fix(start): migrate to Rsbuild splitChunks config

[chenjiahan]

Summary

Rsbuild v2 deprecates performance.chunkSplit in favor of the top-level splitChunks option.

This migrates the Start Rsbuild client config to splitChunks with preset: 'none' and chunks: 'async', preserving the existing behavior of splitting only async route chunks.

The Vue Start e2e config no longer supplies the deprecated override.

Related Links

• Rsbuild v1 to v2 migration guide

Summary by CodeRabbit

• Bug Fixes

  • Updated client-side chunk splitting to the Rsbuild v2 configuration format.
  • Preserved asynchronous route code splitting while preventing unnecessary vendor and shared chunks.

• Chores

  • Added a patch release note for the updated chunk configuration.

[coderabbitai]

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: 1bd45848-eea7-41f2-a5b4-4fd961eb5050

📥 Commits

Reviewing files that changed from the base of the PR and between cb281d7 and 4337e7e.

📒 Files selected for processing (3)

• .changeset/modern-chunks-split.md
• e2e/vue-start/basic/rsbuild.config.ts
• packages/start-plugin-core/src/rsbuild/planning.ts

💤 Files with no reviewable changes (1)

• e2e/vue-start/basic/rsbuild.config.ts

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.

---

📝 Walkthrough

Walkthrough

The client Rsbuild configuration now uses v2 splitChunks with preset: 'none' and chunks: 'async'. The Vue Start example removes the legacy configuration. A patch changeset documents the migration.

Changes

Rsbuild chunk splitting

Layer / File(s)	Summary
Async client chunk-splitting migration packages/start-plugin-core/src/rsbuild/planning.ts, e2e/vue-start/basic/rsbuild.config.ts, .changeset/modern-chunks-split.md	The client configuration uses async-only splitChunks with shared and vendor chunk splitting disabled. The example removes the legacy strategy, and the changeset documents the patch release.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk:⚪ Minimal · up to 4337e

This change updates the build configuration to the supported split-chunk option while preserving async route splitting behavior; no actionable merge-blocking risk remains.

Suggested reviewers:schiller-manuel

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files. (1 skipped: 1 unsupported.)	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the migration from the deprecated Rsbuild chunk-splitting configuration to the v2 splitChunks configuration.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 4337e7e

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	21m 33s	View ↗
nx run-many --target=build --exclude=examples/*...	✅ Succeeded	2m 8s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-08-21 21:18:34 UTC

[pkg-pr-new]

More templates

• tanstack-router-solid-example-authenticated-routes
• tanstack-router-solid-example-authenticated-routes-firebase
• tanstack-router-solid-example-basic
• tanstack-router-solid-example-basic-default-search-params
• tanstack-router-solid-example-basic-devtools-panel
• tanstack-router-solid-example-basic-file-based
• tanstack-router-solid-example-basic-non-nested-devtools
• tanstack-router-solid-example-basic-solid-query
• tanstack-router-solid-example-basic-solid-query-file-based
• tanstack-router-solid-example-basic-ssr-file-based
• tanstack-router-solid-example-basic-ssr-streaming-file-based
• tanstack-router-solid-example-basic-virtual-file-based
• tanstack-router-solid-example-basic-virtual-inside-file-based
• tanstack-router-solid-example-deferred-data
• tanstack-router-solid-i18n-paraglide
• tanstack-router-solid-example-kitchen-sink
• tanstack-router-solid-example-kitchen-sink-file-based
• tanstack-router-solid-example-kitchen-sink-solid-query
• tanstack-router-solid-example-kitchen-sink-solid-query-file-based
• tanstack-router-solid-example-large-file-based
• tanstack-router-solid-example-location-masking
• tanstack-router-solid-example-navigation-blocking
• tanstack-router-solid-example-quickstart
• tanstack-router-solid-example-quickstart-esbuild-file-based
• tanstack-router-solid-example-quickstart-file-based
• tanstack-router-solid-example-quickstart-rspack-file-based
• tanstack-router-solid-example-quickstart-webpack-file-based
• @tanstack/router-solid-mono-simple
• router-solid-mono-simple-lazy
• router-solid-monorepo-solid-query
• tanstack-router-solid-example-scroll-restoration
• tanstack-solid-router-search-validator-adapters
• tanstack-solid-start-example-basic
• tanstack-solid-start-example-basic-auth
• tanstack-solid-start-example-basic-authjs
• tanstack-solid-start-example-basic-cloudflare
• tanstack-solid-start-example-basic-netlify
• tanstack-solid-start-example-basic-nitro
• tanstack-start-example-basic-solid-query
• tanstack-solid-start-example-basic-static
• tanstack-solid-start-bun-hosting
• tanstack-solid-start-example-convex-better-auth
• tanstack-solid-start-example-counter
• tanstack-solid-start-i18n-paraglide
• tanstack-solid-start-example-large
• tanstack-solid-start-streaming-data-from-server-functions
• tanstack-solid-start-example-supabase-basic
• tanstack-solid-start-tailwind-v4
• tanstack-router-solid-example-view-transitions
• tanstack-router-solid-example-with-framer-motion
• tanstack-router-solid-example-with-trpc
• tanstack-router-react-example-authenticated-routes
• tanstack-router-react-example-authenticated-routes-firebase
• tanstack-router-react-example-basic
• tanstack-router-react-example-basic-default-search-params
• tanstack-router-react-example-basic-devtools-panel
• tanstack-router-react-example-basic-file-based
• tanstack-router-react-example-basic-non-nested-devtools
• tanstack-router-react-example-react-query
• tanstack-router-react-example-basic-react-query-file-based
• tanstack-router-react-example-basic-ssr-file-based
• tanstack-router-react-example-basic-ssr-streaming-file-based
• tanstack-router-react-example-basic-virtual-file-based
• tanstack-router-react-example-basic-virtual-inside-file-based
• tanstack-router-react-example-deferred-data
• tanstack-router-i18n-paraglide
• tanstack-router-react-example-kitchen-sink
• tanstack-router-react-example-kitchen-sink-file-based
• tanstack-router-react-example-kitchen-sink-react-query
• tanstack-router-react-example-kitchen-sink-react-query-file-based
• tanstack-router-react-example-large-file-based
• tanstack-router-react-example-location-masking
• tanstack-router-react-example-navigation-blocking
• tanstack-router-react-example-quickstart
• tanstack-router-react-example-quickstart-esbuild-file-based
• tanstack-router-react-example-quickstart-file-based
• tanstack-router-react-example-quickstart-rspack-file-based
• tanstack-router-react-example-quickstart-webpack-file-based
• router-monorepo-react-query
• router-mono-simple
• router-mono-simple-lazy
• tanstack-router-react-example-scroll-restoration
• tanstack-search-validator-adapters
• tanstack-start-example-bare
• tanstack-start-example-basic
• tanstack-start-example-basic-auth
• tanstack-router-react-example-basic-authjs
• tanstack-start-example-basic-cloudflare
• tanstack-start-example-basic-react-query
• tanstack-start-example-basic-rsbuild
• tanstack-start-example-basic-static
• tanstack-start-bun-hosting
• tanstack-start-example-clerk-basic
• tanstack-start-example-convex-trellaux
• tanstack-start-example-counter
• tanstack-start-i18n-paraglide
• tanstack-start-example-large
• tanstack-start-example-material-ui
• tanstack-start-example-rscs
• tanstack-start-streaming-data-from-server-functions
• tanstack-start-example-supabase-basic
• tanstack-start-tailwind-v4
• tanstack-start-example-trellaux
• tanstack-start-example-workos
• tanstack-router-react-example-view-transitions
• tanstack-router-react-example-with-framer-motion
• tanstack-router-react-example-with-trpc
• tanstack-router-react-example-with-trpc-react-query
• tanstack-router-vue-example-basic-jsx
• tanstack-router-vue-example-basic-file-based-jsx
• tanstack-router-vue-example-basic-file-based-sfc

@tanstack/arktype-adapter

npm i https://pkg.pr.new/@tanstack/arktype-adapter@8135

@tanstack/eslint-plugin-router

npm i https://pkg.pr.new/@tanstack/eslint-plugin-router@8135

@tanstack/eslint-plugin-start

npm i https://pkg.pr.new/@tanstack/eslint-plugin-start@8135

@tanstack/history

npm i https://pkg.pr.new/@tanstack/history@8135

@tanstack/nitro-v2-vite-plugin

npm i https://pkg.pr.new/@tanstack/nitro-v2-vite-plugin@8135

@tanstack/react-router

npm i https://pkg.pr.new/@tanstack/react-router@8135

@tanstack/react-router-devtools

npm i https://pkg.pr.new/@tanstack/react-router-devtools@8135

@tanstack/react-router-ssr-query

npm i https://pkg.pr.new/@tanstack/react-router-ssr-query@8135

@tanstack/react-start

npm i https://pkg.pr.new/@tanstack/react-start@8135

@tanstack/react-start-client

npm i https://pkg.pr.new/@tanstack/react-start-client@8135

@tanstack/react-start-rsc

npm i https://pkg.pr.new/@tanstack/react-start-rsc@8135

@tanstack/react-start-server

npm i https://pkg.pr.new/@tanstack/react-start-server@8135

@tanstack/router-cli

npm i https://pkg.pr.new/@tanstack/router-cli@8135

@tanstack/router-core

npm i https://pkg.pr.new/@tanstack/router-core@8135

@tanstack/router-devtools

npm i https://pkg.pr.new/@tanstack/router-devtools@8135

@tanstack/router-devtools-core

npm i https://pkg.pr.new/@tanstack/router-devtools-core@8135

@tanstack/router-generator

npm i https://pkg.pr.new/@tanstack/router-generator@8135

@tanstack/router-plugin

npm i https://pkg.pr.new/@tanstack/router-plugin@8135

@tanstack/router-ssr-query-core

npm i https://pkg.pr.new/@tanstack/router-ssr-query-core@8135

@tanstack/router-utils

npm i https://pkg.pr.new/@tanstack/router-utils@8135

@tanstack/router-vite-plugin

npm i https://pkg.pr.new/@tanstack/router-vite-plugin@8135

@tanstack/solid-router

npm i https://pkg.pr.new/@tanstack/solid-router@8135

@tanstack/solid-router-devtools

npm i https://pkg.pr.new/@tanstack/solid-router-devtools@8135

@tanstack/solid-router-ssr-query

npm i https://pkg.pr.new/@tanstack/solid-router-ssr-query@8135

@tanstack/solid-start

npm i https://pkg.pr.new/@tanstack/solid-start@8135

@tanstack/solid-start-client

npm i https://pkg.pr.new/@tanstack/solid-start-client@8135

@tanstack/solid-start-server

npm i https://pkg.pr.new/@tanstack/solid-start-server@8135

@tanstack/start-client-core

npm i https://pkg.pr.new/@tanstack/start-client-core@8135

@tanstack/start-fn-stubs

npm i https://pkg.pr.new/@tanstack/start-fn-stubs@8135

@tanstack/start-plugin-core

npm i https://pkg.pr.new/@tanstack/start-plugin-core@8135

@tanstack/start-server-core

npm i https://pkg.pr.new/@tanstack/start-server-core@8135

@tanstack/start-static-server-functions

npm i https://pkg.pr.new/@tanstack/start-static-server-functions@8135

@tanstack/start-storage-context

npm i https://pkg.pr.new/@tanstack/start-storage-context@8135

@tanstack/valibot-adapter

npm i https://pkg.pr.new/@tanstack/valibot-adapter@8135

@tanstack/virtual-file-routes

npm i https://pkg.pr.new/@tanstack/virtual-file-routes@8135

@tanstack/vue-router

npm i https://pkg.pr.new/@tanstack/vue-router@8135

@tanstack/vue-router-devtools

npm i https://pkg.pr.new/@tanstack/vue-router-devtools@8135

@tanstack/vue-router-ssr-query

npm i https://pkg.pr.new/@tanstack/vue-router-ssr-query@8135

@tanstack/vue-start

npm i https://pkg.pr.new/@tanstack/vue-start@8135

@tanstack/vue-start-client

npm i https://pkg.pr.new/@tanstack/vue-start-client@8135

@tanstack/vue-start-server

npm i https://pkg.pr.new/@tanstack/vue-start-server@8135

@tanstack/zod-adapter

npm i https://pkg.pr.new/@tanstack/zod-adapter@8135

commit: 4337e7e

[codspeed-hq]

Merging this PR will regress 9 benchmarks

⚠️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

⚡ 9 improved benchmarks
❌ 9 regressed benchmarks
✅ 162 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	mem server server-fn-churn (react)	399.9 KB	1,066.8 KB	-62.52%
❌	Memory	mem server error-paths redirect (vue)	423.5 KB	620.5 KB	-31.74%
❌	Memory	mem server peak-large-page (solid)	1.1 MB	1.3 MB	-13.93%
❌	Memory	mem server error-paths redirect (react)	296.3 KB	325.1 KB	-8.86%
❌	Memory	mem server error-paths unmatched (vue)	580.1 KB	628.6 KB	-7.71%
❌	Memory	mem server peak-large-page (vue)	1 MB	1.1 MB	-7.57%
❌	Memory	mem server error-paths not-found (solid)	570 KB	609.4 KB	-6.46%
❌	Simulation	client-async-pipeline navigation loop (react)	102.8 ms	107.1 ms	-3.99%
❌	Memory	mem server serialization-payload (vue)	4.4 MB	4.5 MB	-3.48%
⚡	Memory	mem server error-paths unmatched (react)	1,830.3 KB	415 KB	×4.4
⚡	Memory	mem server error-paths not-found (vue)	2,071.7 KB	479.9 KB	×4.3
⚡	Memory	mem server request-churn (react)	712.7 KB	659.9 KB	+8%
⚡	Memory	mem server aborted-requests (vue)	1,058.3 KB	993 KB	+6.57%
⚡	Memory	mem server error-paths not-found (react)	435.6 KB	419 KB	+3.95%
⚡	Memory	mem client navigation-churn (vue)	1.6 MB	1.5 MB	+3.87%
⚡	Memory	mem server request-churn (solid)	746.4 KB	719.9 KB	+3.69%
⚡	Memory	mem server aborted-requests (solid)	1.2 MB	1.2 MB	+3.32%
⚡	Memory	mem client loader-data-retention (solid)	162.2 KB	157.5 KB	+3.02%

Tip

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

---

_{Comparing chenjiahan:chenjiahan/fix-rsbuild-split-chunks-config (4337e7e) with main (cb281d7)}