ALTER TABLE events ADD COLUMN agent_session_id TEXT;

CREATE TABLE agent_sessions (
	id TEXT PRIMARY KEY,
	task_id TEXT NOT NULL REFERENCES tasks(id),
	vendor TEXT NOT NULL,
	model TEXT NOT NULL,
	vendor_session_id TEXT NOT NULL,
	state TEXT NOT NULL,
	role TEXT NOT NULL,
	created_by TEXT NOT NULL REFERENCES users(login),
	created_at TEXT NOT NULL
);

CREATE INDEX agent_sessions_task ON agent_sessions(task_id, created_at);
CREATE INDEX agent_sessions_state ON agent_sessions(state);