fix(router-generator): fix parent resolution logic

[schiller-manuel]

fixes #6261

Summary by CodeRabbit

• Tests

  • Added comprehensive test coverage for lazy-loaded routes with pathless layout configurations.

• Refactor

  • Optimized route parent lookup logic to improve route generation performance.

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR fixes a regression where conflicting configuration paths error occurred when lazy-loading layout and index routes nested within a pathless route. The fix optimizes parent route resolution in the generator by replacing an upward loop search with a direct check on the immediate parent route.

Changes

Cohort / File(s)	Summary
Generator logic optimization packages/router-generator/src/generator.ts	Replaced fallback loop for parent route discovery with direct immediate-parent check via routeNodesByPath. Optimizes parent route resolution when closer parents exist.
Test fixtures for lazy layout and index in pathless routes packages/router-generator/tests/generator/lazy-only-layout-and-index-in-pathless/routes/__root.tsx, _layout/route.tsx, _layout/path.lazy.tsx, _layout/path.index.lazy.tsx	Added root route and nested lazy-loaded layout/path route definitions to test the pathless layout scenario with lazy-loaded child routes.
Generated route tree snapshot packages/router-generator/tests/generator/lazy-only-layout-and-index-in-pathless/routeTree.snapshot.ts	Generated test snapshot defining complete type-safe route hierarchy with lazy-loaded routes, route mappings, and module augmentation for TanStack Router integration.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• fix: Fix conflicting paths error when lazy loading layout and index r… #6251 — Modifies parent-resolution logic in generator.ts with fallback loop implementation for finding closer parent nodes
• fix: generator perf and pathless routes relative to parent  #6121 — Refactors parent-route resolution in generator.ts to use RoutePrefixMap instead of loop-based lookup
• fix: ignore route pieces in RoutePrefixMap #6186 — Filters lazy/loader/component route pieces during parent-route candidate selection to avoid incorrect preference matching

Suggested labels

package: router-generator

Suggested reviewers

• nlynzaad

Poem

🐰 A pathless route once lost its way,
Conflicting paths made it go astray,
But now with parents found up front,
No loops, just checks—we've done the stunt!
Lazy routes hop without a fright,
The generator's fixed, all set right! 🎯

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately describes the main change: fixing parent resolution logic in the router-generator, which directly addresses the bug fix referenced in issue #6261.
Linked Issues check	✅ Passed	The code changes fix the parent route resolution logic by replacing a fallback loop with direct parent checking, which resolves the conflicting path error for lazy-loaded layout and index routes in pathless directories [#6261].
Out of Scope Changes check	✅ Passed	All changes are scoped to the parent resolution logic fix and test files for the specific issue; no unrelated modifications are present.

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✨ Finishing touches

• 📝 Generate docstrings

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit 67c56ba

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	18m 42s	View ↗
nx run-many --target=build --exclude=examples/*...	✅ Succeeded	37s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-01-18 11:00:41 UTC

[pkg-pr-new]

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commit: 67c56ba