build db migration

backend/src/db.ts

@@ -50,18 +50,20 @@ db.exec(`
 
   CREATE INDEX IF NOT EXISTS idx_memes_parent_id ON memes(parent_id);
   CREATE INDEX IF NOT EXISTS idx_memes_created_at ON memes(created_at DESC);
-  CREATE INDEX IF NOT EXISTS idx_memes_collection_id ON memes(collection_id);
   CREATE INDEX IF NOT EXISTS idx_meme_tags_meme_id ON meme_tags(meme_id);
   CREATE INDEX IF NOT EXISTS idx_meme_tags_tag_id ON meme_tags(tag_id);
 `);
 
 // Migration: add collection_id column if upgrading from earlier schema
+// Must run BEFORE creating the index on that column
 const memesCols = db.prepare('PRAGMA table_info(memes)').all() as { name: string }[];
 if (!memesCols.find((c) => c.name === 'collection_id')) {
   db.exec('ALTER TABLE memes ADD COLUMN collection_id INTEGER REFERENCES collections(id) ON DELETE SET NULL');
-  db.exec('CREATE INDEX IF NOT EXISTS idx_memes_collection_id ON memes(collection_id)');
 }
 
+// Create index after the column is guaranteed to exist (handles both fresh and migrated DBs)
+db.exec('CREATE INDEX IF NOT EXISTS idx_memes_collection_id ON memes(collection_id)');
+
 // Seed the default UNSORTED collection
 const defaultCollection = db
   .prepare('SELECT id FROM collections WHERE is_default = 1')