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[nest] Fix NestJS Vercel build output - #2988
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Deployed NestJS workflows previously stayed `pending` forever: nothing emitted a queue-consumer function for Vercel Queue to discover, so runs were never dispatched. This adds a Vercel Build Output path for NestJS. `workflow-nest build --vercel` (also triggered when the VERCEL env var is set) now writes `.vercel/output`: - the combined workflow queue-consumer `flow.func` is produced by the shared `VercelBuildOutputAPIBuilder` — the same code path Nitro/Next/etc. use — so it is registered with `experimentalTriggers` and discovered by VQS; - the NestJS app is bundled (from the SWC-compiled `dist/`) as a catch-all function with the workflow world statically injected; - routing is merged into `config.json` (workflow routes + filesystem win, then fall through to the app). `WorkflowModule` now lazy-loads the build toolchain (@workflow/builders, esbuild, SWC) so importing it no longer pulls the compiler into the runtime serverless bundle. The builders remain available via the `workflow/nest/builder` and `workflow/nest/vercel-builder` subpaths. Verified end-to-end: deployed a NestJS app to Vercel and a triggered workflow ran to completion (previously stuck pending). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
🦋 Changeset detectedLatest commit: 6e6f9ab The changes in this PR will be included in the next version bump. This PR includes changesets to release 16 packages
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📊 Workflow Benchmarks❌ The benchmark run for commit Backend:
📜 Previous results (1)dad0793Fri, 17 Jul 2026 20:03:00 GMT · run logs
Avg deltas compare against the most recent benchmark run on 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) 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 All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor ( Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the |
🧪 E2E Test Results✅ All tests passed Summary
Details by Category✅ ▲ Vercel Production
✅ 💻 Local Development
✅ 📦 Local Production
✅ 🐘 Local Postgres
✅ 🪟 Windows
✅ 📋 Other
✅ vercel-multi-region
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…` meta-package, breaking the documented `import { NestLocalBuilder } from "workflow/nest"` and leaving no working alternative.
This commit fixes the issue reported at packages/nest/src/index.ts:6
## The bug
This PR changed `packages/nest/src/index.ts` from a value+type export:
```ts
export { type NestBuilderOptions, NestLocalBuilder } from './builder.js';
```
to a type-only export:
```ts
export type { NestBuilderOptions } from './builder.js';
```
The rationale is valid — `builder.ts` imports `@workflow/builders` (esbuild/SWC) at top level, and the runtime entry must stay free of build-time deps so a NestJS app can be bundled into a serverless function. The `NestLocalBuilder` value is instead intended to be reached via the `workflow/nest/builder` subpath (as the new comment in `index.ts` states).
The problem is that the escape hatch was only half-wired:
- `@workflow/nest`'s own `package.json` *does* expose a `./builder` subpath (`./dist/builder.js`).
- But the recommended consumer package is the **meta `workflow` package**, whose `package.json` only exposes `./nest` → `./dist/nest.js`, and `packages/workflow/src/nest.ts` is just `export * from '@workflow/nest'` (the runtime entry that no longer value-exports `NestLocalBuilder`). There was **no** `./nest/builder` subpath in the meta package.
### Concrete trigger
A user following the API-reference docs writes:
```ts
import { NestLocalBuilder } from "workflow/nest";
```
(`docs/content/docs/v5/api-reference/workflow-nest/nest-local-builder.mdx` line 15 and the v4 equivalent.) At runtime this resolves to `@workflow/nest`'s main entry, which now exports only the *type* `NestBuilderOptions` — so `NestLocalBuilder` is `undefined`, and `new NestLocalBuilder(...)` throws `TypeError: NestLocalBuilder is not a constructor`. There was also no `workflow/nest/builder` subpath to fall back to, so the value class was completely unreachable through the `workflow` meta package.
## The fix
1. Added a `./nest/builder` subpath to `packages/workflow/package.json` mapping to `./dist/nest-builder.js`.
2. Created `packages/workflow/src/nest-builder.ts` = `export * from '@workflow/nest/builder'`, mirroring the existing `src/nest.ts` pattern, so the value export is threaded through the meta package and compiled to `dist/nest-builder.js`.
3. Updated the v4 and v5 `nest-local-builder.mdx` docs to the working import path `import { NestLocalBuilder } from "workflow/nest/builder"`.
This restores reachability of `NestLocalBuilder` for meta-package consumers while preserving the PR's goal of keeping build-time deps out of the runtime entry.
Note: the sandbox has no installed `node_modules`, so a full `tsc` build could not be executed; the change is structurally identical to the already-working `./nest` subpath wiring.
Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>
Co-authored-by: VaguelySerious <mittgfu@gmail.com>Signed-off-by: Peter Wielander <mittgfu@gmail.com>
| '@swc/core/*', | ||
| '@swc/wasm', | ||
| 'esbuild', | ||
| '*.node', |
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ai review: *.node is still always externalized, but this builder does not trace or copy external files into appFuncDir; the emitted function contains only index.js, package.json, and .vc-config.json. Any Nest app dependency with a native addon therefore keeps a runtime reference to a .node file that is absent from the deployed .func, causing MODULE_NOT_FOUND on cold start. Please trace/copy native artifacts (and their package layout) into the function, or fail the build with a clear unsupported-dependency error instead of producing a broken deployment.
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Addressed as a documented limitation rather than adding native-module tracing, which is out of scope for this exploratory integration (reliably tracing/copying .node artifacts also requires handling the runtime resolution these modules do via bindings/node-gyp-build).
*.node stays externalized so esbuild does not fail the build on a .node file it cannot bundle; I added a comment at that line making the intentional choice and its consequence explicit (b047a12), and called out the limitation in the changeset-linked README section ("Deploying to Vercel") plus the changeset. If native-addon support is needed we can follow up with @vercel/nft tracing.
| @@ -0,0 +1,5 @@ | |||
| --- | |||
| '@workflow/nest': minor | |||
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ai review: This is marked as a minor change, but the PR removes the public NestLocalBuilder value export from the @workflow/nest and workflow/nest main entries. Existing documented imports stop working; adding a new /builder subpath provides a migration target but does not preserve compatibility. Because this bump type also governs stable backports, please either retain a compatible main-entry export or mark the change as major.
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Bumped @workflow/nest to major (b047a12). Retaining the main-entry NestLocalBuilder export is not an option — it would re-drag the build toolchain (@workflow/builders, esbuild, SWC) into the runtime bundle of every app that imports WorkflowModule, which is the bug this PR fixes — so the subpath (@workflow/nest/builder) is the migration target and the changeset now documents it as a breaking change.
| Commands: | ||
| init Generate .swcrc configuration with the workflow plugin | ||
| build Build workflow bundles (and the Vercel Build Output when on Vercel) |
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ai review: The package README still documents only the init CLI command and has no Vercel deployment/build instructions. Repository standards require corresponding README updates when package functionality changes, and direct @workflow/nest consumers otherwise have no package-local documentation for this new command. Please update packages/nest/README.md with build, its options, the Vercel entry module, and the vercel-build flow.
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Updated packages/nest/README.md (b047a12): added a "Deploying to Vercel" section (serverless entry module, skipBuild on Vercel, the vercel-build flow, native-addon limitation), documented the build command with an options table (--vercel, --dirs, --entry, --out-dir, --module), and noted the NestLocalBuilder/NestVercelBuilder subpaths in "How It Works".
…ive-addon limitation - Changeset: bump @workflow/nest to major (removing NestLocalBuilder from the main entry is a breaking change) and document the subpath migration + the native-addon limitation. - README: document the `build` command and its options, the Vercel entry module and `vercel-build` flow, the NestVercelBuilder subpath, and the native-addon limitation. - vercel-builder: comment why `*.node` is externalized and that native addons are not yet traced/copied into the deployed function. - Minor wording: Workflow DevKit -> Workflow SDK. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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| ```typescript | ||
| // _vercel/entry.ts | ||
| import { NestFactory } from '@nestjs/core'; | ||
| import { AppModule } from '../src/app.module'; |
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ai review: This entry bypasses the nest build output by importing ../src/app.module, so the Vercel builder feeds the Nest TypeScript graph back through esbuild. That contradicts the builder assumption that it bundles already-compiled JS, and esbuild does not emit the TypeScript emitDecoratorMetadata that Nest constructor injection relies on; apps with injected providers can therefore boot with missing DI metadata. Please import ../dist/app.module.js here, matching the checked-in workbench and the v5 guide, so the SWC-compiled decorator metadata is retained.
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Good catch — fixed in 6e6f9ab. The entry example now imports the compiled ../dist/app.module.js (produced by nest build, whose SWC pass emits emitDecoratorMetadata) instead of raw ../src/app.module, and adds import 'reflect-metadata'. This matches the checked-in workbench/nest/_vercel/entry.ts and the getting-started docs, both of which already used dist/ + reflect-metadata.
…t + reflect-metadata The entry snippet imported AppModule from raw `../src/app.module` and omitted `import 'reflect-metadata'`. Importing raw TS routes the app back through esbuild (which does not emit `emitDecoratorMetadata`), breaking NestJS constructor injection; the entry must import the `nest build` output (`../dist/app.module.js`) and register reflect-metadata — matching the workbench entry and getting-started docs. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
No backport to The new To override, re-run the Backport to stable workflow manually via |
Closes#1472 and #878
NestJS currently produces no
.vercel/output, so nothing emits a queue-consumer function withexperimentalTriggers, and Vercel Queue never dispatches the run.Every other server framework (Express/Fastify/Hono) sidesteps this by being a Nitro app whose Vercel preset emits the consumer. NestJS has its own compiler/DI and can't ride that path, so it needs to emit the Build Output itself.
Approach
Keep
nest build(SWC compiles decorators +emitDecoratorMetadatanatively). After it,workflow-nest build --vercel(also auto-detected via theVERCELenv var) writes a complete.vercel/output:flow.func(+webhook/[token].func, static manifest, routing) is produced by the sharedVercelBuildOutputAPIBuilder, i.e. the exact code path Nitro/Next/etc. use, so it's registered with the__wkf_workflow_*experimentalTriggersand VQS discovers it. Single combined trigger — matches current arch.dist/) is bundled as a catch-all function, with the workflow world statically injected (createWorkflowWorldTargetEsbuildPlugin) sostart()works inside it.config.json: workflow routes + filesystem win, then fall through to the app.WorkflowModulenow lazy-loads the build toolchain (@workflow/builders, esbuild, SWC) so importing it no longer drags the compiler into the runtime serverless bundle. The runtime entry (workflow/nest) no longer re-exports the builders; they live atworkflow/nest/builderandworkflow/nest/vercel-builder.This deliberately avoids the earlier #1472 hacks (base64-embedding bundles into source,
/tmpwrites,globalThisinjection, separate step/flow triggers) — each now has a clean shared equivalent.Testing
peter-w).POST /api/start→wrun_…; the run completed (both steps + asleepran):{ "status": "completed", "returnValue": { "hello": "Hello, vercel!", "bye": "Goodbye, vercel.", "completedAt": "…" } }pending.@workflow/builders) and boots underVERCEL=1.flow.func/.vc-config.jsoncarries the__wkf_workflow_*queue trigger.@workflow/nestunit tests pass (37).Status / notes
@vercel/nft-style tracing is a more robust future option if the allowlist proves brittle.