Vite resolver can't reach host/client_app/node_modules from wheel-installed module pages, even when deps are installed

[antosubash]

Summary

Sister issue to #116. Even after sm host sync-js-deps puts a module's required npm packages into host/client_app/node_modules, Vite still can't resolve those bare imports from .tsx files that live outside the host directory. The Node module-resolution algorithm walks up from each importer's directory looking for node_modules, and from .venv/lib/python3.12/site-packages/<module>/pages/Foo.tsx (or modules/<pkg>/<pkg>/pages/Foo.tsx) the walk never reaches host/client_app/node_modules — there is no symlink in any intermediate directory.

So #116 fixes the install; this issue is what's left after the install: the resolve still fails.

The host's vite.config.ts template already hand-aliases react, react-dom, @inertiajs/react, but every other bare specifier a module page can plausibly import (sonner, lucide-react, clsx, class-variance-authority, tailwind-merge, cmdk, maplibre-gl, pmtiles, recharts, vaul, @simple-module-py/ui/..., @simple-module-py/i18n/..., …) is left to Node resolution. The comment in the scaffolded vite.config.ts claims:

Subpath imports (e.g. @simple-module-py/ui/components/ui/badge) resolve via the symlinked node_modules in module dirs and the package's own exports map.

But no such symlinks are created by sm gen-pages, sm sync-js-deps, or anything else the framework ships.

Reproduction

1. Fresh sm new host, install the framework's modules + a wheel-installed module that imports e.g. sonner.
2. cd client_app && npm install sonner so the dep is present in host/client_app/node_modules/sonner.
3. Open any page that triggers loading the module's .tsx.

[plugin:vite:import-analysis] Failed to resolve import "sonner" from
"../../.venv/lib/python3.12/site-packages/<mod>/pages/UploadCard.tsx".

The package is installed; Vite just can't see it from that importer.

Expected

sm gen-pages (or a sibling command, or a Vite plugin shipped under simple_module_hosting) should make module pages able to resolve any package that lives in host/client_app/node_modules. Two viable shapes:

A. Ship a simple_module_hosting/vite_plugin.ts (npm-published or template-copied into the scaffold) that intercepts bare-specifier resolution and retries against host/client_app/node_modules whenever the importer is outside the host directory:

{
  name: 'sm:module-host-resolve',
  enforce: 'pre',
  async resolveId(id, importer) {
    if (!importer || importer.startsWith(__dirname)) return null;
    if (id.startsWith('.') || id.startsWith('/') || id.startsWith('\0') || id.includes('?')) return null;
    return this.resolve(id, path.join(hostNodeModules, '__entry__'), { skipSelf: true });
  },
}

B. Have sm gen-pages materialize a node_modules symlink (or junction) inside each module's package root that points at host/client_app/node_modules. This is what the vite.config.ts comment already claims happens.

(A) is portable and doesn't litter the wheel install tree; (B) lets Node resolution work without a custom plugin and is closer to how npm/pnpm workspaces do it.

Acceptance

• A fresh sm new host with one wheel-installed module that imports sonner boots make dev cleanly, with no hand-edits to client_app/vite.config.ts.
• The scaffolded vite.config.ts either contains the resolver plugin from (A) or the comment about "symlinked node_modules in module dirs" matches reality.

Workaround

In host/client_app/vite.config.ts, add a pre-resolver before react():

const moduleHostResolve = {
  name: 'host:module-host-resolve',
  enforce: 'pre' as const,
  async resolveId(id: string, importer?: string) {
    if (!importer) return null;
    if (id.startsWith('.') || id.startsWith('/') || id.startsWith('\0')) return null;
    if (id.startsWith('virtual:') || id.startsWith('@vite/') || id.includes('?')) return null;
    if (importer.startsWith(__dirname) || importer.startsWith(hostNodeModules)) return null;
    try {
      const resolved = await this.resolve(id, path.join(hostNodeModules, '__entry__'), { skipSelf: true });
      if (resolved) return resolved;
    } catch { /* fall through */ }
    return null;
  },
};

Related

• Module wheels declare empty 'dependencies' but their .tsx imports lucide-react/sonner directly; Makefile never runs sm host sync-js-deps #116 — modules don't declare their JS deps; orthogonal but stacked: until both are fixed, every fresh checkout fails at npm run dev.
• @simple-module-py/ui exports map ('.', './*') doesn't cover ./components/*, ./layouts/* — vite can't resolve subpath imports from module pages #110, @simple-module-py/ui exports map: './*': './src/*' can't resolve nested subpaths or extension-less imports #115 — earlier @simple-module-py/ui exports-map fixes; those don't help when the importer can't find the package at all.

[antosubash]

Fixed in #130.