fix(solid-query): untrack the result read in useMutationState's cache subscription

[daviduzumeri]

🎯 Changes

useMutationState's mutation-cache subscription reads the hook's own result signal:

const unsubscribe = mutationCache().subscribe(() => {
  const nextResult = replaceEqualDeep(result(), getResult(mutationCache(), options()))
  if (result() !== nextResult) setResult(nextResult)
})

MutationCache notifies synchronously, so when a mutation is started from inside a Solid computation, that callback runs while the computation is still the active listener. The result() read therefore registers the signal as a dependency of that computation — and setResult immediately invalidates it.

The practical effect: calling mutate from inside a createEffect re-runs the effect on every mutation, and an unguarded mutate loops. It also attaches a spurious dependency to whatever computation happens to be running when any mutation settles, which is hard to attribute when it shows up as a runaway effect cascade in production.

The read is now untracked. Behaviour is otherwise identical.

Regression test

Added to useMutationState.test.tsx: an effect that triggers one mutation, with a guard so a genuine loop still terminates.

• before: expected 2 to be 1 — the effect re-ran
• after: passes

Relationship to #9644

#9644 proposed the same untrack alongside a useIsMutating fix. That PR has been open since Sept 2025, last updated June 2026, and is now conflicted; its useIsMutating half has since landed separately. This is just the remaining half, rebased on main with a test and a changeset. Happy to close it in favour of #9644 if that one is revived.

Also related: #10907 (the enabled: false SSR hang) was a different symptom of solid-query reading signals from cache callbacks, and is already fixed.

✅ 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.

Scope of what I ran: vitest run for @tanstack/solid-query — 247 runtime tests pass (13 files). useQuery.test-d.tsx fails 5 type assertions, but it does so identically on unmodified main with my changes stashed, so it is pre-existing and unrelated to this change.

🚀 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

  • Prevented mutation-triggered computations from rerunning synchronously when their own mutation state changes.
  • Improved reactive behavior for useMutationState when mutations are initiated within reactive effects.

• Tests

  • Added coverage confirming effects run only once when triggering a mutation through useMutationState.

[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: 87c13d4c-1e8e-48cc-a463-91e752e50bf6

📥 Commits

Reviewing files that changed from the base of the PR and between f6ae1cc and 8b985bb.

📒 Files selected for processing (3)

• .changeset/solid-query-mutation-state-untrack.md
• packages/solid-query/src/__tests__/useMutationState.test.tsx
• packages/solid-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 reads its result signal with untrack during mutation-cache updates. A regression test verifies that mutations started in createEffect do not synchronously rerun the effect. A patch changeset documents the fix.

Changes

Mutation state tracking

Layer / File(s)	Summary
Untrack mutation result reads packages/solid-query/src/useMutationState.ts	useMutationState uses untrack(result) for the previous result before structural sharing and comparison.
Regression coverage and release note packages/solid-query/src/__tests__/useMutationState.test.tsx, .changeset/solid-query-mutation-state-untrack.md	The test verifies that an effect-triggered mutation runs the effect once. The changeset records the patch release note.

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

Merge Risk: ⚪ Minimal · up to 8b985

This change prevents mutation-cache updates from spuriously rerunning Solid computations while preserving existing result behavior, with regression coverage for the reported loop. No actionable merge-blocking risk remains.

🚥 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 2 functions across 2 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the main change: untracking the result read in the Solid Query mutation-state cache subscription.
Description check	✅ Passed	The description includes all required template sections, explains the motivation and implementation, documents the regression test and test results, and includes the changeset release impact.
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 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files. (1 skipped: 1 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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