Uh oh!
There was an error while loading. Please reload this page.
[core] Make a duplicate attr_set inert instead of terminal - #3849
Conversation
A workflow-body attribute write draws a correlation id that resolves exactly once: the dispatcher's consumer takes the matching event and deregisters. A second event under that id therefore has no callback left and never will. `attr_set` had no entry in ENTITY_EVENT_CLASS_BY_TYPE, so the duplicate skip could not take it, and `PARKABLE_EVENT_TYPES` does list the type, so it was parked for a consumer that could never come. Parking is settled by the workflow function returning, and a survivor there is reported through `strandedEvent` as a replay divergence. So the run did all of its work, every step succeeded, and the final replay failed it, deterministically enough to burn the whole replay-divergence recovery budget and terminate with CORRUPTED_EVENT_LOG. Give `attr_set` a class so the straggler is skipped like every other one: committed but inert. Parking still covers the first arrival, for a replay that walks past an attribute event before the body reaches the call that claims it. An attribute write from a step body carries no correlation id and is consumed by the structural lifecycle consumer, so it is unaffected. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
🦋 Changeset detectedLatest commit: 0d4612c The changes in this PR will be included in the next version bump. This PR includes changesets to release 20 packages
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 |
🧪 E2E Test Results❌ Some tests failed ❌ Failed E2E Tests▲ Vercel Production (8 failed)python-node (8 failed):
💻 Local Development (1 failed)vite-stable-quickjs (1 failed):
🌐 Cross-language Conformance (9 failed)python (9 failed):
|
| Passed | Failed | Skipped | Total | |
|---|---|---|---|---|
| ❌ ▲ Vercel Production | 3570 | 8 | 742 | 4320 |
| ❌ 💻 Local Development | 3921 | 1 | 558 | 4480 |
| ✅ 📦 Local Production | 3922 | 0 | 558 | 4480 |
| ✅ 🐘 Local Postgres | 3922 | 0 | 558 | 4480 |
| ✅ 🪟 Windows | 320 | 0 | 0 | 320 |
| ❌ 🌐 Cross-language Conformance | 0 | 9 | 132 | 141 |
| ✅ vercel-http-transport | 817 | 0 | 143 | 960 |
| ✅ vercel-multi-region | 27 | 0 | 0 | 27 |
| ✅ vercel-ws-transport | 553 | 0 | 87 | 640 |
| Total | 17052 | 18 | 2778 | 19848 |
Details by Category
❌ ▲ Vercel Production
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-node | 132 | 0 | 28 |
| ✅ astro-quickjs | 132 | 0 | 28 |
| ✅ example-node | 132 | 0 | 28 |
| ✅ example-quickjs | 132 | 0 | 28 |
| ✅ express-node | 132 | 0 | 28 |
| ✅ express-quickjs | 132 | 0 | 28 |
| ✅ fastify-node | 132 | 0 | 28 |
| ✅ fastify-quickjs | 132 | 0 | 28 |
| ✅ hono-node | 132 | 0 | 28 |
| ✅ hono-quickjs | 132 | 0 | 28 |
| ✅ nest-node | 132 | 0 | 28 |
| ✅ nest-quickjs | 132 | 0 | 28 |
| ✅ nextjs-turbopack-node | 157 | 0 | 3 |
| ✅ nextjs-turbopack-quickjs | 157 | 0 | 3 |
| ✅ nextjs-webpack-node | 157 | 0 | 3 |
| ✅ nextjs-webpack-quickjs | 157 | 0 | 3 |
| ✅ nitro-node | 132 | 0 | 28 |
| ✅ nitro-quickjs | 132 | 0 | 28 |
| ✅ nuxt-node | 132 | 0 | 28 |
| ✅ nuxt-quickjs | 132 | 0 | 28 |
| ❌ python-node | 0 | 8 | 152 |
| ✅ sveltekit-node | 151 | 0 | 9 |
| ✅ sveltekit-quickjs | 151 | 0 | 9 |
| ✅ tanstack-start-node | 132 | 0 | 28 |
| ✅ tanstack-start-quickjs | 132 | 0 | 28 |
| ✅ vite-node | 132 | 0 | 28 |
| ✅ vite-quickjs | 132 | 0 | 28 |
❌ 💻 Local Development
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-stable-node | 134 | 0 | 26 |
| ✅ astro-stable-quickjs | 134 | 0 | 26 |
| ✅ express-stable-node | 134 | 0 | 26 |
| ✅ express-stable-quickjs | 134 | 0 | 26 |
| ✅ fastify-stable-node | 134 | 0 | 26 |
| ✅ fastify-stable-quickjs | 134 | 0 | 26 |
| ✅ hono-stable-node | 134 | 0 | 26 |
| ✅ hono-stable-quickjs | 134 | 0 | 26 |
| ✅ nest-stable-node | 134 | 0 | 26 |
| ✅ nest-stable-quickjs | 134 | 0 | 26 |
| ✅ nextjs-turbopack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-turbopack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-turbopack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-turbopack-stable-quickjs | 160 | 0 | 0 |
| ✅ nextjs-webpack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-webpack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-webpack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-webpack-stable-quickjs | 160 | 0 | 0 |
| ✅ nitro-stable-node | 134 | 0 | 26 |
| ✅ nitro-stable-quickjs | 134 | 0 | 26 |
| ✅ nuxt-stable-node | 134 | 0 | 26 |
| ✅ nuxt-stable-quickjs | 134 | 0 | 26 |
| ✅ sveltekit-stable-node | 153 | 0 | 7 |
| ✅ sveltekit-stable-quickjs | 153 | 0 | 7 |
| ✅ tanstack-start-node | 134 | 0 | 26 |
| ✅ tanstack-start-quickjs | 134 | 0 | 26 |
| ✅ vite-stable-node | 134 | 0 | 26 |
| ❌ vite-stable-quickjs | 133 | 1 | 26 |
✅ 📦 Local Production
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-stable-node | 134 | 0 | 26 |
| ✅ astro-stable-quickjs | 134 | 0 | 26 |
| ✅ express-stable-node | 134 | 0 | 26 |
| ✅ express-stable-quickjs | 134 | 0 | 26 |
| ✅ fastify-stable-node | 134 | 0 | 26 |
| ✅ fastify-stable-quickjs | 134 | 0 | 26 |
| ✅ hono-stable-node | 134 | 0 | 26 |
| ✅ hono-stable-quickjs | 134 | 0 | 26 |
| ✅ nest-stable-node | 134 | 0 | 26 |
| ✅ nest-stable-quickjs | 134 | 0 | 26 |
| ✅ nextjs-turbopack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-turbopack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-turbopack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-turbopack-stable-quickjs | 160 | 0 | 0 |
| ✅ nextjs-webpack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-webpack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-webpack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-webpack-stable-quickjs | 160 | 0 | 0 |
| ✅ nitro-stable-node | 134 | 0 | 26 |
| ✅ nitro-stable-quickjs | 134 | 0 | 26 |
| ✅ nuxt-stable-node | 134 | 0 | 26 |
| ✅ nuxt-stable-quickjs | 134 | 0 | 26 |
| ✅ sveltekit-stable-node | 153 | 0 | 7 |
| ✅ sveltekit-stable-quickjs | 153 | 0 | 7 |
| ✅ tanstack-start-node | 134 | 0 | 26 |
| ✅ tanstack-start-quickjs | 134 | 0 | 26 |
| ✅ vite-stable-node | 134 | 0 | 26 |
| ✅ vite-stable-quickjs | 134 | 0 | 26 |
✅ 🐘 Local Postgres
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-stable-node | 134 | 0 | 26 |
| ✅ astro-stable-quickjs | 134 | 0 | 26 |
| ✅ express-stable-node | 134 | 0 | 26 |
| ✅ express-stable-quickjs | 134 | 0 | 26 |
| ✅ fastify-stable-node | 134 | 0 | 26 |
| ✅ fastify-stable-quickjs | 134 | 0 | 26 |
| ✅ hono-stable-node | 134 | 0 | 26 |
| ✅ hono-stable-quickjs | 134 | 0 | 26 |
| ✅ nest-stable-node | 134 | 0 | 26 |
| ✅ nest-stable-quickjs | 134 | 0 | 26 |
| ✅ nextjs-turbopack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-turbopack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-turbopack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-turbopack-stable-quickjs | 160 | 0 | 0 |
| ✅ nextjs-webpack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-webpack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-webpack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-webpack-stable-quickjs | 160 | 0 | 0 |
| ✅ nitro-stable-node | 134 | 0 | 26 |
| ✅ nitro-stable-quickjs | 134 | 0 | 26 |
| ✅ nuxt-stable-node | 134 | 0 | 26 |
| ✅ nuxt-stable-quickjs | 134 | 0 | 26 |
| ✅ sveltekit-stable-node | 153 | 0 | 7 |
| ✅ sveltekit-stable-quickjs | 153 | 0 | 7 |
| ✅ tanstack-start-node | 134 | 0 | 26 |
| ✅ tanstack-start-quickjs | 134 | 0 | 26 |
| ✅ vite-stable-node | 134 | 0 | 26 |
| ✅ vite-stable-quickjs | 134 | 0 | 26 |
✅ 🪟 Windows
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ nextjs-turbopack-node | 160 | 0 | 0 |
| ✅ nextjs-turbopack-quickjs | 160 | 0 | 0 |
❌ 🌐 Cross-language Conformance
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ❌ python | 0 | 9 | 132 |
✅ vercel-http-transport
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ example | 132 | 0 | 28 |
| ✅ express | 132 | 0 | 28 |
| ✅ hono | 132 | 0 | 28 |
| ✅ nextjs-turbopack | 157 | 0 | 3 |
| ✅ nitro | 132 | 0 | 28 |
| ✅ vite | 132 | 0 | 28 |
✅ vercel-multi-region
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ nextjs-turbopack | 27 | 0 | 0 |
✅ vercel-ws-transport
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ example | 132 | 0 | 28 |
| ✅ express | 132 | 0 | 28 |
| ✅ nextjs-turbopack | 157 | 0 | 3 |
| ✅ vite | 132 | 0 | 28 |
📊 Workflow Benchmarkscommit Backend:
Streams
📈 STSO distribution vs main (inline / queue-hop histograms)1020 steps (inline) Cumulative STSO time: main 153650ms → this run 144769ms (Δ -8881ms, -6%) 📈 CRTT drill-down vs main (RTT distributions & profiles)RTT over stream progress (avg per tenth of stream, bars scaled min→max): RTT by chunk size (avg per log size bin, ~160B → ~12KB serialized, bars scaled min→max): Delivery jitter over stream progress (avg positive CDV per tenth of stream, bars scaled min→max): 📜 Previous results (1)20f051fThu, 27 Aug 2026 17:22:14 GMT · run logs
Streams
ℹ️ Metric definitions & methodologyStreams: first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach. The collapsed STSO distribution section above buckets every step gap, split inline (same warm process — pure framework overhead) vs queue-hop (fresh process — dispatch, reinit, replay). The collapsed CRTT drill-down: per-variant RTT histograms (fixed log bins, Best/P75/P90/P99 deltas compare against the most recent benchmark run on Metrics — TTFS: time to first step body (in-deployment start() → first step body) · Fan-out TTFS: fan-out time to first step (in-deployment start() → first of the parallel step bodies to complete) · Fan-out TTLS: fan-out time to last step (in-deployment start() → last of the parallel step bodies to complete, i.e. when the Promise.all resolves) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · CRTT: chunk round-trip time (per-chunk write → read latency, one clock domain: deployment → stream backend → same deployment) · CDV: chunk delay variation / delivery jitter (inter-arrival gap minus inter-write gap per seq-adjacent pair; skew-free; the row is each run's MAX positive value, so one stall moves it) Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · Promise.all(100 steps): 100 trivial no-op steps started together in a single Promise.all; Fan-out TTFS is the first of them to complete and Fan-out TTLS the last, both from the in-deployment clientStart, so their gap is the spread the runtime adds across the fan-out · paced control (100/s, 60B): the control: 300 tiny (~60B) deltas metronome-paced at 100/s — zero workload structure, so it reads the transport floor and flush cadence, and disambiguates transport-wide vs workload-specific when a replay row moves · size sweep (100/s, 160B-12KB): same pacing as the control with deltas padded in rotation across seven log-spaced sizes (~160B–12KB) — rotation decouples size from stream position, so it isolates whether chunk size causes latency · replay gateway-gpt-5.4-nano-2000t (1x): raw provider SSE cadence captured at the AI gateway boundary (gpt-5.4-nano, the most popular gateway model; per-token deltas p50 208B = the modal production chunk size), replayed exactly as measured — the typical customer's workload; its CDV is the typical customer's real delivery jitter · replay eve-gpt-5.6-sol-2000t (1x): a captured eve turn (gpt-5.6-sol, the most-used demanding eve model; ~2000 output tokens = production p50 turn length) replayed exactly as measured — eve's envelope protocol re-ships the cumulative message so sizes ramp 142B→13KB; the demanding outlier tenant's reality · replay eve-gpt-5.6-sol-2000t (2x): the same eve capture at 2x — the headroom/stress row; real fast-tier models emit the same chunk sizes at proportionally higher rate, so time compression is a faithful speed model · first chunk (pooled): every run's seq-0 RTT pooled across all stream scenarios — the first chunk precedes any workload differentiation, so pooling samples one shared stream-open path with exact percentiles Replay cadences (semantic sha256) — eve-gpt-5.6-sol-2000t 🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600 All timestamps are deployment-side; runs are triggered in-deployment, so the CI runner and api.vercel.com sit outside every measured window. TTFS = Cold starts stay in the numbers (real bursty-workload latency, inflates P75+); Best is the warm floor. |
Sim WorldSimulated world deterministic testing for races. Traces 🟠 world-sim scenario book — 1 fail of 41 total
Full trace: |
About these numbersSizes are gzip; parentheses show the change against
|
The class map alone decides a straggler only where the walk meets it after a consumption recorded the class. When neither copy has a consumer yet both park — the walk steps over the first and re-enters in the same tick, with nothing consumed and so no class recorded — and the drain then claims one and holds the other for a callback that will never be registered. That survivor is `strandedEvent`, which is the CORRUPTED_EVENT_LOG this branch set out to stop, reached by the other road. `dropParkedDuplicates` releases it on the same terms the walk skips one. Not an `attr_set` property: `wait_completed` parks in pairs too, and `ONE_SHOT_EVENT_TYPES` only sees the order where the consumption came first. Giving `attr_set` a class also moved the observability UI, which reads the same `entityEventClass` to grey out events a run passed over. It kept treating the straggler as live, because its terminal-class set had no `attr_set` while the dispatcher's consumer does deregister on the first event under an id. The two now share `classifyEntityEvent` and `TERMINAL_EVENT_CLASSES` rather than each keeping a copy of the rule. That sharing needs the entity rule to be exact, because a step-written `attr_set` carries no correlation id: keyed on the run it would collapse every attribute write a run made into one class, and a captured production log in `__fixtures__` holds forty. `classifyEntityEvent` gives such an event no class at all, so neither side can read the second as a repeat of the first. The shared fixture corpus had nothing for `attr_set`, which is why the drift between the two halves went unseen. It has four now, and each of them fails on both sides without the fix above it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
pranaygp
commented
Aug 28, 2026
Took this over to finish it — the bot's suggestion was correct, and chasing it turned up a second gap in a neighbouring codebase. Pushed as 0d4612c. 1. The parked ordering (the bot's finding)Confirmed and reproduced. The class map decides a straggler only where the walk meets it after a consumption recorded the class. When neither copy has a consumer yet, both park — the walk steps over the first and re-enters in the same tick, with nothing consumed and so no class recorded — and
2. The observability UI stopped agreeing with the runtimeGiving The two now share 3. Step-written attribute events must not collapseThat sharing needs the entity rule to be exact. A step-written Coverage
Green: core 2291, world 165, web-shared 212, typecheck clean. Sim book unchanged at 41 scenarios / 1 fail — Not done: a sim-world scenario for the duplicate write. Producing a genuine second The two failing checks are both pre-existing: |
No backport to This is a genuine correctness fix (a parked duplicate To override, re-run the Backport to stable workflow manually via |
Problem
A workflow-body attribute write draws a correlation id that resolves exactly once: the dispatcher's consumer takes the matching event and deregisters. If the log ends up holding a second
attr_setunder that id — two replays at the same body position draw the same id, and a World commits both — that second event has no callback left, and never will.attr_sethad no entry inENTITY_EVENT_CLASS_BY_TYPE, so the duplicate skip could not take it. It is inPARKABLE_EVENT_TYPES, so it was parked instead, waiting for a consumer that cannot come.Parking is settled by the workflow function returning, and anything still held there is reported through
strandedEvent:So the run did all of its work — every step completed successfully — and then the final replay, the one where the body returns, failed it. Because the log is immutable, every recovery replay reproduced it identically, which burned the whole
REPLAY_DIVERGENCE_MAX_RETRIESbudget in about a second and terminated the run withCORRUPTED_EVENT_LOG.This has been observed in production. It is rare (it needs two replays to land on the same drawn attribute id), but when it happens the run is always lost, always at the very end, and always after the user-visible work has already succeeded.
Fix
Give
attr_setan entity event class. The straggler then takesskipDuplicateEventlike every other one — committed but inert, which is the invariantduplicate-events.test.tsalready documents forstep_created/step_started/wait_created.Parking still covers the case it was added for: an
attr_setthe walk reaches before the body has made the call that claims it. That one is a first arrival, still owed to a consumer, and is unaffected.An attribute write from a step body carries no correlation id and is claimed by the structural lifecycle consumer in
workflow.tson the way past, so it is consumed rather than skipped, and several of them never collapse into one class.Tests
Three, all failing before the change except the guard:
events-consumer.test.ts— a secondattr_setfor a resolved id is skipped, reports throughonDuplicateEvent, leaves nothing stranded, and the walk still reaches the event after it.events-consumer.test.ts— a first-arrivalattr_setwith no subscriber yet still parks and is still claimable by a late subscriber (guards against the skip swallowing it; passes before and after).duplicate-events.test.ts— drives the realsetAttributesprimitive against a log holding the duplicate, and assertsstrandedEventis undefined once the body returns. This is the exact predicateworkflow.tsevaluates.packages/core2284 passed,packages/world165 passed.Note
This is the read side. The write side — a World committing two events under one drawn id — is worth closing separately; this change means a run survives it either way.