perf(start-server-core): skip update for server context

[Sheraff]

Summary

• Set request-scoped additionalContext directly before router.load()
• Avoid an unnecessary router.update() and redundant location parse during SSR

Tests

• CI=1 NX_DAEMON=false pnpm nx run @tanstack/start-server-core:test:types --outputStyle=stream --skipRemoteCache
• CI=1 NX_DAEMON=false pnpm nx run @tanstack/start-server-core:test:unit --outputStyle=stream --skipRemoteCache

Summary by CodeRabbit

• Refactor
  • Improved server-side startup path to reduce SSR overhead, resulting in faster initial responses and lower latency during server rendering. Delivered as a minor patch with no public API changes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: e6708028-5d83-4cf2-866d-f9a15f3aac3f

📥 Commits

Reviewing files that changed from the base of the PR and between 7eb946a and a3026ac.

📒 Files selected for processing (1)

• .changeset/large-insects-own.md

✅ Files skipped from review due to trivial changes (1)

• .changeset/large-insects-own.md

---

📝 Walkthrough

Walkthrough

The PR changes createStartHandler to inject per-request serverContext by directly assigning routerInstance.options.additionalContext (replacing a prior router.update call) and adds a changeset documenting the patch release.

Changes

Router Context Injection Optimization

Layer / File(s)	Summary
Direct options assignment packages/start-server-core/src/createStartHandler.ts, .changeset/large-insects-own.md	serverContext is injected by directly assigning routerInstance.options.additionalContext instead of calling routerInstance.update() before router load; a changeset notes a patch bump.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Suggested reviewers

• schiller-manuel

Poem

🐰 I hop to set context, quick and spry,
No update roundabout — just assign and fly.
A tidy start, the router wakes with cheer,
Tiny patch, swift path, the endpoint's near. ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly reflects the main change: skipping an unnecessary router.update() call for performance optimization in start-server-core when setting server context.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/ssr-additional-context-update

---

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit 7eb946a

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	15m 4s	View ↗
nx run-many --target=build --exclude=examples/*...	✅ Succeeded	1m 44s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-06-11 08:25:03 UTC

[github-actions]

🚀 Changeset Version Preview

3 package(s) bumped directly, 10 bumped as dependents.

🟩 Patch bumps

Package	Version	Reason
@tanstack/react-router	1.170.15 → 1.170.16	Changeset
@tanstack/solid-router	1.170.15 → 1.170.16	Changeset
@tanstack/start-server-core	1.169.14 → 1.169.15	Changeset
@tanstack/react-start	1.168.25 → 1.168.26	Dependent
@tanstack/react-start-client	1.168.13 → 1.168.14	Dependent
@tanstack/react-start-rsc	0.1.24 → 0.1.25	Dependent
@tanstack/react-start-server	1.167.19 → 1.167.20	Dependent
@tanstack/solid-start	1.168.25 → 1.168.26	Dependent
@tanstack/solid-start-client	1.168.13 → 1.168.14	Dependent
@tanstack/solid-start-server	1.167.19 → 1.167.20	Dependent
@tanstack/start-plugin-core	1.171.17 → 1.171.18	Dependent
@tanstack/vue-start	1.168.24 → 1.168.25	Dependent
@tanstack/vue-start-server	1.167.19 → 1.167.20	Dependent

[github-actions]

Bundle Size Benchmarks

• Commit: 5d26c5a18ea2
• Measured at: 2026-06-11T08:09:02.926Z
• Baseline source: history:56bd271ba088
• Dashboard: bundle-size history

Scenario	Current (gzip)	Delta vs baseline	Initial gzip	Raw	Brotli	Trend
react-router.minimal	87.29 KiB	0 B (0.00%)	87.15 KiB	273.66 KiB	75.88 KiB	▁▁▁▁▁▁▁▁▁▃█
react-router.full	91.02 KiB	0 B (0.00%)	90.88 KiB	285.56 KiB	79.09 KiB	██████▁▁▁▁▄
solid-router.minimal	35.48 KiB	0 B (0.00%)	35.36 KiB	105.86 KiB	32.03 KiB	▆▆▆▆▆▆▆█▁▁▁
solid-router.full	40.53 KiB	0 B (0.00%)	40.41 KiB	121.08 KiB	36.46 KiB	▆▆▆▆▆▆▆█▁▁▁
vue-router.minimal	52.97 KiB	0 B (0.00%)	52.84 KiB	149.90 KiB	47.62 KiB	███████▁▁▁▁
vue-router.full	58.96 KiB	0 B (0.00%)	58.83 KiB	168.66 KiB	52.87 KiB	▁▁▁▁▁▁▁████
react-start.minimal	101.91 KiB	0 B (0.00%)	101.77 KiB	321.98 KiB	88.21 KiB	▁▁▁▁▁▁▁▂▂▃█
react-start.deferred-hydration	102.65 KiB	0 B (0.00%)	101.80 KiB	323.36 KiB	88.90 KiB	▁▁▁▁▁▁▂▂▂▂█
react-start.full	105.31 KiB	0 B (0.00%)	105.18 KiB	331.91 KiB	91.06 KiB	▃▃████▁▁▁▂▆
react-start.rsbuild.minimal	99.63 KiB	0 B (0.00%)	99.46 KiB	316.43 KiB	85.79 KiB	▃▃▃▃▃▃▁▂▂▃█
react-start.rsbuild.minimal-iife	100.03 KiB	0 B (0.00%)	99.87 KiB	317.37 KiB	86.08 KiB	▃▃▃▃▃▃▁▂▂▃█
react-start.rsbuild.full	102.86 KiB	0 B (0.00%)	102.68 KiB	326.48 KiB	88.53 KiB	▅▅████▁▁▁▁▅
solid-start.minimal	49.60 KiB	0 B (0.00%)	49.47 KiB	151.93 KiB	43.79 KiB	▆▆▆▆▆▆▆█▁▁▁
solid-start.deferred-hydration	52.86 KiB	0 B (0.00%)	49.53 KiB	159.97 KiB	46.81 KiB	▄▄▄▄▄▄▄█▁▁▁
solid-start.full	55.40 KiB	0 B (0.00%)	55.27 KiB	168.97 KiB	48.80 KiB	▁▁▇▇▇▇▇█▆▆▆
vue-start.minimal	71.02 KiB	0 B (0.00%)	70.89 KiB	207.04 KiB	62.93 KiB	▁▁▁▁▁▁▁████
vue-start.full	75.01 KiB	0 B (0.00%)	74.88 KiB	219.68 KiB	66.40 KiB	▁▁▇▇▇▇▇████

Current gzip tracks all emitted client JS chunks. Initial gzip tracks only the entry/import graph. Trend sparkline is historical current gzip ending with this PR measurement; lower is better.

[pkg-pr-new]

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commit: a3026ac

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

---

_{Comparing perf/ssr-additional-context-update (a3026ac) with main (56bd271)}