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Leaderboard — privacy-safe, denormalized

The leaderboard at /app/leaderboard is a public-readable ranking of ImtehanHub users by score. It is denormalized into its own collection so that it can be readable by everyone without exposing private data on the user document. Display name + score + last-update timestamp, nothing else.

TL;DR — Anyone signed in can view the leaderboard. Your displayed entry is your Google profile name + your score. Email, role, billing, activity, and stats stay private.

Why a separate collection​

The full user document at users/{uid} carries email, role, billing, full stats, achievements, theme preferences, board, and more. None of that should be public.

A separate leaderboard/{uid} collection holds only:

{
  uid: 'firebase-uid',
  displayName: 'Your Name',
  score: 72.4,                 // typically accuracy * sqrt(tests) or similar
  updatedAt: '2026-05-10T...',
}

Firestore security rules:

  • Read: any authenticated user can read any leaderboard entry.
  • Write: only the owner (request.auth.uid == resource.data.uid) can write — and the write is triggered by a signed-in user submitting a test, never by a manual call.

The user document at users/{uid} stays read-restricted to the owner. The leaderboard is a curated projection, not a window onto the user.

What "score" means​

The score is intentionally simple — it rewards both accuracy and volume. The exact formula is in src/services/leaderboard-service.ts and roughly:

score = accuracy * log2(testCount + 1)

This means:

  • A student with 95% accuracy and 4 tests has a low-ish score (high accuracy, low volume).
  • A student with 70% accuracy and 200 tests has a strong score (decent accuracy, sustained engagement).
  • A student with 100% accuracy and 1000 tests is at the top.

The formula was tuned to avoid both extremes (high-accuracy-but-took-1-test gaming, and low-accuracy-but-spammed-tests gaming).

Displayed information​

For each entry, the leaderboard shows:

  • Rank (1, 2, 3, ...).
  • Display name (your Google profile name).
  • Score (rounded to 1 decimal).
  • A small trend indicator (↑ / → / ↓) compared to the same time last week.

What is not shown:

  • Email.
  • Role (admin / institute manager / user).
  • Plan tier (Free / Pro / Unlimited).
  • Class / subject specialisation.
  • Streak.
  • Any specific test history.

Filters and views​

The leaderboard supports:

  • All-time (default).
  • Last 7 days — score recomputed from tests submitted in the last week.
  • Last 30 days.

Filter is via URL state: /app/leaderboard?range=30d.

A per-class leaderboard (?class=c9) is on the roadmap.

Joining the leaderboard​

Your entry is created automatically the first time you submit a test as a signed-in user. After every subsequent test, the entry's score and updatedAt are recomputed and written.

If you delete your account (data deletion), your leaderboard entry is also deleted.

Hiding from the leaderboard​

A privacy toggle on /app/profile lets you opt out of the leaderboard. With opt-out:

  • Your entry is removed from the leaderboard collection.
  • Your tests still update your private stats.
  • Your entry is not recreated on subsequent tests.

You can opt back in any time. The opt-out toggle is per-account and immediate.

Display name​

Your displayName on the leaderboard is your Google profile name (the one Google has, not your email). You can override it on the Profile page with a custom display name (alphanumeric, 3-20 chars, no obscenity).

Some students use their real name to show off; some use a pseudonym for privacy. Both are fine.

Performance​

With thousands of entries, the leaderboard query is paginated (top 50 by default; load more via Firestore cursor pagination). The full leaderboard is never loaded at once.

The /app/leaderboard page also caches the top 100 in TanStack Query for 60 seconds, so refreshes feel instant within that window.

Common questions​

Can I see my rank globally?​

Yes — your own entry shows your global rank at the top of the page, even if you are not in the top-50 visible window.

Why can I not see the leaderboard without signing in?​

Public leaderboard would expose all display names to anyone, which crosses a privacy line for many parents (uncomfortable with their child's name on a public-internet ranking). Sign-in keeps the surface within the verified-user community.

Does the leaderboard influence pricing or features?​

No — it is purely a ranking. Pro / Unlimited tiers are paid; the leaderboard is unrelated.

Why is my old high score gone in the 7-day view?​

The 7-day view scores only tests in the last 7 days. If you took a test 8 days ago and none since, you are not in the 7-day list (you remain in the all-time list).

Can my institute see the leaderboard?​

Same rules — your institute manager sees the leaderboard like any other signed-in user. They see only display name and score for everyone, including their own students.

Next​

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Last updated on by Ahsan Mahmood (aoneahsan)