[FEATURE] Implement checkpoints in the VSCode extension

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When using Claude Code in VSCode extension, I often need to experiment with different code approaches. But the extension doesn't support checkpoints like the terminal version does.

When Claude makes multiple file changes that don't work as expected, I find it difficult to roll back to a previous state quickly.

The current workflow requires me to manually use git commits before each major change, or switch to the terminal version for complex tasks. This breaks my VSCode workflow and adds friction.

Proposed Solution

I'd like to be able to click a "Create Checkpoint" button in the VSCode extension to save the current conversation and file state.

There should be a checkpoint panel in the sidebar that shows all saved checkpoints with timestamps and descriptions.

The interface should show a "Restore" button next to each checkpoint, and optionally a "Diff" button to compare current state with that checkpoint.

Alternative Solutions

I've tried using git commits before major changes, but this adds extra steps and clutters my git history with temporary commits.

Currently I work around this by switching to the terminal version of Claude Code when I need checkpoint functionality.

Other tools like Cursor IDE have similar undo/checkpoint features built into their AI assistant interface.

Priority

Critical - Blocking my work

Feature Category

File operations

Use Case Example

Example scenario:

I'm working on an embedded C project with Claude in VSCode

I ask Claude to refactor a driver module, which modifies 5 files

The refactored code has issues and I want to go back

With checkpoints, I could restore all files to the pre-refactor state in one click

This would save me time because I don't need to manually revert each file or use git reset

Additional Context

The terminal version of Claude Code already supports checkpoints, so the core logic exists
This feature would bring feature parity between terminal and VSCode extension
Many users prefer working entirely within VSCode rather than switching to terminal