CREATE TABLE IF NOT EXISTS operation_locks (
    slot INTEGER PRIMARY KEY CHECK (slot = 1),
    kind TEXT NOT NULL CHECK (kind IN ('rotation', 'dns_sync')),
    owner_id TEXT NOT NULL UNIQUE,
    lease_until TEXT,
    created_at TEXT NOT NULL
);

INSERT OR IGNORE INTO operation_locks(slot, kind, owner_id, lease_until, created_at)
SELECT 1, 'rotation', id, NULL, strftime('%Y-%m-%dT%H:%M:%fZ', 'now')
FROM rotation_runs
WHERE active_slot = 1
LIMIT 1;