fix(lit-query): propagate mutation state generics

[Osraka]

🎯 Changes

@tanstack/lit-query did not receive the useMutationState generic inference added to the other framework adapters in #10373. As a result, a selector with an explicitly typed MutationState<TData, TError, TVariables> still saw Mutation<unknown, Error, unknown, unknown>.

This PR:

• derives the selector's Mutation type from the selected MutationState result
• adds a focused compile-time regression test
• keeps runtime filtering/subscription behavior and scalar selector inference unchanged

The regression test fails on current main and passes with this change.

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested code changes locally with pnpm run test:pr, or these tests do not apply to this pull request.
• I fully understand the code in this pull request, including any code generated with AI assistance.

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

• Bug Fixes

  • Improved TypeScript type inference for useMutationState.
  • Generic mutation types now flow correctly into the select callback, providing accurate types for mutation data, errors, and variables.

• Tests

  • Added type-level coverage to verify generic mutation types are correctly propagated.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Team

Run ID: 6b4187b3-a2ac-4277-93fd-f64003eda4ad

📥 Commits

Reviewing files that changed from the base of the PR and between a85d4f1 and 185d545.

📒 Files selected for processing (3)

• .changeset/lit-mutation-state-generics.md
• packages/lit-query/src/tests/mutation-state-types.test.ts
• packages/lit-query/src/useMutationState.ts

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

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📝 Walkthrough

Walkthrough

useMutationState now propagates mutation generic parameters to the select callback. The change updates type inference and controller wiring, adds a type-level test, and records a patch release for @tanstack/lit-query.

Changes

Lit mutation state generic propagation

Layer / File(s)	Summary
Mutation type propagation packages/lit-query/src/useMutationState.ts	useMutationState infers the mutation type from MutationState, passes it through MutationStateOptions and MutationStateController, and supplies it to the select callback.
Type-level validation and release metadata packages/lit-query/src/tests/mutation-state-types.test.ts, .changeset/lit-mutation-state-generics.md	The type test verifies the propagated Mutation generics. The changeset records a patch release.

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Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 185d5

This change improves mutation-state generic inference while preserving existing runtime cache, filtering, subscription, and callback behavior; no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: propagating mutation state generics in @tanstack/lit-query.
Description check	✅ Passed	The description is complete and relevant. It explains the issue, implementation, regression test, runtime impact, checklist completion, and included changeset.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 …
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 unsupported.)

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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