Module undo 

Undo stack for file mutations. Undo stack for file mutations.

Snapshots file contents before Write/Edit/Delete tool execution. Each turn’s mutations are grouped into a single undo entry.

How it works

1. Before any file mutation, the current file contents are snapshotted
2. All mutations in a single turn are grouped into one undo entry
3. /undo restores all files from the most recent entry
4. Stack depth is unlimited — undo as many turns as needed

What gets tracked

• Write: snapshots the file if it existed (for overwrite), or marks as “created”
• Edit: snapshots the file before the edit
• Delete: snapshots the file contents before deletion

Git checkpointing provides a separate safety net via git stash-style snapshots before each turn. /undo is faster (in-memory) but git checkpoints survive process crashes.

Structs

UndoEntry

A snapshot of file states before a turn’s mutations.

UndoStack

Stack of undo entries, one per turn.

Functions

extract_file_path

Extract the target file path from tool arguments.

is_mutating_tool

Check if a tool name is a file-mutating tool that should be snapshotted.