Returns a specification to start this module under a supervisor.

See Supervisor.

@spec start_session(keyword()) :: {:ok, String.t(), pid()} | {:error, term()}

Start a Session. Accepts :id (generated if absent), :workspace, :role, :force_release_writer_lease?, and :force_release_reason. Forced lease release is a break-glass resume path for stale/ambiguous writer evidence; active leases are refused. Returns {:ok, session_id, pid} so the caller always learns the id.

@spec stop_all_sessions() :: {:ok, map()} | {:error, map()}

Stop every live Session owned by this runtime.

This is a CLI shutdown helper, not a stale-writer recovery path: it only terminates processes that are currently supervised in this BEAM instance. Stale lease files left by crashed or killed processes remain fail-closed for explicit resume handling.

@spec stop_session(String.t()) :: {:ok, :stopped | :not_running} | {:error, map()}

Stop one live Session by id.

Presenter/Manager cleanup for fail-closed error paths that started a Session and then refused it (e.g. a failed resume-posture restore): the process must not survive its own rejection as an untracked live writer. A Session that is not running is a no-op success.