fix(router-core): fix search middleware type to use schema output

[sprusr]

Summary

The type for search passed to a route's search middleware is currently set to the input of whatever is passed to validateSearch. In reality this value is the output of the search validator.

In the majority of cases these types are the same, but it becomes a pronounced issue with asymmetric schemas, for example with Zod codecs:

// input is number, output is BigInt
const numberToBigInt = z.codec(z.int(), z.bigint(), {
  decode: (num) => BigInt(num),
  encode: (bigint) => Number(bigint),
});

const searchSchema = z.object({
  codec: numberToBigInt.optional(),
})

The value that we get in the search middleware is a BigInt but it's typed as a number.

Changes

Simple switch from ResolveFullSearchSchemaInput to ResolveFullSearchSchema.

Reproduction

You can find here a small TanStack Start project with a demo of the mismatch: https://github.com/sprusr/tanstack-router-search-middleware-types

Summary by CodeRabbit

• Refactor
  • Updated the type definitions for search middleware configuration to align with the resolved search schema structure. This change affects how middleware functions receive and process search parameters in routes.

[github-actions]

Bundle Size Benchmarks

• Commit: b1c061aff918
• Measured at: 2026-05-11T16:48:47.955Z
• Baseline source: history:b1c061aff918
• 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	274.07 KiB	75.85 KiB	▁▁▁▁▁▁▁▁▁██
react-router.full	90.82 KiB	0 B (0.00%)	90.68 KiB	285.58 KiB	78.89 KiB	▁▁▁▁▁▁▁▁▁██
solid-router.minimal	35.51 KiB	0 B (0.00%)	35.39 KiB	106.36 KiB	31.97 KiB	▁▁▁▁▁▁▁▁▁██
solid-router.full	40.23 KiB	0 B (0.00%)	40.10 KiB	120.58 KiB	36.14 KiB	▁▁▁▁▁▁▁▁▁██
vue-router.minimal	53.29 KiB	0 B (0.00%)	53.15 KiB	151.51 KiB	47.85 KiB	▁▁▁▁▁▁▁▁▁██
vue-router.full	58.41 KiB	0 B (0.00%)	58.28 KiB	167.69 KiB	52.39 KiB	▁▁▁▁▁▁▁▁▁██
react-start.minimal	101.97 KiB	0 B (0.00%)	101.83 KiB	322.51 KiB	88.17 KiB	▁▁▁▁▁▁▁▁▃██
react-start.full	105.41 KiB	0 B (0.00%)	105.27 KiB	332.84 KiB	91.19 KiB	▁▁▁▁▁▁▁▁▄██
react-start.rsbuild.minimal	99.60 KiB	0 B (0.00%)	99.43 KiB	316.97 KiB	85.64 KiB	▁▁▁▁▁▁▁▁▄██
react-start.rsbuild.full	102.89 KiB	0 B (0.00%)	102.72 KiB	327.41 KiB	88.45 KiB	▁▁▁▁▁▁▁▁▃██
solid-start.minimal	49.61 KiB	0 B (0.00%)	49.48 KiB	152.48 KiB	43.78 KiB	▁▁▁▁▁▁▁▁▄██
solid-start.full	55.40 KiB	0 B (0.00%)	55.27 KiB	169.39 KiB	48.72 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.

[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: 418768e3-9988-440e-856e-a2dc87c7b4d1

📥 Commits

Reviewing files that changed from the base of the PR and between b1c061a and 60d6382.

📒 Files selected for processing (1)

• packages/router-core/src/route.ts

---

📝 Walkthrough

Walkthrough

The type of search middlewares in UpdatableRouteOptions was updated to use the resolved full search schema output type rather than the input type. The generic parameter passed to SearchMiddleware now references ResolveFullSearchSchema instead of ResolveFullSearchSchemaInput, changing what input/output shape middleware functions expect.

Changes

Search Middleware Type Update

Layer / File(s)	Summary
Search Middleware Type Annotation packages/router-core/src/route.ts	UpdatableRouteOptions.search.middlewares now types SearchMiddleware against ResolveFullSearchSchema (output type) instead of ResolveFullSearchSchemaInput (input type).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A type flows through the router's core,
From input shape to output lore,
The middleware now sees the final light,
Resolved schemas shining oh so bright!
One line of change, precise and clear,
TypeScript whispers in the ear.

🚥 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 accurately describes the main change: fixing the search middleware type to use schema output instead of input, which matches the core TypeScript typing fix in the changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

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[sprusr]

Long time TanStack Router fan, first time contributor. I spent a bit of time validating my theory with this one, so hopefully haven't jumped to the wrong conclusion.

As an aside, I would love to see more comprehensive support of asymmetrical schemas particularly when it comes to search params. An example use case: I'm unhappy with the appearance of how arrays of strings are encoded in the url by default, and would prefer to have them as space-separated values - being able to do this with Zod codecs would be wonderful (I am already, but it relies on own middleware).

[sprusr]

In fact if maintainers agree with conclusions here then I think buildLocation has wrong sided types too, which affects Link and navigate at least.