name	firebase-development
description	This skill should be used when working with Firebase projects, including initializing projects, adding Cloud Functions or Firestore collections, debugging emulator issues, or reviewing Firebase code. Triggers on "firebase", "firestore", "cloud functions", "emulator", "firebase auth", "deploy to firebase", "firestore rules".

Firebase Development

Overview

This skill system guides Firebase development using proven patterns from production projects. It routes to specialized sub-skills based on detected intent.

Sub-skills:

firebase-development:project-setup - Initialize new Firebase projects
firebase-development:add-feature - Add functions/collections/endpoints
firebase-development:debug - Troubleshoot emulator and runtime issues
firebase-development:validate - Review Firebase code for security/patterns

When This Skill Applies

Starting new Firebase projects
Adding Cloud Functions or Firestore collections
Debugging emulator issues or rule violations
Reviewing Firebase code for security and patterns
Setting up multi-hosting configurations
Implementing authentication (API keys or Firebase Auth)

Routing Logic

Keywords by Sub-Skill

project-setup:

"new firebase project", "initialize firebase", "firebase init"
"set up firebase", "create firebase app", "start firebase project"

add-feature:

"add function", "create endpoint", "new tool", "add api"
"new collection", "add feature", "build", "implement"

debug:

"error", "not working", "debug", "emulator issue"
"rules failing", "permission denied", "troubleshoot", "deployment failed"

validate:

"review firebase", "check firebase", "validate", "audit firebase"
"look at firebase code", "security review"

Routing Process

Analyze Request: Check for routing keywords
Match Sub-Skill: Identify best match based on keyword density
Announce: "I'm using the firebase-development:[sub-skill] skill to [action]"
Route: Load and execute the sub-skill
Fallback: If ambiguous, use AskUserQuestion with 4 options

Fallback Example

If intent is unclear, ask:

Question: "What Firebase task are you working on?"
Options:
  - "Project Setup" (Initialize new Firebase project)
  - "Add Feature" (Add functions, collections, endpoints)
  - "Debug Issue" (Troubleshoot errors or problems)
  - "Validate Code" (Review against patterns)

Reference Projects

Patterns are extracted from three production Firebase projects:

Project	Path	Key Patterns
oneonone	`/Users/dylanr/work/2389/oneonone`	Express API, custom API keys, server-write-only
bot-socialmedia	`/Users/dylanr/work/2389/bot-socialmedia-server`	Domain-grouped functions, Firebase Auth + roles
meme-rodeo	`/Users/dylanr/work/2389/meme-rodeo`	Individual function files, entitlements

Pattern Summaries

Multi-Hosting Setup

Three options based on needs:

Option	When to Use	Key Feature
`site:` based	Multiple independent URLs	Simple, no build coordination
`target:` based	Need predeploy hooks	Build scripts run automatically
Single + rewrites	Smaller projects	All under one domain

Details: See docs/examples/multi-hosting-setup.md

Authentication

Pattern	When to Use	Example
Custom API keys	MCP tools, server-to-server	oneonone
Firebase Auth + roles	User-facing apps	bot-socialmedia
Hybrid	Both patterns needed	Web UI + API access

Details: See docs/examples/api-key-authentication.md

Cloud Functions Architecture

Pattern	When to Use	Structure
Express app	API with middleware, routing	`app.post('/mcp', handler)`
Domain-grouped	Feature-rich apps	`posts.ts`, `journal.ts`
Individual files	Maximum modularity	One function per file

Details: See docs/examples/express-function-architecture.md

Security Model

Model	When to Use	Complexity
Server-write-only	Light-write apps, high security	Simple rules
Client-write + validation	High-volume writes, real-time	Complex rules

Strongly prefer server-write-only for light-write applications.

Details: See docs/examples/firestore-rules-patterns.md

Emulator-First Development

Always develop locally with emulators:

firebase emulators:start
# Access UI at http://127.0.0.1:4000

Key settings in firebase.json:

singleProjectMode: true - Essential for emulators to work together
ui.enabled: true - Access debug UI

Details: See docs/examples/emulator-workflow.md

Modern Tooling Standards

All Firebase projects follow these standards:

Tool	Purpose	Config File
TypeScript	Type safety	`tsconfig.json`
vitest	Testing	`vitest.config.ts`
biome	Linting + formatting	`biome.json`

ABOUTME Comment Pattern

Every TypeScript file starts with 2-line ABOUTME comment:

// ABOUTME: Brief description of what this file does
// ABOUTME: Second line with additional context

Testing Requirements

Unit tests: Test handlers/utilities in isolation
Integration tests: Test with emulators running
Both required for every feature

Common Gotchas

Issue	Solution
Emulator ports in use	`lsof -i :5001`, kill process
Admin SDK vs Client SDK	Admin bypasses rules, client respects rules
Cold start delays	First call takes 5-10s, normal
Data persistence	Use Ctrl+C (not kill) to export data
CORS in functions	`app.use(cors({ origin: true }))`

Summary

This orchestrator routes to specialized sub-skills:

Detects intent via keywords
Routes to appropriate sub-skill
Sub-skills use TodoWrite checklists
All reference shared patterns in docs/examples/

Sub-Skills:

firebase-development:project-setup - Initialize new projects
firebase-development:add-feature - Add functions/collections
firebase-development:debug - Troubleshoot issues
firebase-development:validate - Review code

firebase-development

Install Skill

SKILL.md