Agents can take back their own suggestions

An agent that suggests a new task and later finds its reasoning was wrong can now withdraw that suggestion, or name a newer one that replaces it. Until now it could only say so in its message, so both suggestions stayed on the canvas and both could be started. A suggestion you haven't accepted yet now disappears from the canvas right away. If you already accepted it, the card stays and is marked "replaced by …" or "withdrawn by the agent", it shows up as needing you and sends a notification. You then choose to remove it, which stops its work and can be undone, or to keep it.