Here’s a refined `chrome_vscode_bridge_design_task.md` file for your repo. Feel free to adjust paths, placeholders, or formatting to match your project's style.

---

# Chrome ↔ VSCode Bridge Design 🛠️

## Overview

Design and implement a minimal debugging bridge between a Python backend (using a hypothetical `fastled` library) and a Chrome-based frontend, invokable from VS Code. The goal is to allow:

* **Step-through debugging** (`step`, `next`, `in`, `out`)
* **Program counter**, call stack, local variable inspection
* Integration with VS Code Python or Node debugger

---

## 📘 Architecture

```
[VS Code] ↔ [Chrome Frontend CLI: Puppeteer + CDP] ↔ HTTP ↔ [Python Debug API (fastled)]
```

1. **Backend** (`Python + Flask`)

   * Exposes endpoints:

     * `POST /start` — begins execution, stops at first pause
     * `POST /step/next` — advances one logical step
     * `GET /state` — returns `{ pc, function, locals }`
   * Internally uses generator-based control flow and `inspect` to snapshot state.
2. **Frontend** (`Node.js + Puppeteer`)

   * Launches Chrome with remote-debugging enabled
   * Serves a minimal UI (e.g. HTML + JS) to send `start`, `step`, and poll `state`
   * Renders debugging state to the user; future CDP integration for real-time UI
3. **VS Code Integration**

   * Launch configuration invokes the frontend script
   * Stepping and inspection occur in the Chrome UI
   * Optionally hooks into VS Code Debug Console for unified control

---

## 📄 Files

### 1. `debug_fastled_api.py` (Backend)

```python
import fastled, inspect
from flask import Flask, jsonify, request

app = Flask(__name__)
_state, _step_generator = {}, None

def compute(n):
    x = n * 2
    y = fastled.compute(x)
    yield from report_and_pause()
    return y

def report_and_pause():
    frame = inspect.currentframe().f_back
    _state.update({
        "pc": frame.f_lineno,
        "func": frame.f_code.co_name,
        "locals": frame.f_locals.copy()
    })
    yield True

@app.route('/start', methods=['POST'])
def start():
    global _step_generator
    n = request.json.get("n", 5)
    def runner():
        gen = compute(n)
        try: next(gen)
        except StopIteration: pass
    _step_generator = runner
    return jsonify({"status": "started"})

@app.route('/state', methods=['GET'])
def state():
    return jsonify(_state)

@app.route('/step/next', methods=['POST'])
def step_next():
    try:
        _step_generator()
        return jsonify({"status": "paused", **_state})
    except Exception:
        return jsonify({"status": "done"})

if __name__ == "__main__":
    app.run(port=5000)
```

---

### 2. `debug_fastled_frontend.js` (Frontend)

```js
const puppeteer = require('puppeteer-core');
const fetch = require('node-fetch');

(async () => {
  const browser = await puppeteer.launch({
    executablePath: '/path/to/chrome',
    args: ['--remote-debugging-port=9222']
  });
  const [page] = await browser.pages();

  const html = `
    <button id="start">Start</button>
    <button id="step">Next</button>
    <pre id="out"></pre>
    <script>
      document.getElementById('start').onclick = async () => {
        await fetch('http://localhost:5000/start', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({ n: 10 })
        });
        update();
      };
      document.getElementById('step').onclick = async () => {
        await fetch('http://localhost:5000/step/next', { method: 'POST' });
        update();
      };
      async function update() {
        const res = await fetch('http://localhost:5000/state');
        document.getElementById('out').textContent = JSON.stringify(await res.json(), null, 2);
      }
    </script>
  `;
  await page.setContent(html);
})();
```

---

## ⛓️ Integration with VS Code

Add this to `.vscode/launch.json`:

```jsonc
{
  "configurations": [
    {
      "name": "Chrome-FastLED Debug Bridge",
      "type": "node",
      "request": "launch",
      "program": "${workspaceFolder}/debug_fastled_frontend.js"
    }
  ]
}
```

* Launch this first to start Chrome with debugging enabled
* Use the UI to `Start`, `Next`, and inspect state output
* Optionally, add CDP logic to highlight lines in VS Code or Chrome DevTools

---

## ✅ Roadmap & Next Steps

| Task                                    | Status        |
| --------------------------------------- | ------------- |
| Generator-based stepping API            | ✅ Implemented |
| Backend state introspection (PC/locals) | ✅ Implemented |
| Frontend stepping UI (buttons + state)  | ✅ Implemented |
| VS Code `launch.json` integration       | ✅ Drafted     |
| CDP / DevTools integration              | 🔲 To Do      |
| Support for `step in`, `step out`       | 🔲 To Do      |
| Breakpoints, multi-file support         | 🔲 To Do      |

---

## 🔧 Future Enhancements

* **Full CDP client**: translate HTTP state to actual Chrome DevTools UI breakpoints/stepping
* **Rich UI**: live code view, synchronized highlighting, variable inspectors
* **Language-agnostic bridge**: plug in Node.js or other backends
* **VS Code Extension support**: unify stepping flows and tooltips

---

## 📎 Summary

This bridge provides:

* A **Python backend** exposing stepping and state via HTTP
* A **Node.js/pupeteer frontend** for remote-debug Chrome UI
* **VS Code launch config** for seamless integration

You're all set to explore, refine, or build upon this foundation. Let me know if you'd like help developing CDP integration or full VS Code extension support!
