# prompt-gen

A local web app for building and reusing prompt templates. Write a prompt once with `{{variable}}` placeholders, save it as a preset, then fill in the fields to generate new prompts on demand.

![prompt-gen screenshot](https://shx.reversed.dev/u/dspbfv.png)

## Features

- **Presets** — save any number of named templates with descriptions
- **Live variable filling** — input fields are generated automatically from `{{variable_name}}` placeholders in your template
- **AI rewrite** — send the filled prompt to GPT for improvement with one click
- **Persistent storage** — everything saved to a local `settings.json`, no database

## Quick start (Docker)

```bash
docker compose up --build
```

Open [http://localhost:8000](http://localhost:8000).

Data persists in a Docker named volume. To back it up:

```bash
docker compose cp app:/app/data/settings.json ./settings.json
```

## Quick start (local dev)

**Requirements:** Python 3.11+, Node 18+

```bash
# Install dependencies
pip install -r requirements.txt
cd frontend && npm install && npm run build && cd ..

# Run
uvicorn backend.main:app --host 127.0.0.1 --port 8001
```

Open [http://localhost:8001](http://localhost:8001).

### Hot-reload dev mode

```bash
# Terminal 1 — backend
uvicorn backend.main:app --port 8001 --reload

# Terminal 2 — frontend
cd frontend && npm run dev
```

Frontend dev server runs on [http://localhost:5173](http://localhost:5173) and proxies `/api` to port 8001.

## AI rewrite

Click the ⚙ icon and enter your OpenAI API key. The key is stored in `settings.json` and never sent to the frontend. Once set, the **✦ Rewrite with AI** button becomes active in the prompt runner.

The model defaults to `gpt-4.1`. Override it with the `OPENAI_MODEL` environment variable:

```bash
OPENAI_MODEL=gpt-4o uvicorn backend.main:app --port 8001
# or in docker-compose.yml under environment:
```

## Template syntax

Use `{{variable_name}}` anywhere in your template. Variable names must start with a letter or underscore and contain only letters, numbers, and underscores.

```
Resolve {{issue_id}} in {{repo}}. Create the PR as {{author}}.
```

Duplicate variable names collapse to a single input field. Variables appear in the order they first appear in the template.

## Configuration

All settings are stored in `settings.json` at the project root (or at `$SETTINGS_PATH` when set).

```json
{
  "openai_api_key": "sk-...",
  "presets": [
    {
      "id": "a1b2c3d4",
      "name": "My template",
      "description": "optional",
      "template": "Resolve {{issue_id}} in {{repo}}.",
      "variables": ["issue_id", "repo"],
      "created_at": "2026-06-26T10:00:00Z",
      "updated_at": "2026-06-26T10:00:00Z"
    }
  ]
}
```

## API

The FastAPI backend exposes a simple REST API at `/api`.

| Method | Path | Description |
|--------|------|-------------|
| `GET` | `/api/presets` | List all presets |
| `POST` | `/api/presets` | Create a preset |
| `PUT` | `/api/presets/{id}` | Update a preset |
| `DELETE` | `/api/presets/{id}` | Delete a preset |
| `GET` | `/api/settings` | Check if OpenAI key is set |
| `POST` | `/api/settings` | Save OpenAI API key |
| `POST` | `/api/rewrite` | Rewrite a prompt with AI |

Interactive docs available at [http://localhost:8001/docs](http://localhost:8001/docs) when running locally.

## Stack

- **Frontend** — React 18, Tailwind CSS v3, Vite
- **Backend** — FastAPI, uvicorn
- **Storage** — `settings.json` (flat file, no database)