fix(react): Prevent lazy route handlers from updating wrong navigation span

[onurtemizkan]

Following up on #18346

Fixes a remaining race condition where the args.patch callback and completion handler in wrapPatchRoutesOnNavigation were still calling getActiveRootSpan() at resolution time instead of using the captured span. This caused wrong span updates when users navigated away during lazy route loading.

The fix uses the captured activeRootSpan consistently, adds a !spanJson.timestamp check to skip updates on ended spans, and removes the WINDOW.location fallback. In captureCurrentLocation, returns null when navigation context exists but targetPath is undefined, instead of falling back to stale WINDOW.location.

Also added E2E tests that simulate rapid navigation scenarios where a slow lazy route handler completes after the user navigated elsewhere.

[Copilot]

Pull request overview

This PR fixes a race condition in React Router lazy route handling where navigation spans could be incorrectly updated when users navigate away during lazy route loading.

Changes:

• Use captured navigation span consistently instead of calling getActiveRootSpan() at resolution time in wrapPatchRoutesOnNavigation
• Add !spanJson.timestamp guard to prevent updates on already-ended spans
• Remove WINDOW.location fallback when navigation context exists but targetPath is undefined to avoid using stale location data

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/react/src/reactrouter-compat-utils/lazy-routes.tsx	Updated captureCurrentLocation to return null instead of falling back to WINDOW.location when inside navigation context with undefined targetPath
packages/react/src/reactrouter-compat-utils/instrumentation.tsx	Modified wrapPatchRoutesOnNavigation to use captured activeRootSpan consistently in both args.patch callback and completion handler, added !spanJson.timestamp checks, removed WINDOW.location fallback
packages/react/test/reactrouter-compat-utils/lazy-routes.test.ts	Added edge case tests for captureCurrentLocation behavior with and without navigation context
packages/react/test/reactrouter-compat-utils/instrumentation.test.tsx	Added unit tests for race condition fix verifying ended spans are not updated
dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/tests/transactions.test.ts	Added E2E tests simulating rapid navigation scenarios to validate the race condition fix

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