The RTBRequest supplied for cross-validation is unusable
The envelope passed alongside the mutation set is not a JSON object, so no mutation can be checked against the auction it targets.
What it means
Mutation validation was asked for, but the RTBRequest envelope supplied as context could not be read as a JSON object.
Why it matters
Every mutation check is relative: an intent is checked against applicable_intents, a path against the impressions and deals the auction carries. Without the envelope there is nothing to be relative to, and reporting the mutations as clean would be reporting that no checks ran.
How to fix it
Pass the RTBRequest envelope the agent answered, not the bare bid request and not the mutation set again.
Example that trips it
rtblint validate --type artf-response --request rtb-request.json rtb-response.json
The --request file must be the RTBRequest envelope, which is what carries applicable_intents and the auction.
Check your payload
Paste a bid request or response into the tester to see whether this code fires against it, or gate on the id in CI with the CLI: the id is stable, wording is not.
Back to the full diagnostic code reference.