fix race condition that resulted in live queries becoming stuck

[samwillis]

fixes #645

The original reproduction from that issue updated to the preview package from this PR: https://stackblitz.com/edit/tanstack-db-init-jm98exso?file=src%2FApp.tsx

Summary

The bug was in the capturePreSyncVisibleState() method in state.ts. Here's what was happening:

The Race Condition:

1. When the first transaction (T1) completed, capturePreSyncVisibleState() captured the visible state for key "0" (with optimistic data)
2. Then recomputeOptimisticState() cleared T1's optimistic state
3. commitPendingTransactions() couldn't run yet because T2 was still persisting
4. When T2 completed, capturePreSyncVisibleState() was called again and cleared all previous captures with this.preSyncVisibleState.clear()
5. At this point, key "0" was no longer in the optimistic state (cleared when T1 completed), so it wasn't recaptured
6. When commitPendingTransactions() finally ran, it had no previousVisibleValue for key "0", causing it to emit INSERT instead of UPDATE

The Fix:
I modified capturePreSyncVisibleState() to:

1. Remove the this.preSyncVisibleState.clear() call to preserve previously captured state
2. Add a check if (!this.preSyncVisibleState.has(key)) before capturing to avoid overwriting earlier captures

This ensures that when transactions complete at different times (due to async delays in onInsert), each key's visible state is captured at the correct moment - when its corresponding transaction completes and before its optimistic state is cleared. The state is then preserved until all sync operations can be committed together.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9f0f852

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

This PR includes changesets to release 12 packages

Name	Type
@tanstack/db	Patch
@tanstack/angular-db	Patch
@tanstack/electric-db-collection	Patch
@tanstack/query-db-collection	Patch
@tanstack/react-db	Patch
@tanstack/rxdb-db-collection	Patch
@tanstack/solid-db	Patch
@tanstack/svelte-db	Patch
@tanstack/trailbase-db-collection	Patch
@tanstack/vue-db	Patch
todos	Patch
@tanstack/db-example-react-todo	Patch

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@tanstack/react-db

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@tanstack/rxdb-db-collection

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@tanstack/solid-db

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@tanstack/trailbase-db-collection

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@tanstack/vue-db

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commit: 9f0f852

[github-actions]

Size Change: +7 B (+0.01%)

Total Size: 75.2 kB

Filename	Size	Change
./packages/db/dist/esm/collection/state.js	3.82 kB	+7 B (+0.18%)

ℹ️ View Unchanged

Filename	Size
./packages/db/dist/esm/collection/change-events.js	943 B
./packages/db/dist/esm/collection/changes.js	1.01 kB
./packages/db/dist/esm/collection/events.js	660 B
./packages/db/dist/esm/collection/index.js	3.18 kB
./packages/db/dist/esm/collection/indexes.js	1.16 kB
./packages/db/dist/esm/collection/lifecycle.js	1.8 kB
./packages/db/dist/esm/collection/mutations.js	2.5 kB
./packages/db/dist/esm/collection/subscription.js	1.65 kB
./packages/db/dist/esm/collection/sync.js	1.42 kB
./packages/db/dist/esm/deferred.js	230 B
./packages/db/dist/esm/errors.js	3.1 kB
./packages/db/dist/esm/index.js	1.56 kB
./packages/db/dist/esm/indexes/auto-index.js	806 B
./packages/db/dist/esm/indexes/base-index.js	835 B
./packages/db/dist/esm/indexes/btree-index.js	2 kB
./packages/db/dist/esm/indexes/lazy-index.js	1.21 kB
./packages/db/dist/esm/indexes/reverse-index.js	577 B
./packages/db/dist/esm/local-only.js	827 B
./packages/db/dist/esm/local-storage.js	2.02 kB
./packages/db/dist/esm/optimistic-action.js	294 B
./packages/db/dist/esm/proxy.js	3.86 kB
./packages/db/dist/esm/query/builder/functions.js	615 B
./packages/db/dist/esm/query/builder/index.js	4.04 kB
./packages/db/dist/esm/query/builder/ref-proxy.js	938 B
./packages/db/dist/esm/query/compiler/evaluators.js	1.55 kB
./packages/db/dist/esm/query/compiler/expressions.js	631 B
./packages/db/dist/esm/query/compiler/group-by.js	2.04 kB
./packages/db/dist/esm/query/compiler/index.js	2.04 kB
./packages/db/dist/esm/query/compiler/joins.js	2.52 kB
./packages/db/dist/esm/query/compiler/order-by.js	1.21 kB
./packages/db/dist/esm/query/compiler/select.js	1.28 kB
./packages/db/dist/esm/query/ir.js	785 B
./packages/db/dist/esm/query/live-query-collection.js	340 B
./packages/db/dist/esm/query/live/collection-config-builder.js	2.69 kB
./packages/db/dist/esm/query/live/collection-subscriber.js	1.86 kB
./packages/db/dist/esm/query/optimizer.js	3.08 kB
./packages/db/dist/esm/SortedMap.js	1.24 kB
./packages/db/dist/esm/transactions.js	3 kB
./packages/db/dist/esm/utils.js	1.01 kB
./packages/db/dist/esm/utils/browser-polyfills.js	365 B
./packages/db/dist/esm/utils/btree.js	6.01 kB
./packages/db/dist/esm/utils/comparison.js	754 B
./packages/db/dist/esm/utils/index-optimization.js	1.73 kB

_{compressed-size-action::db-package-size}

[github-actions]

Size Change: 0 B

Total Size: 1.47 kB

ℹ️ View Unchanged

Filename	Size
./packages/react-db/dist/esm/index.js	152 B
./packages/react-db/dist/esm/useLiveQuery.js	1.32 kB

_{compressed-size-action::react-db-package-size}

[KyleAMathews]

looks great!

[obeattie]

Just tried this in my codebase and it definitely fixes the issue I was seeing. You guys rock.