fix(router-core): reject overlapping parameter affixes by Sheraff · Pull Request #8154 · TanStack/router

Sheraff · 2026-08-22T16:18:44Z

Summary

reject route matches when a parameter prefix and suffix overlap within the matched path
apply the length guard to required, optional, and wildcard parameters
preserve valid empty parameters where the affixes meet without overlapping
add regression coverage for all three parameter kinds

Context

A route such as /ab{$id}bc incorrectly matched /abc: abc starts with ab and ends with bc, but both affixes claimed the same b. Parameter extraction then returned that shared character as the parameter value.

The matcher now requires the matched path to be at least as long as the combined prefix and suffix before accepting both affixes. /abc is rejected, while /abbc remains valid with an empty parameter value.

Bundle size

react-router.minimal: +4 B gzip locally.

Summary by CodeRabbit

Bug Fixes

Improved route matching for dynamic, optional, and wildcard segments with overlapping prefixes and suffixes.
Prevented invalid or incomplete URLs—including paths with extra trailing characters—from matching routes incorrectly.
Preserved complete wildcard path remainders during suffix matching.
Ensured route parameters are extracted correctly when prefixes or suffixes are absent.

Tests

Added coverage for valid and invalid routes involving overlapping prefixes and suffixes, including trailing-character edge cases.

coderabbitai · 2026-08-22T16:19:19Z

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📒 Files selected for processing (1)

packages/router-core/src/new-process-route-tree.ts

🚧 Files skipped from review as they are similar to previous changes (1)

packages/router-core/src/new-process-route-tree.ts

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📝 Walkthrough

Walkthrough

Route matching now stores dynamic segment affixes as required strings and validates prefix and suffix placement for wildcard, optional dynamic, and regular dynamic segments. Tests cover parameter extraction and rejection of paths with trailing characters.

Changes

Route affix matching

Layer / File(s)	Summary
Affix contracts and extraction `packages/router-core/src/new-process-route-tree.ts`, `packages/router-core/tests/new-process-route-tree.test.ts`	Dynamic segment prefixes and suffixes now use required string values. Parameter extraction uses their lengths directly. Snapshots expect empty strings when affixes are absent.
Affix length validation `packages/router-core/src/new-process-route-tree.ts`, `packages/router-core/tests/new-process-route-tree.test.ts`	Wildcard, optional dynamic, and regular dynamic matching now validate that prefixes and suffixes fit the candidate URL. Tests reject paths with an extra trailing character while preserving valid parameter assertions.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: 🔵 Low · up to c9838

The matcher now rejects overlapping parameter affixes while preserving valid empty parameters, but the regression coverage does not confirm the extracted parameter values, leaving a bounded correctness risk. The PR is mergeable with explicit owner awareness or follow-up to add those assertions.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 60.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 2 files.	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 title clearly and concisely describes the main change: rejecting overlapping parameter affixes in router-core.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Commit unit tests in branch fix/router-affix-overlap

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nx-cloud · 2026-08-22T16:21:41Z

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☁️ Nx Cloud last updated this comment at 2026-08-22 19:40:50 UTC

github-actions · 2026-08-22T16:22:08Z

🚀 Changeset Version Preview

5 package(s) bumped directly, 18 bumped as dependents.

🟩 Patch bumps

Package	Version	Reason
`@tanstack/react-router`	1.170.31 → 1.170.32	Changeset
`@tanstack/router-core`	1.171.26 → 1.171.27	Changeset
`@tanstack/solid-router`	1.170.29 → 1.170.30	Changeset
`@tanstack/start-plugin-core`	1.171.38 → 1.171.39	Changeset
`@tanstack/vue-router`	1.170.28 → 1.170.29	Changeset
`@tanstack/react-start`	1.168.48 → 1.168.49	Dependent
`@tanstack/react-start-client`	1.168.29 → 1.168.30	Dependent
`@tanstack/react-start-rsc`	0.1.47 → 0.1.48	Dependent
`@tanstack/react-start-server`	1.167.36 → 1.167.37	Dependent
`@tanstack/router-cli`	1.167.32 → 1.167.33	Dependent
`@tanstack/router-generator`	1.167.32 → 1.167.33	Dependent
`@tanstack/router-plugin`	1.168.34 → 1.168.35	Dependent
`@tanstack/router-vite-plugin`	1.167.34 → 1.167.35	Dependent
`@tanstack/solid-start`	1.168.46 → 1.168.47	Dependent
`@tanstack/solid-start-client`	1.168.28 → 1.168.29	Dependent
`@tanstack/solid-start-server`	1.167.35 → 1.167.36	Dependent
`@tanstack/start-client-core`	1.170.26 → 1.170.27	Dependent
`@tanstack/start-server-core`	1.169.30 → 1.169.31	Dependent
`@tanstack/start-static-server-functions`	1.167.31 → 1.167.32	Dependent
`@tanstack/start-storage-context`	1.167.28 → 1.167.29	Dependent
`@tanstack/vue-start`	1.168.45 → 1.168.46	Dependent
`@tanstack/vue-start-client`	1.167.31 → 1.167.32	Dependent
`@tanstack/vue-start-server`	1.167.35 → 1.167.36	Dependent

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Actionable comments posted: 1

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Inline comments:
In `@packages/router-core/tests/new-process-route-tree.test.ts`:
- Around line 689-696: Extend the parameterized “does not match overlapping
affixes” test to assert rawParams for each accepted match: required and wildcard
parameters must use empty values where appropriate, optional parameters must use
their intended representation, and the full-remainder wildcard route must
include a non-empty multi-segment case. Keep the existing route-selection
assertions and use the relevant findRouteMatch result for these parameter
checks.

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📥 Commits

Reviewing files that changed from the base of the PR and between eb9ddac and 0b1b37e.

📒 Files selected for processing (2)

packages/router-core/src/new-process-route-tree.ts
packages/router-core/tests/new-process-route-tree.test.ts

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pkg-pr-new · 2026-08-22T16:23:59Z

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commit: a4b4133

github-actions · 2026-08-22T16:25:38Z

Bundle Size Benchmarks

Commit: adf3e3c46a06
Measured at: 2026-08-22T19:30:25.967Z
Baseline source: history:eb9ddac3e2c8
Dashboard: bundle-size history

The following scenarios have bundle-size changes compared with the baseline:

Scenario	Current (gzip)	Initial (gzip)	Raw	Brotli	Trend
`react-router.minimal`	83.8 KiB +5 B	83.7 KiB +7 B	262.5 KiB +37 B	73.0 KiB +78 B	▃▃▆▆▆▅███▁▁▂
`react-router.full`	87.3 KiB +4 B	87.2 KiB +5 B	274.2 KiB +37 B	75.9 KiB -25 B	▃▃███▅███▁▁▂
`solid-router.minimal`	33.1 KiB +3 B	33.0 KiB +3 B	96.3 KiB +37 B	29.9 KiB -70 B	▆▆▇▇▇▇███▁▁▁
`solid-router.full`	38.0 KiB +5 B	37.9 KiB +1 B	111.0 KiB +37 B	34.2 KiB +4 B	▆▆███▆▇▇▇▁▁▂
`vue-router.minimal`	49.5 KiB +5 B	49.4 KiB +1 B	138.3 KiB +37 B	44.6 KiB -62 B	▄▄███▆███▁▁▂
`vue-router.full`	55.1 KiB +7 B	55.0 KiB +8 B	156.6 KiB +37 B	49.5 KiB -60 B	▃▃███▅▇▇▇▁▁▂
`react-start.minimal`	96.7 KiB +12 B	96.6 KiB +13 B	304.7 KiB +37 B	83.7 KiB -33 B	▁▁▆▆▆▄███▁▁▃
`react-start.deferred-hydration`	97.4 KiB +5 B	96.6 KiB +9 B	306.1 KiB +37 B	84.5 KiB -1 B	▁▁▇▇▇▄███▂▂▃
`react-start.full`	99.9 KiB +6 B	99.7 KiB +6 B	314.5 KiB +37 B	86.6 KiB +35 B	▁▁▆▆▆▃███▁▁▂
`react-start.rsbuild.minimal`	100.0 KiB +5 B	99.8 KiB +5 B	315.1 KiB +37 B	86.3 KiB +114 B	▂▂███▄▆▆▆▁▁▁
`react-start.rsbuild.minimal-iife`	100.4 KiB +4 B	100.3 KiB +4 B	316.0 KiB +37 B	86.7 KiB +43 B	▂▂███▄▆▆▆▁▁▁
`react-start.rsbuild.full`	103.3 KiB +3 B	103.2 KiB +3 B	325.2 KiB +37 B	89.0 KiB +88 B	▂▂███▅▆▆▆▁▁▁
`solid-start.minimal`	46.0 KiB -1 B	45.9 KiB 0 B	137.4 KiB +37 B	40.9 KiB +78 B	▄▄███▅███▁▁▁
`solid-start.deferred-hydration`	49.1 KiB +4 B	45.9 KiB +2 B	144.9 KiB +37 B	43.7 KiB 0 B	▅▅▇▇▇▃███▁▁▂
`solid-start.full`	51.1 KiB +3 B	51.0 KiB +2 B	152.8 KiB +37 B	45.3 KiB +9 B	▃▃▆▆▆▅███▁▁▁
`vue-start.minimal`	65.6 KiB +11 B	65.5 KiB +5 B	189.2 KiB +37 B	58.4 KiB -7 B	▄▄███▅███▁▁▃
`vue-start.full`	69.5 KiB +12 B	69.3 KiB +10 B	201.5 KiB +37 B	61.6 KiB -95 B	▃▃███▅███▁▁▃

Current gzip tracks all emitted client JS chunks. Initial gzip tracks only the entry/import graph. Trend sparkline is historical current gzip ending with this PR measurement; lower is better.

codspeed-hq · 2026-08-22T16:37:51Z

Merging this PR will regress 0 benchmarks

⚠️

Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 5 improved benchmarks
❌ 6 (👁 6) regressed benchmarks
✅ 169 untouched benchmarks

Performance Changes

	Mode	Benchmark	`BASE`	`HEAD`	Efficiency
⚡	Memory	`mem server error-paths not-found (vue)`	2,149.3 KB	493.1 KB	×4.4
⚡	Memory	`mem server aborted-requests (vue)`	1,086.1 KB	958.3 KB	+13.33%
⚡	Memory	`mem server error-paths error (react)`	1,047.4 KB	973.2 KB	+7.62%
⚡	Memory	`mem client interrupted-navigations (vue)`	367 KB	351.9 KB	+4.26%
⚡	Memory	`mem server aborted-requests (solid)`	1.2 MB	1.2 MB	+3.3%
👁	Memory	`mem server error-paths redirect (vue)`	423.9 KB	819.1 KB	-48.24%
👁	Memory	`mem server error-paths unmatched (vue)`	578 KB	598.8 KB	-3.47%
👁	Memory	`mem server peak-large-page (vue)`	1 MB	1.1 MB	-7%
👁	Memory	`mem server error-paths not-found (solid)`	571 KB	863.3 KB	-33.86%
👁	Memory	`mem server aborted-requests (react)`	831.9 KB	859.6 KB	-3.23%
👁	Memory	`mem client unique-location-churn (vue)`	465.6 KB	487.5 KB	-4.49%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

_{Comparing fix/router-affix-overlap (a4b4133) with main (eb9ddac)}

fix(router-core): reject overlapping parameter affixes

0b1b37e

github-actions Bot added the package: router-core label Aug 22, 2026

coderabbitai Bot reviewed Aug 22, 2026

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Comment thread packages/router-core/tests/new-process-route-tree.test.ts Outdated

Sheraff and others added 6 commits August 22, 2026 19:13

perf(router-core): reduce affix overlap check size

72d3e0d

test(router-core): assert affix match parameters

bdd2855

ci: apply automated fixes

02639f5

perf(router-core): normalize route affixes

ebfa894

ci: apply automated fixes

c983879

add test case

a4b4133

Sheraff merged commit 0eb4573 into main Aug 22, 2026
26 checks passed

Sheraff deleted the fix/router-affix-overlap branch August 22, 2026 19:47

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fix(router-core): reject overlapping parameter affixes - #8154

fix(router-core): reject overlapping parameter affixes#8154
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