CREATE TABLE task_message (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    task_id UUID NOT NULL REFERENCES agent_task_queue(id) ON DELETE CASCADE,
    seq INTEGER NOT NULL,
    type TEXT NOT NULL,
    tool TEXT,
    content TEXT,
    input JSONB,
    output TEXT,
    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX idx_task_message_task_id_seq ON task_message(task_id, seq);