Add hierarchical AGENTS.md documentation for AI coding agents

Creates token-efficient documentation system to guide AI agents:
- Root AGENTS.md: Universal conventions, JIT index, and architecture overview
- client/AGENTS.md: Frontend patterns (React, TanStack Query, Shadcn UI, Firebase)
- server/AGENTS.md: Backend patterns (Express, Drizzle ORM, auth middleware)
- shared/AGENTS.md: Database schema and type management (Drizzle + Zod)

Key features:
- Nearest-wins hierarchy (agents read closest AGENTS.md to working file)
- JIT indexing with ripgrep commands (no content dumps)
- Real file examples for DO/DON'T patterns
- Pre-PR checklists with copy-paste commands
- 1600+ lines of actionable guidance across all layers

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

Author: hexawulf

AGENTS.md

@@ -0,0 +1,179 @@
+# CodePatchwork - AGENTS.md
+
+## Project Snapshot
+
+**Type**: Full-stack TypeScript web application (single project, not a monorepo)  
+**Stack**: React 18 + Vite (frontend) | Express + PostgreSQL (backend) | Firebase Auth  
+**Architecture**: Client/server with shared types via `shared/` directory  
+**Note**: Sub-directories have their own detailed AGENTS.md files — always check the closest one to your working file.
+
+---
+
+## Root Setup Commands
+
+```bash
+# Install dependencies
+npm install
+
+# Start development (both client + server)
+npm run dev
+
+# Build for production (client + server)
+npm run build
+
+# Typecheck
+npm run check
+
+# Database: Push schema changes
+npm run db:push
+```
+
+---
+
+## Universal Conventions
+
+### Code Style
+- **TypeScript strict mode** enabled
+- **ESM modules** (`"type": "module"`)
+- **Path aliases**: `@/` (client/src), `@shared/` (shared types), `@assets/` (assets)
+- **Functional React components** with hooks (no class components)
+- **TailwindCSS** for all styling (no inline styles)
+
+### Commit & Branch
+- **No strict format enforced**, but prefer descriptive messages
+- Branch from `main`, PRs welcome
+- See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines
+
+---
+
+## Security & Secrets
+
+- **NEVER commit** Firebase credentials, API keys, or tokens
+- **Environment variables**: Use `.env` file (not committed)
+  - `DATABASE_URL` - PostgreSQL connection string
+  - `VITE_FIREBASE_*` - Firebase client config (safe for client)
+  - Keep Firebase Admin SDK JSON in `.gitignore`
+- **No PII in logs** - Winston logs to `~/logs/codepatchwork.log`
+
+---
+
+## JIT Index (what to open, not what to paste)
+
+### Directory Structure
+
+```
+client/          → Frontend React app [see client/AGENTS.md](client/AGENTS.md)
+  src/
+    components/  → UI components (Shadcn + custom)
+    pages/       → Route pages
+    hooks/       → Custom React hooks
+    contexts/    → Global state providers
+    lib/         → Utilities, Firebase config, query client
+
+server/          → Backend Express API [see server/AGENTS.md](server/AGENTS.md)
+  routes.ts      → All API endpoints (1100+ lines)
+  storage.ts     → Database operations (Drizzle)
+  db.ts          → PostgreSQL pool
+  logger.ts      → Winston logger
+
+shared/          → Shared types & schemas [see shared/AGENTS.md](shared/AGENTS.md)
+  schema.ts      → Drizzle tables + Zod validation
+
+scripts/         → Database and migration utilities
+public/          → Static assets
+```
+
+### Quick Find Commands
+
+```bash
+# Find a React component
+rg -n "export (default function|function)" client/src/components
+
+# Find a page
+rg -n "export default" client/src/pages
+
+# Find a hook
+rg -n "export (const use|function use)" client/src/hooks
+
+# Find API endpoints
+rg -n "app\.(get|post|put|patch|delete)" server/routes.ts
+
+# Find database operations
+rg -n "export (async function|const)" server/storage.ts
+
+# Find Drizzle schemas
+rg -n "export const.*=.*pgTable" shared/schema.ts
+
+# Find all TypeScript errors
+npm run check
+```
+
+---
+
+## Definition of Done
+
+Before creating a PR, ensure:
+
+1. ✅ Code typechecks: `npm run check`
+2. ✅ Client builds: `npm run build` succeeds
+3. ✅ No hardcoded credentials (run `scripts/check-no-hardcode.sh`)
+4. ✅ Firebase env vars use `VITE_` prefix for client-side
+5. ✅ Database migrations tested if `shared/schema.ts` changed
+
+**Note**: Tests exist in `__tests__` directories but no test runner is configured in package.json yet.
+
+---
+
+## Architecture Overview
+
+```
+┌─────────────────┐
+│  Client (Vite)  │  React + TailwindCSS
+│  Port: Vite Dev │  TanStack Query for data fetching
+└────────┬────────┘
+         │ HTTP (fetch via apiRequest)
+         │
+┌────────▼────────┐
+│ Server (Express)│  TypeScript + esbuild
+│  Auth Middleware│  Firebase Admin SDK
+└────────┬────────┘
+         │
+┌────────▼────────┐
+│ Storage Layer   │  Drizzle ORM
+│  (storage.ts)   │  Interface abstraction
+└────────┬────────┘
+         │
+┌────────▼────────┐
+│   PostgreSQL    │  Tables: users, snippets, collections, comments
+└─────────────────┘
+```
+
+---
+
+## Technologies at a Glance
+
+| Layer | Technologies |
+|-------|-------------|
+| **Frontend** | React 18, TypeScript, Vite, TailwindCSS, Shadcn UI, Prism.js, Wouter, TanStack Query |
+| **Backend** | Express, TypeScript, esbuild, Firebase Admin, Winston, express-session |
+| **Database** | PostgreSQL, Drizzle ORM, Drizzle Kit |
+| **Auth** | Firebase Authentication (Google OAuth + Email/Password) |
+| **Validation** | Zod (schemas in `shared/schema.ts`) |
+
+---
+
+## Common Pitfalls
+
+1. **Database column naming**: DB uses lowercase (e.g., `userid`), TS uses camelCase (e.g., `userId`). Drizzle handles mapping.
+2. **Environment variables**: Client-side vars must use `VITE_` prefix or they won't be exposed.
+3. **Path imports**: Always use `@/` and `@shared/` aliases, never relative paths across major boundaries.
+4. **Auth tokens**: API expects `Authorization: Bearer <token>` header. Use `apiRequest()` from `queryClient.ts` for automatic token handling.
+
+---
+
+## Next Steps
+
+For detailed guidance:
+- Working on **frontend code**? → [client/AGENTS.md](client/AGENTS.md)
+- Working on **backend API**? → [server/AGENTS.md](server/AGENTS.md)
+- Modifying **database schema**? → [shared/AGENTS.md](shared/AGENTS.md)