buildDatabaseSchema fails for layers installed via gh: extends (node_modules type stripping)

[BlueBazze]

Describe the bug

When a Nuxt app uses layers installed via gh: extends (which are resolved into node_modules/.c12/), buildDatabaseSchema fails because the generated hub/db/schema.entry.ts contains absolute-path re-exports pointing to .ts files under node_modules:

export * from '/project/node_modules/.c12/gh_Org_layer_abc123/server/db/schema/users.postgresql.ts'

When tsdown processes this entry file, Node's type stripping is invoked on those .ts files, which fails because Node does not support stripping types from files under node_modules.

Steps to reproduce

1. Create a Nuxt layer that defines DB schema files in server/db/schema/*.ts
2. In a consuming app, extend that layer via gh: syntax:

  // nuxt.config.ts
  export default defineNuxtConfig({
    extends: [
      ['gh:Org/layer#main', { auth: process.env.GITHUB_TOKEN, install: true }],
    ],
    modules: ['@nuxthub/core'],
    hub: { db: 'postgresql' },
  })

3. Run nuxi dev or nuxi build
4. See error: Stripping types is currently unsupported for files under node_modules,
   for "file:///project/node_modules/.c12/gh_Org_layer_abc123/server/db/schema/example.po
   stgresql.ts"

Expected behavior

Schema files from gh: extended layers should work regardless of their resolved location on disk. The schema .ts files from layers under node_modules/.c12/ should be copied to the build directory (outside node_modules) before being passed to tsdown, so that Node's type stripping can process them.

[BlueBazze]

Local workaround module that goes through schema.entry.ts and copies all schema files into .nuxt.
(ai generated)

import { defineNuxtModule } from "@nuxt/kit";
import { dirname, join, relative } from "pathe";
import { cp, mkdir, rm } from "node:fs/promises";

/**
 * Fixes NuxtHub schema building for layers installed via `gh:` extends.
 *
 * Those layers live under `node_modules/.c12/` and tsdown (used by NuxtHub's
 * `buildDatabaseSchema`) invokes Node's type stripping on their `.ts` files.
 * Node does not support stripping types from files under `node_modules`.
 *
 * This module copies each layer's entire schema directory to the build dir
 * (preserving relative imports between schema files) and remaps the paths.
 */
export default defineNuxtModule({
  meta: { name: "hub-layer-schema-fix" },
  setup(_options, nuxt) {
    nuxt.hook(
      "hub:db:schema:extend",
      async ({ paths }: { paths: string[] }) => {
        const nodeModuleEntries: [number, string][] = [];
        for (let i = 0; i < paths.length; i++) {
          const p = paths[i];
          if (p && p.includes("node_modules")) {
            nodeModuleEntries.push([i, p]);
          }
        }
        if (nodeModuleEntries.length === 0) return;

        const layerSchemasDir = join(
          nuxt.options.buildDir,
          "hub/db/layer-schemas",
        );
        await rm(layerSchemasDir, { recursive: true, force: true });

        // Group by schema directory so we copy each directory once
        const copiedDirs = new Map<string, string>();

        for (const [idx, originalPath] of nodeModuleEntries) {
          const schemaDir = dirname(originalPath);

          if (!copiedDirs.has(schemaDir)) {
            // Derive a stable subdir name from the layer's .c12 folder
            const segments = originalPath.split("/");
            const c12Idx = segments.indexOf(".c12");
            const layerName =
              (c12Idx >= 0 && segments[c12Idx + 1]) || `layer-${copiedDirs.size}`;
            const targetDir = join(layerSchemasDir, layerName);

            await mkdir(targetDir, { recursive: true });
            await cp(schemaDir, targetDir, { recursive: true });
            copiedDirs.set(schemaDir, targetDir);
          }

          const copiedDir = copiedDirs.get(schemaDir);
          if (!copiedDir) continue;
          paths[idx] = join(copiedDir, relative(schemaDir, originalPath));
        }
      },
    );
  },
});