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.
The panel's shared Brand.panel_box background is ~80% opaque, which
compounded with the dialog's own dim backdrop let the screen behind
show through and washed out the card against it. Force full opacity
on this dialog's panel specifically, since other panel_box overlays
still rely on the shared translucency.
Import and export were stubbed with status-text placeholders; wire them
to the existing backend endpoints with a real file picker (web JS
bridge or native FileDialog) and browser/desktop download, plus an
import preview with create/update/skip/error counts before commit.
Also fix the library and study screens' theme-refresh handlers, which
were no-op stubs so cards never restyled on a theme toggle, and add
responsive layout handling for narrow viewports.
Adds a full flashcards system: FSRS-based scheduling, cloze/basic
card types, CSV import/export, media storage, and study UI, wired
into navigation and the dashboard alongside existing question flows.
hz