current_study_day_start_utc() passed use_space=true to
Time.get_datetime_string_from_unix_time(), producing "2026-07-21
00:00:00Z" (space separator) instead of ISO-8601. The server's
System.Text.Json DateTime converter rejects that with a 400, which
the client surfaces as a generic "could not be loaded" error -
blocking every study session. Confirmed against the live API: the
space-separated value 400s, the corrected T-separated value returns
a card.
hz
15e9f9779e