feat: move file-system routing from SolidStart into router-neutral packages

[brenelz]

Implements the architecture refined by @ryansolid in #571 — shapes vs machinery, shared analysis / per-consumer emission — building on the pnpm workspace layout from #570 (this branch includes that PR's commit; the new work is the top commit).

What's in here

@solidjs/file-routes (new, router-neutral)

The machinery, ported from SolidStart's config/fs-routes:

• Bundler-agnostic core — BaseFileSystemRouter scans a directory into a flat, neutral route manifest (paths in a neutral pattern language, module refs with export picks). No Vite imports in the core.
• Pluggable convention — PageFileSystemRouter is exactly the convention Start has proven ([id], [[opt]], [...rest], (group), index, route export, md/mdx), overridable via toPath/toRoute or a custom router.
• Export analysis behind its own seam (analyze.ts, oxc-parser) — the compiler-shaped slice, kept separable so a compiler that already reports exports can provide it instead.
• Server conventions intentionally excluded — GET/POST export handling stays in Start, which can extend PageFileSystemRouter.

@solidjs/file-routes/vite (delivery adapter)

• Serves the manifest as the solid:file-routes virtual module: $-prefixed refs become code-split dynamic imports, $$-prefixed refs become static imports, each tree-shaken to the picked exports (?pick).
• Watcher-driven HMR (add/change/remove routes without a restart).
• routers: { client, ssr, ... } option keyed by Vite environment, so Start can compose it with different conventions per environment.

@solidjs/router/fs (emission adapter, new subpath export)

• createFileRoutes(manifest) — nests the flat manifest by path prefix, strips (group) segments, merges route configs, emits lazy RouteDefinitions tagged info.filesystem.
• <FileRoutes /> — the runtime component for <Router> children.
• @solidjs/router does not depend on @solidjs/file-routes; the adapter only consumes the virtual module, so Start's bring-your-own-router story is preserved.

examples/file-routes

A plain Vite + Solid Router SPA (no Start) exercising the whole path — nested layout, index routes, params with typed route config + preload + createAsync, catch-all 404. Wired into the workspace so the root build doubles as an end-to-end check.

// vite.config.ts
plugins: [solid({ extensions: [".jsx", ".tsx"] }), fileRoutes()]

<Router root={Layout}>
  <FileRoutes />
</Router>

Notes for reviewers

• Ported fixes: single-extension globs were treated as literal brace patterns by picomatch (*.{tsx}); the watcher used to invalidate the virtual module during the initial scan — routes are now pre-built before the reloader attaches.
• solid({ extensions: [".jsx", ".tsx"] }) is required because vite-plugin-solid's dev filter tests the raw id, which the ?pick query defeats — same reason Start passes extensions. Could be fixed upstream in vite-plugin-solid.
• The virtual module id is the neutral solid:file-routes (Start currently uses solid-start:routes); <FileRoutes> here is the SPA/client variant — Start keeps its per-request SSR variant and composes the rest.
• Follow-up on the Start side: delete its fs-routes/ internals and rebase SolidStartServerFileRouter + config wiring onto @solidjs/file-routes.

Verification

• 33 new @solidjs/file-routes tests (incl. ported solid-start specs for export analysis + tree-shaking) and 264 router tests (incl. new emission-adapter unit tests and a mounted <Router><FileRoutes/></Router> rendering test) — all passing.
• arethetypeswrong green (esm-only profile) for both packages including the new subpaths.
• Example verified live: dev server, client navigation, preload, HMR route add, and production build producing per-route chunks with route configs shaken out of component chunks.

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: d1f2a86

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@solidjs/file-routes	Minor
@solidjs/router	Minor
example-file-routes	Patch

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