[Bug] Contribution graph shows future years (2027, 2028) when switching org filters in UTC+ timezones

[tech-hoon]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

Profile

Body

Description

When logged out with a browser timezone ahead of UTC, switching organization filters on a profile's contribution graph shows a future year (2027, then 2028).

Steps to reproduce

Logged out, browser timezone ahead of UTC (e.g. Asia/Seoul):

1. Open any profile with 2+ organization filter buttons under the contribution graph
2. Click one org filter → "N contributions in 2026 in org-a" (correct)
3. Click a different org filter → "0 contributions in 2027 in org-b" (expected 2026)
4. Click the same filter again → "0 contributions in 2028"

Likely cause

Step 3 requests from=2026-01-01&to=2027-01-01. In UTC the same request uses to=2026-12-31. The year-end date is shifted by the timezone offset, and the next request builds on that wrong year.

Tested

Timezone	Result
Asia/Seoul, Asia/Tokyo (UTC+9)	2027 → 2028
Europe/Berlin (UTC+1)	2027
UTC, America/Los_Angeles	Correct
Logged in (Asia/Seoul)	Correct

Chrome 156.0.8078.80, macOS 26.2. I also once saw the section load indefinitely and return HTTP 429, but could not reproduce it.

[github-actions[bot]]

💬 Your Product Feedback Has Been Submitted 🎉

Thank you for taking the time to share your insights with us! Your feedback is invaluable as we build a better GitHub experience for all our users.

Here's what you can expect moving forward ⏩

• Your input will be carefully reviewed and cataloged by members of our product teams. 
  • Due to the high volume of submissions, we may not always be able to provide individual responses.
  • Rest assured, your feedback will help chart our course for product improvements.
• Other users may engage with your post, sharing their own perspectives or experiences. 
• GitHub staff may reach out for further clarification or insight. 
  • We may 'Answer' your discussion if there is a current solution, workaround, or roadmap/changelog post related to the feedback.

Where to look to see what's shipping 👀

• Read the Changelog for real-time updates on the latest GitHub features, enhancements, and calls for feedback.
• Explore our Product Roadmap, which details upcoming major releases and initiatives.

What you can do in the meantime 💻

• Upvote and comment on other user feedback Discussions that resonate with you.
• Add more information at any point! Useful details include: use cases, relevant labels, desired outcomes, and any accompanying screenshots.

As a member of the GitHub community, your participation is essential. While we can't promise that every suggestion will be implemented, we want to emphasize that your feedback is instrumental in guiding our decisions and priorities.

Thank you once again for your contribution to making GitHub even better! We're grateful for your ongoing support and collaboration in shaping the future of our platform. ⭐