The lifecycle job marked rows with an unconditional UPDATE before
sending, so two overlapping invocations (cron tick + manual hit, or
retry) both passed the SELECT, both ran the UPDATE — re-writing the
same value — and both sent the same email. Real duplicates went out to
licensees. Rows are now claimed with a conditional UPDATE (... AND
asked_at IS NULL), and the send happens only when the claim reports
rowsAffected 1; a racing invocation claims nothing and sends nothing.
Tests: lifecycle suite gains a lost-claim case; 36 nook API tests pass.
Issue: FRE-11
Michael Freno
0b128f6639