Fix duplicate transforms of Nitro build artifacts

[NathanColosimo]

Summary

• skip Workflow transforms for generated Nitro build artifacts
• cover both the Vite and Nitro Rollup transform hooks with a regression test

Testing

• pnpm vitest run packages/nitro/src/index.test.ts
• pnpm --filter @workflow/nitro build
• reproduced and verified the fix with TanStack Start, ssr.noExternal: true, and @ai-sdk/gateway@4.0.16

Closes #2894

[changeset-bot]

🦋 Changeset detected

Latest commit: aaa603e

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

This PR includes changesets to release 16 packages

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

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[vercel]

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, Comment	Jul 14, 2026 9:39pm
example-nextjs-workflow-webpack	Ready	Preview, Comment	Jul 14, 2026 9:39pm
example-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-astro-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-express-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-fastify-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-hono-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-nitro-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-nuxt-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-sveltekit-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-tanstack-start-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workbench-vite-workflow	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workflow-docs	Ready	Preview, Comment, Open in v0	Jul 14, 2026 9:39pm
workflow-swc-playground	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workflow-tarballs	Ready	Preview, Comment	Jul 14, 2026 9:39pm
workflow-web	Ready	Preview, Comment	Jul 14, 2026 9:39pm

[github-actions]

🧪 E2E Test Results

✅ All tests passed

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	1453	0	230	1683
✅ 💻 Local Development	1617	0	219	1836
✅ 📦 Local Production	1617	0	219	1836
✅ 🐘 Local Postgres	1617	0	219	1836
✅ 🪟 Windows	153	0	0	153
✅ 📋 Other	894	0	177	1071
✅ vercel-multi-region	27	0	0	27
Total	7378	0	1064	8442

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro	126	0	27
✅ example	126	0	27
✅ express	126	0	27
✅ fastify	126	0	27
✅ hono	126	0	27
✅ nextjs-turbopack	150	0	3
✅ nextjs-webpack	150	0	3
✅ nitro	126	0	27
✅ nuxt	126	0	27
✅ sveltekit	145	0	8
✅ vite	126	0	27

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable	128	0	25
✅ express-stable	128	0	25
✅ fastify-stable	128	0	25
✅ hono-stable	128	0	25
✅ nextjs-turbopack-canary	134	0	19
✅ nextjs-turbopack-stable	153	0	0
✅ nextjs-webpack-canary	134	0	19
✅ nextjs-webpack-stable	153	0	0
✅ nitro-stable	128	0	25
✅ nuxt-stable	128	0	25
✅ sveltekit-stable	147	0	6
✅ vite-stable	128	0	25

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable	128	0	25
✅ express-stable	128	0	25
✅ fastify-stable	128	0	25
✅ hono-stable	128	0	25
✅ nextjs-turbopack-canary	134	0	19
✅ nextjs-turbopack-stable	153	0	0
✅ nextjs-webpack-canary	134	0	19
✅ nextjs-webpack-stable	153	0	0
✅ nitro-stable	128	0	25
✅ nuxt-stable	128	0	25
✅ sveltekit-stable	147	0	6
✅ vite-stable	128	0	25

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable	128	0	25
✅ express-stable	128	0	25
✅ fastify-stable	128	0	25
✅ hono-stable	128	0	25
✅ nextjs-turbopack-canary	134	0	19
✅ nextjs-turbopack-stable	153	0	0
✅ nextjs-webpack-canary	134	0	19
✅ nextjs-webpack-stable	153	0	0
✅ nitro-stable	128	0	25
✅ nuxt-stable	128	0	25
✅ sveltekit-stable	147	0	6
✅ vite-stable	128	0	25

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack	153	0	0

✅ 📋 Other

App	Passed	Failed	Skipped
✅ e2e-local-dev-nest-stable	128	0	25
✅ e2e-local-dev-tanstack-start-	128	0	25
✅ e2e-local-postgres-nest-stable	128	0	25
✅ e2e-local-postgres-tanstack-start-	128	0	25
✅ e2e-local-prod-nest-stable	128	0	25
✅ e2e-local-prod-tanstack-start-	128	0	25
✅ e2e-vercel-prod-tanstack-start	126	0	27

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

commit aaa603e · Tue, 14 Jul 2026 21:56:02 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Avg (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	stream	1226 (-9.8%)	1690 🔴	1768 🔴	1903 🔴	30
TTFS	hook + stream	1645 (+2.6%)	1907 🔴	1987 🔴	2138 🔴	30
STSO	1020 steps (1-20)	263 (-6.9%)	288 🔴	345 🔴	351 🔴	19
STSO	1020 steps (101-120)	432 (-3.1%)	486 🔴	739 🔴	741 🔴	19
STSO	1020 steps (1001-1020)	868 (+4.1%)	931 🔴	1024 🔴	1172 🔴	19
WO	stream	1226 (-9.8%)	1690	1768	1903	30
WO	hook + stream	1645 (+2.6%)	1907	1987	2138	30
SL	stream	4148 (-14%)	5726 🔴	5844 🔴	6190 🔴	30
SL	hook + stream	4739 (±0%)	5153 🔴	5663 🔴	5806 🔴	30

_{Avg deltas compare against the most recent benchmark run on main at the time of this run.}

_{Metrics — TTFS: time to first step body execution · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (time outside step bodies, client start → last step body exit) · SL: stream latency (first chunk write → visible to the reader)}

_{Scenarios — stream: one step that streams chunks back to the client; no hooks, so the run stays in turbo mode · hook + stream: registers a hook before the same streaming step, which exits turbo mode · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges}

_{🟢/🔴 mark percentiles within/above target. Targets (p75/p90/p99, ms) — TTFS 200/300/600 · SL 50/60/125 · STSO (1-20) 20/30/60 · STSO (101-120) 30/45/90 · STSO (1001-1020) 40/60/120}

_{TTFS/WO compare client vs deployment clocks and SL compares the step runner’s clock vs the client’s (NTP-synced in CI). WO ends at the last step body exit, the closest observable proxy for the final step-completion request.}

[TooTallNate]

Reviewed the fix, the exclusion mechanics, and the tests. Approving.

The widening is principled, not a spot fix. Excluding all of buildDir/ (instead of just buildDir/workflow) is the right boundary: everything under Nitro's build directory is generated output — either already-transformed chunks (the re-registration crash from #2894) or build machinery — and user source never lives there, so there's nothing legitimate left to transform. It also strictly subsumes the old exclusion, so the previous failure mode that exclusion guarded ("undefined class references when Nitro's bundler renames variables") stays covered.

Mechanics verified against @workflow/rollup's matcher: exclude entries are prefix-matched after normalizing backslashes on both sides, so the raw replace(/[\\/]+$/, '') + '/' construction (replacing the old pathe join) is cross-platform safe, and the appended trailing slash prevents sibling-directory false positives (/tmp/.nitro-source staying transformed while /tmp/.nitro/... is skipped) — which the regression test pins explicitly. Nice detail that the test drives both transform surfaces (the lazy Vite plugin and the rollup:before plugin) through the real nitro.setup path with a serde class — the actual crash vector — rather than testing the exclusion list in isolation.

Verified locally: 33/33 nitro tests pass (my initial single failure was a worktree artifact — the pre-existing world-target alias test needs @workflow/world-postgres built; unrelated to this change). CI is fully green, including every nitro/nuxt/tanstack-start/vite lane across dev, prod, and postgres — which also empirically answers the one risk I checked for (dev-mode workflow discovery surviving the wider exclusion). Changeset is a correct @workflow/nitro patch.

One non-blocking defense-in-depth thought: this fixes the duplicate transform at the Nitro layer, but the crash mechanism — a second registration IIFE calling a non-configurable defineProperty(classId), with a wrong chunk-path-derived id to boot — will reproduce identically in any future pipeline that re-feeds transformed output. The SWC-emitted registration could be made resilient (skip or alias when the class already carries a classId, similar to how aliasSerializationClass sidesteps the redefine-throw) so the failure mode degrades to a benign no-op instead of 500ing every SSR request. Worth a follow-up issue if one doesn't exist.

[github-actions]

Backport PR opened against stable: #2928. Merge conflicts were resolved by AI — please review carefully. (backport job run)