fix(schema): prefer mjs in hub schema hook

docs/content/4.integrations/1.nuxthub.md

@@ -133,6 +133,10 @@ The module analyzes your `server/auth.config.ts` at build time:
 **Restart Required**: After adding/removing plugins that affect database structure, restart the dev server to regenerate the schema.
 ::
 
+::note
+When Nuxt resolves `buildDir` to `node_modules/.cache/nuxt/.nuxt`, the module mirrors `schema.<dialect>.ts` to root `.nuxt/better-auth/` and uses that mirrored path for NuxtHub schema extension. This avoids Node type-stripping failures for `.ts` files under `node_modules`. In normal buildDir layouts, the hook prefers `schema.<dialect>.ts` and falls back to `schema.<dialect>.mjs`.
+::
+
 ## Accessing the Database
 
 With NuxtHub, you get access to the Drizzle database instance in your server config:

src/module/schema.ts

@@ -15,6 +15,31 @@ interface SchemaContext {
   serverConfigPath: string
 }
 
+function isInsideNodeModules(path: string): boolean {
+  return path.split(/[\\/]/).includes('node_modules')
+}
+
+export function resolveHubSchemaPath(
+  buildDir: string,
+  rootDir: string,
+  dialect: string,
+  exists: (path: string) => boolean = existsSync,
+): string | null {
+  const rootTsPath = join(rootDir, '.nuxt', 'better-auth', `schema.${dialect}.ts`)
+  if (isInsideNodeModules(buildDir) && exists(rootTsPath))
+    return rootTsPath
+
+  const tsPath = join(buildDir, 'better-auth', `schema.${dialect}.ts`)
+  if (exists(tsPath))
+    return tsPath
+
+  const mjsPath = join(buildDir, 'better-auth', `schema.${dialect}.mjs`)
+  if (exists(mjsPath))
+    return mjsPath
+
+  return null
+}
+
 async function loadAuthOptions(context: SchemaContext) {
   const isProduction = !context.nuxt.options.dev
   const configFile = `${context.serverConfigPath}.ts`
@@ -64,23 +89,23 @@ export async function setupBetterAuthSchema(
     await writeFile(schemaPathTs, schemaCode)
     await writeFile(schemaPathMjs, schemaCode)
 
+    if (isInsideNodeModules(nuxt.options.buildDir)) {
+      const rootSchemaDir = join(nuxt.options.rootDir, '.nuxt', 'better-auth')
+      const rootSchemaPathTs = join(rootSchemaDir, `schema.${dialect}.ts`)
+      await mkdir(rootSchemaDir, { recursive: true })
+      await writeFile(rootSchemaPathTs, schemaCode)
+    }
+
     addTemplate({ filename: `better-auth/schema.${dialect}.ts`, getContents: () => schemaCode, write: true })
     addTemplate({ filename: `better-auth/schema.${dialect}.mjs`, getContents: () => schemaCode, write: true })
 
     consola.info(`Generated ${dialect} schema (.ts + .mjs)`)
 
     const nuxtWithHubHooks = nuxt as Nuxt & { hook: (name: string, cb: (arg: { paths: string[], dialect: string }) => void) => void }
     nuxtWithHubHooks.hook('hub:db:schema:extend', ({ paths, dialect: hookDialect }) => {
-      const tsPath = join(nuxt.options.buildDir, 'better-auth', `schema.${hookDialect}.ts`)
-      const mjsPath = join(nuxt.options.buildDir, 'better-auth', `schema.${hookDialect}.mjs`)
-
-      if (existsSync(tsPath)) {
-        paths.unshift(tsPath)
-        return
-      }
-
-      if (existsSync(mjsPath))
-        paths.unshift(mjsPath)
+      const schemaPath = resolveHubSchemaPath(nuxt.options.buildDir, nuxt.options.rootDir, hookDialect)
+      if (schemaPath)
+        paths.unshift(schemaPath)
     })
   }
   catch (error) {

test/schema-hook-path-priority.test.ts

@@ -0,0 +1,85 @@
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'pathe'
+import { afterEach, describe, expect, it } from 'vitest'
+import { resolveHubSchemaPath } from '../src/module/schema'
+
+const tempDirs: string[] = []
+
+function createBuildDir() {
+  const dir = mkdtempSync(join(tmpdir(), 'nuxt-better-auth-schema-'))
+  tempDirs.push(dir)
+  return dir
+}
+
+afterEach(() => {
+  for (const dir of tempDirs.splice(0, tempDirs.length))
+    rmSync(dir, { recursive: true, force: true })
+})
+
+describe('resolveHubSchemaPath', () => {
+  it('prefers .ts when both .ts and .mjs exist', () => {
+    const buildDir = createBuildDir()
+    const rootDir = createBuildDir()
+    const schemaDir = join(buildDir, 'better-auth')
+    const tsPath = join(schemaDir, 'schema.sqlite.ts')
+    const mjsPath = join(schemaDir, 'schema.sqlite.mjs')
+
+    mkdirSync(schemaDir, { recursive: true })
+    writeFileSync(tsPath, 'export {}', { flag: 'w' })
+    writeFileSync(mjsPath, 'export {}', { flag: 'w' })
+
+    const selected = resolveHubSchemaPath(buildDir, rootDir, 'sqlite')
+    expect(selected).toBe(tsPath)
+  })
+
+  it('prefers mirrored root .nuxt schema.ts when buildDir is under node_modules', () => {
+    const rootDir = createBuildDir()
+    const buildDir = join(rootDir, 'node_modules', '.cache', 'nuxt', '.nuxt')
+    const buildSchemaDir = join(buildDir, 'better-auth')
+    const rootSchemaDir = join(rootDir, '.nuxt', 'better-auth')
+    const rootTsPath = join(rootSchemaDir, 'schema.sqlite.ts')
+    const buildMjsPath = join(buildSchemaDir, 'schema.sqlite.mjs')
+
+    mkdirSync(buildSchemaDir, { recursive: true })
+    mkdirSync(rootSchemaDir, { recursive: true })
+    writeFileSync(buildMjsPath, 'export {}', { flag: 'w' })
+    writeFileSync(rootTsPath, 'export {}', { flag: 'w' })
+
+    const selected = resolveHubSchemaPath(buildDir, rootDir, 'sqlite')
+    expect(selected).toBe(rootTsPath)
+  })
+
+  it('falls back to .ts when .mjs does not exist', () => {
+    const buildDir = createBuildDir()
+    const rootDir = createBuildDir()
+    const schemaDir = join(buildDir, 'better-auth')
+    const tsPath = join(schemaDir, 'schema.sqlite.ts')
+
+    mkdirSync(schemaDir, { recursive: true })
+    writeFileSync(tsPath, 'export {}', { flag: 'w' })
+
+    const selected = resolveHubSchemaPath(buildDir, rootDir, 'sqlite')
+    expect(selected).toBe(tsPath)
+  })
+
+  it('falls back to .mjs when .ts does not exist', () => {
+    const buildDir = createBuildDir()
+    const rootDir = createBuildDir()
+    const schemaDir = join(buildDir, 'better-auth')
+    const mjsPath = join(schemaDir, 'schema.sqlite.mjs')
+
+    mkdirSync(schemaDir, { recursive: true })
+    writeFileSync(mjsPath, 'export {}', { flag: 'w' })
+
+    const selected = resolveHubSchemaPath(buildDir, rootDir, 'sqlite')
+    expect(selected).toBe(mjsPath)
+  })
+
+  it('returns null when no schema files exist', () => {
+    const buildDir = createBuildDir()
+    const rootDir = createBuildDir()
+    const selected = resolveHubSchemaPath(buildDir, rootDir, 'sqlite')
+    expect(selected).toBeNull()
+  })
+})