thurbox: Skill for Claude Code

Thurbox extensions

Working reference indexed by AGENTS.md. The rationale behind these decisions is owned by the docs under docs/; a change that invalidates what this says updates it in the same PR.

Extensions

An extension is an opt-in, agent-agnostic add-on that builds on thurbox-cli without touching the core binary: an extension.toml manifest plus whatever files it lays down, installed with thurbox-cli extension install <url|dir|git+repo|name>.

extensions/ in this repo holds only the two built-ins, hooks and ui-skill. Both ship embedded in the binary and auto-activate, so neither is something a user installs by name — which is why agent::extension_config::OFFICIAL_EXTENSIONS, the bare-name registry behind extension available and the typo hints, is currently empty. The mechanism is intact; there is simply nothing that resolves by bare name. Anything else installs from a URL, a local path, or a repository (git+https://...).

• extensions/hooks/ (built-in, on by default) — status-hook delivery for the built-in agents, so the default agent's session status works with zero setup. Its assets are include_str!d by session_ops::builtin_hooks, so the directory is load-bearing: delete a file and the binary stops compiling. Which hook mechanism each agent gets, and the states each can report, is per-agent in docs/AGENTS.md → "Status hook mechanisms".
• extensions/ui-skill/ (built-in, on by default) — it ships no session, no automation and no agent. It installs a single agent skill, thurbox-ui, into each coding CLI's personal skill directory (~/.claude/skills/, ~/.codex/skills/, ~/.config/opencode/skills/, ~/.copilot/skills/, ~/.agents/skills/ — each guarded by requires_dir, so a CLI the user does not have is skipped), so an agent in any session knows how to change thurbox's own interface. It replaces the workaround of attaching the interface directory to every session as an extra repo: a skill loads only when the request is about the TUI, where an extra repo is in front of the agent always. Like hooks it is embedded + auto-activated (see below) — for the same reason: someone who does not already know the interface is editable will not go looking for the extension that says so. Opt out with thurbox-cli extension deactivate ui-skill. The payload is one SKILL.md — the short form of ui/AGENTS.md + ui/README.md — and it hard-codes no paths, opening with thurbox-cli plugin dir so one file is correct for a release build, a dev build and a THURBOX_UI_DIR override alike. Delivery is the ordinary [[external_files]] machinery, marker-guarded: install/update/uninstall act on thurbox's own copies and leave one the user has taken ownership of alone (drop the Managed by line and it is theirs), while reinstall and install --force overwrite as they do everywhere else.