[alexeyco]

Summary

New plugin: the gitui.open action opens gitui in a new herdr tab rooted at the repository (argv-exec, straight into the TUI). The plugin takes read-only git snapshots before and after the session and, when something changed, delivers a short English summary to the agent in the focused pane: created commits, amend/rebase vs reset, branch switch (including detached HEAD), push (via ahead-count decrease), and staged/unstaged/untracked deltas. Nothing changed — nothing is sent.

Undeliverable summaries are kept under HERDR_PLUGIN_STATE_DIR/sessions/ (7-day prune), prompts are capped at 64 KiB. Error and no-agent paths hold the pane until Enter. Git state is never mutated; gitui is resolved from PATH with an install hint on failure.

Docs mirror herdr-revdiff: README, docs/how-it-works.md (behavioral spec), docs/development.md, AGENTS, CONTRIBUTING, CHANGELOG, SECURITY; CI (version-sync, MSRV, lint, prettier, test matrix) and a 4-target release workflow.

Testing

• cargo fmt --check
• cargo clippy --all-targets --locked -- -D warnings
• cargo test --locked — 70 tests (unit + hermetic e2e with stub herdr/gitui and real git repos)
• cargo build --release --locked
• npx --yes prettier@3.9.6 --check "**/*.md"
• Manual smoke on herdr 0.9.3: commit in gitui → gitui session summary: prompt delivered to the caller agent, tab auto-closed; non-git dir → error held until Enter