fix(start): keep server-only routes out of RSC bundles by schiller-manuel · Pull Request #7944 · TanStack/router

schiller-manuel · 2026-08-03T21:40:59Z

Use the Start storage context for request cancellation and focused server entrypoints to keep unrelated route dependencies out of the RSC module graph. Add emitted-build regression coverage for the boundary.

fixes #7938

Summary by CodeRabbit

New Features
- Added dedicated server entrypoints for shared constants and virtual modules.
- Added an RSC build-boundary endpoint for validating server-only route behavior.
Bug Fixes
- Improved request-cancellation handling during server component rendering.
- Prevented server-only dependencies from leaking into React Server Component output.
Tests
- Added end-to-end coverage for RSC build-boundary isolation and server-rendered output.

Use the Start storage context for request cancellation and focused server entrypoints to keep unrelated route dependencies out of the RSC module graph. Add emitted-build regression coverage for the boundary. fixes #7938

nx-cloud · 2026-08-03T21:41:37Z

View your CI Pipeline Execution ↗ for commit 819175d

Command	Status	Duration	Result
`nx affected --targets=test:eslint,test:unit,tes...`	✅ Succeeded	11m 6s	View ↗
`nx run-many --target=build --exclude=examples/*...`	✅ Succeeded	2m 9s	View ↗

☁️ Nx Cloud last updated this comment at 2026-08-03 21:53:57 UTC

github-actions · 2026-08-03T21:42:26Z

🚀 Changeset Version Preview

5 package(s) bumped directly, 4 bumped as dependents.

🟩 Patch bumps

Package	Version	Reason
`@tanstack/react-start-rsc`	0.1.33 → 0.1.34	Changeset
`@tanstack/solid-start-server`	1.167.22 → 1.167.23	Changeset
`@tanstack/start-plugin-core`	1.171.25 → 1.171.26	Changeset
`@tanstack/start-server-core`	1.169.17 → 1.169.18	Changeset
`@tanstack/vue-start-server`	1.167.22 → 1.167.23	Changeset
`@tanstack/react-start`	1.168.34 → 1.168.35	Dependent
`@tanstack/react-start-server`	1.167.22 → 1.167.23	Dependent
`@tanstack/solid-start`	1.168.33 → 1.168.34	Dependent
`@tanstack/vue-start`	1.168.32 → 1.168.33	Dependent

coderabbitai · 2026-08-03T21:43:15Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: db97db87-df0e-4dc2-9a75-effabe60c12f

📥 Commits

Reviewing files that changed from the base of the PR and between b5e540d and 819175d.

⛔ Files ignored due to path filters (1)

pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (25)

.changeset/calm-barrels-focus.md
.changeset/tidy-ravens-rest.md
e2e/react-start/rsc/src/routeTree.gen.ts
e2e/react-start/rsc/src/routes/api.rsc-build-boundary.ts
e2e/react-start/rsc/src/utils/rscBuildBoundarySentinel.ts
e2e/react-start/rsc/tests/rsc-build-boundary.spec.ts
packages/react-start-rsc/eslint.config.js
packages/react-start-rsc/package.json
packages/react-start-rsc/src/createCompositeComponent.ts
packages/react-start-rsc/src/renderServerComponent.ts
packages/react-start-rsc/tests/createServerComponent.test-d.tsx
packages/solid-start-server/src/defaultRenderHandler.tsx
packages/solid-start-server/src/defaultStreamHandler.tsx
packages/start-plugin-core/src/post-build.ts
packages/start-plugin-core/src/rsbuild/virtual-modules.ts
packages/start-plugin-core/src/vite/serialization-adapters-plugin.ts
packages/start-plugin-core/src/vite/start-compiler-plugin/plugin.ts
packages/start-plugin-core/src/vite/start-manifest-plugin/plugin.ts
packages/start-plugin-core/tests/post-server-build.test.ts
packages/start-plugin-core/tests/rsbuild/post-build.test.ts
packages/start-plugin-core/tests/start-manifest-plugin.test.ts
packages/start-server-core/package.json
packages/start-server-core/vite.config.ts
packages/vue-start-server/src/defaultRenderHandler.tsx
packages/vue-start-server/src/defaultStreamHandler.tsx

💤 Files with no reviewable changes (1)

packages/react-start-rsc/package.json

📝 Walkthrough

Walkthrough

The change adds focused start-server-core subpaths, updates server consumers, moves RSC cancellation handling to Start context, and adds an end-to-end test that checks server-only dependencies stay out of RSC output.

Changes

Focused server entrypoints

Layer / File(s)	Summary
Subpath exports and consumer imports `packages/start-server-core/...`, `packages/start-plugin-core/...`, `packages/solid-start-server/...`, `packages/vue-start-server/...`, `packages/start-plugin-core/tests/...`, `.changeset/calm-barrels-focus.md`	`@tanstack/start-server-core` now exports `constants` and `virtual-modules` subpaths. Start plugins use these subpaths. Solid and Vue handlers use their router SSR server modules. Tests and changeset metadata match the import changes.
RSC request context and import boundary `packages/react-start-rsc/...`, `.changeset/tidy-ravens-rest.md`	RSC stream cancellation now uses `ctx.request.signal`. The root `@tanstack/start-server-core` dependency and imports are removed. ESLint rules reject root-barrel imports.
RSC build-boundary route and validation `e2e/react-start/rsc/src/...`, `e2e/react-start/rsc/tests/rsc-build-boundary.spec.ts`	The RSC example adds a server-only sentinel route and generated route wiring. The test verifies the sentinel appears in SSR files and not in RSC files.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant PlaywrightTest
  participant RscBuildBoundaryRoute
  participant SSRBuild
  participant RSCBuild
  PlaywrightTest->>RscBuildBoundaryRoute: Request /api/rsc-build-boundary
  RscBuildBoundaryRoute-->>PlaywrightTest: Return build-boundary sentinel
  PlaywrightTest->>SSRBuild: Scan executable SSR files
  SSRBuild-->>PlaywrightTest: Require sentinel
  PlaywrightTest->>RSCBuild: Scan executable RSC files
  RSCBuild-->>PlaywrightTest: Reject sentinel

Possibly related PRs

TanStack/router#7938: Both changes remove root @tanstack/start-server-core imports from RSC rendering files.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the primary change: preventing server-only routes from entering RSC bundles.
Linked Issues check	✅ Passed	The changes remove the RSC root-barrel dependency, use Start storage context, and add emitted-build coverage for server-only route exclusion.
Out of Scope Changes check	✅ Passed	The import updates, subpath exports, changesets, and regression tests directly support focused server entrypoints and RSC bundle isolation.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch fix-7938

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github-actions · 2026-08-03T21:44:36Z

Bundle Size Benchmarks

This pull request does not affect bundle size in any measured scenario.

pkg-pr-new · 2026-08-03T21:46:09Z

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commit: 819175d

codspeed-hq · 2026-08-03T21:53:48Z

Merging this PR will degrade performance by 21.68%

⚠️

Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 8 improved benchmarks
❌ 5 regressed benchmarks
✅ 167 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	`BASE`	`HEAD`	Efficiency
❌	Memory	`mem server error-paths unmatched (vue)`	468.9 KB	2,207.6 KB	-78.76%
❌	Memory	`mem server error-paths unmatched (react)`	369.2 KB	1,450.6 KB	-74.55%
❌	Memory	`mem server error-paths not-found (solid)`	416.3 KB	983.7 KB	-57.68%
❌	Memory	`mem server server-fn-churn (vue)`	269.4 KB	416.2 KB	-35.28%
❌	Memory	`mem server server-fn-churn (solid)`	263.5 KB	273.6 KB	-3.69%
⚡	Memory	`mem server error-paths redirect (vue)`	809.1 KB	450.2 KB	+79.74%
⚡	Memory	`mem server error-paths redirect (solid)`	504.4 KB	442.7 KB	+13.93%
⚡	Memory	`mem client preload-churn (vue)`	758.9 KB	667.8 KB	+13.63%
⚡	Simulation	`ssr server-fn multipart (solid)`	63 ms	59.3 ms	+6.18%
⚡	Memory	`mem server error-paths not-found (react)`	280.9 KB	266.5 KB	+5.4%
⚡	Simulation	`ssr server-fn raw-stream (solid)`	111.8 ms	106.7 ms	+4.77%
⚡	Simulation	`client-async-pipeline navigation loop (react)`	51.7 ms	49.9 ms	+3.73%
⚡	Simulation	`ssr server-fn raw-response (solid)`	57.2 ms	55.3 ms	+3.4%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

_{Comparing fix-7938 (819175d) with main (b5e540d)}

fix(start): keep server-only routes out of RSC bundles

819175d

Use the Start storage context for request cancellation and focused server entrypoints to keep unrelated route dependencies out of the RSC module graph. Add emitted-build regression coverage for the boundary. fixes #7938

github-actions Bot added package: solid-start-server package: start-plugin-core package: start-server-core package: vue-start-server package: react-start-rsc labels Aug 3, 2026

schiller-manuel merged commit 65f7b7f into main Aug 3, 2026
25 of 26 checks passed

schiller-manuel deleted the fix-7938 branch August 3, 2026 22:02

This was referenced Aug 3, 2026

ci: Version Packages #7945

Merged

ci: Version Packages #7946

Merged

FrancoKaddour mentioned this pull request Aug 4, 2026

fix(react-start-rsc): avoid pulling the router entry into the RSC bundle via start-server-core barrel import #7938

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fix(start): keep server-only routes out of RSC bundles - #7944

fix(start): keep server-only routes out of RSC bundles#7944
schiller-manuel merged 1 commit into
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fix-7938

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