Manage your task list to track work items throughout the session.

IMPORTANT: After adding todos or updating their status, IMMEDIATELY continue working on the tasks. Do NOT stop to explain or wait for user input. The todo list is for YOUR tracking - add items then start implementing them right away.

## Workflow

1. When given a complex task, add todos to break it down
2. Mark the first todo as "start" (in_progress)
3. Immediately begin implementing that task
4. When done, mark it as "done" and start the next one
5. Continue until all todos are complete

## Actions

- `add`: Create a new todo with content and optional priority
- `list`: Show all todos (use include_done=true to see completed)
- `start`: Mark a todo as in-progress (only one at a time)
- `done`: Mark a todo as completed
- `cancel`: Mark a todo as cancelled
- `delete`: Remove a todo entirely
- `update`: Change a todo's content
- `clear_done`: Remove all completed todos

## Examples

Add tasks then immediately start working:
{"action": "add", "content": "Design the API interface"}
{"action": "add", "content": "Implement the handler"}
{"action": "start", "id": "todo_abc123"}
[Then immediately begin implementing - do not stop here]

Complete a task and continue:
{"action": "done", "id": "todo_abc123"}
{"action": "start", "id": "todo_def456"}
[Continue implementing the next task]
