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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518

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feat(world-vercel): synthesize per-event client spans on the WS transport#3518
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@shalabhcshalabhc commented Aug 13, 2026•
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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.

@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
@shalabhc
shalabhc requested review from a team, fantix and msullivan as code ownersAugust 13, 2026 00:59
@shalabhcshalabhc mentioned this pull request Aug 13, 2026
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🦋 Changeset detected

Latest commit: 78a7c62

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

This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.

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🧪 E2E Test Results

✅ All tests passed

E2E Test Summary

Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category

✅ ▲ Vercel Production

AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
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✅ vite-node128028
✅ vite-quickjs128028

✅ 💻 Local Development

AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
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✅ vite-stable-quickjs130026

✅ 📦 Local Production

AppPassedFailedSkipped
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✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
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✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026

✅ 🐘 Local Postgres

AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026

✅ 🪟 Windows

AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600

✅ vercel-multi-region

AppPassedFailedSkipped
✅ nextjs-turbopack2700

📋 View full workflow run

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📊 Workflow Benchmarks

⏳ Benchmarks are running for 78a7c62... (run logs)

ℹ️ Metric definitions & methodology

Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)

All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.

Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.

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Sim World

Simulated world deterministic testing for races. Traces

🟠 Mint-ordered log — 6 fail of 41 total

log=mint-ordered · fence=per-spec

scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0

Full trace: world-sim-mint.txt

🟢 Append-only log — 0 fail of 41 total

log=append-only · fence=per-spec

scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0

Full trace: world-sim-append-only.txt

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shalabhc commented Aug 13, 2026

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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.

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feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
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shalabhc wants to merge 1 commit into
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shalabhc/ws-synthetic-trace-spans-clean
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feat(world-vercel): synthesize per-event client spans on the WS transport#3518
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@shalabhc
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Aug 13, 2026•

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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
@shalabhc
shalabhc
requested review from
a team, fantix and msullivan
as code ownersAugust 13, 2026 00:59
@shalabhcshalabhc
mentioned this pull request
Aug 13, 2026
 Merged

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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
Not sure what this means? Click here to learn what changesets are.
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workflow-webReadyReadyPreviewAug 13, 2026 1:02am
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600
✅ vercel-multi-region
AppPassedFailedSkipped
✅ nextjs-turbopack2700
📋 View full workflow run
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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
@shalabhc
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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
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@shalabhc
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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
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as code ownersAugust 13, 2026 00:59
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mentioned this pull request
Aug 13, 2026
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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
Not sure what this means? Click here to learn what changesets are.
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The latest updates on your projects. Learn more about Vercel for GitHub.
ProjectDeploymentActionsUpdated (UTC)
example-nextjs-workflow-turbopackReadyReadyPreviewAug 13, 2026 1:02am
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workbench-astro-workflowReadyReadyPreviewAug 13, 2026 1:02am
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workbench-fastify-workflowReadyReadyPreviewAug 13, 2026 1:02am
workbench-hono-workflowReadyReadyPreviewAug 13, 2026 1:02am
workbench-nestjs-workflowReadyReadyPreviewAug 13, 2026 1:02am
workbench-nitro-workflowReadyReadyPreviewAug 13, 2026 1:02am
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workbench-sveltekit-workflowReadyReadyPreviewAug 13, 2026 1:02am
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600
✅ vercel-multi-region
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✅ nextjs-turbopack2700
📋 View full workflow run
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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
@shalabhc
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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
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feat(world-vercel): synthesize per-event client spans on the WS transport#3518
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@shalabhc
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Aug 13, 2026•

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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
@shalabhc
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a team, fantix and msullivan
as code ownersAugust 13, 2026 00:59
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mentioned this pull request
Aug 13, 2026
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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
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The latest updates on your projects. Learn more about Vercel for GitHub.
ProjectDeploymentActionsUpdated (UTC)
example-nextjs-workflow-turbopackReadyReadyPreviewAug 13, 2026 1:02am
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workbench-astro-workflowReadyReadyPreviewAug 13, 2026 1:02am
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@shalabhc
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600
✅ vercel-multi-region
AppPassedFailedSkipped
✅ nextjs-turbopack2700
📋 View full workflow run
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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
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feat(world-vercel): synthesize per-event client spans on the WS transport#3518
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@shalabhc
@shalabhcshalabhc
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Aug 13, 2026•

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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
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a team, fantix and msullivan
as code ownersAugust 13, 2026 00:59
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Aug 13, 2026
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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
Not sure what this means? Click here to learn what changesets are.
Click here if you're a maintainer who wants to add another changeset to this PR
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The latest updates on your projects. Learn more about Vercel for GitHub.
ProjectDeploymentActionsUpdated (UTC)
example-nextjs-workflow-turbopackReadyReadyPreviewAug 13, 2026 1:02am
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example-workflowReadyReadyPreviewAug 13, 2026 1:02am
workbench-astro-workflowReadyReadyPreviewAug 13, 2026 1:02am
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@shalabhc
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600
✅ vercel-multi-region
AppPassedFailedSkipped
✅ nextjs-turbopack2700
📋 View full workflow run
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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
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var __re = new RegExp('^' + ".*" + '
feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
@shalabhc
shalabhc
requested review from
a team, fantix and msullivan
as code ownersAugust 13, 2026 00:59
@shalabhcshalabhc
mentioned this pull request
Aug 13, 2026
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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
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@workflow/vitePatch
@workflow/nuxtPatch
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600
✅ vercel-multi-region
AppPassedFailedSkipped
✅ nextjs-turbopack2700
📋 View full workflow run
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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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var __re = new RegExp('^' + ".*" + '
feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
Skip to content
feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
Closed
shalabhc wants to merge 1 commit into
mainfrom 
shalabhc/ws-synthetic-trace-spans-clean
Closed
feat(world-vercel): synthesize per-event client spans on the WS transport#3518
shalabhc wants to merge 1 commit into
mainfrom 
shalabhc/ws-synthetic-trace-spans-clean
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@shalabhc
@shalabhcshalabhc
commented
Aug 13, 2026•

edited

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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
@shalabhc
shalabhc
requested review from
a team, fantix and msullivan
as code ownersAugust 13, 2026 00:59
@shalabhcshalabhc
mentioned this pull request
Aug 13, 2026
 Merged

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Aug 13, 2026

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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
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Click here if you're a maintainer who wants to add another changeset to this PR
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@shalabhc
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Aug 13, 2026

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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
✅ nextjs-webpack-stable-node15600
✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
✅ hono-stable-node130026
✅ hono-stable-quickjs130026
✅ nest-stable-node130026
✅ nest-stable-quickjs130026
✅ nextjs-turbopack-canary-node137019
✅ nextjs-turbopack-canary-quickjs137019
✅ nextjs-turbopack-stable-node15600
✅ nextjs-turbopack-stable-quickjs15600
✅ nextjs-webpack-canary-node137019
✅ nextjs-webpack-canary-quickjs137019
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✅ nextjs-webpack-stable-quickjs15600
✅ nitro-stable-node130026
✅ nitro-stable-quickjs130026
✅ nuxt-stable-node130026
✅ nuxt-stable-quickjs130026
✅ sveltekit-stable-node14907
✅ sveltekit-stable-quickjs14907
✅ tanstack-start-node130026
✅ tanstack-start-quickjs130026
✅ vite-stable-node130026
✅ vite-stable-quickjs130026
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack-node15600
✅ nextjs-turbopack-quickjs15600
✅ vercel-multi-region
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✅ nextjs-turbopack2700
📋 View full workflow run
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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
@shalabhc
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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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feat(world-vercel): synthesize per-event client spans on the WS transport by shalabhc · Pull Request #3518 · vercel/workflow · GitHub
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feat(world-vercel): synthesize per-event client spans on the WS transport - #3518
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feat(world-vercel): synthesize per-event client spans on the WS transport#3518
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@shalabhc
@shalabhcshalabhc
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Clean replacement for #3452 after its branch history diverged during rebase. Contains only the original WS-span change and no copied main changes.\n\n- Synthesizes a client span per WS event frame, preserving HTTP/WS trace comparability.\n- Adds an explicit WS connect span and transport-honesty attributes.\n- Fixes the default port for wss URLs.\n\nSupersedes #3452.
@vercel@shalabhc
feat(world-vercel): synthesize per-event client spans on the WS trans…
78a7c62
…port
PR #3084 added the opt-in `WORKFLOW_EVENTS_TRANSPORT=ws` path and listed
"no client-side span on the WS path" as a known limitation. Because event
writes become multiplexed frames on one long-lived socket rather than
individual `fetch` calls, the per-event `http POST` CLIENT span that the
HTTP transport produced simply disappeared — traces went from one span
per event to nothing between the invocation and the server.
Restore it by synthesizing a request-shaped span around each frame, and
give the upgrade its own span:
- Extract `withHttpClientSpan` / `recordClientSpanStatus` from
`instrumentedFetch` in `http-core.ts` so the synthetic span is emitted
by the same envelope as the real one and cannot drift from it.
`InstrumentedFetchOptions` now extends `HttpClientSpanOptions`.
- `postEventFrameOverWs` opens `http POST` with `url.full` pointing at the
v4 REST endpoint the frame is forwarded into, so per-event traces and
latency dashboards keep working across the flag. Extract `eventsV4Url`
so that URL cannot drift from the one the HTTP path actually requests.
- Tag both transports with `workflow.events.transport` (`http` | `ws`) and
`workflow.event.type`; the WS path additionally sets
`network.protocol.name=websocket`, `workflow.events.ws.url` (the real
wire destination) and `workflow.events.ws.req_id` (join key to the
server's log line for the frame), so the span is never mistaken for a
real HTTP request.
- Add a `workflow.events.ws.connect` span around the upgrade — the one
genuinely-HTTP request here, previously the invisible half of every WS
write's latency — carrying `workflow.events.ws.reconnect_attempt`. This
also puts `resolveUpgradeHeaders`' trace-context injection inside a
client span, as AGENTS.md requires.
- Fix `parseServer` to treat `wss:` as TLS (port 443, not 80).
Out of scope, deliberately: per-frame `traceparent` (needs a frame-meta
field plus a server change) and Vercel's outgoing-requests view (that
instruments global `fetch`, so a frame structurally cannot appear there).
Covered by `ws-transport-spans.test.ts`, which drives the real selection +
transport + adapter stack over a fake socket and asserts span shape,
failure reporting, retry behaviour and HTTP/WS parity.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-Authored-By: shalabhchaturvedi-7802 <shalabh.chaturvedi@vercel.com>
Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com>
@shalabhc
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requested review from
a team, fantix and msullivan
as code ownersAugust 13, 2026 00:59
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mentioned this pull request
Aug 13, 2026
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🦋 Changeset detected
Latest commit: 78a7c62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 17 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
Not sure what this means? Click here to learn what changesets are.
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example-nextjs-workflow-turbopackReadyReadyPreviewAug 13, 2026 1:02am
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The implementation is unchanged from approved #3452; this PR exists solely because the old branch acquired duplicated main commits during rebase. For the remaining review question: workflow.events.transport and workflow.event.type are supplied only by the event-write HTTP/WS callers. The extracted generic helper does not add them, so GET/LIST calls remain untagged.
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🧪 E2E Test Results
✅ All tests passed
E2E Test Summary
Summary
PassedFailedSkippedTotal
✅ ▲ Vercel Production346605904056
✅ 💻 Local Development353605204056
✅ 📦 Local Production381005584368
✅ 🐘 Local Postgres381005584368
✅ 🪟 Windows31200312
✅ vercel-multi-region270027
Total149610222617187
Details by Category
✅ ▲ Vercel Production
AppPassedFailedSkipped
✅ astro-node128028
✅ astro-quickjs128028
✅ example-node128028
✅ example-quickjs128028
✅ express-node128028
✅ express-quickjs128028
✅ fastify-node128028
✅ fastify-quickjs128028
✅ hono-node128028
✅ hono-quickjs128028
✅ nest-node128028
✅ nest-quickjs128028
✅ nextjs-turbopack-node15303
✅ nextjs-turbopack-quickjs15303
✅ nextjs-webpack-node15303
✅ nextjs-webpack-quickjs15303
✅ nitro-node128028
✅ nitro-quickjs128028
✅ nuxt-node128028
✅ nuxt-quickjs128028
✅ sveltekit-node14709
✅ sveltekit-quickjs14709
✅ tanstack-start-node128028
✅ tanstack-start-quickjs128028
✅ vite-node128028
✅ vite-quickjs128028
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable-node130026
✅ astro-stable-quickjs130026
✅ express-stable-node130026
✅ express-stable-quickjs130026
✅ fastify-stable-node130026
✅ fastify-stable-quickjs130026
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📋 View full workflow run
@github-actions
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Aug 13, 2026

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📊 Workflow Benchmarks
⏳ Benchmarks are running for 78a7c62... (run logs)
ℹ️ Metric definitions & methodology
Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)
All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.
Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.
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Sim World
Simulated world deterministic testing for races. Traces
🟠 Mint-ordered log — 6 fail of 41 total
log=mint-ordered · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
❌ stale-read-step-count-forkcompleted171.0mMISMATCH1
❌ stale-read-equal-step-countscompleted141.0mMISMATCH1
❌ step-vs-step-forkcompleted120msMISMATCH1
❌ step-vs-step-fork-fencedcompleted120msMISMATCH1
✅ fence-catches-benign-directioncompleted125msok0
❌ in-flight-before-decisioncompleted171.0mMISMATCH1
✅ in-flight-before-decision-countedcompleted201.0mok0
❌ in-flight-after-decisionfailed142.0mMISMATCH1
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-mint.txt
🟢 Append-only log — 0 fail of 41 total
log=append-only · fence=per-spec
scenariooutcomeeventsvirtreplayviolations
✅ smoke-no-stepscompleted30msok0
✅ smoke-one-stepcompleted60msok0
✅ hook-at-step-startedcompleted120msok0
✅ hook-at-step-completedcompleted120msok0
✅ hook-at-hook-createdcompleted120msok0
✅ deadline-hook-winscompleted71.0hok0
✅ deadline-expirescompleted71.0hok0
✅ long-sleepcompleted1130.0dok0
✅ hook-never-arrivesstalled30msskipped0
✅ step-retries-twicecompleted102.0sok0
✅ parallel-stepscompleted90msok0
✅ hook-on-execution-statecompleted120msok0
✅ peek-hook-before-branchcompleted120msok0
✅ peek-hook-after-branchcompleted120msok0
✅ peek-hook-at-registrationcompleted120msok0
✅ race-hook-before-probecompleted120msok0
✅ race-hook-after-probecompleted120msok0
✅ race-duplicate-deliverycompleted130msok0
✅ attr-hook-before-stepcompleted110msok0
✅ attr-hook-after-stepcompleted110msok0
✅ attr-from-step-bodycompleted130msok0
✅ fork-hook-after-timeoutcompleted141.0mok0
✅ fork-hook-before-timeoutcompleted141.0mok0
✅ count-hook-after-timeoutcompleted171.0mok0
✅ count-hook-before-timeoutcompleted201.0mok0
✅ stale-read-step-count-forkcompleted201.0mok0
✅ stale-read-equal-step-countscompleted141.0mok0
✅ step-vs-step-forkcompleted120msok0
✅ step-vs-step-fork-fencedcompleted120msok0
✅ fence-catches-benign-directioncompleted125msok0
✅ in-flight-before-decisioncompleted171.0mok0
✅ in-flight-before-decision-countedcompleted171.0mok0
✅ in-flight-after-decisioncompleted192.0mok0
✅ stale-read-step-count-fork-fencedcompleted201.0mok0
✅ fork-hook-winscompleted131.0mok0
✅ fork-timeout-winscompleted131.0mok0
✅ unclaimed-payload-under-forkcompleted171.0mok0
✅ claimed-payload-under-forkcompleted171.0mok0
✅ writers-independent-step-bodiescompleted120msok0
✅ writers-scripted-tempocompleted120msok0
✅ cancel-mid-stepcancelled70msskipped0
Full trace: world-sim-append-only.txt
@shalabhc
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Aug 13, 2026

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Closing the temporary replacement: #3452 has now been repaired in place with a clean force-with-lease rebase.
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