fix(db): skip deletes for unsent keys in filterDuplicateInserts

[v-anton]

🎯 Changes

filterDuplicateInserts forwarded delete changes for keys never present in sentKeys. When SSE delivers deletes for items filtered out by the where clause, the spurious -1 multiplicity corrupts D2's TopKState window.

The fix checks the return value of sentKeys.delete() — if false, the key was never sent, so the delete is skipped.

✅ Checklist

• I have tested this code locally with pnpm test:pr.
• I have followed the steps in the Contributing guide.

🚀 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 spurious delete events from being emitted for items that were never previously sent, improving synchronization consistency and preventing downstream mismatches.

• Tests

  • Added unit tests covering change-filtering behavior, including mixed insert/delete scenarios and “ghost delete” cases, to ensure deletes are only forwarded when appropriate and tracking state is updated correctly.

[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: 8a2cca51-9630-4d3d-ad22-04f4b62c5a5b

📥 Commits

Reviewing files that changed from the base of the PR and between 2774f87 and 2a36fbf.

📒 Files selected for processing (1)

• packages/db/tests/collection-subscriber-duplicate-inserts.test.ts

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📝 Walkthrough

Walkthrough

filterDuplicateInserts now skips delete changes for keys never recorded in sentKeys. Unit tests validate empty-input behavior, ghost-delete skipping, forwarding/removal of known deletes, and mixed insert/delete sequences. A changeset records the patch release.

Changes

Delete Guard Fix

Layer / File(s)	Summary
Delete guard and unit tests packages/db/src/query/live/utils.ts, packages/db/tests/collection-subscriber-duplicate-inserts.test.ts	filterDuplicateInserts adds a guard checking sentKeys before forwarding deletes; deletes for unknown keys are skipped. Tests import the function and validate empty input, ghost-delete skipping, forwarding/removal of known deletes, and mixed insert/delete sequences with assertions on sentKeys.
Release documentation .changeset/fix-ghost-delete-sentkeys.md	Changeset file declares a patch version bump for @tanstack/db and documents the fix for skipping deletes in filterDuplicateInserts.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

• samwillis

Poem

🐰 I peeked at sentKeys in the night,
A ghostly delete met no prior sight.
I skip the phantom, keep counts true,
Hop, patch, and tidy—now D2's queued! 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The pull request title clearly and concisely describes the main change: skipping deletes for unsent keys in the filterDuplicateInserts function.
Description check	✅ Passed	The pull request description follows the template structure, includes clear explanation of the problem and fix, and completes all required checklist items including changeset generation.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

packages/db/tests/collection-subscriber-duplicate-inserts.test.ts (1)

457-508: ⚡ Quick win

Add an explicit empty-batch/empty-set corner-case test in this block.

The new tests reproduce the bug well, but this added suite still misses an explicit changes = [] + sentKeys = new Set() case.

Proposed test addition

 describe(`filterDuplicateInserts`, () => {
+  it(`should return empty output for empty changes and empty sentKeys`, () => {
+    const sentKeys = new Set<string | number>()
+    const changes: Array<ChangeMessage<TestItem, string>> = []
+
+    const result = filterDuplicateInserts(changes, sentKeys)
+
+    expect(result).toEqual([])
+    expect(sentKeys.size).toBe(0)
+  })
+
   it(`should skip deletes for keys never sent to D2`, () => {

As per coding guidelines, `**/*.test.{ts,tsx,js}`: "Test corner cases including: empty arrays/sets, single-element collections, undefined vs null values, resolved promises, async race conditions, and limit/offset edge cases".

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/db/tests/collection-subscriber-duplicate-inserts.test.ts` around
lines 457 - 508, Add a corner-case unit test for filterDuplicateInserts that
covers an empty changes array and an empty sentKeys set: create changes = [] and
sentKeys = new Set(), call filterDuplicateInserts(changes, sentKeys), and assert
the result is an empty array and sentKeys remains empty (or unchanged). Place
this test in the existing describe(`filterDuplicateInserts`) block alongside the
other it(...) cases so it validates the empty-batch/empty-set path for the
filterDuplicateInserts function.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@packages/db/tests/collection-subscriber-duplicate-inserts.test.ts`:
- Around line 457-508: Add a corner-case unit test for filterDuplicateInserts
that covers an empty changes array and an empty sentKeys set: create changes =
[] and sentKeys = new Set(), call filterDuplicateInserts(changes, sentKeys), and
assert the result is an empty array and sentKeys remains empty (or unchanged).
Place this test in the existing describe(`filterDuplicateInserts`) block
alongside the other it(...) cases so it validates the empty-batch/empty-set path
for the filterDuplicateInserts function.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b5ed8e11-d4d5-4876-8783-a230926a8d39

📥 Commits

Reviewing files that changed from the base of the PR and between be656be and 2774f87.

📒 Files selected for processing (3)

• .changeset/fix-ghost-delete-sentkeys.md
• packages/db/src/query/live/utils.ts
• packages/db/tests/collection-subscriber-duplicate-inserts.test.ts