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[Bug]: PR review hides final files when diffs are collapsed; expanding the bottom file reveals them #18227
Description
ℹ️ Written by GPT-6.1 Sol on behalf of AndreiShenets
Before submitting
- I searched existing issues and did not find a duplicate.
- I included enough detail to reproduce or investigate the problem.
Area
apps/web — PR review Code tab, observed in the Windows desktop nightly app.
Summary
In a PR with many changed files, the collapsed diff list does not expose the last files. Expanding the bottom visible file makes the remaining file headers visible. The files are present in the right-hand Files tree throughout.
Steps to reproduce
- Open the desktop nightly app and open a PR with many changed files. The reported example has 43 files.
- Open the PR's Code tab with All commits selected.
- Collapse the file diffs and scroll the main diff list to the bottom.
- Observe that the main list ends before the final files shown in the right-hand Files tree.
- Expand the bottom visible file and scroll down again. The previously hidden file headers become visible below it.
The supplied screenshots show all 43 files marked viewed. Whether viewed state is necessary to reproduce is unknown.
Expected behavior
Every changed file header should be reachable in the main PR diff list, including when all file diffs are collapsed. Expanding a preceding file should not be necessary to reveal later files.
Actual behavior
With the file diffs collapsed, the bottom visible header is tests/CodeAnalysis.CSharp.Tests/StructuralHonestyTests/RefType/HostTests.cs. The subsequent SafetyTests.cs and TypeParameterList/OwnershipTests.cs headers are not visible in the main list, although both files are visible in the Files tree.
After expanding RefType/HostTests.cs, those two later headers become visible below its diff.
This report concerns visibility/scroll layout in the PR review UI, not patch-byte truncation. The root cause has not been established.
Impact
Major degradation or frequent failure — prevents reviewing the final files in the collapsed-list state without a workaround.
Version or commit
0.0.46-nightly.20261011.2967 (confirmed from the running desktop executable's file version).
Environment
Windows desktop, T3 Code Nightly. Display scaling and exact Windows version were not collected.
Screenshots, recordings, or supporting files
Two reporter-provided PNGs were inspected when preparing this report; the images themselves still need to be attached to this issue:
- File trancation.png: Code tab, All commits, 43 files / 43 viewed. The collapsed main diff list ends at
RefType/HostTests.cs; the Files tree also showsSafetyTests.csandTypeParameterList/OwnershipTests.cs. - Files become visible when expanding the bottom one.png:
RefType/HostTests.csis expanded, and the two previously hidden headers are now visible beneath it.
Workaround
Expand the bottom visible file diff, then scroll down to reach the remaining file headers.
Activity
juliusmarminge commentedon Oct 11, 2026
Note
Grok responding on behalf of Julius.
Needs a retest on a newer nightly — and the screenshots never landed on the issue.
You reported against
0.0.46-nightly.20261011.2967(published 08:07 UTC). Guided reviews (#18124) merged later the same day (09:58 UTC) and changed the sharedStyledDiffCodeViewseparator/virtualizer geometry that the PR Code tab uses. Please try again on the latest Nightly with a large PR, diffs collapsed, All commits selected.Also attach the two PNGs named in the report (
File trancation.pngandFiles become visible when expanding the bottom one.png). Without them we cannot judge how far the list falls short.Notes from a quick code pass (not a confirmed root cause):
StyledDiffCodeView/ PierreCodeView. It does not use the ChangesDiffPanellazy list, so open PRs fix(web): scrolling a large diff no longer stalls while collapsed files load #16027 and fix(web): keep lazy diff files collapsed after loading #17680 (DiffPanel-only) would not cover this surface.If it still reproduces on latest Nightly with screenshots, comment and we will reopen investigation. If it does not, we can close this.
AndreiShenets commentedon Oct 11, 2026
The nightly build is the latest, no new updates. The scrrenshots are pasted inside the bug
AndreiShenets commentedon Oct 11, 2026
ℹ️ Written by
GPT-6.1 Solon behalf of AndreiShenetsConfirming that the collapsed-file-list visibility issue still reproduces on the current Windows desktop nightly:
0.0.46-nightly.20261011.2980.The version was verified from the running desktop executable's file version. It matches the latest published nightly, v0.0.46-nightly.20261011.2980, published on October 11, 2026 at 14:37:21 UTC, and is newer than the originally reported
.2967build.The reporter's new screenshots show the PR Code tab with All commits, 19 files, and 0 / 19 viewed, with the file diffs collapsed:
tests/CodeAnalysis.CSharp.Tests/StructuralHonestyTests/TypeParameterConstraintClause/TriviaTests.cs.TypeParameterConstraintClause/Tests.cs; the subsequentTypeParameterConstraintClause/TriviaTests.csheader is not reachable in that view.This also demonstrates that marking the files viewed is not required for the reported visibility problem. The new screenshots compare full and truncated views; they do not document the expand-bottom-file workaround from the original report.
AndreiShenets commentedon Oct 17, 2026
@juliusmarminge @maria-rcks please take a look to the PR for this bug. The fix looks very small when the bug is very irritating.