CodeLadder – Chrome Extension (MV3)

Step-by-step coding mentor for LeetCode-like problems.
Graduated hints (H1 → H2 → H3 → Plan → Pseudocode), no spoilers by default. BYOK (Bring Your Own) Gemini key.

✨ Features

• On-page mentor widget (draggable; position persists).
• Hint ladder: H1 (nudge) → H2 (concept) → H3 (approach) → Plan → Pseudocode.
• AI integration (BYOK): calls Gemini from the background; the key never touches content scripts or the page.
• Monaco code capture: reliably reads the editor’s real buffer for context (not just visible lines).
• Clean error messages for common cases (invalid key, rate limit, model busy).

🧩 How it works

• A content script injects the widget on leetcode.com / leetcode.cn.
• You pick a hint level and (optionally) type what you’re stuck on.
• Content → Background: sends problem title/URL/difficulty, your question, and editor code.
• Background builds a prompt and calls Gemini → returns a small next-step hint.

📦 Install (Load Unpacked)

1. Download or clone this repo.
2. Open Chrome → visit chrome://extensions.
3. Toggle Developer mode (top-right).
4. Click Load unpacked → select the project folder.
5. Click the extension’s Options page → paste your Gemini API key → Save.

BYOK = Bring Your Own Key. Each user creates their own key and pastes it.
The key is saved only in your browser profile via chrome.storage.local.

🔑 Get a Gemini API key (summary)

• Create a Web API key in Google AI Studio.
• Copy the key (looks like AIza…) and paste it in the extension Options page.
• Free tier has quotas; see troubleshooting below.

🖱️ Draggable widget

Drag the widget by its header; position is saved.

📸 More screenshots

Hint example (H1/H2/H3):

Pseudocode example:

🧪 What to test

• H1/H2/H3/Plan/Pseudocode on a few problems.
• Empty editor vs. with your code (the model can comment on your actual code).
• leetcode.com and leetcode.cn.
• Error handling paths: 401 (bad key), 429 (free-tier rate limit), 503 (model busy).

🛠️ Troubleshooting

• “API key invalid” (401/403): Open Options and re-paste a valid Gemini key.
• “Free-tier rate limit hit” (429): Wait a bit and try again.
• “Model is busy” (503): Wait ~20–60s and click again (busiest times cause this).
• No widget? Ensure the page matches leetcode.com/* or leetcode.cn/*. Reload the extension and the page.

🛡️ Privacy & security

• Your Gemini key is not hard-coded in the repo; it’s stored locally via chrome.storage.local.
• Network calls happen from the background service worker.
• The extension only sends context (title/URL/difficulty, your question, and editor code) when you click Get hint.
• No analytics.

🗂️ Project structure