[seongwon030]

Closes #25638

• If you've added code that should be tested, please add tests.
• Ensure your code lints and the test suite passes (pnpm run lint) & (pnpm run test).
• Link an issue if there is one related to your pull request. If no issue is linked, one will be auto-generated and linked.

location.pathname is percent-encoded, but React Router decodes the pathname before matching, so RouteMatch.pathname and pathnameBase are decoded. The React Router instrumentation compared the two with plain string equality, so a route like /clubs/:clubId visited as /clubs/%ED%95%9C%EA%B8%80 never matched and the transaction fell back to the raw URL with source url. Every non-ASCII parameter value became its own transaction name. Descendant routes (<Routes> nested under a /* route) produced the raw URL with source route.

Decoding never changes the number of / segments (an encoded slash stays %2F), so this compares segment counts instead of strings: getNormalizedName checks that the branch spans as many segments as the location, and the descendant-route lookups strip the parent pathnameBase from the raw location.pathname by segment count, the way useRoutes does. The remainder stays encoded, so React Router decodes it exactly once when matching it again. This works whichever side is encoded (older 6.x routers matched the raw pathname or used decodeURI), and values like %2541 or 100%25 are not decoded twice. Since the check no longer relies on string equality, a basename ending in / ('/', '/app/') or differing in case from the URL now yields a parameterized name as well; the basename is prefixed without its trailing slash so the name has no //.

Validation (in packages/react):

• vitest run on the React Router suites (react-router, reactrouterv6, reactrouter-descendant-routes, reactrouter-cross-usage, reactrouter-compat-utils/*): 277 tests passed; the whole package: 400 passed
• 11 of these tests fail on develop; the %2541, trailing-slash basename and descendant 100%25 tests also fail on the previous (decoding) revision of this PR
• pnpm run lint and pnpm run lint:types clean; oxfmt --check passed on the changed files
• Browser integration tests (Playwright) were not run

[s1gr1d]

Thanks, the looking into this and tests are great!

Instead of decoding, could we compare segment counts? Decoding never changes the number of / segments, so we don't need decodePathname. That also avoids two issues: /clubs/%2541 still doesn't match, because match.pathname gets decoded twice. And descendant routes now pass decoded paths back into matchRoutes, so /clubs/100%25 logs a "could not be decoded" warning.

Your tests already pass with the segment approach. Could you add those two URLs as cases too?

[s1gr1d]

Heads-up: react-router 6.22.1+ already decodes match.pathname, so this decodes it a second time. A literal %41 in a param then doesn't match.

[seongwon030]

Right, that double decode is gone with the segment-count approach. Resolved in the follow-up commit.

[seongwon030]

Thanks, that's much simpler. I removed decodePathname: getNormalizedName now compares segment counts, and the descendant lookups strip the parent pathnameBase from the raw pathname by segment count, so React Router decodes the remainder only once.

/clubs/%2541 and /clubs/100%25 are added as unit and pageload cases, plus a descendant case asserting the "could not be decoded" warning is gone. Those fail on the previous revision.

One side effect worth a look: a basename ending in / ('/', '/app/') always failed the old string comparison and fell back to the URL. With segment counts it now matches, so I prefix the basename without its trailing slash to avoid //users (covered by a test). For the same reason a URL that differs from the basename only in case (/APP/clubs/abc under /app) is now parameterized as /app/clubs/:clubId instead of falling back to the raw URL.

[s1gr1d]

Regarding the side-effect syou mentioned, they are fine: a basename with a trailing slash now gets parameterized like any other, and the case-insensitive match is the same as what React Router does.