message_agent callers previously got provider prose (a raw 401
paragraph, a missing-provider essay) and could not branch on the
failure class. Now the #93091 item-1 reason enum rides the whole relay
roundtrip:
- Desktop relay drain forwards bot_relay.deliver's error.data.reason
into bot_relay.reply (and prefers it for the attention badge over
free-text re-parsing);
- write_reply already persisted reason / classified fallbacks;
- the sender-side waiter prints "[reason: <code>]" ahead of the free
text, so the completion notification the sending agent receives is
machine-branchable.
Additive everywhere: healthy replies unchanged, reasonless errors
classify to a code, old consumers keep working.
Teknium