The frontend sends full ISO timestamps (e.g. 2026-03-19T17:55:29Z) but the controller expected LocalDate (yyyy-MM-dd). This caused null parsing, which threw NullPointerException in the repository WHERE clause. Changed to accept Instant directly with sensible defaults (last 7 days). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>