One rule

What it means

A SAST rule’s source must be rules: holding exactly one rule, and nothing else.

Example detail messages returned with this error:

• source must be rules: with exactly one rule.
• source must hold only rules:.

What to do

Put one rule per entry. Add a second rule as a second entry.

Response shape

All fremforge API errors are RFC 9457 problem+json:

{
  "type": "https://docs.frem.sh/reference/api/errors/one-rule",
  "title": "Bad Request",
  "status": 400,
  "detail": "..."
}

Branch on type, not on title or detail - those are human-readable and may be reworded.