Customization Types

Customization types

The primitive kinds crickets recognizes via each primitive's kind field. You author a primitive under its kind's subdir inside a plugin group — src/<group>/<subdir>/<name> — and the generator emits it into that group's plugin for each host in its supported_hosts. This page is what each kind is and when to reach for which; for where each lands see Per-host paths, and for the frontmatter contract see Manifest Schema.

⚡ Quick Reference

Kind	Authored in	What it is	Effective on
skill	skills/<name>/SKILL.md	agent-invoked helper — the model triggers it on a context match	both
command	commands/<name>.md	user-typed /slash command	both
agent	agents/<name>.md	specialized sub-agent for fan-out work	both
hook	hooks/<name>/	script the host runs at a session event (Hooks)	both — observe-only on Antigravity
snippet	snippets/<name>.md	standing instruction fragment — emits as an Antigravity rules/ file; Claude plugins can't ship instruction files, so it's dropped and the convention is carried directly in CLAUDE.md / AGENTS.md instead	Antigravity
output-style	output-styles/<name>.md	named output-style — agent reads it when referenced by name (e.g. terse); adjusts verbosity or format	both
rule	rules/<name>.md	standing behavioral rule — merged into the agent's context as a persistent instruction (e.g. edit-over-write)	both

These seven ship today. The kind enum also reserves mcp-server, status-line, workflow, and settings-fragment — no primitive uses them yet, so the generator emits none. The full enum lives in Manifest Schema.

Note

Group-level scripts/ is not a kind. A src/<group>/scripts/ dir holds verbatim helper scripts (e.g. code-review/scripts/cross-review.sh, developer-workflows/scripts/capability_probe.py) — no frontmatter, no kind, not discovered as a primitive. The generator copies the whole dir wholesale (excluding __pycache__) into the plugin at <plugin>/scripts/, both hosts. A primitive references a bundled script through the host's plugin path — ${CLAUDE_PLUGIN_ROOT}/scripts/<name> on Claude Code, or a relative scripts/<name> on Antigravity, which runs primitives from inside the plugin dir and sets no plugin-root variable. See src/SCHEMA.md § Group-level assets.

Choosing skill vs command vs agent

You want…	Use
a helper the agent triggers on a keyword or context match (e.g. pii-scrubber)	skill
a user-typed /something command	command
a specialized agent for a specific task (e.g. evaluator, explorer)	agent

One concept can ship as several primitives — e.g. an evaluator agent plus a skill that auto-invokes it.

Grouping primitives into a plugin

Primitives that belong together live in one group (src/<group>/), which emits as one installable plugin. The group's group.yaml declares whether it's standalone or requires another group, and what it enhances — see Manifest Schema for that contract. Independent customizations go in separate groups.

Related

• Plugin anatomy — what a plugin is + its overall structure.
• Per-host paths — where each kind lands in the plugin, per host.
• Manifest Schema — the frontmatter + group.yaml contract.
• Hooks — the hook catalog + how hooks run.
• Add a skill — a worked authoring recipe.