Using Arkhe Skills

---
name: using-arkhe-skills
description: Use when starting any conversation - establishes how arkhe skills bootstrap on Claude Code, Antigravity CLI (agy) / Gemini CLI, and Codex CLI, and maps Claude-only tools (AskUserQuestion, TaskCreate, EnterPlanMode, the Skill tool, the Agent tool) to their cross-platform equivalents
---

<SUBAGENT-STOP>
If dispatched as a subagent to execute a specific task, skip this skill.
</SUBAGENT-STOP>

# Using arkhe Skills Across Platforms

arkhe plugins ship the same `SKILL.md` files across CLI harnesses. This bootstrap establishes how to access skills and how to translate platform tool names into equivalent operations on Claude Code, Antigravity CLI (`agy`), Gemini CLI, and Codex CLI.

## How to Access Skills

- **Claude Code:** Use the `Skill` tool. When invoked, the skill content is loaded and presented to follow directly.
- **Antigravity CLI (`agy`):** Skill metadata (name + description) is auto-loaded into the system prompt at session start. When triggers fire, use `view_file` to load `skills/<skill-name>/SKILL.md` from the plugin directory, then follow its instructions.
- **Gemini CLI (Legacy):** Skill metadata is loaded into system prompt. Use `read_file` to load `skills/<skill-name>/SKILL.md`.
- **Codex CLI:** Skill index and trigger phrases are inlined in `AGENTS.md` at install time. Follow the skill body directly when a trigger phrase fires.

## Platform Tool Mapping

arkhe SKILL.md files reference core agent primitives. On each platform, substitute the equivalent operation from this table.

| Primitive / Claude tool | Antigravity CLI (`agy`) equivalent | Gemini CLI (Legacy) equivalent | Codex CLI equivalent |
|---|---|---|---|
| `AskUserQuestion` | `ask_question` (native interactive modal with chip UI options) | Ask a plain-text question with numbered choices and await reply. | Plain-text question with numbered choices. |
| `TaskCreate` / `TaskUpdate` | `manage_task` or inline TODO list rendered on each turn | Inline TODO list rendered on each turn | Inline TODO list rendered on each turn |
| `EnterPlanMode` / `ExitPlanMode` | Native `--mode plan` / `accept-edits` mode | Announce plan mode and gate writes on approval | Announce plan mode and gate writes on approval |
| Skill tool (`Skill`) | `view_file` on `skills/<name>/SKILL.md` | `read_file` on `skills/<name>/SKILL.md` | Skill content inlined in `AGENTS.md` |
| Agent tool (`subagent_type`) | `invoke_subagent` / `define_subagent` (native background/concurrent subagent execution) | Inline agent prompt into current session | Inline agent prompt into current session |

## Command Naming Across Platforms

Commands ship from the same `plugins/<plugin>/commands/<name>.md` source on every platform, but the slash-command syntax differs:

| Platform | Form | Example |
|---|---|---|
| Claude Code | `/<plugin>:<command>` (plugin-namespaced) | `/core:think` |
| Antigravity CLI (`agy`) / Gemini CLI | `/<command>` (or `agy plugin` commands) | `/think` |
| Codex CLI | Trigger phrase in chat (no slash) | "think through whether to use Postgres or Redis" |

When this skill or other arkhe docs refer to `core:think`, `core:debug`, etc., resolve them through this table — same command, platform-specific invocation.

## Subagent-Heavy Commands

Six arkhe commands dispatch subagents on Claude Code and Antigravity CLI (`agy`). On legacy Gemini and Codex CLI, they run inline with the agent's prompt collapsed into the command body.

The affected commands:

- `core:debug` (with `--deep`)
- `core:think`
- `core:research`
- `core:double-check` (with `--deep`)
- `spring-boot:spring-review`
- `spring-boot:verify-upgrade`

## Instruction Priority

1. **User's explicit instructions** (CLAUDE.md, GEMINI.md, AGENTS.md, direct requests) — highest priority
2. **arkhe skills** — override default system behavior where they conflict
3. **Default system prompt** — lowest priority

If `CLAUDE.md`, `GEMINI.md`, or `AGENTS.md` says "do not use TDD" and a skill says "always use TDD," follow the user's instructions. The user is in control.

## Where Skills Live

- **Canonical source:** `plugins/<plugin>/skills/<skill>/SKILL.md`
- **Claude Code:** loaded via `.claude-plugin/marketplace.json`
- **Antigravity CLI / Gemini CLI:** loaded via `plugins/<plugin>/plugin.json` or `.gemini-extensions/<plugin>/plugin.json` (skills directory is a symlink to the canonical source)
- **Codex CLI:** loaded via `.codex-marketplace/<plugin>/AGENTS.md` (skill index synthesized at build time; full content via symlinked `skills/`)

Skill bodies are not duplicated across platforms. One file, cross-platform support.