Implement Pad

Implement following your Pad (a markdown file named pad.md in this repository that has instructions for you) following the "Execution" section below.

Execution

1. Find the Pad by searching the name pad.md in this repo. if you can't find or find multiple, ask the user its path and stop your work.
2. Read the "Instruction" in the Pad and understand user's instruction.
3. Check the language used in the "Instruction" section and use the same language for your work.
4. Read the "Current" section and the source code referred in the section to understand current implementation.
5. Read the "New" section, especially the "Step-by-step Implementation" in the "Implementation Plan" subsection, to understand how you should implement.
6. Follow the step-by-step implementation plan to complete the implementation.
7. Verify all behaviors in the Pad are satisfied:
   • Read the ## New section's ### Behavior subsection in the Pad
   • This section contains test cases that must ALL be satisfied
   • Prioritize automated testing:
   • Only use manual testing when:
     • No testing framework is available, OR
     • Automated tests fail due to complexity or environmental issues (e.g., UI tests with element finding issues, async timing problems)
   • For each behavior listed in the format "Given [initial state], When [action], Then [expected outcome]":
     • Verify using automated tests (preferred) or manual testing (fallback)
   • If any behavior is NOT satisfied, fix the implementation and verify again
   • Repeat this verification loop until ALL behaviors are confirmed to work correctly
8. When all behaviors are verified, inform the user that implementation is complete and all behaviors have been confirmed.