[Fix] #1312 Streak logic duplication resolved.

[palxsh01]

Summary

Extracts the duplicated streak calculation algorithm into a single shared module
at src/lib/streak.ts, removing ~230 lines of copy-pasted logic spread across
6 source files. Also fixes two silent bugs uncovered during the consolidation.

Closes #1312

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Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

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Changes Made

• Created src/lib/streak.ts exposing two shared exports:
  • calculateStreakFromDates(activeDates, freezeDates?) — full calculation with freeze date support
  • calculateCurrentStreak(dates) — lightweight wrapper returning only the current streak number
• Removed inline streak logic from 6 source files: streak/route.ts, streak-shield/route.ts, public-profile-data.ts, compare/route.ts, leaderboard/route.ts, weekly-summary/route.ts
• Updated calculateStreakFromDates.test.ts and leaderboard-streak.test.ts to import from the shared module instead of maintaining local copies
• Fixed silent bug in compare/route.ts where longestStreak was never tracked — endpoint returned only current streak
• Fixed behavioral divergence in streak-shield/route.ts where dateDiffDays used Date.UTC() instead of ISO string truncation, causing off-by-one results for users near UTC midnight

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How to Test

1. Run npm run type-check — should pass with no errors
2. Run npm test — all 285 tests should pass
3. Run npm run lint — should pass
4. Manually verify that /api/metrics/streak, /api/badge/streak-shield, and /api/public/[username] return consistent streak values for the same GitHub user

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Screenshots (if UI change)

N/A — backend refactor only, no UI changes.

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Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

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Accessibility Checklist

• Proper keyboard navigation tested
• Responsive UI verified
• Accessibility labels added where needed

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Additional Notes

All existing tests continue to pass (285/285). All merge conflicts have been resolved, ready for a clean merge and PR.

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[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[Karanjot786]

Hey @palxsh01! Saw your work on GSSoC 2026.

We are building TermUI, a TypeScript terminal UI framework with React-style hooks and JSX, rendered entirely in the terminal.

We have 99 unassigned GSSoC issues open, including test coverage tasks across the packages. Your TypeScript background transfers directly.

• Open issues (GSSoC 2026)
• TermUI on GSSoC

Karanjot, TermUI maintainer

[Priyanshu-byte-coder]

This PR has merge conflicts with main (which has since received many merges). Please rebase:

git fetch origin
git rebase origin/main
git push --force-with-lease

[palxsh01]

Hi @Priyanshu-byte-coder,
Rebased and fixed the merge conflicts. The PR should merge successfully now. Request you to merge as soon as possible to avoid further merge conflicts.

[github-actions]

🎉 Merged! Thanks for contributing to DevTrack.

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Keep an eye on open issues for your next contribution!