ALTER TABLE runtime_instance
    ADD COLUMN IF NOT EXISTS owner_id text NOT NULL DEFAULT 'control-plane',
    ADD COLUMN IF NOT EXISTS purpose text NOT NULL DEFAULT 'session',
    ADD COLUMN IF NOT EXISTS lease_token text NOT NULL DEFAULT '',
    ADD COLUMN IF NOT EXISTS node_id text NOT NULL DEFAULT '';

ALTER TABLE runtime_instance
    DROP CONSTRAINT IF EXISTS runtime_instance_purpose_check;
ALTER TABLE runtime_instance
    ADD CONSTRAINT runtime_instance_purpose_check
    CHECK (purpose IN ('session', 'task', 'listener'));

CREATE UNIQUE INDEX IF NOT EXISTS runtime_instance_active_lease_token_idx
    ON runtime_instance (lease_token)
    WHERE released_at IS NULL AND lease_token <> '';

CREATE TABLE IF NOT EXISTS runtime_use_lease (
    token text PRIMARY KEY,
    runtime_instance_id text NOT NULL REFERENCES runtime_instance(id),
    owner_id text NOT NULL,
    purpose text NOT NULL CHECK (purpose IN ('task', 'listener')),
    task_id text REFERENCES operation_task(id),
    lease_until timestamptz NOT NULL,
    acquired_at timestamptz NOT NULL DEFAULT now(),
    released_at timestamptz,
    CHECK (length(token) BETWEEN 16 AND 128),
    CHECK (length(owner_id) BETWEEN 1 AND 128)
);

CREATE INDEX IF NOT EXISTS runtime_use_lease_active_runtime_idx
    ON runtime_use_lease (runtime_instance_id, lease_until)
    WHERE released_at IS NULL;

CREATE UNIQUE INDEX IF NOT EXISTS runtime_use_lease_active_task_idx
    ON runtime_use_lease (task_id)
    WHERE released_at IS NULL AND task_id IS NOT NULL;