Add planning and review guidelines to CLAUDE.md

- Add Plan & Review section with instructions for creating detailed implementation plans
- Require writing plans to .claude/tasks/TASK_NAME.md before starting work
- Emphasize MVP approach and getting approval before proceeding
- Add guidelines for updating plans during implementation with detailed change descriptions

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -32,6 +32,20 @@ This is a pnpm-based monorepo using Turborepo with the following structure:
 - `packages/supabase` - Supabase setup and configuration
 - `packages/sandbox` - Sandboxed code execution using Daytona SDK
 
+## Plan & Review
+
+### Before starting work
+- Always in plan mode to make a plan
+- After get the plan, make sure you write the plan to `.claude/tasks/TASK_NAME.md`
+- The plan should be a detailed implementation plan and the reasoning behind them, as well as tasks broken down.
+- If the task require external knowledge or certain packages, also research to get latest knowledge (Use Task tool for research)
+- Don't over plan it, always think MVP.
+- Once you write the plan, firstly ask me to review it. Do not continue until I approve the plan.
+
+### While implementing
+- You should update the plan as you work.
+- After you complete tasks in the plan, you should update and append detailed descriptions of the changes you made, so following tasks can be easily hand over to other engineers.
+
 ## Development Workflow
 
 When writing code, follow this workflow to ensure code quality: