fix(db): preserve explicit gcTime of 0 on live query collections

[spokodev]

The live query config builder built its collection options with gcTime: this.config.gcTime || 5000. A gcTime of 0 disables garbage collection (the core lifecycle treats gcTime <= 0 as "never GC"), but 0 || 5000 evaluates to 5000, so an explicit gcTime: 0 on a live query collection is silently replaced by the 5s default and the collection is garbage collected 5s after its last subscriber unsubscribes.

Use ?? so only undefined falls back to the default; an explicit 0 is forwarded and GC is disabled as documented.

Repro: liveQueryCollectionOptions({ query, gcTime: 0 }).gcTime returns 5000 instead of 0. Added a regression test.

Summary by CodeRabbit

• Bug Fixes
  • Fixed live query settings so an explicitly set gcTime: 0 is preserved instead of being replaced with the default timeout.
  • Live query behavior now respects disabled garbage collection as intended.
  • Added coverage to verify that gcTime: 0 continues to work 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: 09101176-28b1-45f3-b1b1-f6284f180fd3

📥 Commits

Reviewing files that changed from the base of the PR and between a93abf6 and f9be1a6.

📒 Files selected for processing (3)

• .changeset/live-query-gctime-zero.md
• packages/db/src/query/live/collection-config-builder.ts
• packages/db/tests/query/live-query-collection.test.ts

---

📝 Walkthrough

Walkthrough

This PR fixes a bug in @tanstack/db's live query collection config where an explicit gcTime: 0 was incorrectly replaced with a 5000ms default due to falsy-value coercion via ||. The fix switches to ?? so only undefined triggers the default.

Changes

gcTime Default Fix

Layer / File(s)	Summary
Nullish-coalescing fix for gcTime default packages/db/src/query/live/collection-config-builder.ts	Changes this.config.gcTime || 5000 to this.config.gcTime ?? 5000 so gcTime: 0 is preserved instead of falling back to the default.
Test coverage and changeset packages/db/tests/query/live-query-collection.test.ts, .changeset/live-query-gctime-zero.md	Adds a test asserting liveQueryCollectionOptions returns gcTime: 0 when explicitly configured, and adds a changeset documenting the patch.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Possibly related PRs

• TanStack/db#1568: Also touches gcTime plumbing in the live/query collection configuration path.

Suggested reviewers: kevin-dp

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main fix: preserving an explicit gcTime of 0 for live query collections.
Description check	✅ Passed	The description explains the bug, fix, and regression test, but it does not follow the repository template sections exactly.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}