Add review thread diff to our GitHub comments viewer by Urgau · Pull Request #2352 · rust-lang/triagebot

Urgau · 2026-03-23T20:52:26Z

Current our GitHub comments viewer doesn't display the associated diff of each review thread. This PR aims to fix that by retrieving the "diff hunk" from GitHub GraphQL query and displaying the relevant lines.

Asked in #triagebot > moving "view all comments" forward @ 💬.

cc @steffahn

steffahn · 2026-03-23T23:11:19Z

Github seems to have a logic where for non-ranged line selections, the 3 previous lines (unless they don't exist, e.g. at start of file) are also shown. Compare LHS GitHub’s native way of displaying it vs. RHS this PR:

For diffs with both a + and a - it looks to be 2 previous lines:

In this case, the - is missing completely (there’s probably some subtle difference in what line or side or so the review actually applies to), and the github rendering seems to always up these to be 4 lines

(on rust#153997)

As further test cases, there’s a 3-line selection here (shows as only 3 lines), and a first-line-of-file case here.

steffahn · 2026-03-24T00:52:26Z

there’s probably some subtle difference in what line or side or so the review actually applies to

Oh I see it: the case where the - wasn’t visible is actually due to shifted line numbers. Your filter currently only creates a single range of line numbers and treats old lines and new lines the same (i.e. filtering with the same range).

steffahn · 2026-03-24T01:14:10Z

-        GitHubIssueState, GitHubIssueStateReason, GitHubIssueWithComments, GitHubReviewState,
-        GitHubSimplifiedAuthor,
+        GitHubGraphQlComment, GitHubGraphQlReactionGroup, GitHubGraphQlReview,
+        GitHubGraphQlReviewThread, GitHubGraphQlReviewThreadComment, GitHubIssueState,
+        GitHubIssueStateReason, GitHubIssueWithComments, GitHubReviewState, GitHubSimplifiedAuthor,


Review comment only used used as a test case in and by itself

steffahn · 2026-03-24T01:16:25Z

+        GitHubGraphQlComment, GitHubGraphQlReactionGroup, GitHubGraphQlReview,
+        GitHubGraphQlReviewThread, GitHubGraphQlReviewThreadComment, GitHubIssueState,
+        GitHubIssueStateReason, GitHubIssueWithComments, GitHubReviewState, GitHubSimplifiedAuthor,


Second review comment only used used as a test case in and by itself (different range)

steffahn · 2026-03-24T01:20:22Z

Uhhh… these 2 ranges of my above review comments (from “-21” to ”+23” vs “+21” to “+23”) look relatively identical, considering only the currently used information of

    start_line: Option<usize>,
    end_line: Option<usize>,

in the code 😅
both printing

Some(21), Some(23)
Some(21), Some(23)

if I debug-print the thing.

steffahn · 2026-03-24T01:34:37Z

Ah!! We have diffSide and startDiffSide in the API!

steffahn · 2026-03-24T02:28:10Z

-                .sum::<usize>();
+                .sum::<usize>()
+            + issue_with_comments.review_threads.as_ref().map_or(0, |rt| {
+                rt.nodes


View changes since this review

Another test review comment.

steffahn · 2026-03-24T02:28:17Z

+                .sum::<usize>()
+            + issue_with_comments.review_threads.as_ref().map_or(0, |rt| {
+                rt.nodes
+                    .iter()


View changes since this review

Yet another test review comment.

steffahn · 2026-03-24T02:30:17Z

I'm currently implementing a fix for the whole logic :-)

steffahn · 2026-03-24T03:21:07Z

(feel free to include my commit 8d919c8 with Urgau#1)

Example screenshot of this thread itself with that fix:

Another still remaining relevant bug then is that the current display seems to be collapsing spaces. This probably just needs an element (or style) that makes it behave like pre or something like that.

Urgau · 2026-03-24T18:02:10Z

Thanks you very much @steffahn!

I saw in the GraphQl documentation startDiffSide and diffSide fields but I couldn't figure out what they did, glad you were able to figure it out.

Another still remaining relevant bug then is that the current display seems to be collapsing spaces. This probably just needs an element (or style) that makes it behave like pre or something like that.

I was using white-space: preserve-spaces, but it's a bit too experimental (only implemented in Firefox atm). Switched to pre-wrap.

steffahn · 2026-03-24T18:11:22Z

Switched to pre-wrap.

That appears to be fixing it :-)

Urgau · 2026-03-24T18:13:34Z

@Kobzol here are two links to test the feature locally:

steffahn · 2026-03-24T18:18:00Z

FYI, the enum DiffLineRange is also made with the idea in mind that we might want to add these annotations eventually, to make that really straightforward.

enum DiffLineRange {
    Single(ChangeLineNumber), // doesn't display any annotation
    Range {
        start: ChangeLineNumber, // displays with "Comment on
        end: ChangeLineNumber,   // lines … to …" annotation
    },
}

enum ChangeLineNumber {
    Removed(usize), // red number with `-`
    Added(usize),   // green mumber with `+`
}

Urgau · 2026-03-24T19:58:19Z

FYI, the enum DiffLineRange is also made with the idea in mind that we might want to add these annotations eventually, to make that really straightforward.

Interesting, I personally look at those annotations and I don't see how they are useful, but if you think they are useful, we can add them later.

steffahn · 2026-03-24T21:03:50Z

    utils::{immutable_headers, is_known_and_public_repo},
 };

-pub const STYLE_URL: &str = "/gh-comments/style@0.0.4.css";


Another test case, pointing to a "removed" line

test reply

steffahn · 2026-03-24T21:17:11Z

test comment on whole file

Kobzol · 2026-03-25T09:11:56Z

After hovering on a resolved/hidden review thread comment, it would be nice to change the cursor to pointer and underline the text, so make it clear that you can click on it, right now it looks like read-only text, but it actually expands once you click on it.

Otherwise looks great. Though I think we're well past a point where a templating engine would really come in handy 😅

Urgau · 2026-03-25T17:35:09Z

Good point on the header not changing the cursor on hover, it's fixed.

Kobzol

Great job!

View changes since this review

Urgau requested a review from Kobzol March 23, 2026 20:52

steffahn reviewed Mar 24, 2026

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steffahn mentioned this pull request Mar 24, 2026

Refactor and fix logic for relevant lines range Urgau/triagebot#1

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Urgau force-pushed the gh-comments-review-thread-diff branch from cee34de to 9d99903 Compare March 24, 2026 17:56

Urgau force-pushed the gh-comments-review-thread-diff branch from 9d99903 to 56205c4 Compare March 24, 2026 18:07

steffahn reviewed Mar 24, 2026

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Comment thread src/gh_comments/style.css

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test comment on whole file

Urgau and others added 4 commits March 25, 2026 18:32

Add review thread diff to our GitHub comments viewer

8b8cdc5

Fix under-estimation of issue with comments size

5186d3a

Refactor and fix logic for relevant lines range

3baec59

Prefer pre-wrap (more compatible) and update styles.css version

9571ec6

Urgau force-pushed the gh-comments-review-thread-diff branch from 56205c4 to 9571ec6 Compare March 25, 2026 17:32

Kobzol approved these changes Mar 25, 2026

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Kobzol added this pull request to the merge queue Mar 25, 2026

Merged via the queue into rust-lang:master with commit d51d1ea Mar 25, 2026
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