fix(virtual-core): correct lane assignments when lane count changes dynamically

[shunn2]

…ynamically

🎯 Changes

Fixes issue where changing lane count dynamically causes layout breakage with items retaining old lane numbers, resulting in out-of-bounds errors in responsive masonry layouts.

After clearing measurements cache on lane change, the virtualizer was incorrectly restoring from initialMeasurementsCache which contained stale lane assignments.

Added check to skip initialMeasurementsCache restoration during lane transitions using the lanesSettling flag.

Related Issue: #1063

✅ Checklist

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

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

[changeset-bot]

🦋 Changeset detected

Latest commit: 011c9b9

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

This PR includes changesets to release 7 packages

Name	Type
@tanstack/virtual-core	Patch
@tanstack/angular-virtual	Patch
@tanstack/lit-virtual	Patch
@tanstack/react-virtual	Patch
@tanstack/solid-virtual	Patch
@tanstack/svelte-virtual	Patch
@tanstack/vue-virtual	Patch

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☁️ Nx Cloud last updated this comment at 2025-12-16 16:02:00 UTC

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commit: 011c9b9