feat: embedding dimension validation + migration system

- Add /api/admin/embeddings/dimension (GET column dim, POST test model dim)
- Add /api/admin/embeddings/migrate (alter column, clear, re-index)
- Admin form warns on dimension mismatch after save, offers migrate button
- Remove hardcoded 1536 from validate endpoint and embedding service
- Add validateDimension() utility to EmbeddingService
- Fix health route: import prisma correctly, use router instead of missing registry
- i18n keys for dimension warning (EN/FR)

memento-note/app/api/admin/embeddings/dimension/route.ts

@@ -0,0 +1,59 @@
+import { NextResponse } from 'next/server'
+import { prisma } from '@/lib/prisma'
+import { auth } from '@/auth'
+import { embeddingService } from '@/lib/ai/services/embedding.service'
+
+export async function GET() {
+  try {
+    const session = await auth()
+    if (!session?.user?.id || (session.user as { role?: string }).role !== 'ADMIN') {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+    }
+
+    const colDimResult: Array<{ dim: number | null }> = await prisma.$queryRawUnsafe(
+      `SELECT a.atttypmod AS dim FROM pg_attribute a JOIN pg_class c ON a.attrelid = c.oid WHERE c.relname = 'NoteEmbedding' AND a.attname = 'embedding'`
+    )
+    const dbDimension = colDimResult[0]?.dim ?? null
+
+    const countResult: Array<{ total: bigint }> = await prisma.$queryRawUnsafe(
+      `SELECT COUNT(*)::bigint AS total FROM "NoteEmbedding"`
+    )
+    const embeddingCount = Number(countResult[0]?.total ?? 0)
+
+    return NextResponse.json({
+      success: true,
+      dbDimension,
+      embeddingCount,
+    })
+  } catch (error) {
+    console.error('[EMBEDDING_DIMENSION] Error:', error)
+    return NextResponse.json({ success: false, error: String(error) }, { status: 500 })
+  }
+}
+
+export async function POST() {
+  try {
+    const session = await auth()
+    if (!session?.user?.id || (session.user as { role?: string }).role !== 'ADMIN') {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+    }
+
+    const result = await embeddingService.generateEmbedding('dimension test')
+    const modelDimension = result.dimension
+
+    const colDimResult: Array<{ dim: number | null }> = await prisma.$queryRawUnsafe(
+      `SELECT a.atttypmod AS dim FROM pg_attribute a JOIN pg_class c ON a.attrelid = c.oid WHERE c.relname = 'NoteEmbedding' AND a.attname = 'embedding'`
+    )
+    const dbDimension = colDimResult[0]?.dim ?? null
+
+    return NextResponse.json({
+      success: true,
+      modelDimension,
+      dbDimension,
+      match: modelDimension === dbDimension,
+    })
+  } catch (error) {
+    console.error('[EMBEDDING_DIMENSION] Test error:', error)
+    return NextResponse.json({ success: false, error: String(error) }, { status: 500 })
+  }
+}

memento-note/app/api/admin/embeddings/migrate/route.ts

@@ -0,0 +1,99 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { prisma } from '@/lib/prisma'
+import { auth } from '@/auth'
+import { embeddingService } from '@/lib/ai/services/embedding.service'
+import { getSystemConfig } from '@/lib/config'
+
+export async function POST(req: NextRequest) {
+  try {
+    const session = await auth()
+    if (!session?.user?.id || (session.user as { role?: string }).role !== 'ADMIN') {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+    }
+
+    const body = await req.json().catch(() => ({}))
+    const targetDimension = body.targetDimension as number | undefined
+
+    const config = await getSystemConfig()
+
+    const testResult = await embeddingService.generateEmbedding('dimension test')
+    const modelDimension = testResult.dimension
+
+    const colDimResult: Array<{ dim: number | null }> = await prisma.$queryRawUnsafe(
+      `SELECT a.atttypmod AS dim FROM pg_attribute a JOIN pg_class c ON a.attrelid = c.oid WHERE c.relname = 'NoteEmbedding' AND a.attname = 'embedding'`
+    )
+    const dbDimension = colDimResult[0]?.dim ?? null
+
+    const newDimension = targetDimension || modelDimension
+
+    if (dbDimension === newDimension) {
+      return NextResponse.json({
+        success: true,
+        message: 'Dimensions match, no migration needed',
+        dbDimension,
+        modelDimension,
+      })
+    }
+
+    const existingCount: Array<{ total: bigint }> = await prisma.$queryRawUnsafe(
+      `SELECT COUNT(*)::bigint AS total FROM "NoteEmbedding"`
+    )
+    const count = Number(existingCount[0]?.total ?? 0)
+
+    await prisma.$executeRawUnsafe(
+      `DROP INDEX IF EXISTS "NoteEmbedding_embedding_hnsw"`
+    )
+
+    await prisma.$executeRawUnsafe(
+      `TRUNCATE TABLE "NoteEmbedding"`
+    )
+
+    await prisma.$executeRawUnsafe(
+      `ALTER TABLE "NoteEmbedding" ALTER COLUMN "embedding" TYPE vector(${newDimension}) USING NULL`
+    )
+
+    await prisma.$executeRawUnsafe(`
+      CREATE INDEX "NoteEmbedding_embedding_hnsw" ON "NoteEmbedding"
+      USING hnsw ("embedding" vector_cosine_ops)
+      WITH (m = 16, ef_construction = 64)
+    `)
+
+    const docChunkExists: Array<{ exists: boolean }> = await prisma.$queryRawUnsafe(
+      `SELECT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name = 'DocumentChunk' AND column_name = 'embedding') AS exists`
+    )
+
+    if (docChunkExists[0]?.exists) {
+      await prisma.$executeRawUnsafe(
+        `DROP INDEX IF EXISTS "DocumentChunk_embedding_hnsw_idx"`
+      )
+      await prisma.$executeRawUnsafe(
+        `TRUNCATE TABLE "DocumentChunk"`
+      )
+      await prisma.$executeRawUnsafe(
+        `ALTER TABLE "DocumentChunk" ALTER COLUMN "embedding" TYPE vector(${newDimension}) USING NULL`
+      )
+      await prisma.$executeRawUnsafe(`
+        CREATE INDEX "DocumentChunk_embedding_hnsw_idx" ON "DocumentChunk"
+        USING hnsw ("embedding" vector_cosine_ops)
+        WITH (m = 16, ef_construction = 64)
+      `)
+    }
+
+    await prisma.systemConfig.upsert({
+      where: { key: 'AI_EMBEDDING_DIMENSION' },
+      update: { value: String(newDimension) },
+      create: { key: 'AI_EMBEDDING_DIMENSION', value: String(newDimension) },
+    })
+
+    return NextResponse.json({
+      success: true,
+      message: `Migration complete: vector(${dbDimension}) → vector(${newDimension}). ${count} old embeddings cleared. Re-indexing needed.`,
+      previousDimension: dbDimension,
+      newDimension,
+      clearedEmbeddings: count,
+    })
+  } catch (error) {
+    console.error('[EMBEDDING_MIGRATE] Error:', error)
+    return NextResponse.json({ success: false, error: String(error) }, { status: 500 })
+  }
+}

memento-note/app/api/admin/embeddings/validate/route.ts

@@ -32,10 +32,14 @@ export async function GET() {
     )
     const validCount = Number(withEmbedding[0]?.count ?? 0)
 
+    const dimResult: Array<{ dim: number | null }> = await prisma.$queryRawUnsafe(
+      `SELECT a.atttypmod AS dim FROM pg_attribute a JOIN pg_class c ON a.attrelid = c.oid WHERE c.relname = 'NoteEmbedding' AND a.attname = 'embedding'`
+    )
+    const dbDim = dimResult[0]?.dim ?? 1536
+
     const invalidResult: Array<{ count: bigint }> = await prisma.$queryRawUnsafe(
       `SELECT COUNT(*)::bigint as count FROM "NoteEmbedding" e
-       WHERE e."embedding" IS NULL
-          OR array_length(string_to_array(replace(replace(e."embedding"::text, '[', ''), ']', ''), ','), 1) != 1536`
+       WHERE e."embedding" IS NULL`
     )
     const invalidCount = Number(invalidResult[0]?.count ?? 0)
 
@@ -43,6 +47,7 @@ export async function GET() {
 
     return NextResponse.json({
       success: true,
+      dbDimension: dbDim,
       summary: {
         total,
         valid: validCount - invalidCount,