fix: prefer valid position for comment line fallback

src/normalize.rs

@@ -197,12 +197,27 @@ fn to_commit_item(commit: CommitDto) -> CommitItem {
 }
 
 fn to_comment_item(comment: ReviewCommentDto) -> CommentItem {
+    let line = if let Some(value) = comment.line.filter(|value| *value > 0) {
+        Some(value)
+    } else if let Some(value) = comment
+        .position
+        .filter(|value| *value > 0)
+        .and_then(|value| i64::try_from(value).ok())
+    {
+        Some(value)
+    } else {
+        comment
+            .original_position
+            .filter(|value| *value > 0)
+            .and_then(|value| i64::try_from(value).ok())
+    };
+
     CommentItem {
         id: comment.id,
         user: comment.user.login,
         created_at: comment.created_at,
         path: comment.path,
-        line: comment.line,
+        line,
         body: comment.body,
     }
 }

tests/normalize_tests.rs

@@ -249,3 +249,56 @@ fn normalize_does_not_merge_unrelated_comments_on_same_file() {
     assert_eq!(doc.threads[1].root_comment.id, 11);
     assert_eq!(doc.threads[1].replies.len(), 0);
 }
+
+#[test]
+fn normalize_uses_non_zero_position_when_line_is_missing() {
+    let bundle = PullBundleDto {
+        pull: PullDto {
+            number: 101,
+            title: "T".into(),
+            state: "open".into(),
+            body: None,
+            user: UserDto {
+                login: "alice".into(),
+            },
+            base: PullBranchDto {
+                ref_name: "main".into(),
+            },
+            head: PullBranchDto {
+                ref_name: "feature/z".into(),
+            },
+            created_at: "2026-04-08T10:00:00Z".into(),
+            updated_at: "2026-04-08T10:00:00Z".into(),
+            merged_at: None,
+            additions: None,
+            deletions: None,
+            changed_files: None,
+        },
+        reviews: vec![],
+        comments: vec![ReviewCommentDto {
+            id: 1001,
+            body: "position based comment".into(),
+            created_at: "2026-04-08T12:00:00Z".into(),
+            updated_at: None,
+            user: UserDto {
+                login: "bob".into(),
+            },
+            path: Some("src/main.rs".into()),
+            line: None,
+            pull_request_review_id: Some(1),
+            in_reply_to: None,
+            original_position: Some(42),
+            position: Some(41),
+            commit_id: Some("abc123".into()),
+            original_commit_id: Some("abc123".into()),
+            diff_hunk: None,
+        }],
+        commits: vec![],
+        files: vec![],
+    };
+
+    let doc = normalize_bundle("org/repo", bundle);
+    assert_eq!(doc.threads.len(), 1);
+    assert_eq!(doc.threads[0].root_comment.path.as_deref(), Some("src/main.rs"));
+    assert_eq!(doc.threads[0].root_comment.line, Some(41));
+}