Hunk Auto Diff

Herdr plugin that automatically opens a hunk diff in a split pane whenever a coding agent (Claude Code, Codex, etc.) finishes a turn with uncommitted changes.

No keybinding, no manual action — when the agent in a pane goes idle and its working tree is dirty, a split opens on the right running hunk diff --watch. Focus stays on the agent pane.

Install

herdr plugin install scott306lr/herdr-plugin-hunk-autodiff

Behavior

On every pane.agent_status_changed event where the agent becomes idle:

1. Resolves the pane's cwd; exits silently unless it is inside a git repo with working-tree changes.
2. If a hunk session is already live for that repo (hunk session get --repo), does nothing — the existing pane's --watch keeps it fresh.
3. If the diff is unchanged since a pane was last opened for it, does nothing — closing the hunk pane keeps it closed until new changes appear.
4. Otherwise splits the agent's pane to the right (--no-focus), labels it hunk, and runs hunk diff --watch.

Requirements

• Herdr 0.7.0 or newer
• python3
• hunk (or bunx hunkdiff as fallback)
• An agent integration that reports agent state to herdr (herdr integration install claude, codex, …)

Notes

• Herdr runs plugin event hooks with a minimal PATH; the plugin resolves hunk from common install locations (/opt/homebrew/bin, /usr/local/bin, ~/.local/bin).
• Diff signatures are stored under the plugin state dir (HERDR_PLUGIN_STATE_DIR), one small file per repo.

License

MIT