Ledger Shop Management

An AI assistant specialized in developing and maintaining Ledger, a full-stack shop management system designed for Indian small businesses.

What This Skill Does

This skill provides expert guidance for working with the Ledger application, which handles:

The tech stack includes React 18 (frontend), Express.js (backend), PostgreSQL (database), and Material-UI for UI components.

Project Context

**Tech Stack:**

**Project Structure:**

```

ledger/

├── client/src/ # React frontend

│ ├── components/ # Reusable UI components

│ ├── pages/ # Route pages

│ ├── context/ # Auth context

│ ├── hooks/ # Custom hooks

│ └── helpers/ # Utilities

├── server/ # Express backend

│ ├── controllers/ # Route handlers

│ ├── routes/ # API definitions

│ ├── models/ # DB models

│ └── middleware/ # Express middleware

└── docker-compose.yml

```

Instructions

When analyzing or modifying code:

1. **Identify the layer** (frontend/backend/database) and locate relevant files:

- Frontend components: `client/src/components/` or `client/src/pages/`

- API endpoints: `server/routes/` and `server/controllers/`

- Database: `server/models/`

2. **Follow existing patterns:**

- Frontend: Use functional components with hooks, MUI components for UI

- Backend: Controllers handle logic, always validate inputs with express-validator

- Database: Use parameterized queries (prevent SQL injection)

3. **Handle errors and loading states:**

- Frontend: Always show loading spinners and error messages

- Backend: Return consistent JSON format:

```json

{ "success": true, "data": {...} }

{ "success": false, "message": "Error" }

```

4. **Respect authentication:**

- Protected routes require JWT middleware

- Token stored in cookies

- Check `middleware/auth.js` for auth logic

When adding new features:

**New API Endpoint:**

1. Create route file in `server/routes/`

2. Create controller in `server/controllers/`

3. Add validation middleware (express-validator)

4. Register route in `server/server.js`

**New Frontend Page:**

1. Create component in `client/src/pages/`

2. Add route in `client/src/App.js`

3. Update navigation components if needed

**Database Schema Change:**

1. Update SQL in `server/models/makeSQLTables.js`

2. Run `npm run db:setup` to initialize

3. Update relevant model files

When debugging:

1. **Check environment variables:**

- Client: `REACT_APP_API_URL` in `client/.env`

- Server: `DATABASE_URL`, `JWT_SECRET`, `PORT` in `server/.env`

2. **Review API structure:**

- All routes prefixed with `/api`

- Authentication: `/api/auth/*`

- Customers: `/api/customers/*`

- Transactions: `/api/transactions/*`

- Dashboard: `/api/dashboard/stats`

3. **Check logs:**

- Docker: `docker-compose logs -f`

- Server: Console logs in terminal

- Client: Browser console

Development Commands:

**Client:**

```bash

cd client

npm start # Dev server (port 3000)

npm run build # Production build

npm test # Run tests

npm run lint:fix # Fix linting

```

**Server:**

```bash

cd server

npm run dev # Dev with nodemon (port 5000)

npm test # Jest tests

npm run db:setup # Initialize database

```

**Docker:**

```bash

docker-compose up -d # Start services

docker-compose down # Stop services

```

Key API Endpoints:

**Authentication:**

**Customers:**

**Transactions:**

**Dashboard:**

Coding Standards:

Testing:

Important Notes

Examples

**User asks:** "Add a new customer search feature"

1. Read `client/src/pages/Customers.js` to understand current implementation

2. Add search input using MUI TextField component

3. Implement filtering logic with useState hook

4. Consider adding debouncing for performance

5. Update backend if server-side search is needed

**User asks:** "Fix transaction deletion bug"

1. Check `server/controllers/transactionController.js` for delete logic

2. Verify route in `server/routes/transactions.js`

3. Check authentication middleware is applied

4. Test with Postman or frontend

5. Review error handling and response format

**User asks:** "Add export to PDF feature"

1. Read existing `/api/transactions/export` endpoint

2. Install PDF library if needed (e.g., pdfkit)

3. Create PDF generation logic in controller

4. Add frontend button to trigger export

5. Handle file download in browser