fix(comments): associate comments with their commit when reviewing per-commit

AGENTS.md

@@ -240,6 +240,8 @@ These are non-obvious things the implementation chain hit. Worth preserving for
 
 12. **`cd` into the worktree before running `cargo`.** `cargo` resolves `Cargo.toml` from `pwd`. Running gates from the wrong worktree silently exercises the wrong tree.
 
+13. **Comments are commit-scoped via `Comment::commit_id`.** When the inline commit selector shows exactly one commit, `App::save_comment` stamps that commit's SHA on the comment. Comments with `commit_id = Some(sha)` are hidden when a different commit (or a subset not containing `sha`) is selected; `commit_id = None` (legacy, review-level, or made against the full cumulative diff) is always visible. The filter runs in `rebuild_annotations`, both diff renderers, the comment navigator (via filtered annotations), and the submit preflight. `App::comment_visible(&Comment)` is the single predicate. `AnnotatedLine::LineComment`/`FileComment` `comment_idx` is the **absolute** index into the stored `Vec`/`HashMap` value — `delete_comment_at_cursor` and `enter_edit_mode` must look it up directly, not re-count by side.
+
 ### Keeping Docs Updated
 
 When adding user-facing features, update the relevant documentation:

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file.
 
+## [Unreleased]
+
+### Bug Fixes
+
+- **comments:** Associate comments with their commit when reviewing per-commit, preventing comments from one commit bleeding into another commit's diff view
+
 ## [0.18.0] - 2026-06-20
 
 ### Bug Fixes

src/model/comment.rs

@@ -172,6 +172,15 @@ pub struct Comment {
     /// inline comments; review-level / summary comments don't get one.
     #[serde(default)]
     pub remote_comment_id: Option<String>,
+    /// The commit SHA this comment was made against, when it was created
+    /// while the inline commit selector showed exactly one commit. `None`
+    /// for review-level comments, for comments made against the full
+    /// cumulative diff (all commits selected), and for legacy session JSON
+    /// predating this field. Filtering by the active commit selection hides
+    /// comments whose `commit_id` does not intersect the selection; `None`
+    /// comments are always shown.
+    #[serde(default)]
+    pub commit_id: Option<String>,
 }
 
 impl Comment {
@@ -188,6 +197,7 @@ impl Comment {
             lifecycle_state: CommentLifecycleState::default(),
             remote_review_id: None,
             remote_comment_id: None,
+            commit_id: None,
         }
     }
 
@@ -210,6 +220,7 @@ impl Comment {
             lifecycle_state: CommentLifecycleState::default(),
             remote_review_id: None,
             remote_comment_id: None,
+            commit_id: None,
         }
     }
 
@@ -221,6 +232,15 @@ impl Comment {
         self
     }
 
+    /// Builder: set `commit_id` and return self. Called by
+    /// `App::save_comment` when the inline commit selector shows exactly
+    /// one commit, so the comment is scoped to that commit and hidden when
+    /// a different commit (or subset) is selected.
+    pub fn with_commit_id(mut self, commit_id: impl Into<String>) -> Self {
+        self.commit_id = Some(commit_id.into());
+        self
+    }
+
     /// True if this comment has been pushed/submitted to the forge and is
     /// therefore locked from local edits/deletions.
     pub fn is_locked(&self) -> bool {

src/model/review.rs

@@ -540,6 +540,75 @@ mod tests {
         assert_eq!(restored.commit_selection_range, Some((1, 3)));
     }
 
+    #[test]
+    fn should_round_trip_comment_commit_id_on_session() {
+        // given a session with a file comment and a line comment both scoped
+        // to a single commit
+        use crate::model::comment::LineSide;
+        let mut session = test_session();
+        session.add_file(PathBuf::from("src/lib.rs"), FileStatus::Modified, SOME_HASH);
+        let file_comment = Comment::new(
+            "file note on commit aaa".to_string(),
+            CommentType::Note,
+            None,
+        )
+        .with_commit_id("aaa111");
+        let line_comment = Comment::new(
+            "line note on commit bbb".to_string(),
+            CommentType::Issue,
+            Some(LineSide::New),
+        )
+        .with_commit_id("bbb222");
+        let review = session.get_file_mut(&PathBuf::from("src/lib.rs")).unwrap();
+        review.add_file_comment(file_comment.clone());
+        review.add_line_comment(42, line_comment.clone());
+
+        // when serialized and restored
+        let json = serde_json::to_string(&session).unwrap();
+        let restored: ReviewSession = serde_json::from_str(&json).unwrap();
+
+        // then the commit_id survives the round trip
+        let r = restored.files.get(&PathBuf::from("src/lib.rs")).unwrap();
+        assert_eq!(r.file_comments.len(), 1);
+        assert_eq!(
+            r.file_comments[0].commit_id,
+            Some("aaa111".to_string()),
+            "file comment commit_id must round-trip"
+        );
+        let line = r.line_comments.get(&42).unwrap();
+        assert_eq!(line.len(), 1);
+        assert_eq!(
+            line[0].commit_id,
+            Some("bbb222".to_string()),
+            "line comment commit_id must round-trip"
+        );
+    }
+
+    #[test]
+    fn should_default_commit_id_to_none_for_legacy_comment_json() {
+        // given a comment JSON saved before commit_id existed
+        let json = r#"{
+            "id": "legacy-id",
+            "content": "old note",
+            "comment_type": "note",
+            "created_at": "2024-01-01T00:00:00Z",
+            "line_context": null,
+            "side": null,
+            "line_range": null,
+            "author": "user",
+            "lifecycle_state": "local_draft",
+            "remote_review_id": null,
+            "remote_comment_id": null
+        }"#;
+        // when
+        let comment: Comment = serde_json::from_str(json).unwrap();
+        // then
+        assert_eq!(
+            comment.commit_id, None,
+            "comment JSON without commit_id must default to None"
+        );
+    }
+
     #[test]
     fn should_default_commit_selection_range_to_none_for_legacy_session() {
         // given a session JSON saved before commit_selection_range existed

src/output/markdown.rs

@@ -11,9 +11,16 @@ use crate::forge::remote_comments::{
     PrCommentsVisibility, RemoteReviewThread, filter_threads, group_threads_by_path,
 };
 use crate::model::{CommentType, LineRange, LineSide, ReviewSession};
-
-/// (file_path, line_range, side, comment_type, content)
-type CommentEntry<'a> = (String, Option<LineRange>, Option<LineSide>, String, &'a str);
+use crate::slug::short_sha;
+/// (file_path, line_range, side, comment_type, content, commit_id)
+type CommentEntry<'a> = (
+    String,
+    Option<LineRange>,
+    Option<LineSide>,
+    String,
+    &'a str,
+    Option<&'a str>,
+);
 
 /// Generate markdown content from the review session.
 /// Returns the markdown string or an error if there are no comments.
@@ -346,6 +353,7 @@ fn generate_markdown(
             None,
             export_comment_type_label(&comment.comment_type, comment_types),
             &comment.content,
+            None,
         ));
     }
 
@@ -364,6 +372,7 @@ fn generate_markdown(
                 None,
                 export_comment_type_label(&comment.comment_type, comment_types),
                 &comment.content,
+                comment.commit_id.as_deref(),
             ));
         }
 
@@ -383,6 +392,7 @@ fn generate_markdown(
                     comment.side,
                     export_comment_type_label(&comment.comment_type, comment_types),
                     &comment.content,
+                    comment.commit_id.as_deref(),
                 ));
             }
         }
@@ -395,7 +405,9 @@ fn generate_markdown(
         let _ = writeln!(md);
         local_section_written = true;
     }
-    for (i, (file, line_range, side, comment_type, content)) in all_comments.iter().enumerate() {
+    for (i, (file, line_range, side, comment_type, content, commit_id)) in
+        all_comments.iter().enumerate()
+    {
         let number = i + 1;
         let location = match (line_range, side) {
             // Range on deleted side (old lines)
@@ -415,13 +427,19 @@ fn generate_markdown(
             // File comment
             (None, _) => format!("`{file}`"),
         };
+        // Append the commit short SHA so the LLM knows which commit the
+        // comment was made against — crucial for per-commit reviews.
+        let commit_suffix = match commit_id {
+            Some(sha) => format!(" (commit {})", short_sha(sha)),
+            None => String::new(),
+        };
         let marker = format!("{number}.");
         let continuation_indent = " ".repeat(marker.len() + 1);
         let mut content_lines = content.split('\n').map(|line| line.trim_end_matches('\r'));
         let first_line = content_lines.next().unwrap_or_default();
         let _ = writeln!(
             md,
-            "{marker} **[{comment_type}]** {location} - {first_line}"
+            "{marker} **[{comment_type}]** {location}{commit_suffix} - {first_line}"
         );
         for line in content_lines {
             let _ = writeln!(md, "{continuation_indent}{line}");
@@ -854,6 +872,57 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn should_include_commit_sha_in_export_for_commit_scoped_comments() {
+        let mut session = create_test_session();
+        // Add a line comment scoped to commit abc1234567890
+        if let Some(review) = session.get_file_mut(&PathBuf::from("src/main.rs")) {
+            review.add_line_comment(
+                10,
+                Comment::new(
+                    "Wrong variable name".to_string(),
+                    CommentType::Issue,
+                    Some(LineSide::New),
+                )
+                .with_commit_id("abc1234567890"),
+            );
+        }
+
+        let markdown = generate_markdown(
+            &session,
+            &DiffSource::CommitRange(vec!["abc1234567890".to_string()]),
+            &comment_types(),
+            true,
+            &[],
+            None,
+        );
+
+        assert!(
+            markdown.contains("`src/main.rs:10` (commit abc1234) - Wrong variable name"),
+            "commit-scoped comment must include the short SHA in the export; got:\n{markdown}"
+        );
+    }
+
+    #[test]
+    fn should_omit_commit_suffix_for_unscoped_comments() {
+        let session = create_test_session();
+
+        let markdown = generate_markdown(
+            &session,
+            &DiffSource::WorkingTree,
+            &comment_types(),
+            true,
+            &[],
+            None,
+        );
+
+        // Existing comments have commit_id = None — no (commit ...) suffix
+        assert!(
+            !markdown.contains("(commit "),
+            "unscoped comments must not have a commit suffix; got:\n{markdown}"
+        );
+    }
+
     #[test]
     fn should_fail_export_when_no_comments() {
         // given

src/review_cli.rs

@@ -100,6 +100,7 @@ fn add_comment(
             content: request_parts.content,
             comment_type,
             author,
+            commit_id: None,
         },
     )?;
     let output = CommentOutput::from_target(&target, &comment);
@@ -846,6 +847,7 @@ mod tests {
                     content: "check this".to_string(),
                     comment_type: CommentType::Issue,
                     author: crate::model::comment::DEFAULT_AUTHOR.to_string(),
+                    commit_id: None,
                 },
             )
             .unwrap();

src/review_store.rs

@@ -180,6 +180,11 @@ pub struct AddCommentRequest {
     /// picking a sensible default (`Comment::DEFAULT_AUTHOR`) when none is
     /// supplied.
     pub author: String,
+    /// Commit SHA to stamp on the comment when it was created while the
+    /// inline commit selector showed exactly one commit. `None` for
+    /// review-level comments and full-range selections. Library callers
+    /// (the `review add` CLI) leave this `None`.
+    pub commit_id: Option<String>,
 }
 
 /// Where a new local draft comment should be attached.
@@ -216,6 +221,7 @@ pub fn add_comment_to_session(
     }
 
     let author = request.author;
+    let commit_id = request.commit_id;
     let comment = match request.target {
         CommentTarget::Review => {
             let comment = Comment::new(content, request.comment_type, None).with_author(author);
@@ -224,21 +230,31 @@ pub fn add_comment_to_session(
         }
         CommentTarget::File { path } => {
             let review = file_review_mut(session, &path)?;
-            let comment = Comment::new(content, request.comment_type, None).with_author(author);
+            let mut comment = Comment::new(content, request.comment_type, None).with_author(author);
+            if let Some(sha) = &commit_id {
+                comment = comment.with_commit_id(sha.clone());
+            }
             review.add_file_comment(comment.clone());
             comment
         }
         CommentTarget::Line { path, line, side } => {
             let review = file_review_mut(session, &path)?;
-            let comment =
+            let mut comment =
                 Comment::new(content, request.comment_type, Some(side)).with_author(author);
+            if let Some(sha) = &commit_id {
+                comment = comment.with_commit_id(sha.clone());
+            }
             review.add_line_comment(line, comment.clone());
             comment
         }
         CommentTarget::LineRange { path, range, side } => {
             let review = file_review_mut(session, &path)?;
-            let comment = Comment::new_with_range(content, request.comment_type, Some(side), range)
-                .with_author(author);
+            let mut comment =
+                Comment::new_with_range(content, request.comment_type, Some(side), range)
+                    .with_author(author);
+            if let Some(sha) = &commit_id {
+                comment = comment.with_commit_id(sha.clone());
+            }
             review.add_line_comment(range.end, comment.clone());
             comment
         }
@@ -284,6 +300,7 @@ mod tests {
                 content: "looks good".to_string(),
                 comment_type: CommentType::Praise,
                 author: crate::model::comment::DEFAULT_AUTHOR.to_string(),
+                commit_id: None,
             },
         )
         .unwrap();
@@ -304,6 +321,7 @@ mod tests {
                 content: "file note".to_string(),
                 comment_type: CommentType::Note,
                 author: crate::model::comment::DEFAULT_AUTHOR.to_string(),
+                commit_id: None,
             },
         )
         .unwrap();
@@ -328,6 +346,7 @@ mod tests {
                 content: "range note".to_string(),
                 comment_type: CommentType::Suggestion,
                 author: crate::model::comment::DEFAULT_AUTHOR.to_string(),
+                commit_id: None,
             },
         )
         .unwrap();
@@ -349,6 +368,7 @@ mod tests {
                 content: "note".to_string(),
                 comment_type: CommentType::Note,
                 author: crate::model::comment::DEFAULT_AUTHOR.to_string(),
+                commit_id: None,
             },
         )
         .unwrap_err();
@@ -394,6 +414,7 @@ mod tests {
                     content: "line note".to_string(),
                     comment_type: CommentType::Note,
                     author: crate::model::comment::DEFAULT_AUTHOR.to_string(),
+                    commit_id: None,
                 },
             )
             .unwrap();