CREATE TABLE task_usage (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    task_id UUID NOT NULL REFERENCES agent_task_queue(id) ON DELETE CASCADE,
    provider TEXT NOT NULL DEFAULT '',
    model TEXT NOT NULL,
    input_tokens BIGINT NOT NULL DEFAULT 0,
    output_tokens BIGINT NOT NULL DEFAULT 0,
    cache_read_tokens BIGINT NOT NULL DEFAULT 0,
    cache_write_tokens BIGINT NOT NULL DEFAULT 0,
    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
    UNIQUE (task_id, provider, model)
);

CREATE INDEX idx_task_usage_task_id ON task_usage(task_id);