payload.message_type_mismatch

Refused 400 policy

payload.message_type disagrees with the envelope's message_type.

Outcome	Refused, 400
Source	policy: This bus's operational rules (identity, grants, size, idempotency, story ownership). Not a verdict of the SOM standard.
Checked at	SOM envelope, version and payload (see the order of checks)

What it means

Some families repeat message_type inside the payload. SOM selects the payload schema by the envelope's message_type only, so a payload that says something else was probably written for another schema.

How to fix it

Make both message_type values the same.

---

Branch on the rule id, never on the violation's message text. All rules: rule catalogue.