[evicted:ephemeral] Bio Bridge step bugs (Apr 2026, FIXED): UPSERT accumulati...¶

[evicted:ephemeral] Bio Bridge step bugs (Apr 2026, FIXED): UPSERT accumulation + merge_step_deltas double-count. Fix: DELETE existing activity before re-insert + PW2-only data source + truncate timestamps to seconds. See vault:[[Bio Bridge Step Bugs]]