Review (Spaced Repetition)

The Review tab implements gamified spaced repetition to help you retain the knowledge you capture.

Algorithm: SuperMemo-2 (SM-2)

Project Nexus uses the classic SM-2 algorithm to schedule reviews. The algorithm tracks two variables per node:

Variable	Default	Description
interval	1 day	Days until the next review.
ease_factor	2.5	Multiplier applied to the interval on each successful review.

After each review, the next interval is calculated based on your rating:

• Forgot (0): interval resets to 1. ease_factor decreases.
• Hard (3): small interval increase.
• Good (4): interval × ease_factor.
• Easy (5): interval × ease_factor × 1.3.

Daily Review Queue

The Review tab loads all nodes where next_review_date ≤ today. They are presented one at a time as flashcards.

Flashcard UI

Each flashcard shows:

1. The node title and source URL.
2. Entity tags extracted from the DB, displayed as badges on each card (up to 3).
3. A "Reveal" button to show the summary.
4. After reveal: rating buttons (Forgot, Hard, Good, Easy) and a Snooze dropdown (1h / 1d defer via server action).

Enhancements & Gestures

• 3D Card Flip: Smooth CSS 3D flip animations during rate and skip actions (with prefers-reduced-motion playback support).
• Mobile Swipe Gestures: Swipe right to reveal, swipe left to skip.
• Audio Effects: Web Audio API sound effects trigger on interactions (with a localStorage toggle to mute).
• Queue Preview: The UI shows the next 2 upcoming cards visually stacked beneath the current active card.
• Celebration Screen: Once the daily queue is complete, an enhanced celebration screen is displayed featuring CSS confetti and bounce animations.

Review Streak & Goals

By maintaining a daily review habit, you unlock further visual enhancements:

• Active Streak Flame: An animated flame icon indicates an active review streak.
• Daily Review Goal: Set a numeric review goal (default 10, click-to-edit). Progress is tracked via a mini progress bar, persisting in localStorage.

Stats & Tracker

The Review tab header displays:

• Due today — number of cards in the current queue.
• Current streak — consecutive days of reviewing.
• Session Accuracy: A live session accuracy percentage tracker shown during the session and on the final completion screen.

Review Records

Each node has a corresponding entry in the reviews table:

reviews (
  id uuid,
  node_id uuid,       -- links to nodes table
  user_id uuid,       -- RLS enforced
  next_review_date date,
  interval integer,
  ease_factor numeric
)

Review records are created automatically when a node is captured and deleted when a node is deleted.