Add migration to add litter_id column to dogs table

server/db/migrate_litter_id.js

@@ -0,0 +1,52 @@
+const Database = require('better-sqlite3');
+const path = require('path');
+
+function migrateLitterId(dbPath) {
+  console.log('Running litter_id migration...');
+  
+  const db = new Database(dbPath);
+  db.pragma('foreign_keys = ON');
+  
+  try {
+    // Check if litter_id column already exists
+    const tableInfo = db.prepare("PRAGMA table_info(dogs)").all();
+    const hasLitterId = tableInfo.some(col => col.name === 'litter_id');
+    
+    if (hasLitterId) {
+      console.log('litter_id column already exists. Skipping migration.');
+      db.close();
+      return;
+    }
+    
+    // Add litter_id column to dogs table
+    db.exec(`
+      ALTER TABLE dogs ADD COLUMN litter_id INTEGER;
+    `);
+    
+    // Create index for litter_id
+    db.exec(`
+      CREATE INDEX IF NOT EXISTS idx_dogs_litter ON dogs(litter_id);
+    `);
+    
+    // Add foreign key relationship (SQLite doesn't support ALTER TABLE ADD CONSTRAINT)
+    // So we'll rely on application-level constraint checking
+    
+    console.log('✓ Added litter_id column to dogs table');
+    console.log('✓ Created index on litter_id');
+    console.log('Migration completed successfully!');
+    
+    db.close();
+  } catch (error) {
+    console.error('Migration failed:', error.message);
+    db.close();
+    throw error;
+  }
+}
+
+module.exports = { migrateLitterId };
+
+// Run migration if called directly
+if (require.main === module) {
+  const dbPath = process.env.DB_PATH || path.join(__dirname, '../../data/breedr.db');
+  migrateLitterId(dbPath);
+}