- Share a disk-backed per-day dateutc set between live recorder and backfill - Validate timestamps before saving; dedupe existing files at startup and on read - Use station-local day (not UTC) for rain totals, streaks, degree days and monthly summary so dailyrainin resets line up (Sept rain was 4.37in vs 2.24in) Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>