# Command Groups

URL: /docs/usage/groups/
Section: usage
Tags: groups, commands, nesting, hierarchy

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Groups organize commands into namespaces, creating a hierarchical CLI structure. Each group becomes a subcommand that has its own subcommands. Creating groups from milo import CLI cli = CLI(name="myapp", description="My tool") site = cli.group("site", description="Site operations") @site.command("build", description="Build the site") def build(output: str = "_site") -> str: return f"Building to {output}" @site.command("serve", description="Start dev server") def serve(port: int = 8080) -> str: return f"Serving on port {port}" myapp site build --output dist myapp site serve --port 3000 Nesting groups Groups can contain sub-groups to any depth: config = site.group("config", description="Config management") @config.command("show", description="Show merged config") def config_show() -> dict: return {"theme": "dark", "lang": "en"} @config.command("set", description="Update a config value") def config_set(key: str, value: str) -> dict: return {"updated": key, "value": value} myapp site config show myapp site config set --key theme --value light Group aliases Groups support aliases just like commands: site = cli.group("site", description="Site operations", aliases=("s",)) config = site.group("config", description="Config management", aliases=("cfg",)) myapp s build # same as: myapp site build myapp s cfg show # same as: myapp site config show Dotted paths Commands in groups are addressable via dotted paths for programmatic access: cmd = cli.get_command("site.build") cmd = cli.get_command("site.config.show") result = cli.call("site.build", output="dist") Walking all commands walk_commands() traverses the entire command tree, yielding dotted paths: for path, cmd in cli.walk_commands(): print(f"{path}: {cmd.description}") # Output: # greet: Say hello # site.build: Build the site # site.serve: Start dev server # site.config.show: Show merged config This is used by --llms-txt and --mcp to discover all commands including those inside groups. Adding external groups Groups can be defined separately and added later: from milo import Group db = Group("db", description="Database operations") @db.command("migrate", description="Run migrations") def migrate() -> str: ... @db.command("seed", description="Seed test data") def seed() -> str: ... cli.add_group(db) Freezing groups Convert a mutable Group to an immutable GroupDef snapshot: frozen = site.to_def() print(frozen.name) # "site" print(frozen.commands) # {"build": CommandDef(...), ...} print(frozen.groups) # {"config": GroupDef(...)} Tip Tip Groups integrate fully with --llms-txt (nested headings), --mcp (dot-notation tool names), and help output. All commands in groups are discoverable by AI agents.

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Metadata:
- Author: lbliii
- Word Count: 340
- Reading Time: 2 minutes