The hibernation PR (5c1a9d0) accidentally removed the delivery_confirmed
fix that was introduced for issue #689. When io.ReadAll fails after the
target has already responded with headers (200-399), the message WAS
delivered — stripping delivery_confirmed from the error response caused
callers to treat a successful send as a hard failure.
Restore the full original body-read error block:
- deliveryConfirmed flag (true when status 200-399)
- log line with status/bytes_read context
- logA2ASuccess call when deliveryConfirmed (audit trail accuracy)
- proxyA2AError.Response includes "delivery_confirmed" field so callers
can distinguish "not delivered" from "delivered, body lost"
The hibernation auto-wake feature (resolveAgentURL status='hibernated'
check) is orthogonal and untouched.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
84584af2e6