fix(app-router): support soft navigation in static exports

[james-elicx]

Summary

• emit App Router Flight payloads as .txt assets in output: "export", matching Next.js and the configured HTML/trailing-slash layout
• fetch those portable text/plain assets for static-export navigation while preserving the visible URL, route params, metadata, and client document state
• force export prefetches onto the available full-route artifact and fall back to the static 404 document when an artifact is missing
• handle deployment skew, parallel-slot params, and basePath roots without falling back to a document navigation
• namespace exported HTML, Flight, metadata, 404, and public/ assets under basePath for verbatim static hosts
• extend the static-export fixture and comprehensive example verification

Next.js parity

This follows Next.js's export transport in packages/next/src/client/components/router-reducer/fetch-server-response.ts and its trailing-slash regression in test/e2e/app-dir/static-export-skew-trailing-slash/static-export-skew-trailing-slash.test.ts. The .txt extension is only a static-host transport name; the contents remain Flight/RSC bytes. Normal vinext server prerenders continue to emit .rsc.

Temporary CI prerequisite

This draft currently carries the two focused commits from #3108 because CI against main consistently reproduced the prerender footer and Node stream-test races that PR fixes. They remain separate from the static-export commits and can be dropped once #3108 lands.

Validation

• vp check
• vp test run tests/app-rsc-cache-busting.test.ts tests/prerender.test.ts (157 tests)
• vp test run tests/link.test.ts (130 tests)
• vp test run tests/app-prefetch-rsc-request.test.ts tests/app-browser-entry.test.ts (260 tests)
• PLAYWRIGHT_PROJECT=static-export pnpm run test:e2e (23 tests)
• PLAYWRIGHT_PROJECT=static-export-basepath pnpm run test:e2e (3 tests)
• pnpm --dir examples/static-export build && pnpm --dir examples/static-export verify (50 emitted files)

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@vinext/cloudflare@3112

npm i https://pkg.pr.new/create-vinext-app@3112

npm i https://pkg.pr.new/@vinext/types@3112

npm i https://pkg.pr.new/vinext@3112

commit: a722e76

[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
static-export	preview	production
web	preview	production

[github-actions]

Performance benchmarks

Compared a722e76 against base c1a78a7 using alternating same-runner rounds. Next.js was unchanged and skipped.

1 improved · 0 regressed · 5 within ±1.5%

Scenario	Framework	Baseline	Current	Change
Client bundle size (gzip)	vinext	142.2 KB	142.2 KB	⚫ +0.0%
Client entry size (gzip)	vinext	129.5 KB	129.5 KB	⚫ +0.0%
Dev server cold start	vinext	3.20 s	3.14 s	🟢 -1.7%
Production build time	vinext	3.47 s	3.43 s	⚫ -1.0%
RSC entry closure size (gzip)	vinext	116.6 KB	116.6 KB	⚫ +0.0%
Server bundle size (gzip)	vinext	198.1 KB	198.3 KB	⚫ +0.1%

View detailed results and traces

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