Technical Case Study · AI & Agents

FlashAI

Spaced-repetition flashcard app

Solves the "PDF graveyard" problem by transforming uploaded lecture PDFs into 15–20 exam-quality flashcards in seconds. Streams NDJSON responses from Groq across 5 cognitive card types, isolates per-user SuperMemo SM-2 review schedules, and supports 1-click community deck cloning, live learner presence, and 6-digit email OTP cross-device sync.

Test Coverage244 Passing Tests

First Card Stream~1.0s NDJSON

TypeScript Core97.3% Strict TS

Next.js 14TypeScriptGroq NDJSON StreamSuperMemo SM-2Prisma ORMPostgreSQLTailwind CSS244 Vitest Tests

Problem Statement

Passive re-reading of technical notes leads to rapid memory decay, while manual flashcard creation is tedious and standard LLM wrappers block the UI waiting for full JSON payloads.

Deterministic Architecture Advantage

Streams flashcards in sub-second NDJSON chunks from Groq LLaMA-3.3-70B and schedules long-term reviews using a deterministic SuperMemo SM-2 algorithm updating card easiness factor (EF >= 1.3), repetition count, and day intervals.

Execution Pipeline & System Topology

STEP 01

PDF Extraction & Rate Gate

Validates MIME/size bounds, extracts text via pdf-parse, and checks sliding-window rate limiters.

Next.js 15 API + pdf-parseHTTP 429 Retry-After Guard

STEP 02

Groq NDJSON Streamer

Streams 5 cognitive card types line-by-line via ReadableStream with sanitizeJsonLine recovery.

Groq API (gpt-oss-120b)~1s Time-to-First-Card

STEP 03

Isolated SM-2 Scheduler

Computes deterministic Ease Factor and interval updates per user; resets state on community deck clones.

TypeScript SM-2 + Vitest244 Automated Tests

STEP 04

Neon PostgreSQL & OTP Sync

Persists Users, VerificationCodes, Decks, Flashcards, XP streaks, and live leaderboard podiums.

Prisma 6.6 + Neon PostgresMulti-Device Sync

Verification & Engineering Highlights

Built for the Cuemath AI Builder campus placement challenge: features hybrid guest onboarding + 6-digit CSPRNG email OTP cross-device account linking with 5-attempt brute-force lockout.
Enforces a 5-category cognitive taxonomy per PDF: Definition, Reasoning ("why/how"), Common Misconception, Worked Example, and Edge Case.
Includes Community Deck Library with 1-click deck cloning (resetting SM-2 state per learner), 45-second sliding-window live learner presence heartbeat, and 244 passing Vitest tests.

src/lib/sm2.ts

typescript

export interface SM2State {
  interval: number;    // Days until next review
  repetitions: number; // Consecutive successful recalls
  easeFactor: number;  // SuperMemo EF (clamped >= 1.3)
}

export function calculateSM2(quality: 0 | 1 | 2 | 3 | 4 | 5, prev: SM2State): SM2State {
  let { interval, repetitions, easeFactor } = prev;

  if (quality >= 3) {
    if (repetitions === 0) interval = 1;
    else if (repetitions === 1) interval = 6;
    else interval = Math.round(interval * easeFactor);
    repetitions += 1;
  } else {
    repetitions = 0;
    interval = 1;
  }

  const delta = 0.1 - (5 - quality) * (0.08 + (5 - quality) * 0.02);
  easeFactor = Math.max(1.3, Number((easeFactor + delta).toFixed(2)));

  return { interval, repetitions, easeFactor };
}