fix(router-core): correct splat param extraction after a skipped optional param

[Sheraff]

Summary by CodeRabbit

• Bug Fixes

  • Fixed route parameter extraction to properly align path segments when optional parameters are skipped during route matching.

• Tests

  • Added test coverage for route matching scenarios with optional parameters followed by wildcard segments.

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR fixes a bug in the extractParams function where pathIndex wasn't being properly decremented when handling optional parameter segments with skipped nodes. A test case verifying the fix with a skipped optional parameter followed by a wildcard segment is also added.

Changes

Cohort / File(s)	Summary
Bug Fix packages/router-core/src/new-process-route-tree.ts	Decrements pathIndex by 1 when handling OPTIONAL_PARAM segment with a skipped node, ensuring proper alignment between path segments and route parameter extraction.
Test Coverage packages/router-core/tests/new-process-route-tree.test.ts	Adds new test case "skipped optional, ends with wildcard" validating parameter extraction for route pattern /{-$foo}/bar/$ matching path /bar/rest.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• refactor(router-core): Process routeTree into segment tree instead of flatRoutes #5722: Modifies the same extractParams logic and route tree matching behavior in new-process-route-tree.ts.
• refactor(router-core): index nodes can skip the stack loop, they cannot have children #6173: Changes how skipped nodes (optionals, wildcards, index matches) are handled during route matching in new-process-route-tree.ts.
• refactor(router-core): processRouteTree in its own file #5128: Modifies route-tree processing implementation including parameter extraction behavior.

Suggested reviewers

• schiller-manuel
• nlynzaad

Poem

🐰 A path once wandered, confused and slow,
With optional skips that threw pathIndex low.
Now properly decremented, the segments align,
Wildcards catch rest with a fix so fine! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: fixing splat parameter extraction after a skipped optional parameter, which is exactly what the code modifications address.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

• 📝 Generate docstrings

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit 4f19845

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---

☁️ Nx Cloud last updated this comment at 2026-01-21 11:23:03 UTC

[pkg-pr-new]

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commit: 4f19845