Per-Subtopic Mastery Tracker

[ankit2101]

Summary

Structured tracking of which subtopics a student has mastered across all attempts. Build a per-student subtopic mastery map showing attempt count and average key-point coverage per subtopic.

Why

The data foundation that unlocks Weak Topic Re-Queue (#1) and the Heat Map (#3) at a granular level. Currently missed topics are stored as free text — this structures them. Embibe's entire competitive advantage rests on this granularity.

Implementation Notes

• New SubtopicMastery model: (student_id, chapter_id, topic_tag, attempt_count, avg_coverage, last_attempt_at)
• Updated post-test logic to upsert mastery records per topic_tag
• New admin view: per-student subtopic breakdown table
• Feeds into Weak Topic Re-Queue (Issue Weak Topic Re-Queue System #1) and Spaced Repetition (Issue Spaced Repetition Scheduler #2)

Acceptance Criteria

• Subtopic mastery updated after every test completion
• Admin can view per-student subtopic breakdown for any chapter
• Mastery shown as percentage (covered key points / total key points)
• Integrated with Weak Topic Re-Queue if both features are implemented