Add "Viewed" tracking for individual diff sections (hunks) within a file

[sharon-fdm]

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Product Feedback

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When reviewing a PR, GitHub lets me mark entire files as "Viewed" which is very helpful for tracking progress. However, large files with many changes are hard to review in one pass. I often review part of a file, context-switch, and come back later unable to remember which sections (hunks) within that file I already reviewed.

Proposal: Add a "Viewed" checkbox (or similar indicator) per diff hunk within a file, not just per file. This would let reviewers track their progress within large diffs the same way they already track it across files.

Use case: A file has +222 / -83 lines across 10+ diff hunks. I review the first 5 hunks, get pulled away, and return later. Currently I have to re-read everything to find where I left off. With per-hunk tracking, I would see exactly which sections I already covered.

[komacoder]

I support this idea. Another benefit would be for teams reviewing very large pull requests together. Reviewers could easily see which hunks they've already checked after taking a break or switching tasks. It would make long reviews much less repetitive and reduce the chance of missing changes.

[karmaxexclusive]

This would be especially valuable for large PRs where a single file contains many independent hunks.
One possible implementation could be a lightweight per-hunk "Viewed" state that's stored only for the current reviewer and automatically invalidated if that hunk changes in a new commit. That would avoid reviewers accidentally skipping updated code while still letting them resume exactly where they left off.
It could also be useful to show a small progress indicator (for example, 7/12 hunks reviewed) next to the file in the Files changed view. That would make long reviews much easier to manage after interruptions without affecting existing workflows.