CREATE TABLE IF NOT EXISTS fieldlens_access_requests (
  subject text PRIMARY KEY,
  username text,
  email text,
  status text NOT NULL CHECK (status IN ('pending', 'approved', 'rejected')),
  approved_role text CHECK (
    approved_role IS NULL OR approved_role IN (
      'fieldlens-operator',
      'fieldlens-supervisor',
      'fieldlens-admin'
    )
  ),
  requested_at timestamptz NOT NULL DEFAULT now(),
  reviewed_at timestamptz,
  reviewed_by text
);

CREATE INDEX IF NOT EXISTS idx_fieldlens_access_requests_status_requested
  ON fieldlens_access_requests(status, requested_at);