feat(world-vercel): enrich STSO event spans by shalabhc · Pull Request #3536 · vercel/workflow

shalabhc · 2026-08-14T00:01:50Z

Enrich the existing v4 event-write http POST CLIENT span. No new span is created.

The modified span is emitted by HTTP event writes through fetchV4 / instrumentedFetch and WebSocket event writes through the existing synthetic parity span in postEventFrameOverWs / withHttpClientSpan.

Added attributes

workflow.client.version on every v4 event write, formatted as @workflow/world-vercel/<version>
step.stso_ms when the event input carries step-to-step overhead telemetry
step.latency_optimizations when the event input carries the active runtime optimization list, such as lazyStepStart, turbo, and optimisticStart

The span already inherits the client application OTEL service.name and carries the event type, transport, URL, and status. The added fields allow sampled STSO analysis by client service, Workflow SDK version, and runtime mode on one span.

Validation

Dependency-aware @workflow/world-vercel build
ws-transport-spans.test.ts: 13 tests passed
@workflow/world-vercel typecheck
Biome and git diff --check

changeset-bot · 2026-08-14T00:01:55Z

🦋 Changeset detected

Latest commit: ba4e6f4

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

This PR includes changesets to release 17 packages

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

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

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

vercel · 2026-08-14T00:02:00Z

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview	Aug 14, 2026 5:15pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 14, 2026 5:15pm
example-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-astro-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-express-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-fastify-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-hono-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-nestjs-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-nitro-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-nuxt-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-python-workflow	Error		Aug 14, 2026 5:15pm
workbench-sveltekit-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-tanstack-start-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workbench-vite-workflow	Ready	Preview	Aug 14, 2026 5:15pm
workflow-docs	Ready	Preview, v0	Aug 14, 2026 5:15pm
workflow-swc-playground	Ready	Preview	Aug 14, 2026 5:15pm
workflow-tarballs	Ready	Preview	Aug 14, 2026 5:15pm
workflow-web	Ready	Preview	Aug 14, 2026 5:15pm

github-actions · 2026-08-14T00:02:13Z

🧪 E2E Test Results

✅ All tests passed

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3466	590	4056
✅ 💻 Local Development	3810	558	4368
✅ 📦 Local Production	3810	558	4368
✅ 🐘 Local Postgres	3810	558	4368
✅ 🪟 Windows	312	0	312
✅ vercel-multi-region	27	0	27
Total	15235	2264	17499

Details by Category

✅ ▲ Vercel Production

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

✅ 💻 Local Development

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

✅ 📦 Local Production

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

✅ 🐘 Local Postgres

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

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	156	0	0
✅ nextjs-turbopack-quickjs	156	0	0

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

📋 View full workflow run

github-actions · 2026-08-14T00:02:14Z

📊 Workflow Benchmarks

commit ba4e6f4 · Fri, 14 Aug 2026 17:33:36 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1301 (+438%) 🔻	1462 🔴 (+26%) 🔻	1475 🔴 (+22%) 🔻	1532 🔴 (+18%) 🔻	30
TTFS	stream	407 (+60%) 🔻	1456 🔴 (+29%) 🔻	1479 🔴 (+25%) 🔻	1665 🔴 (+34%) 🔻	30
TTFS	hook + stream	554 (+26%) 🔻	1779 🔴 (+26%) 🔻	1812 🔴 (+25%) 🔻	1935 🔴 (+25%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	8904 (-0.6%)	9118 (-11%)	9130 (-17%) 💚	10557 (-91%) 💚	10
Fan-out TTLS	Promise.all(100 steps)	17450 (-1.7%)	17933 (-6.0%)	17936 (-9.0%)	20529 (-83%) 💚	10
STSO	1020 steps (inline)	114 (-19%) 💚	164 (-22%) 💚	184 (-27%) 💚	272 (-51%) 💚	1019
WO	1020 steps	161271 (-25%) 💚	161271 (-25%) 💚	161271 (-25%) 💚	161271 (-25%) 💚	1
SL	stream latency	83 (-22%) 💚	130 🔴 (-13%)	134 🔴 (-26%) 💚	219 🔴 (-74%) 💚	30
SO	stream overhead (text)	104 (-17%) 💚	158 (-44%) 💚	172 (-59%) 💚	508 (-43%) 💚	30
SO	stream overhead (structured)	104 (-25%) 💚	161 (-55%) 💚	208 (-70%) 💚	421 (-62%) 💚	30

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

1020 steps (inline)

Cumulative STSO time: main 214388ms → this run 161115ms (Δ -53273ms, -25%)

  100-150 ms  █░░░░░░░░░░░░░░░┃         main  11  this 452  +441
  150-200 ms  ██████████████████┃█████  main 653  this 511  -142
  200-250 ms  ┃████████                 main 248  this  38  -210
  250-300 ms  ┃█                        main  54  this  12   -42
  300-350 ms  ┃                         main  17  this   3   -14
  350-400 ms  ┃                         main  14  this   1   -13
  400-450 ms  ┃                         main   4  this   1    -3
  450-500 ms  ┃                         main   4  this   0    -4
  500-550 ms  ┃                         main   3  this   0    -3
  550-600 ms  ┃                         main   3  this   0    -3
  600-650 ms  ┃                         main   2  this   0    -2
  650-700 ms  ┃                         main   2  this   0    -2
  700-750 ms  ┃                         main   0  this   1    +1
  750-800 ms  ┃                         main   1  this   0    -1
  850-900 ms  ┃                         main   1  this   0    -1
1000-1050 ms  ┃                         main   1  this   0    -1
5100-5150 ms  ┃                         main   1  this   0    -1

📜 Previous results (2)

`f703e17`

Fri, 14 Aug 2026 16:31:51 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	268 (-30%) 💚	1376 🔴 (+23%) 🔻	1386 🔴 (+22%) 🔻	1430 🔴 (-6.7%)	30
TTFS	stream	224 (-78%) 💚	1342 🔴 (+27%) 🔻	1352 🔴 (+26%) 🔻	1410 🔴 (+27%) 🔻	30
TTFS	hook + stream	1573 (+23%) 🔻	1679 🔴 (+21%) 🔻	1721 🔴 (+21%) 🔻	1877 🔴 (+16%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	8856 (-0.7%)	10084 (+1.3%)	10330 (+2.5%)	14629 (+8.2%)	10
Fan-out TTLS	Promise.all(100 steps)	17572 (-0.6%)	18970 (+0.5%)	19138 (+0.7%)	24484 (+4.5%)	10
STSO	1020 steps (inline)	133 (+8.1%)	170 (-11%)	185 (-19%) 💚	280 (-52%) 💚	1019
WO	1020 steps	169621 (-13%)	169621 (-13%)	169621 (-13%)	169621 (-13%)	1
SL	stream latency	85 (+7.6%)	125 🔴 (+14%)	144 🔴 (+12%)	214 🔴 (-38%) 💚	30
SO	stream overhead (text)	99 (-11%)	161 (-11%)	179 (-13%)	228 (-62%) 💚	30
SO	stream overhead (structured)	98 (+2.1%)	160 (+2.6%)	194 (+16%) 🔻	306 (+68%) 🔻	30

`83e8ee8`

Fri, 14 Aug 2026 00:24:34 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1334 (+250%) 🔻	1490 🔴 (+34%) 🔻	1574 🔴 (+38%) 🔻	1615 🔴 (+5.4%)	30
TTFS	stream	367 (-63%) 💚	1527 🔴 (+44%) 🔻	1582 🔴 (+48%) 🔻	1639 🔴 (+48%) 🔻	30
TTFS	hook + stream	1570 (+23%) 🔻	1682 🔴 (+21%) 🔻	1716 🔴 (+20%) 🔻	1869 🔴 (+15%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	8855 (-0.7%)	9542 (-4.1%)	10867 (+7.8%)	15161 (+12%)	10
Fan-out TTLS	Promise.all(100 steps)	17489 (-1.0%)	18114 (-4.0%)	19416 (+2.2%)	24838 (+6.0%)	10
STSO	1020 steps (inline)	141 (+15%)	178 (-6.8%)	196 (-14%)	289 (-50%) 💚	1019
WO	1020 steps	176571 (-9.6%)	176571 (-9.6%)	176571 (-9.6%)	176571 (-9.6%)	1
SL	stream latency	95 (+20%) 🔻	137 🔴 (+25%) 🔻	151 🔴 (+17%) 🔻	385 🔴 (+12%)	30
SO	stream overhead (text)	120 (+8.1%)	187 (+3.9%)	199 (-3.4%)	1077 🔴 (+78%) 🔻	30
SO	stream overhead (structured)	121 (+26%) 🔻	186 (+19%) 🔻	203 (+22%) 🔻	473 (+160%) 🔻	30

ℹ️ Metric definitions & methodology

_{The collapsed STSO distribution section above buckets every step gap of the sequential-steps run (not a sampled window), split by whether the step ending the gap ran inline — in the same warm process as the step before it, so the gap is pure framework overhead — or after a queue-hop — the first step of a fresh process, which pays queue dispatch, client reinit and event-log replay. Bars overlay the two runs: █ is main, ┃ marks where this run lands, ░ bridges the gap when this run has more samples in a bucket.}

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

_{Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · Fan-out TTFS: fan-out time to first step (in-deployment start() → first of the parallel step bodies to complete) · Fan-out TTLS: fan-out time to last step (in-deployment start() → last of the parallel step bodies to complete, i.e. when the Promise.all resolves) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)}

_{Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · Promise.all(100 steps): 100 trivial no-op steps started together in a single Promise.all; Fan-out TTFS is the first of them to complete and Fan-out TTLS the last, both from the in-deployment clientStart, so their gap is the spread the runtime adds across the fan-out · stream latency: parallel reader/writer steps on a dedicated stream; SL is the in-deployment write->read propagation (readAt - writtenAt) · stream overhead (text): writer streams 300 variable-length text token deltas paced at 100/s for 3s (a haiku-size LLM's token throughput) while a parallel reader drains the whole stream; SO is the end-to-end write+consume time beyond the 3s generation window (overhead/backpressure) · stream overhead (structured): same workload as stream overhead (text), but each delta is an AI-SDK-style structured object ({ type: 'text-delta', id, text }) instead of a raw string, so the SO gap vs the text scenario is the added serialization cost}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600 · SL 50/60/125 · SO 250/500/1000}

_{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. Fan-out TTFS/TTLS are the first and last step completions of a single Promise.all over trivial steps, from the same anchor, so the gap between the two rows is the spread the runtime adds across the fan-out. 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.}

github-actions · 2026-08-14T00:05:22Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 Mint-ordered log — 3 fail of 41 total

log=mint-ordered · fence=per-spec

scenario	outcome	events	virt	replay	violations
✅ `smoke-no-steps`	completed	3	0ms	ok	0
✅ `smoke-one-step`	completed	6	0ms	ok	0
✅ `hook-at-step-started`	completed	12	0ms	ok	0
✅ `hook-at-step-completed`	completed	12	0ms	ok	0
✅ `hook-at-hook-created`	completed	12	0ms	ok	0
✅ `deadline-hook-wins`	completed	7	1.0h	ok	0
✅ `deadline-expires`	completed	7	1.0h	ok	0
✅ `long-sleep`	completed	11	30.0d	ok	0
✅ `hook-never-arrives`	stalled	3	0ms	skipped	0
✅ `step-retries-twice`	completed	10	2.0s	ok	0
✅ `parallel-steps`	completed	9	0ms	ok	0
✅ `hook-on-execution-state`	completed	12	0ms	ok	0
✅ `peek-hook-before-branch`	completed	12	0ms	ok	0
✅ `peek-hook-after-branch`	completed	12	0ms	ok	0
✅ `peek-hook-at-registration`	completed	12	0ms	ok	0
✅ `race-hook-before-probe`	completed	12	0ms	ok	0
✅ `race-hook-after-probe`	completed	12	0ms	ok	0
✅ `race-duplicate-delivery`	completed	13	0ms	ok	0
✅ `attr-hook-before-step`	completed	11	0ms	ok	0
✅ `attr-hook-after-step`	completed	11	0ms	ok	0
✅ `attr-from-step-body`	completed	13	0ms	ok	0
✅ `fork-hook-after-timeout`	completed	14	1.0m	ok	0
✅ `fork-hook-before-timeout`	completed	14	1.0m	ok	0
✅ `count-hook-after-timeout`	completed	17	1.0m	ok	0
✅ `count-hook-before-timeout`	completed	20	1.0m	ok	0
✅ `stale-read-step-count-fork`	completed	20	1.0m	ok	0
✅ `stale-read-equal-step-counts`	completed	14	1.0m	ok	0
✅ `step-vs-step-fork`	completed	12	0ms	ok	0
✅ `step-vs-step-fork-fenced`	completed	12	0ms	ok	0
✅ `fence-catches-benign-direction`	completed	12	5ms	ok	0
❌ `in-flight-before-decision`	failed	9	1.0m	MISMATCH	1
❌ `in-flight-before-decision-counted`	failed	9	1.0m	MISMATCH	1
❌ `in-flight-after-decision`	failed	9	1.0m	MISMATCH	1
✅ `stale-read-step-count-fork-fenced`	completed	20	1.0m	ok	0
✅ `fork-hook-wins`	completed	13	1.0m	ok	0
✅ `fork-timeout-wins`	completed	13	1.0m	ok	0
✅ `unclaimed-payload-under-fork`	completed	17	1.0m	ok	0
✅ `claimed-payload-under-fork`	completed	17	1.0m	ok	0
✅ `writers-independent-step-bodies`	completed	12	0ms	ok	0
✅ `writers-scripted-tempo`	completed	12	0ms	ok	0
✅ `cancel-mid-step`	cancelled	7	0ms	skipped	0

Full trace: world-sim-mint.txt

🟢 Append-only log — 0 fail of 41 total

log=append-only · fence=per-spec

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

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

karthikscale3

looks good

Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com> Co-Authored-By: Shalabh Chaturvedi <7066873+shalabhc@users.noreply.github.com>

Co-Authored-By: Shalabh Chaturvedi <7066873+shalabhc@users.noreply.github.com>

github-actions · 2026-08-14T18:34:33Z

No backport to stable for 63cc09e (AI decision).

This commit adds new observability capability — three new OTEL semantic-convention attributes (workflow.client.version, step.stso_ms, step.latency_optimizations) on the existing event-write client span, plus a widened attribute type to carry string arrays. It is additive feature work (enabling sampled STSO analysis by service/version/runtime mode), not a fix for a correctness, crash, or data-loss defect on the maintenance line, and the PR is titled and scoped as a feat. Maintenance-branch users gain no stability benefit from it.

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

63cc09e24f41ea0f691d6190309cfd92fb8de94e

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vercel Bot and others added 2 commits August 14, 2026 17:11

feat(world-vercel): enrich STSO event spans

32b3cd9

Co-Authored-By: shalabhc <shalabh.chaturvedi@vercel.com> Co-Authored-By: Shalabh Chaturvedi <7066873+shalabhc@users.noreply.github.com>

feat(world-vercel): add optimizations to STSO spans

ba4e6f4

Co-Authored-By: Shalabh Chaturvedi <7066873+shalabhc@users.noreply.github.com>

shalabhc force-pushed the investigate-stso-latency branch from f703e17 to ba4e6f4 Compare August 14, 2026 17:11

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shalabhc marked this pull request as ready for review August 14, 2026 18:33

shalabhc merged commit 63cc09e into main Aug 14, 2026
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shalabhc deleted the investigate-stso-latency branch August 14, 2026 18:33

github-actions Bot mentioned this pull request Aug 14, 2026

Version Packages (beta) #3466

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feat(world-vercel): enrich STSO event spans - #3536

feat(world-vercel): enrich STSO event spans#3536
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