[core] Add a retention option to start() - #3787
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Adds `start({ retention })` for expressing a data-retention preference for
after a run completes. It is the typed spelling of a new reserved
`$retention` run attribute, which Worlds read at terminal cleanup.
- 'default' is not written at all, so it stays exactly equivalent to
omitting the option and spends none of the per-run attribute budget.
- 'none' and custom World-specific strings are seeded onto the run, with
the reserved-namespace opt-in set so the server accepts the `$` key.
- The value goes through the same validation as caller attributes, so an
oversized custom value fails in start() rather than at the World boundary.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
🦋 Changeset detectedLatest commit: 1888c75 The changes in this PR will be included in the next version bump. This PR includes changesets to release 20 packages
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📊 Workflow Benchmarkscommit Backend:
Streams
📈 STSO distribution vs main (inline / queue-hop histograms)1020 steps (inline) Cumulative STSO time: main 136860ms → this run 149131ms (Δ +12271ms, +9%) 📈 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): 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. |
🧪 E2E Test Results❌ Some tests failed ❌ Failed E2E Tests▲ Vercel Production (8 failed)python-node (8 failed):
🌐 Cross-language Conformance (9 failed)python (9 failed):
|
| Passed | Failed | Skipped | Total | |
|---|---|---|---|---|
| ❌ ▲ Vercel Production | 3570 | 8 | 742 | 4320 |
| ✅ 💻 Local Development | 3922 | 0 | 558 | 4480 |
| ✅ 📦 Local Production | 3922 | 0 | 558 | 4480 |
| ✅ 🐘 Local Postgres | 3922 | 0 | 558 | 4480 |
| ✅ 🪟 Windows | 320 | 0 | 0 | 320 |
| ❌ 🌐 Cross-language Conformance | 0 | 9 | 132 | 141 |
| ✅ vercel-http-transport | 817 | 0 | 143 | 960 |
| ✅ vercel-multi-region | 27 | 0 | 0 | 27 |
| ✅ vercel-ws-transport | 553 | 0 | 87 | 640 |
| Total | 17053 | 17 | 2778 | 19848 |
Details by Category
❌ ▲ Vercel Production
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-node | 132 | 0 | 28 |
| ✅ astro-quickjs | 132 | 0 | 28 |
| ✅ example-node | 132 | 0 | 28 |
| ✅ example-quickjs | 132 | 0 | 28 |
| ✅ express-node | 132 | 0 | 28 |
| ✅ express-quickjs | 132 | 0 | 28 |
| ✅ fastify-node | 132 | 0 | 28 |
| ✅ fastify-quickjs | 132 | 0 | 28 |
| ✅ hono-node | 132 | 0 | 28 |
| ✅ hono-quickjs | 132 | 0 | 28 |
| ✅ nest-node | 132 | 0 | 28 |
| ✅ nest-quickjs | 132 | 0 | 28 |
| ✅ nextjs-turbopack-node | 157 | 0 | 3 |
| ✅ nextjs-turbopack-quickjs | 157 | 0 | 3 |
| ✅ nextjs-webpack-node | 157 | 0 | 3 |
| ✅ nextjs-webpack-quickjs | 157 | 0 | 3 |
| ✅ nitro-node | 132 | 0 | 28 |
| ✅ nitro-quickjs | 132 | 0 | 28 |
| ✅ nuxt-node | 132 | 0 | 28 |
| ✅ nuxt-quickjs | 132 | 0 | 28 |
| ❌ python-node | 0 | 8 | 152 |
| ✅ sveltekit-node | 151 | 0 | 9 |
| ✅ sveltekit-quickjs | 151 | 0 | 9 |
| ✅ tanstack-start-node | 132 | 0 | 28 |
| ✅ tanstack-start-quickjs | 132 | 0 | 28 |
| ✅ vite-node | 132 | 0 | 28 |
| ✅ vite-quickjs | 132 | 0 | 28 |
✅ 💻 Local Development
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-stable-node | 134 | 0 | 26 |
| ✅ astro-stable-quickjs | 134 | 0 | 26 |
| ✅ express-stable-node | 134 | 0 | 26 |
| ✅ express-stable-quickjs | 134 | 0 | 26 |
| ✅ fastify-stable-node | 134 | 0 | 26 |
| ✅ fastify-stable-quickjs | 134 | 0 | 26 |
| ✅ hono-stable-node | 134 | 0 | 26 |
| ✅ hono-stable-quickjs | 134 | 0 | 26 |
| ✅ nest-stable-node | 134 | 0 | 26 |
| ✅ nest-stable-quickjs | 134 | 0 | 26 |
| ✅ nextjs-turbopack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-turbopack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-turbopack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-turbopack-stable-quickjs | 160 | 0 | 0 |
| ✅ nextjs-webpack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-webpack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-webpack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-webpack-stable-quickjs | 160 | 0 | 0 |
| ✅ nitro-stable-node | 134 | 0 | 26 |
| ✅ nitro-stable-quickjs | 134 | 0 | 26 |
| ✅ nuxt-stable-node | 134 | 0 | 26 |
| ✅ nuxt-stable-quickjs | 134 | 0 | 26 |
| ✅ sveltekit-stable-node | 153 | 0 | 7 |
| ✅ sveltekit-stable-quickjs | 153 | 0 | 7 |
| ✅ tanstack-start-node | 134 | 0 | 26 |
| ✅ tanstack-start-quickjs | 134 | 0 | 26 |
| ✅ vite-stable-node | 134 | 0 | 26 |
| ✅ vite-stable-quickjs | 134 | 0 | 26 |
✅ 📦 Local Production
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-stable-node | 134 | 0 | 26 |
| ✅ astro-stable-quickjs | 134 | 0 | 26 |
| ✅ express-stable-node | 134 | 0 | 26 |
| ✅ express-stable-quickjs | 134 | 0 | 26 |
| ✅ fastify-stable-node | 134 | 0 | 26 |
| ✅ fastify-stable-quickjs | 134 | 0 | 26 |
| ✅ hono-stable-node | 134 | 0 | 26 |
| ✅ hono-stable-quickjs | 134 | 0 | 26 |
| ✅ nest-stable-node | 134 | 0 | 26 |
| ✅ nest-stable-quickjs | 134 | 0 | 26 |
| ✅ nextjs-turbopack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-turbopack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-turbopack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-turbopack-stable-quickjs | 160 | 0 | 0 |
| ✅ nextjs-webpack-canary-node | 141 | 0 | 19 |
| ✅ nextjs-webpack-canary-quickjs | 141 | 0 | 19 |
| ✅ nextjs-webpack-stable-node | 160 | 0 | 0 |
| ✅ nextjs-webpack-stable-quickjs | 160 | 0 | 0 |
| ✅ nitro-stable-node | 134 | 0 | 26 |
| ✅ nitro-stable-quickjs | 134 | 0 | 26 |
| ✅ nuxt-stable-node | 134 | 0 | 26 |
| ✅ nuxt-stable-quickjs | 134 | 0 | 26 |
| ✅ sveltekit-stable-node | 153 | 0 | 7 |
| ✅ sveltekit-stable-quickjs | 153 | 0 | 7 |
| ✅ tanstack-start-node | 134 | 0 | 26 |
| ✅ tanstack-start-quickjs | 134 | 0 | 26 |
| ✅ vite-stable-node | 134 | 0 | 26 |
| ✅ vite-stable-quickjs | 134 | 0 | 26 |
✅ 🐘 Local Postgres
| App | Passed | Failed | Skipped |
|---|---|---|---|
| ✅ astro-stable-node | 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 |
Sim WorldSimulated world deterministic testing for races. Traces 🟠 world-sim scenario book — 1 fail of 41 total
Full trace: |
1 participant
Adds a
retentionoption tostart()so callers can express a data-retention preference for after a run completes.How it works
The option is the typed spelling of a new reserved run attribute,
$retention, exported from@workflow/worldasRETENTION_ATTRIBUTE.start()seeds it onto the run at creation, alongside the existing$rootRunId/$parentRunIdlineage keys, so it costs no extra write and rides both therun_createdevent and the resilient-start queue input. Worlds read it when a run reaches a terminal state.Decisions worth reviewing:
'default'writes nothing. The docstring says it is the same as omission, so writing$retention: 'default'would only spend one of the 64 per-run attribute slots to express what an absent key already means. It also keepsretention: 'default'from erroring on a World that predates attributes.$retentionattribute. A caller passing bothattributes: { '$retention': ... }(withallowReservedAttributes) andretention:gets the latter.retentionis the supported spelling; the raw attribute is the escape hatch. This is the opposite precedence from lineage, where caller attributes win, because lineage is inferred context andretentionis an explicit choice.'none'and custom values require spec version 4 or later and throw otherwise, matching how initialattributesbehave. Silently dropping a data-deletion preference would be worse than failing.normalizeAttributeChanges, so an oversized custom World value fails instart()with the attribute error rather than at the World boundary.'none' | 'default' | (string & {}), not'none' | 'default' | string. The two are identical at runtime, but the plainstringunion collapses and loses editor completions for the two known values. Same pattern asdeploymentId: 'latest' | (string & {}).Server side
The Vercel World implementation reads this attribute at terminal cleanup and deletes S3 ref payloads and stream content instead of tagging them for lifecycle expiration. That is a separate PR in the backend repo. Until it ships,
'none'is recorded on the run and otherwise inert, which is the safe failure mode: data keeps the plan's retention.Other Worlds ignore the attribute entirely today.
Test plan
New unit tests in
packages/core/src/runtime/start-retention.test.ts(10 cases): seeding and the reserved-namespace opt-in on both creation paths,'default'being byte-identical to omission, custom pass-through, coexistence with lineage and caller attributes, precedence over a hand-written attribute, the reserved-key rejection still firing without the escape hatch, the spec-version gate (and'default'not tripping it), and the oversized/empty value rejections.start.test.ts,start-lineage.test.tsandset-attributes.test.tspass unchanged.🤖 Generated with Claude Code