fix(work): count changes past the line cap in the attempt diff canvas

server/unified_diff.py

@@ -152,6 +152,13 @@ def append_file(old_path: str = "", new_path: str = "") -> dict[str, Any] | None
             old_remaining = max(0, old_remaining - 1)
         if prefix in {" ", "+"}:
             new_remaining = max(0, new_remaining - 1)
+        # The line cap bounds the rendered hunk lines only. File and patch
+        # totals still count every change, so a file after the cap is not
+        # listed as +0 / -0.
+        if prefix == "+":
+            current_file["additions"] += 1
+        elif prefix == "-":
+            current_file["deletions"] += 1
         if parsed_lines >= max_lines:
             truncated = True
             continue
@@ -161,12 +168,10 @@ def append_file(old_path: str = "", new_path: str = "") -> dict[str, Any] | None
             kind = "add"
             line_item = {"kind": kind, "newLine": new_line, "text": text}
             new_line += 1
-            current_file["additions"] += 1
         elif prefix == "-":
             kind = "remove"
             line_item = {"kind": kind, "oldLine": old_line, "text": text}
             old_line += 1
-            current_file["deletions"] += 1
         elif prefix == " ":
             kind = "context"
             line_item = {

tests/test_unified_diff_canvas.py

@@ -216,6 +216,43 @@ def test_parse_unified_diff_caps_files_without_merging_hunks() -> None:
     assert parsed["files"][0]["deletions"] == 1
 
 
+def test_parse_unified_diff_counts_changes_past_the_line_cap() -> None:
+    patch = "\n".join(
+        [
+            "diff --git a/data.txt b/data.txt",
+            "--- a/data.txt",
+            "+++ b/data.txt",
+            "@@ -1,2 +1,3 @@",
+            " keep",
+            "-old",
+            "+new",
+            "+extra",
+            "diff --git a/app.py b/app.py",
+            "--- a/app.py",
+            "+++ b/app.py",
+            "@@ -1 +1 @@",
+            "-before",
+            "+after",
+        ]
+    )
+    parsed = parse_unified_diff(patch, max_lines=2)
+
+    assert parsed["truncated"] is True
+    assert parsed["lineCount"] == 2
+    assert [(item["path"], item["additions"], item["deletions"]) for item in parsed["files"]] == [
+        ("data.txt", 2, 1),
+        ("app.py", 1, 1),
+    ]
+    assert parsed["additions"] == 3
+    assert parsed["deletions"] == 2
+    data, app = parsed["files"]
+    assert data["hunks"][0]["lines"] == [
+        {"kind": "context", "oldLine": 1, "newLine": 1, "text": "keep"},
+        {"kind": "remove", "oldLine": 2, "text": "old"},
+    ]
+    assert app["hunks"][0]["lines"] == []
+
+
 def test_parse_unified_diff_splits_hunk_lines_only_at_newlines() -> None:
     parsed = parse_unified_diff(
         "diff --git a/app.py b/app.py\n"
@@ -330,6 +367,7 @@ def test_parse_unified_diff_reads_copy_headers() -> None:
     test_parse_unified_diff_keeps_spaced_paths_without_marker_lines()
     test_diff_canvas_payload_keeps_report_for_local_mode_switch()
     test_parse_unified_diff_caps_files_without_merging_hunks()
+    test_parse_unified_diff_counts_changes_past_the_line_cap()
     test_parse_unified_diff_splits_hunk_lines_only_at_newlines()
     test_parse_unified_diff_reads_empty_lines_inside_hunks_as_blank_context()
     test_parse_unified_diff_reads_copy_headers()