TypeScript LSP

---
name: typescript-lsp
description: |
  Always active when working in TypeScript projects. Runs tsc diagnostics
  after edits to catch type errors early. Trigger: any .ts or .tsx file edit.
allowed-tools:
  - Bash(npx tsc --noEmit *)
  - Bash(npx tsc --noEmit --pretty *)
  - Read
  - Glob
---

# TypeScript LSP

Run TypeScript compiler diagnostics after edits to catch type errors before
they compound. Provides real-time feedback on type safety.

## Prerequisites

- `typescript` installed in the project (`npm install -D typescript`)
- `tsconfig.json` present in project root

## Steps

1. After any TypeScript file edit, run diagnostics:
   ```bash
   npx tsc --noEmit --pretty 2>&1 | head -50
   ```

2. If errors are found:
   - Read the erroring file at the reported line
   - Fix the type error
   - Re-run diagnostics to confirm the fix

3. Common fixes:
   - Missing type annotations: add explicit types to function parameters
   - Null checks: use optional chaining or nullish coalescing
   - Import errors: verify the export exists in the source module
   - Generic constraints: add `extends` clauses to type parameters

4. For project-wide checks, run:
   ```bash
   npx tsc --noEmit 2>&1 | wc -l
   ```
   Report the total error count and fix systematically.