Per-week "Extra Study (N)" row appears at the end of each LanGo week
section when at least one card is marked. Cards are marked from inside
VocabFlashcardView via a star next to the speaker on reveal. Marks are
keyed by the same SHA256 hash CourseReviewCard uses, so a mark and its
SRS state describe the same logical card.
ExtraStudyMark is CloudKit-synced (private DB), with uniqueness enforced
by fetch-or-create on id since CloudKit forbids @Attribute(.unique).
Skipped for textbook courses: DeckStudyView nils out the mark context
when the deck's courseName matches a TextbookChapter, and CourseView
hides the row when the active course is a textbook — so there are no
orphan marks the user can't reach.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Trey T
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