pi-undo-redo

Undo/redo for Pi conversations and workspace changes with hybrid git/non-git behavior.

In git repositories this extension keeps file snapshots in a shadow git repository and records per-message patch metadata in the Pi session. /undo navigates the conversation tree back to the previous user message and reverts only the files changed by the undone message(s). /redo restores the files and conversation leaf captured before undo.

In non-git directories it does not scan or snapshot the whole workspace. It snapshots only explicit file paths touched by Pi file tools that provide a path (write and edit). Shell commands and custom tools without explicit path metadata are not parsed for paths and are not promised to be undo-restorable.

A dirty guard blocks /undo, /redo, and /tree when unsnapshotted workspace changes would be overwritten.

Commands

• /undo - undo the latest checkpointed user message and restore changed files
• /redo - restore the last undone conversation/file state
• /undo-cleanup - conservatively prune old protected snapshot refs while keeping snapshots referenced by the current session state

Configuration

Configure in ~/.pi/agent/settings.json or .pi/settings.json:

{
  "undoRedo": {
    "storageDir": "E:/pi-undo-redo",
    "largeFileLimitBytes": 2097152,
    "gitTimeoutMs": 30000,
    "enabled": true
  }
}

Defaults:

• storageDir: ~/.pi/agent/state/pi-undo-redo
• largeFileLimitBytes: 2097152 (2 MiB; large explicit non-git files are skipped/fail closed with a warning instead of silently claiming undo support)
• gitTimeoutMs: 30000
• enabled: true

Hybrid behavior

Git repositories

• Uses the existing shadow git snapshot behavior.
• Catches tracked modifications and ordinary non-ignored untracked files, including files created by shell/filesystem commands.
• Respects .gitignore and .git/info/exclude from the source repository.
• Maintains a shadow snapshot of source tracked files plus changed ordinary non-ignored untracked files; ignored files and large untracked files are not copied into the shadow repository.
• /tree restores the workspace snapshot that matches the selected conversation node.

Non-git directories

• Does not root-wide scan/snapshot the cwd, home directory, or project root.
• Before-agent snapshots are empty and cheap; when a Pi write or edit tool is about to run, the extension snapshots only that explicit path's current state.
• Finalization snapshots after-state for those touched files only, supporting create/modify/delete for normal files where possible.
• /undo and /redo restore only checkpoint.files from the session checkpoint.
• /tree restores only the cumulative explicit checkpoint files along the branch up to the target node; it never restores or diffs a whole cwd snapshot.
• Dirty guard checks only affected checkpoint/touched paths, so unrelated sentinel files are not included.
• Shell-created files in non-git mode are not parsed or restored. The extension warns once per agent turn when a bash tool runs in non-git mode.

Path safety in non-git mode

Explicit paths are normalized relative to the workspace root. Relative paths resolve against Pi's current ctx.cwd; absolute paths are accepted only when they remain inside the workspace root. Paths containing NUL, escaping via .., or targeting dangerous workspace directories such as .git, .pi, or node_modules are rejected. Windows-style paths normalize to /-separated relative paths in checkpoint metadata.

Notes

• Snapshots are protected with internal shadow-git refs so stored tree objects are not immediately lost to Git GC.
• Restore avoids recursive directory deletion for file/dir conflicts; unsafe conflicts fail closed instead of deleting unknown directory contents.
• Non-git mode intentionally trades shell/filesystem auto-discovery for safety and bounded scope. Use a git repository when full OpenCode-style shell/file-system change capture is required.