██▃▁▃▇▂▄  94–111ms
sweep    ▃▃▃▁▁▁▂▄██  95–125ms
gw 1x    ▃▃▄▂▁▃█▃▅▂  89–118ms
eve 1x   ▃▃▃▃▁▂▄▄█▃  82–141ms
eve 2x   █▁▂▂▂▃▇█▃▄  98–145ms

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

sweep  █▇▃▃▁▁▁  105–108ms

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

control  ▁▁█▅▁▂▄▄▂▇  28–35ms
sweep    ▂▁▃▃▃▃▃▆█▁  34–58ms
gw 1x    ▃▃▆▁▃▃█▅▄▅  25–31ms
eve 1x   ▁▃▃▃▁▁█▅▇▅  18–25ms
eve 2x   █▂▁▂▃▆▃▅▂▆  17–23ms

ℹ️ Metric definitions & methodology

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

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

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

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

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

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

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

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

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

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

[github-actions]

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]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (+5.3 KiB)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	764.3 KiB (+1.2 KiB)

About these numbers

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

ab87b64 · run