query fix(query-core): fix combine not updating when queries change with stable reference

🎯 Changes

Fixes #8781

Problem

With stable combine, results lag one step behind when queries change. This happens because getOptimisticResult runs before setQueries updates this.#result.

Solution

Pass queryHashes to #combineResult to detect query changes before this.#result is updated.

✅ Checklist

[x] I have followed the steps in the Contributing guide.
[x] I have tested this code locally with pnpm run test:pr.

🚀 Release Impact

[x] 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

Fixed an issue where combined query results failed to update when the number of queries changed dynamically. The stable combine reference now properly responds to changes in query composition, ensuring accurate aggregated results when queries are added, removed, or replaced at runtime.

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Dec 07 '25 18:12 minseong0324

🦋 Changeset detected

Latest commit: 89db791104f4435887de45f9eb4ffdd07da0bdb9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 19 packages

Name	Type
@tanstack/query-core	Patch
@tanstack/angular-query-experimental	Patch
@tanstack/query-async-storage-persister	Patch
@tanstack/query-broadcast-client-experimental	Patch
@tanstack/query-persist-client-core	Patch
@tanstack/query-sync-storage-persister	Patch
@tanstack/react-query	Patch
@tanstack/solid-query	Patch
@tanstack/svelte-query	Patch
@tanstack/vue-query	Patch
@tanstack/angular-query-persist-client	Patch
@tanstack/react-query-persist-client	Patch
@tanstack/solid-query-persist-client	Patch
@tanstack/svelte-query-persist-client	Patch
@tanstack/react-query-devtools	Patch
@tanstack/react-query-next-experimental	Patch
@tanstack/solid-query-devtools	Patch
@tanstack/svelte-query-devtools	Patch
@tanstack/vue-query-devtools	Patch

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Dec 07 '25 18:12 changeset-bot[bot]

Walkthrough

This PR fixes a bug where a stable combine reference in QueriesObserver was not being re-invoked when the underlying queries changed dynamically. The fix adds query hash tracking to detect query changes and triggers combine re-evaluation accordingly.

Changes

Cohort / File(s)	Summary
Changeset `.changeset/swift-brooms-teach.md`	Patch version bump for `@tanstack/query-core` with description of fix for stable combine reference updating.
Query Core Tests `packages/query-core/src/__tests__/queriesObserver.test.tsx`	Adds comprehensive test cases for QueriesObserver covering stable combine behavior with dynamic queries: adding/removing/replacing queries, handling duplicate keys, and verifying combine re-invocation and result updates.
Query Core Implementation `packages/query-core/src/queriesObserver.ts`	Adds private field `#lastQueryHashes` to track query hashes; extends `#combineResult` to accept and compare query hashes; updates `getOptimisticResult` to compute and pass query hashes; triggers combine re-evaluation when query hashes change.
React Query Tests `packages/react-query/src/__tests__/useQueries.test.tsx`	Adds test case verifying `useQueries` returns correct results when query count changes with a stable combine reference.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Focus areas:
- Query hash computation and comparison logic in #combineResult to ensure correct change detection
- Timing of #lastQueryHashes updates relative to #lastCombine and #lastResult assignments
- Verify that combine is invoked only when necessary (hash changes) and with correct aggregated results

Possibly related PRs

TanStack/query#9886 — Also modifies QueriesObserver internals around queryHash handling and observer matching to address dynamic query changes.
TanStack/query#9592 — Related updates to QueriesObserver to ensure memoized combine is re-run when queries or their results change.
TanStack/query#9639 — Concurrent changes to QueriesObserver change-detection logic and observer reconfiguration in the same file.

Suggested labels

package: query-core, package: react-query

Suggested reviewers

TkDodo

Poem

🐰 A stable combine, once stuck in time, Now dances with hashes in perfect rhyme, When queries shift left, or swap their place, The combined results show their true face! Hash-tracking magic, so swift and clean— Best observer fix the TanStack's seen! 🥬✨

Pre-merge checks and finishing touches

❌ 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%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The PR title accurately describes the main fix: addressing the issue where a stable combine reference wasn't updating correctly when queries changed dynamically.
Linked Issues check	✅ Passed	The PR implementation fully addresses issue #8781 by tracking queryHashes in QueriesObserver to detect query changes before result updates, fixing the lag when using stable combine references.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the combine function lag issue: tracking queryHashes, updating combineResult signature, modifying getOptimisticResult, and adding comprehensive test coverage.
Description check	✅ Passed	Pull request description includes all required sections: detailed problem statement, solution explanation, completed checklist items, and release impact confirmation with changeset.

✨ Finishing touches

[ ] 📝 Generate docstrings

🧪 Generate unit tests (beta)

[ ] Create PR with unit tests
[ ] Post copyable unit tests in a comment

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Dec 07 '25 18:12 coderabbitai[bot]

View your CI Pipeline Execution ↗ for commit 89db791104f4435887de45f9eb4ffdd07da0bdb9

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☁️ Nx Cloud last updated this comment at 2025-12-07 18:34:00 UTC

Dec 07 '25 18:12 nx-cloud[bot]

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commit: 89db791

Dec 07 '25 18:12 pkg-pr-new[bot]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 60.14%. Comparing base (f15b7fc) to head (89db791).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #9954       +/-   ##
===========================================
+ Coverage   45.89%   60.14%   +14.25%     
===========================================
  Files         200      129       -71     
  Lines        8437     5661     -2776     
  Branches     1943     1555      -388     
===========================================
- Hits         3872     3405      -467     
+ Misses       4116     1952     -2164     
+ Partials      449      304      -145

Components	Coverage Δ
@tanstack/angular-query-experimental	`93.85% <ø> (ø)`
@tanstack/eslint-plugin-query	`∅ <ø> (∅)`
@tanstack/query-async-storage-persister	`43.85% <ø> (ø)`
@tanstack/query-broadcast-client-experimental	`24.39% <ø> (ø)`
@tanstack/query-codemods	`∅ <ø> (∅)`
@tanstack/query-core	`97.90% <100.00%> (+0.51%)`	:arrow_up:
@tanstack/query-devtools	`3.48% <ø> (ø)`
@tanstack/query-persist-client-core	`80.00% <ø> (ø)`
@tanstack/query-sync-storage-persister	`84.61% <ø> (ø)`
@tanstack/query-test-utils	`∅ <ø> (∅)`
@tanstack/react-query	`96.01% <ø> (ø)`
@tanstack/react-query-devtools	`9.25% <ø> (ø)`
@tanstack/react-query-next-experimental	`∅ <ø> (∅)`
@tanstack/react-query-persist-client	`100.00% <ø> (ø)`
@tanstack/solid-query	`77.81% <ø> (ø)`
@tanstack/solid-query-devtools	`64.17% <ø> (ø)`
@tanstack/solid-query-persist-client	`100.00% <ø> (ø)`
@tanstack/svelte-query	`∅ <ø> (∅)`
@tanstack/svelte-query-devtools	`∅ <ø> (∅)`
@tanstack/svelte-query-persist-client	`∅ <ø> (∅)`
@tanstack/vue-query	`71.91% <ø> (ø)`
@tanstack/vue-query-devtools	`∅ <ø> (∅)`

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