Same pattern here. The one thing I'd add before calling it done is the boring failure handling, because that's where the 3am calls actually come from:

1. Store the last-seen review ID instead of "now minus 60 minutes". If cron skips a run or the box reboots, a time window silently drops reviews.
2. Make the model reply in JSON ({"label":"negative","summary":"..."}) and treat anything that doesn't parse as negative. A malformed reply should go to a person, not get ignored by the split("\n").
3. Post a daily "ran 24 times, 31 reviews, 2 flagged" heartbeat to the same Slack channel. Then silence means broken, not quiet.
4. Keep 20 real reviews as a test set and rerun them whenever you change the prompt or model.

Still a cron job and one API call, just one you can trust when nobody's watching. For me it only becomes an agent when the founder also wants a drafted reply.