#Spaced Repetition + Feed Blending (WI-3)

#Context

Implement SM-2 spaced repetition scheduling, blended feed algorithm, and per-card interaction indicators in the feed.

#Challenges

#Challenge 4.1: Spaced Repetition Module

Requirement: Pure calculateNextReview() function with SM-2 variant. Acceptance Criteria:

• packages/shared/src/spaced-repetition.ts exists
• Interval schedule: [4h, 1d, 3d, 7d, 14d, 30d] based on streak
• Exported from packages/shared/src/index.ts Evaluation: PASS

#Challenge 4.2: Interact Route Wiring

Requirement: Card interactions compute spaced repetition fields. Acceptance Criteria:

• /api/cards/[slug]/interact computes nextReviewAt, streak, reviewCount
• Uses calculateNextReview from shared package Evaluation: PASS

#Challenge 4.3: Review API Endpoint

Requirement: Endpoint for fetching facts due for review. Acceptance Criteria:

• apps/web/app/api/review/route.ts exists
• GET returns facts where next_review_at <= now() Evaluation: PASS

#Challenge 4.4: Blended Feed Algorithm

Requirement: Feed mixes content types with weighted blend. Acceptance Criteria:

• /api/feed uses: 40% recent validated, 30% review-due, 20% evergreen, 10% exploration
• Round-robin interleave
• Per-card userStatus field
• New DB queries: getEvergreenFacts, getRandomFacts, getUserFactStatuses, getLatestAnswerInteraction Evaluation: PASS

#Challenge 4.5: Interaction Indicator Badges

Requirement: Feed cards show color-coded completion status. Acceptance Criteria:

• Yellow badge = in progress
• Orange badge = review due
• Green badge = mastered
• Renders in fact-card.tsx Evaluation: PASS

#Evaluation Summary

Challenge	Result
4.1 Spaced Repetition Module	PASS
4.2 Interact Route Wiring	PASS
4.3 Review API Endpoint	PASS
4.4 Blended Feed Algorithm	PASS
4.5 Interaction Badges	PASS

Score: 5/5 PASS