A session interrupted by a gateway restart is flagged resume_pending and
auto-continued on startup via _schedule_resume_pending_sessions(), which
dispatches an empty-text internal MessageEvent. The recovery system note
that should fill that empty turn is gated, in _run_agent(), on
_interruption_is_fresh — the age of the LAST PERSISTED TRANSCRIPT ROW.
For an active thread returned to after >1h of silence, that transcript
clock is stale even though the interruption (last_resume_marked_at) is
seconds old. The gate evaluates False, the note is not prepended, and the
model receives a genuinely blank user turn — replying with confused
'that message came through blank' noise.
Fix (two parts, both default-on, behavior unchanged for healthy turns):
1. resume_pending freshness now also considers last_resume_marked_at (the
restart watchdog's own stamp). The branch fires when EITHER the
transcript clock OR the resume mark is fresh, so the startup scheduler's
freshness decision and the per-turn injection agree.
2. Empty-turn safety net: if the user turn is still blank after all
injections AND the session is resume_pending, backfill a recovery note
so a blank turn can never reach the model. Scoped to resume_pending so
ordinary empty turns (e.g. uncaptioned image) are untouched.
Adds 3 regression tests; the two core ones fail on the pre-fix logic.
c2db3ed7d8