fix(config): match trailing-slash route sources

[james-elicx]

Summary

• match config rewrites, redirects, and headers when sources end in /
• preserve Next.js optional trailing-slash matching after canonical request normalization
• restore generated-static-param ISR routes reached through trailing-slash rewrites

Next.js parity

Targets two failures in the trailing-slash ISR/generateStaticParams deploy-suite cluster. The prerendered destination was correct; the canonical rewritten source failed before ISR assertions because its config source no longer matched.

Validation

• targeted production fixture: rewritten source renders the generated static route
• 16 focused matcher assertions
• scoped format, lint, and type checks
• vp run vinext#build
• independent review: no actionable findings

Full suites are deferred to CI.

[james-elicx]

/bigbonk review for issues

[pkg-pr-new]

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commit: bf41b75

[github-actions]

Example	Preview	Production	Original
app-router-cloudflare	preview	production
pages-router-cloudflare	preview	production
app-router-playground	preview	production	original
realworld-api-rest	preview	production
nextra-docs-template	preview	production
benchmarks	preview	production
hackernews	preview	production	original
workers-cache	preview	production
web	preview	production

[james-elicx]

/bigbonk review for issues

[github-actions]

Performance benchmarks

Compared bf41b75 against base cf9d601 using alternating same-runner rounds. Next.js was unchanged and skipped.

0 improved · 0 regressed · 6 within ±1.5%

Scenario	Framework	Baseline	Current	Change
Client bundle size (gzip)	vinext	132.8 KB	132.8 KB	⚫ +0.0%
Client entry size (gzip)	vinext	118.7 KB	118.7 KB	⚫ +0.0%
Dev server cold start	vinext	2.45 s	2.43 s	⚫ -0.7%
Production build time	vinext	3.05 s	3.04 s	⚫ -0.3%
RSC entry closure size (gzip)	vinext	92.2 KB	92.3 KB	⚫ +0.1%
Server bundle size (gzip)	vinext	166.9 KB	167.0 KB	⚫ +0.0%

View detailed results and traces

_{🟢 improvement · 🔴 regression · ⚫ change below 1.5% · paired base/head}

[ask-bonk]

Review: trailing-slash config route source matching

I verified the core behavioral change against the authoritative Next.js implementation and ran the matchers across a broad parity matrix. The fix is correct and matches Next.js behavior. No actionable issues found.

Verification against Next.js

Next.js compiles config route sources (rewrites/redirects/headers) with path-to-regexp in non-strict mode (getPathMatch in shared/lib/router/utils/path-match.ts, default strict: false). I compiled the vendored Next.js path-to-regexp (.nextjs-ref/.../compiled/path-to-regexp) to derive the ground-truth match table:

source	matches /x	matches /x/
/x	✅	✅
/x/	❌	✅
/:l(en|es)	✅	✅
/:l(en|es)/	❌	✅
/api/:path*/	❌ (/api)	✅ (/api/)

Non-strict path-to-regexp appends an optional trailing-slash matcher, so a slash-ending source matches the slashed canonical form but not the slash-free form. The PR's new test assertions (matchConfigPattern("/en/", "/:lang(en|es)/") ⇒ match, "/en" ⇒ null; same for matchHeaders /docs/) line up exactly with this table.

I ran matchConfigPattern against a 13×13 pattern/pathname matrix (170 cases) cross-checked against the vendored path-to-regexp — all 170 matched Next.js exactly, including the catch-all edge cases (:path* zero-segment, :path+ minimum-segment) that the removed comment was guarding against. Param extraction values are also correct for slash-ending patterns.

Implementation notes (all sound)

• matchConfigPattern: stripping the trailing slash from the pattern only when the pathname had one correctly reproduces non-strict optional-slash semantics without changing catch-all/root behavior. Root / is preserved (length > 1 guard).
• matchRedirect: the locale-static fast path uses normalizedPathname for Map.get keys (derived from slash-free sources), while the linear fallback passes the original pathname into matchConfigPattern. Verified _LOCALE_STATIC_RE requires a non-empty suffix, so a slash-only source like /:lang(en|es)/ falls to the linear path — consistent with the new test.
• matchHeaders: the compiled-regex cache key now matches the (possibly-stripped) source used to build the regex, so there is no cache poisoning. Cache growth is at most 2× a finite static rule set — negligible.
• All callers (matchRewrite, matchesRewriteSource, request pipelines) pass the unstripped pathname, which is what the fix expects.

Tests run (all green)

• New tests/app-trailing-slash-isr.test.ts integration test (rewrite + ISR/GSP end-to-end) — passes
• tests/shims.test.ts matchConfigPattern / matchRedirect / matchHeaders suites — pass
• tests/routing.test.ts, tests/route-sorting.test.ts, tests/isr-cache.test.ts — pass
• 170-case + param-extraction parity checks vs vendored path-to-regexp — pass

LGTM.

[ask-bonk]

Review posted to PR #2255.

Summary

I reviewed PR #2255 (fix(config): match trailing-slash route sources) and found no actionable issues — the fix is correct and matches Next.js behavior.

What the PR does

Makes matchConfigPattern, matchRedirect, and matchHeaders correctly match config route sources (rewrites/redirects/headers) that end in /, so trailing-slash ISR + generateStaticParams rewrites resolve from their canonical slashed URLs.

Verification approach

I cloned the Next.js reference repo and confirmed that Next.js compiles config sources with path-to-regexp in non-strict mode (getPathMatch, default strict: false), which appends an optional trailing-slash matcher. I compiled the vendored path-to-regexp to build a ground-truth match table, then:

• Cross-checked matchConfigPattern against a 170-case pattern/pathname matrix — all matched Next.js exactly, including the catch-all edge cases the removed comment worried about.
• Verified param extraction values for slash-ending patterns.
• Confirmed the locale-static index correctly routes slash-only sources to the linear fallback (via _LOCALE_STATIC_RE requiring a non-empty suffix).
• Confirmed the matchHeaders regex cache key stays consistent with the compiled source (no cache poisoning).
• Ran the new integration test plus shims, routing, route-sorting, and isr-cache suites — all green.

The PR's new test assertions align exactly with verified Next.js semantics. LGTM.

github run