Duplicate rejection means the peer already has the message (e.g.,
delivered earlier via outbox AND pulled via sync in the same
window). Retrying will fail identically forever until TTL expires.
Before this patch: duplicate-rejected outbox entries were retained
with attempts++ and exponential backoff, creating log noise and
outbox bloat for up to 30 days.
After: duplicate-rejected entityIds join the terminal set alongside
accepted ones and are deleted from the outbox. Logged at info level
('outbox entry removed (terminal)') to distinguish from warn-level
transient-rejection retries.
Other rejection reasons (attribution_mismatch, processing_error,
etc.) stay on the retry path; some may also be terminal but are
deferred until observed accumulating.
Jannis Braun
6ff983b46c