[BUG]: currentStreak and lastActivityDate are never updated — Streak5 badge unobtainable, "Experts Online" filter broken

[RounakKumarAgarwal]

Bug Description

Two User fields are read by features but never written anywhere in the backend, so the features that depend on them are effectively dead.

CurrentStreak (models/user.go:32)

• Initialized to 0 at signup (auth.go:98, auth.go:189)
• Read by the Streak5 badge check: if user.CurrentStreak >= 5 in gamification_controller.go:349 and debatevsbot_controller.go:489
• Displayed on profile (profile_controller.go:120, :274)
• Never incremented — no $inc/$set on currentStreak exists anywhere in the codebase.
• Result: streak is permanently 0, so >= 5 is never true → the Streak5 badge can never be earned, even though it's defined in code and shown in the UI.

LastActivityDate (models/user.go:33)

• Read by the "Experts Online" stat: leaderboard.go:182 filters {"lastActivityDate": {"$gte": activeThreshold}} (active within last 30 min)
• Displayed on profile (profile_controller.go:122)
• Never written — not even initialized at signup.
• Result: lastActivityDate is the zero-value time.Time for every user. The leaderboard query is lastActivityDate >= threshold OR updatedAt >= threshold, so that first clause never matches and the whole stat silently falls back to updatedAt — which changes on any profile update, not on actual debate activity. "Experts Online" measures the wrong thing.

In short: the reads are wired up, the writes were never implemented. Both fields need to be updated when a user is active (e.g. on completing a debate / meaningful activity) — incrementing/resetting currentStreak based on day boundaries, and setting lastActivityDate = now.

Steps to Reproduce

1. Create an account and use the app actively over several days (complete debates, etc.).
2. Check your profile — currentStreak stays 0 regardless of daily activity.
3. Reach any amount of activity — the Streak5 badge is never awarded because CurrentStreak never rises above 0.
4. Check the "Experts Online" count on the leaderboard — it does not reflect lastActivityDate (that field is never set); it only ever reflects updatedAt.
5. Search the backend: grep -rn "currentStreak\|lastActivityDate" backend --include=*.go shows reads and a signup-time 0, but no update logic.

Logs and Screenshots

$ grep -rn "currentStreak|CurrentStreak" backend --include=*.go
backend/controllers/auth.go:98: CurrentStreak: 0,
backend/controllers/auth.go:189: CurrentStreak: 0,
backend/controllers/gamification_controller.go:349: if user.CurrentStreak >= 5 && ...
backend/controllers/debatevsbot_controller.go:489: if user.CurrentStreak >= 5 && ...
backend/controllers/profile_controller.go:120,274: "currentStreak": user.CurrentStreak
backend/models/user.go:32: CurrentStreak int ...

→ read + init-to-0 only; never incremented

$ grep -rn "lastActivityDate|LastActivityDate" backend --include=*.go
backend/controllers/leaderboard.go:182: {"lastActivityDate": bson.M{"$gte": activeThreshold}}
backend/controllers/profile_controller.go:122: "lastActivityAt": user.LastActivityDate
backend/models/user.go:33: LastActivityDate time.Time ...

→ read only; never written

Environment Details

• Files: backend/models/user.go (fields), backend/controllers/auth.go (init), gamification_controller.go & debatevsbot_controller.go (Streak5 read), leaderboard.go (active filter read), profile_controller.go (display)
• Backend: Go / MongoDB
• Branch: main
• Note: purely a missing-write-path bug; no schema change needed, the fields already exist — they just need to be updated on user activity

Impact

Medium - Feature works but has issues

Code of Conduct

• I have joined the Discord server and will post updates there
• I have searched existing issues to avoid duplicates