@task.json contains task fields such as fictional title and description, not an initial_instruction. Tracking does not copy or restart the conversation. If there is no session yet, almanac create task --input @task.json --request-key meridian-task-1 creates the task with a new primary session. Without initial_instruction it saves work only. Including that field queues real model execution for the new task, so decide deliberately whether to start work. Reading or creating a bare session does not launch a run.
To change task state, read its task revision, then use a conditional edit such as almanac set TASK_ID --expect 3 --input '{"state":"done"}' --request-key meridian-done-1. This revision differs from the session revision used by sessions track or sessions set. On conflict, reread and reconsider the change. A project can be read and edited through the same root record verbs; inspect schema describe project for its exact fields. Conversations explains how to inspect the primary session, and review explains background change checkpoints.