[ci] Track the /flow route bundle size against main by VaguelySerious · Pull Request #3739 · vercel/workflow

VaguelySerious · 2026-08-22T00:20:03Z

Builds the nextjs-turbopack and hono workbench apps on every PR, measures the /.well-known/workflow/v1/flow route, and posts a sticky comment with the delta against main. Pushes to main produce the baseline artifacts PR runs download. Non-required: it lives in its own workflow file, so it cannot gate the E2E aggregate.

Two numbers per app

Neither app emits an isolable function bundle for that route. Next.js emits a ~1 KB turbopack chunk loader pointing at chunks shared with other routes; nitro inlines the handler into a single server entry.

Gated: what the workflow builders emit for the flow route, before the framework bundles it. Growth beyond max(2%, 50 KiB) raw fails the job. Override with the allow-bundle-size-growth label.
Informational: the framework's own build output. Unrelated changes move it, so it never gates.

Each is only ever compared against its own baseline, never against the other.

Verification

Reproducibility was checked before wiring the gate, since a noisy metric makes one useless: two clean builds of each app produce byte-identical reports.

	Flow bundle	Step registrations	Framework output
nextjs-turbopack	1.32 MiB	1.7 KiB	3.21 MiB
hono	1.28 MiB	261.0 KiB	7.70 MiB

Both loud-failure paths were exercised and exit non-zero: a Tier-1 bundle backdated one day against the build stamp, and a missing _workflows.ts from a skipped prebuild. A plausible wrong number (the 1 KB chunk loader, a stale artifact) is worse than a red job.

Pinned build env

WORKFLOW_SOURCEMAP, WORKFLOW_PUBLIC_MANIFEST and WORKFLOW_TARGET_WORLD are pinned and recorded in each report's fingerprint; the renderer refuses to diff reports whose fingerprints disagree.

WORKFLOW_SOURCEMAP=false is the one that moves the numbers: sourcemap mode defaults to inline outside a production build, which alone takes the Next flow bundle from 1.38 MB to 5.85 MB.

WORKFLOW_TARGET_WORLD was measured to have no effect. Building nextjs-turbopack with local and with vercel gives byte-identical reports on all three metrics, because every world the app depends on is bundled into the framework output either way and the choice is made at runtime. It is pinned anyway, as insurance: packages/next branches on it, so if it ever starts mattering the fingerprint turns that into a refused diff rather than a phantom code change.

Known limitation

The gate does not cover the world adapters. A change confined to @workflow/world-vercel will not move the gated numbers. Documented in the PR comment, the measurement script, and AGENTS.md. Gating world code would need a different metric.

Notes for review

The first PR run after this merges will show "No baseline on main yet" and gate nothing. Baselines exist only once this lands on main or the workflow is dispatched there.
Per-app bundle paths are read from scripts/create-test-matrix.mjs rather than restated, so there is one source of truth.
The app build uses the package script, not turbo run build: hono's turbo.json does not declare node_modules/.nitro/ as an output, so a cache hit would leave the gated file absent.

🤖 Generated with Claude Code

Builds the nextjs-turbopack and hono workbench apps on every PR, measures the /.well-known/workflow/v1/flow route, and posts a sticky comment with the delta against main. Pushes to main produce the baseline artifacts. Two numbers per app, because neither app emits an isolable function bundle for that route: Next.js emits a ~1 KB turbopack chunk loader pointing at chunks shared with other routes, and nitro inlines the handler into a single server entry. The gated number is what the workflow builders emit before the framework bundles it; the framework's own output is reported but never gates, since unrelated changes move it. Verified before wiring the gate: two clean builds of each app produce byte-identical reports, so a delta means a real change. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

changeset-bot · 2026-08-22T00:20:10Z

🦋 Changeset detected

Latest commit: c9af771

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

This PR includes changesets to release 0 packages

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

vercel · 2026-08-22T00:20:11Z

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 22, 2026 12:35am
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 22, 2026 12:35am
example-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-astro-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-express-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-fastify-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-hono-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-nestjs-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-nitro-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-nuxt-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-python-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workbench-vite-workflow	Ready	Preview, v0	Aug 22, 2026 12:35am
workflow-docs	Ready	Preview, v0	Aug 22, 2026 12:35am
workflow-swc-playground	Ready	Preview, v0	Aug 22, 2026 12:35am
workflow-tarballs	Ready	Preview, v0	Aug 22, 2026 12:35am
workflow-web	Ready	Preview, v0	Aug 22, 2026 12:35am

github-actions · 2026-08-22T00:20:21Z

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

promiseAllWorkflow | wrun_41M0KFYH2B0GK0EM7AD867X359 | 🔍 observability
sleepingWorkflow | wrun_41M0KFZ5XW0GK64AYTF7W82BMJ | 🔍 observability
parallelSleepWorkflow | wrun_41M0KFZ5YP0GWC8MYZCZA5314V | 🔍 observability
nullByteWorkflow | wrun_41M0KFZCHX0GJNT7TWP4BK1RSW | 🔍 observability
cancelRun - cancelling a running workflow | wrun_41M0KG57DD0GR68W8XVMTEMQFF | 🔍 observability
cancelRun via CLI - cancelling a running workflow | wrun_41M0KG58N50GWWJN4Q3GNZNA9Q | 🔍 observability
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0KG5G8Z0GS413MW10VX1KTG | 🔍 observability
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0KG613B0GZ1AJ46EQBNJ7JT | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0KG44ADN8K09CN064SXRS8F
promiseAllWorkflow | wrun_41M0KFYH2B0GK0EM7AD867X359
sleepingWorkflow | wrun_41M0KFZ5XW0GK64AYTF7W82BMJ
parallelSleepWorkflow | wrun_41M0KFZ5YP0GWC8MYZCZA5314V
nullByteWorkflow | wrun_41M0KFZCHX0GJNT7TWP4BK1RSW
cancelRun - cancelling a running workflow | wrun_41M0KG57DD0GR68W8XVMTEMQFF
cancelRun via CLI - cancelling a running workflow | wrun_41M0KG58N50GWWJN4Q3GNZNA9Q
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0KG5G8Z0GS413MW10VX1KTG
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0KG613B0GZ1AJ46EQBNJ7JT

⚠️ 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.

15 flaky tests

abortVoidSleepTimeoutWorkflow: documented void sleep().then(abort) pattern works (astro)
cancelRun via CLI - cancelling a running workflow (nextjs-turbopack)
getChunks returns same content as reading the stream (astro)
getChunks returns same content as reading the stream (fastify)
getChunks returns same content as reading the stream (nest)
getChunks returns same content as reading the stream (vite)
getTailIndex returns correct index after stream completes (hono)
health check (CLI) - workflow health command reports healthy endpoints (nextjs-webpack)
hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running (example)
hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running (nextjs-webpack)
no startIndex (reads all chunks) (tanstack-start)
no startIndex (reads all chunks) (vite)
positive startIndex (skips first chunk) (hono)
positive startIndex (skips first chunk) (vite)
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (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.

36 infra events

cold-start-warmup · suite warmup (tanstack-start) · at 00:35:23Z · abandoned wrun_01M0KE8QPAMFFT05H3ATSQP2DZ
run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 00:40:31Z · abandoned wrun_01M0KEJGBWQCNMAC2KQWCYKJ8H
run-pickup-stall · hookWithSleepFinalStepWorkflow - step only on final payload (nextjs-webpack) · at 00:40:44Z · abandoned wrun_01M0KEJXA80EQ3TTGCA1NBWVCV
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (nextjs-webpack) · at 00:40:44Z · abandoned wrun_01M0KEJXGEA8VS8RA3Y1V4V7W4
cold-start-warmup · suite warmup (python) · at 01:06:05Z · abandoned wrun_41M0KFY45D0GY8PFS304GP98E2 · (+7 more)
cold-start-warmup · suite warmup (python) · at 01:06:07Z · abandoned wrun_01M0KFY5WBB7CGCMBX3TDHAFNJ · (+7 more)
run-pickup-stall · sleepingWorkflow (python) · at 01:06:21Z · abandoned wrun_41M0KG1SCC0GVXMK4JTXAZX45X
run-pickup-stall · nullByteWorkflow (python) · at 01:06:21Z · abandoned wrun_41M0KG1SCG0GHZR837ASVASEM6
run-pickup-stall · parallelSleepWorkflow (python) · at 01:06:21Z · abandoned wrun_41M0KG1SCC0GVXMK4JTXAZX45Y
run-pickup-stall · promiseAllWorkflow (python) · at 01:06:22Z · abandoned wrun_41M0KG1SC70GNNFQAE8CBJGG0E
run-pickup-stall · promiseAllWorkflow (python) · at 01:06:22Z · abandoned wrun_01M0KG1V141BYPP6G9ST8WG373
run-pickup-stall · sleepingWorkflow (python) · at 01:06:22Z · abandoned wrun_01M0KG1V1AWGQ0G99T1NEV6JGN
run-pickup-stall · nullByteWorkflow (python) · at 01:06:22Z · abandoned wrun_01M0KG1V1DMNMFDNVQZRQG9390
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 01:06:22Z · abandoned wrun_01M0KG1V13XRY9AW1Z4PGSSZ98
run-pickup-stall · parallelSleepWorkflow (python) · at 01:06:22Z · abandoned wrun_01M0KG1V1BRSW0V4MB0NFRJZJK
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:06:22Z · abandoned wrun_41M0KG1SXZ0GHDQZQVA88RHMNA
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:06:55Z · abandoned wrun_41M0KG2SNA0GGQ8K0JNTW918ER
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 01:07:22Z · abandoned wrun_01M0KG3NMYHS3KDTEKN6GTDHP0
run-pickup-stall · promiseAllWorkflow (python) · at 01:07:22Z · abandoned wrun_01M0KG3NN08BJKKT8B3MYMBY70
run-pickup-stall · sleepingWorkflow (python) · at 01:07:22Z · abandoned wrun_01M0KG3NN219ER4NYRNK7FBZTG
run-pickup-stall · parallelSleepWorkflow (python) · at 01:07:22Z · abandoned wrun_01M0KG3NN4P0ZJ1YMHXWQGT5KV
run-pickup-stall · nullByteWorkflow (python) · at 01:07:22Z · abandoned wrun_01M0KG3NN8MJDMY4F4C1P6MJG3
run-pickup-stall · parallelSleepWorkflow (python) · at 01:07:26Z · abandoned wrun_41M0KG3R5J0GV3VYD8WXTDDTZT
run-pickup-stall · nullByteWorkflow (python) · at 01:07:26Z · abandoned wrun_41M0KG3RVD0GSHEFNQMS9D279W
run-pickup-stall · sleepingWorkflow (python) · at 01:07:27Z · abandoned wrun_41M0KG3SM30GXBHZ55JGAGD75V
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:07:28Z · abandoned wrun_41M0KG3T1N0GJR467PY0AA57JC
run-pickup-stall · promiseAllWorkflow (python) · at 01:07:28Z · abandoned wrun_41M0KG3TPG0GYEH25JDQ9EE1X5
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:08:22Z · abandoned wrun_01M0KG5G8KP0PQKTFJKN3PMBV6
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:08:22Z · abandoned wrun_01M0KG5G8TK26K8CPTTSWXCDQ1
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:08:22Z · abandoned wrun_01M0KG5G8Z26Q19B4XAV4WTCJM
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 01:08:52Z · abandoned wrun_01M0KG6DM8YAQ3SQ6ZJP52MGXV
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:08:52Z · abandoned wrun_01M0KG6DME3Q2YBGYH02X9563H
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 01:09:09Z · abandoned wrun_41M0KG5PEX0GSSN2B0ZNMMXEMV
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:09:10Z · abandoned wrun_41M0KG5V5P0GN8S1J9ZST2GCT9
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:09:22Z · abandoned wrun_01M0KG7AW2Y02V6NXZG76CA4HJ
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 01:10:44Z · abandoned wrun_41M0KG8K280GJCB7C39Q2M7XSV

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	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	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

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

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

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

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

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

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

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

📋 View full workflow run

github-actions · 2026-08-22T00:20:25Z

📊 Workflow Benchmarks

commit c9af771 · Sat, 22 Aug 2026 00:57:36 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	268 (-74%) 💚	1331 🔴 (+16%) 🔻	1371 🔴 (+16%) 🔻	1545 🔴 (+18%) 🔻	30
TTFS	stream	240 (-77%) 💚	1373 🔴 (+21%) 🔻	1409 🔴 (+21%) 🔻	1515 🔴 (+26%) 🔻	30
TTFS	hook + stream	1534 (+26%) 🔻	1723 🔴 (+21%) 🔻	1753 🔴 (+17%) 🔻	1975 🔴 (+2.4%)	30
Fan-out TTFS	Promise.all(100 steps)	539 (-28%) 💚	2016 (+4.3%)	2044 (+5.1%)	2069 (+1.9%)	10
Fan-out TTLS	Promise.all(100 steps)	1709 (-66%) 💚	5864 (-21%) 💚	7006 (-11%)	7951 (-7.5%)	10
STSO	1020 steps (inline)	136 (+31%) 🔻	194 (+37%) 🔻	222 (+38%) 🔻	337 (+73%) 🔻	1019
WO	1020 steps	189480 (+33%) 🔻	189480 (+33%) 🔻	189480 (+33%) 🔻	189480 (+33%) 🔻	1
CRTT	first chunk (pooled)	95 (-22%) 💚	157 (-11%)	184 (-16%) 💚	281 (-49%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	126 (-8%)	161 (-65%)	239 (-63%)	372 (-93%)	133 (-14%)	10
size sweep (100/s, 160B-12KB)	139 (-15%)	179 (-10%)	278 (-9%)	4827 (+963%)	170 (-9%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	152 (-15%)	138 (-47%)	187 (-68%)	612 (-58%)	296 (-64%)	3
replay eve-gpt-5.6-sol-2000t (1x)	145 (-4%)	125 (-34%)	168 (-51%)	293 (-78%)	239 (-70%)	2
replay eve-gpt-5.6-sol-2000t (2x)	147 (-16%)	192 (-29%)	344 (-9%)	1005 (+41%)	412 (+11%)	3

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

1020 steps (inline)

Cumulative STSO time: main 142387ms → this run 189188ms (Δ +46801ms, +33%)

100-150 ms  ┃███████████████████████  main 869  this  23  -846
150-200 ms  ████░░░░░░░░░░░░░░░░░┃    main 143  this 791  +648
200-250 ms  █░░┃                      main   5  this 159  +154
250-300 ms  ┃                         main   2  this  24   +22
300-350 ms  ┃                         main   0  this  13   +13
350-400 ms  ┃                         main   0  this   5    +5
400-450 ms  ┃                         main   0  this   1    +1
450-500 ms  ┃                         main   0  this   1    +1
500-550 ms  ┃                         main   0  this   1    +1
600-650 ms  ┃                         main   0  this   1    +1

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

variant  RTT 1ms→5s+              avg         p50         p90           p99     n
control  ······▃█▁····   130.2 (-77%)  122 (-19%)  239 (-63%)    372 (-93%)  3000
sweep    ······▂█▂··▂·  455.3 (+173%)  131 (-14%)   278 (-9%)  4827 (+963%)  3000
gw 1x    ·····▁▄█▁▁···     126 (-37%)  115 (-16%)  187 (-68%)    612 (-58%)  5295
eve 1x   ·····▁██▁····   108.2 (-38%)   97 (-26%)  168 (-51%)    293 (-78%)  5186
eve 2x   ·····▁▄█▂▁▁··   152.2 (-25%)  119 (-32%)   344 (-9%)   1005 (+41%)  7779

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

control  ▅▃▄▁▁▃▅█▃▁  112–165ms
sweep    ▁▇█▇▇▇▆▅▅▅  157–587ms
gw 1x    █▂▂▁▂▂▃▃▅▁  109–173ms
eve 1x   ▆▁█▃▂▅▅▅▃▂  97–124ms
eve 2x   █▅▂▂▁▃▃▆▂▁  119–222ms

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

sweep  ▁██▆▆▆▇  449–458ms

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

control  ▄▂▂▃▃▂▄█▄▁  29–51ms
sweep    ▁█▁▁▂▁▂▁▁▂  45–187ms
gw 1x    █▅▃▁▂▄▄▅▅▄  29–43ms
eve 1x   ▅▁█▁▄▇▄▅▂▄  20–24ms
eve 2x   █▄▁▂▃▄▂▃▁▃  21–32ms

ℹ️ Metric definitions & methodology

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

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

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

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

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

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

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

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

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

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

github-actions · 2026-08-22T00:20:59Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

github-actions · 2026-08-22T00:23:52Z

Flow route bundle size

hono

No baseline on main yet, so sizes are shown without a comparison.

Metric	Raw	Raw vs main	Gzip	Gzip vs main
Flow route bundle 🔒	1.28 MiB	—	211.3 KiB	—
Step registrations 🔒	260.8 KiB	—	40.1 KiB	—
Framework output	7.38 MiB	—	1.76 MiB	—

Framework output: 55 files, flow handler inlined into the server entry

nextjs-turbopack

No baseline on main yet, so sizes are shown without a comparison.

Metric	Raw	Raw vs main	Gzip	Gzip vs main
Flow route bundle 🔒	1.32 MiB	—	216.7 KiB	—
Step registrations 🔒	1.7 KiB	—	439 B	—
Framework output	3.21 MiB	—	771.9 KiB	—

Framework output: 17 chunks, shared with other routes

How to read this

🔒 marks a gated metric: the job fails when its raw size grows by more than 2% or 50.0 KiB, whichever is larger.
Flow route bundle and Step registrations are what the workflow builders emit for /.well-known/workflow/v1/flow before the framework bundles them. They move only when the SDK moves, which is why they are the gated numbers.
Framework output is the framework's own build output. It is informational: for Next.js the chunks are shared with other routes, and for nitro the flow handler is inlined into a single server entry, so unrelated changes move it.
The two are not comparable to each other, and neither alone is the deployed function. Each is only ever compared against its own baseline from main.
The gated numbers exclude the world adapters: every world the app depends on is bundled into the framework output regardless, and the choice is made at runtime. A change confined to a world package will not move them.
Raw bytes are what the runtime reads and parses on a cold start; gzip is the deployment payload. Only raw is gated.

Measured at c9af771 · run

The same hono build produces 55 files under .output/server on a Linux runner and 54 on macOS, so a report measured off-runner is not comparable to one measured on it. Node's major version was already recorded because zlib ships with Node and moves the gzip numbers; platform and arch cover the raw ones. Cheap to add now: no baseline exists on main yet, so nothing is invalidated. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

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[ci] Track the /flow route bundle size against main - #3739

[ci] Track the /flow route bundle size against main#3739
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VaguelySerious commented Aug 22, 2026

Two numbers per app

Verification

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🧪 E2E Test Results

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

🌐 Cross-language Conformance (9 failed)

⚠️ Flaky E2E Tests (passed on retry)

🛠 Infra Events (absorbed by the harness)

E2E Test Summary

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📊 Workflow Benchmarks

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Sim World

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Flow route bundle size

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nextjs-turbopack

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