fix: remove extra trace lines from duplicate consecutive points

[ayushopchauhan]

Closes #78\n\n## Root Cause\n\nUntangleTraceSubsolver._applyBestRoute() concatenates path segments when rerouting L-shaped corners:\n\nts\nconst newTracePath = [\n ...originalTrace.tracePath.slice(0, p2Index),\n ...bestRoute,\n ...originalTrace.tracePath.slice(p2Index + 1),\n]\n\n\nThe last point of slice(0, p2Index) can be identical to the first point of bestRoute, and the last point of bestRoute can be identical to the first point of slice(p2Index + 1). This produces consecutive duplicate points that render as zero-length extra trace segments.\n\n## Fix\n\n1. New utility: removeDuplicateConsecutivePoints() in simplifyPath.ts\n- Filters consecutive points that are within 1e-9 epsilon distance\n- Reusable across the codebase (same pattern already exists in TraceOverlapIssueSolver)\n\n2. Applied in _applyBestRoute() after the splice:\nts\nconst newTracePath = removeDuplicateConsecutivePoints([\n ...originalTrace.tracePath.slice(0, p2Index),\n ...bestRoute,\n ...originalTrace.tracePath.slice(p2Index + 1),\n])\n\n\n3. Applied as preprocessing in simplifyPath()\n- Deduplicates before collinear reduction, preventing edge cases where duplicates confuse the isVertical/isHorizontal checks\n\n## Files Changed\n\n| File | Change |\n|------|--------|\n| lib/solvers/TraceCleanupSolver/simplifyPath.ts | Added removeDuplicateConsecutivePoints(), applied as preprocessing in simplifyPath() |\n| lib/solvers/TraceCleanupSolver/sub-solver/UntangleTraceSubsolver.ts | Imported and applied dedup in _applyBestRoute() |\n| site/examples/example32-fix-extra-trace-lines.page.tsx | New example page with crossing traces that trigger rerouting |\n| tests/examples/example32.test.ts | Integration test for the fix |\n| tests/unit/removeDuplicateConsecutivePoints.test.ts | 8 unit tests for the dedup function + 2 for simplifyPath |\n\n## Test Results\n\n- 59 pass, 0 fail, 5 skip (full suite)\n- Zero snapshot regressions on existing tests\n- 8 new unit tests for removeDuplicateConsecutivePoints\n- 1 new integration test (example32)\n- TypeScript type-check: clean (tsc --noEmit zero errors)\n\n/claim #78"

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Project	Deployment	Actions	Updated (UTC)
schematic-trace-solver	Ready	Preview, Comment	Mar 24, 2026 1:22pm

[ayushopchauhan]

@seveibar Ready for review. This fixes extra trace lines caused by consecutive duplicate points in _applyBestRoute(). Added removeDuplicateConsecutivePoints() utility (follows existing samePoint dedup pattern from TraceOverlapIssueSolver). 8 unit tests + integration test, zero regressions.

[ayushopchauhan]

Hey @seveibar, friendly nudge - this one's also ready for review. CI green, tests passing. Happy to make changes if needed.