Add Cog — Scaffold a New Discord.py Cog

When to Activate

• Adding new Discord bot functionality
• Creating a new slash command or event handler
• When asked to "add a cog", "create a command", or "add a feature"

Steps

1. Create the Cog File

Create claude_discord/cogs/your_cog.py:

"""Short description of what this Cog does."""

from __future__ import annotations

import logging

import discord
from discord import app_commands
from discord.ext import commands

logger = logging.getLogger(__name__)


class YourCog(commands.Cog):
    """Docstring explaining the Cog's purpose."""

    def __init__(
        self,
        bot: commands.Bot,
        # Add dependencies as constructor params (dependency injection)
    ) -> None:
        self.bot = bot

    # Add commands and listeners here

2. If It Runs Claude CLI

Use the shared helper — never duplicate the streaming logic:

from ._run_helper import run_claude_in_thread

# In your command handler:
runner = self.runner.clone()  # Always clone for concurrent safety
await run_claude_in_thread(
    thread=thread,
    runner=runner,
    repo=self.repo,
    prompt=user_input,
    session_id=existing_session_id,
)

3. Export from Package

Add to claude_discord/cogs/__init__.py:

from .your_cog import YourCog

Add to claude_discord/__init__.py:

from .cogs.your_cog import YourCog
# And add "YourCog" to __all__

4. Write Tests

Create tests/test_your_cog.py:

• Test command validation (invalid inputs, edge cases)
• Test authorization checks
• Mock Discord objects (discord.Interaction, discord.TextChannel, etc.)
• Test error handling paths

5. Verify

Run the verify skill to ensure everything passes:

uv run ruff check claude_discord/
uv run ruff format claude_discord/
uv run pytest tests/ -v --cov=claude_discord

Conventions

• Type hints: Required on all function signatures
• from __future__ import annotations: Required in every file
• Logging: Use logger = logging.getLogger(__name__), never print()
• Authorization: If the Cog accepts user commands, check _is_authorized(user_id)
• Input validation: Validate all user-provided strings with regex before passing to subprocess
• Error handling: Use contextlib.suppress(discord.HTTPException) for non-critical Discord API calls