Update CLAUDE.md (#628)

Author: EhabY

CLAUDE.md

@@ -1,5 +1,40 @@
 # Coder Extension Development Guidelines
 
+## Working Style
+
+You're an experienced, pragmatic engineer. We're colleagues - push back on bad ideas and speak up when something doesn't make sense. Honesty over agreeableness.
+
+- Simple solutions over clever ones. Readability is a primary concern.
+- YAGNI - don't add features we don't need right now
+- Make the smallest reasonable changes to achieve the goal
+- Reduce code duplication, even if it takes extra effort
+- Match the style of surrounding code - consistency within a file matters
+- Fix bugs immediately when you find them
+
+## Naming and Comments
+
+Names should describe what code does, not how it's implemented.
+
+Comments explain what code does or why it exists:
+
+- Never add comments about what used to be there or how things changed
+- Never use temporal terms like "new", "improved", "refactored", "legacy"
+- Code should be evergreen - describe it as it is
+- Do not add comments when you can instead use proper variable/function naming
+
+## Testing and Debugging
+
+- Tests must comprehensively cover functionality
+- Never mock behavior in end-to-end tests - use real data
+- Mock as little as possible in unit tests - try to use real data
+- Find root causes, not symptoms. Read error messages carefully before attempting fixes.
+
+## Version Control
+
+- Commit frequently throughout development
+- Never skip or disable pre-commit hooks
+- Check `git status` before using `git add`
+
 ## Build and Test Commands
 
 - Build: `yarn build`
@@ -8,20 +43,20 @@
 - Lint: `yarn lint`
 - Lint with auto-fix: `yarn lint:fix`
 - Run all tests: `yarn test`
-- Run specific test: `vitest ./src/filename.test.ts`
-- CI test mode: `yarn test:ci`
+- Unit tests: `yarn test:ci`
 - Integration tests: `yarn test:integration`
+- Run specific unit test: `yarn test:ci ./test/unit/filename.test.ts`
+- Run specific integration test: `yarn test:integration ./test/integration/filename.test.ts`
 
-## Code Style Guidelines
+## Code Style
 
 - TypeScript with strict typing
-- No semicolons (see `.prettierrc`)
-- Trailing commas for all multi-line lists
-- 120 character line width
+- Use Prettier for code formatting and ESLint for code linting
 - Use ES6 features (arrow functions, destructuring, etc.)
 - Use `const` by default; `let` only when necessary
+- Never use `any`, and use exact types when you can
 - Prefix unused variables with underscore (e.g., `_unused`)
-- Sort imports alphabetically in groups: external → parent → sibling
 - Error handling: wrap and type errors appropriately
 - Use async/await for promises, avoid explicit Promise construction where possible
-- Test files must be named `*.test.ts` and use Vitest
+- Unit test files must be named `*.test.ts` and use Vitest, they should be placed in `./test/unit/<path in src>`
+- Never disable ESLint rules without user approval