🩺 CodeScalpel

Surgical AI error fixer for TypeScript & JavaScript — verified by your real linter before it ever shows you a change.

CodeScalpel reads a single error reported by the TypeScript / JavaScript language service, asks an LLM to propose a fix, applies the fix invisibly to the in-memory buffer, and then waits for the language server to re-evaluate the file. If the original error is gone AND no new errors appeared near the edit, you get a clean diff to review. Otherwise the buffer is rolled back and you see a clear CANNOT_FIX: <reason>.

It's the only AI fixer that never lies about a fix being correct — because a real linter is always the final judge.

✨ Features

• Surgical — never rewrites whole files. The LLM is forced to output a 1–5 line unified diff, or to admit CANNOT_FIX.
• Verified — every candidate fix is round-tripped through the real TypeScript / JavaScript LSP. No "trust me, it works".
• Multi-provider — works with Groq (free Llama 3.1 70B), Anthropic Claude 3.5 Haiku, and any local Ollama model.
• Private — Ollama runs entirely on your machine. For cloud providers the only data that leaves is the ~10-line error snippet.
• Surgical rollback — failed verifications are silently undone with the editor's built-in undo.
• Honest — when it can't fix something, it says so with a one-sentence reason instead of pretending.

🚀 Quick start

1. Install CodeScalpel from the VS Code Marketplace.
2. Open a TypeScript or JavaScript file with an error.
3. Run CodeScalpel: Fix This Error from the command palette (or click the ⚡ Groq / 🧠 Anthropic / 🏠 Ollama item in the status bar to switch providers first).
4. Add your API key: CodeScalpel: Set API Key.
5. Review the verified diff. Click Apply to keep it, Skip to discard, or Retry with more context for a second attempt.

Free tier: 30 verified fixes per calendar month. Upgrade to Pro for unlimited fixes via CodeScalpel: Enter Pro License Key.

🛠️ Configuration

🔐 API keys & license keys

All secrets are stored with VS Code's SecretStorage, which on macOS / Windows / most Linux desktops is backed by the OS keychain. They never touch settings.json, disk in plain text, or any server.

📊 Telemetry

When codescalpel.telemetryEnabled is true (the default) we send aggregate counters to a Cloudflare worker: fix_attempt, fix_success, fix_failed, command. No code, no file names, no error messages are ever transmitted. The identifier is vscode.env.machineId — a stable, anonymous per-installation token.

Disable at any time via the setting above.

🧪 Supported errors

CodeScalpel only attempts to fix errors whose codes are in a small whitelist of "small change, big win" patterns:

Errors we intentionally ignore: module-not-found, tsconfig issues, and anything that would require editing another file.

🏗️ Architecture

src/
├── extension.ts          # main activation, commands, status bar
├── diagnostics.ts        # error capture + context extraction
├── llm/
│   ├── provider.ts       # interface (LLMProvider, FixContext, LlmResult)
│   ├── anthropic.ts      # Claude 3.5 Haiku implementation
│   ├── groq.ts           # Llama 3.1 70B (default)
│   ├── ollama.ts         # local Ollama implementation
│   ├── prompts.ts        # strict system prompt + few-shot
│   └── index.ts          # factory
├── diffUtils.ts          # unified-diff → TextEdit[]
├── verification.ts       # INVISIBLE LSP verification state machine
├── diffUI.ts             # side-by-side webview diff panel
├── licensing.ts          # free counter + license cache
├── config.ts             # settings + SecretStorage
├── logger.ts             # output channel
└── telemetry.ts          # opt-out anonymous analytics

The verification engine is the core moat. Its job is to apply the LLM's diff to the live buffer, wait for onDidChangeDiagnostics, compare the before/after sets, and either keep the edit (and show the diff) or silently undo it.

🧰 Development

npm install
npm run watch   # tsc --watch
# In VS Code: F5 launches the extension in a new Extension Host window.

Tests

npm test

Pure unit tests for the diff parser, the LLM response parser, and the verification comparator. They run in plain Node (no VS Code required).

Build a .vsix

npm install -g @vscode/vsce
vsce package

📜 License

MIT — see LICENSE.