[Data-integrity] daily streak processor preserves streak when user misses exactly one day

[vedant7007]

Description

while reading through the daily streak processor i noticed the daysDiff === 1 branch is a no-op labeled "Contributed yesterday, hasn't contributed today yet" — but at a midnight cron daysDiff === 1 actually means the user missed all of yesterday. the streak stays intact and can even keep growing while the user contributes only every other day.

The Problem

src/inngest/karma.ts lines 215-297. cron trigger is "0 0 * * *" (daily midnight), so now ≈ todayMidnight. inside the loop:

const todayMidnight = new Date(now.getFullYear(), now.getMonth(), now.getDate()).getTime();
const activeTimestamp = new Date(user.lastContributionAt).getTime();
const daysDiff = Math.floor((todayMidnight - activeTimestamp) / oneDayMs);

if (daysDiff === 0) {
  // award streak_bonus, increment currentStreak
} else if (daysDiff >= 2) {
  // reset currentStreak to 0
} else if (daysDiff === 1) {
  // Valid trailing active window path (Contributed yesterday, hasn't contributed today yet)
  skippedNoOp++;
}

trace: user contributes Monday 12:00 PM. Tuesday 00:00 cron: daysDiff = floor(12h / 24h) = 0 -> awards streak, streak=6. user does nothing on Tuesday. Wednesday 00:00 cron: daysDiff = floor(36h / 24h) = 1 -> skippedNoOp -> streak stays 6. Wednesday 08:00 the user contributes. Thursday 00:00 cron: daysDiff = floor(16h / 24h) = 0 -> awards streak, streak=7.

user grew streak from 5 to 7 while contributing only Monday and Wednesday — missing all of Tuesday. the comment on the daysDiff === 1 branch is inverted: contributing yesterday actually yields daysDiff === 0 at a midnight cron because yesterday's timestamp (e.g. Tue 08:00) is within the last 24h relative to today-midnight.

concrete failure: this corrupts the currentStreak field that gates streak_days_* badges in checkAndAwardBadges and leaderboards. every "streak" milestone can be earned while contributing every other day. only 3+ full-day gaps correctly reset the counter.

Proposed Fix

• treat any daysDiff >= 1 as a streak break (or equivalently, daysDiff !== 0). since the midnight cron guarantees daysDiff === 0 is the only "contributed within the last full day" case, collapse the two else-if branches into one reset branch
• update the comment to reflect actual semantics
• mirror the same-day ledger idempotency guard already used for the karmaTransactionsTable insert so the reset write is applied at most once per gap

I would like to work on this under GSSoC 26. please assign!

for labels i think gssoc + type:bug + level:advanced fits here.

[Dasmat13]

/assign

[github-actions]

Hello @Dasmat13! 👋 Thanks for your interest in working on this issue.

We have automatically notified the maintainers for you. They will review your request and officially assign the issue to you shortly if it's available.

Note: Please do not start working or raise a pull request until you are officially assigned!

[aaniya22]

/assign

[github-actions]

Hello @aaniya22! 👋 Thanks for your interest in working on this issue.

We have automatically notified the maintainers for you. They will review your request and officially assign the issue to you shortly if it's available.

Note: Please do not start working or raise a pull request until you are officially assigned!

[github-actions]

✅ Hi @vedant7007, you have been assigned to this issue! You have 7 days to work on this issue and create a PR. Happy coding! 🚀