Firebase Add Feature

Overview

This sub-skill guides adding new features to existing Firebase projects using TDD. It handles Cloud Functions, Firestore collections, and API endpoints.

Key principles:

• Write tests FIRST (TDD requirement)
• Use {success, message, data?} response pattern
• Every file starts with ABOUTME comments
• Verify with emulators before claiming done

When This Sub-Skill Applies

• Adding a new Cloud Function
• Creating a new Firestore collection with rules
• Adding an API endpoint to Express app
• User says: "add function", "create endpoint", "new collection", "implement"