feat(open-swe): always anchor findings to a single line (#1264)

* feat(open-swe): always anchor findings to a single line

GitHub renders multi-line review comment ranges as walls of context above
the comment, which buries the point. Match Devin Review's behavior and
always collapse `end_line` to `start_line` so each finding is anchored to
the single most relevant line.

Removes the (now unused) `MAX_FINDING_RANGE_LINES` cap and
`clip_finding_range` helper.

* fix(open-swe): collapse end_line before diff-range check

agent/reviewer.py

@@ -109,12 +109,11 @@ Cloning is optional — for most PRs the diff alone is enough.
      issue worth surfacing; `low` = small nit; `informational` = FYI / context,
      not a flaw. Inflated severities erode trust — be honest.
    - `category`: e.g. `correctness`, `security`, `perf`, `style`, `flag`.
-   - `file`, `start_line`, `end_line`: anchor inside the PR diff. Keep
-     ranges tight — anchor to the few lines that actually matter (the call
-     site, the signature line, the conditional). **Do not range-select an
-     entire function**; GitHub renders the full range as context above the
-     comment and buries the point. Ranges over ~10 lines are auto-collapsed
-     to the start line.
+   - `file`, `start_line`: anchor the comment to a single line inside the
+     PR diff — the call site, the signature line, the conditional that's
+     actually wrong. The tool always anchors to one line because GitHub
+     renders multi-line ranges as walls of context that bury the comment.
+     `end_line` is accepted for API compatibility but ignored.
    - `description`: what's wrong, in 1–4 sentences. Markdown is fine.
    - `suggestion`: **only** include for small, obvious fixes that fit in 4
      lines or fewer — a one-liner rename, a missing guard, a typo, a flipped

agent/reviewer_findings.py

@@ -29,13 +29,6 @@ REVIEWER_THREAD_KIND = "reviewer"
 # longer suggestions; the description still gets posted on its own.
 MAX_SUGGESTION_LINES = 4
 
-# Anchoring a finding to a giant range (e.g. an entire function) makes the
-# GitHub comment dump dozens of lines of context above the actual review
-# text, which buries the point. When the range exceeds this, collapse it to
-# the first line — the comment still anchors near the issue without showing
-# the whole block. ~5-line ranges are still useful, so the cap is generous.
-MAX_FINDING_RANGE_LINES = 10
-
 
 def clip_suggestion(suggestion: str | None) -> tuple[str | None, bool]:
     """Return (suggestion_or_none, was_dropped). Drops if over the line cap."""
@@ -46,18 +39,6 @@ def clip_suggestion(suggestion: str | None) -> tuple[str | None, bool]:
     return suggestion, False
 
 
-def clip_finding_range(
-    start_line: int | None,
-    end_line: int | None,
-) -> tuple[int | None, int | None, bool]:
-    """Return (start, end, was_collapsed). Collapses end→start if over cap."""
-    if start_line is None or end_line is None:
-        return start_line, end_line, False
-    if end_line - start_line + 1 > MAX_FINDING_RANGE_LINES:
-        return start_line, start_line, True
-    return start_line, end_line, False
-
-
 Severity = Literal["informational", "low", "medium", "high", "critical"]
 FindingStatus = Literal["open", "resolved", "dismissed"]
 DiffSide = Literal["LEFT", "RIGHT"]

agent/tools/add_finding.py

@@ -9,13 +9,11 @@ from langgraph.config import get_config
 
 from ..reviewer_diff import is_range_in_diff
 from ..reviewer_findings import (
-    MAX_FINDING_RANGE_LINES,
     MAX_SUGGESTION_LINES,
     DiffSide,
     Finding,
     Severity,
     append_finding,
-    clip_finding_range,
     clip_suggestion,
     get_thread_id_from_runtime,
     new_finding,
@@ -54,15 +52,14 @@ def add_finding(
             ``style``, ``flag``, etc.). Free-form; used for grouping in the UI.
         file: Repo-relative path of the file the finding refers to.
         description: Markdown body the user sees.
-        start_line: 1-based start line in the new (post-PR) file. Equal to
-            ``end_line`` for single-line findings; less than ``end_line`` for
-            ranges. Omit (with ``end_line``) for file-level findings.
-        end_line: 1-based end line, inclusive. Defaults to ``start_line``.
-            Keep ranges tight — anchor to the few lines that actually matter
-            for the comment. Ranges over 10 lines are auto-collapsed to a
-            single line because GitHub renders the full range as context
-            above the comment, which buries the point. Don't anchor to an
-            entire function; pick the call site or signature line instead.
+        start_line: 1-based line in the new (post-PR) file to anchor the
+            comment to. Pick the single most relevant line — the call site,
+            the signature, or the line the issue is actually about. Omit
+            (with ``end_line``) for file-level findings.
+        end_line: Accepted for API compatibility, but findings are always
+            anchored to a single line (``start_line``). GitHub renders
+            multi-line ranges as walls of context that bury the comment, so
+            we collapse to one line for a cleaner comment.
         suggestion: Replacement text for ``start_line..end_line``. When set,
             the published GitHub comment includes a ```suggestion``` block so
             the user can click "Commit suggestion". **Only set this for small,
@@ -89,6 +86,9 @@ def add_finding(
     if start_line is not None and end_line is not None and end_line < start_line:
         return {"success": False, "error": "end_line must be >= start_line"}
 
+    if start_line is not None:
+        end_line = start_line
+
     config = get_config()
     configurable = config.get("configurable", {}) if isinstance(config, dict) else {}
     diff_line_set = configurable.get("diff_line_set") if isinstance(configurable, dict) else None
@@ -106,8 +106,6 @@ def add_finding(
             ),
         }
 
-    start_line, end_line, range_collapsed = clip_finding_range(start_line, end_line)
-
     diff_hunk: str | None = None
     if isinstance(diff_text, str) and diff_text:
         from ..reviewer_diff import extract_diff_hunk
@@ -139,14 +137,6 @@ def add_finding(
             "dropped — the finding was recorded with description only. Only "
             "include `suggestion` for small, obvious fixes."
         )
-    if range_collapsed:
-        result["range_collapsed"] = True
-        result["range_warning"] = (
-            f"Range exceeded the {MAX_FINDING_RANGE_LINES}-line cap and was "
-            f"collapsed to a single line ({start_line}). Anchor findings to "
-            "the most relevant line — GitHub renders large ranges as walls "
-            "of context that bury the comment."
-        )
     return result
 
 

tests/test_reviewer_tools.py

@@ -80,7 +80,7 @@ def test_add_finding_persists_to_thread_metadata() -> None:
     assert persisted_thread == "tid-1"
     assert persisted["file"] == "foo.py"
     assert persisted["start_line"] == 11
-    assert persisted["end_line"] == 12
+    assert persisted["end_line"] == 11
     assert persisted["suggestion"] == "renamed = 1"
     assert persisted["status"] == "open"
     assert persisted["first_seen_sha"] == "sha-head"
@@ -175,35 +175,8 @@ def test_add_finding_keeps_short_suggestion() -> None:
     assert captured[0]["suggestion"] == short_suggestion
 
 
-def test_add_finding_collapses_oversized_range() -> None:
-    captured: list[Any] = []
-
-    async def fake_append(thread_id: str, finding: Any) -> Any:
-        captured.append(finding)
-        return finding
-
-    with (
-        patch("agent.tools.add_finding.get_config", return_value=_config()),
-        patch("agent.tools.add_finding.get_thread_id_from_runtime", return_value="tid-1"),
-        patch("agent.tools.add_finding.append_finding", side_effect=fake_append),
-    ):
-        result = add_finding(
-            severity="medium",
-            category="correctness",
-            file="foo.py",
-            description="big function",
-            start_line=15,
-            end_line=40,  # 26 lines — well over the cap
-        )
-
-    assert result["success"] is True
-    assert result.get("range_collapsed") is True
-    assert "range_warning" in result
-    assert captured[0]["start_line"] == 15
-    assert captured[0]["end_line"] == 15
-
-
-def test_add_finding_keeps_small_range() -> None:
+def test_add_finding_always_collapses_to_single_line() -> None:
+    """Multi-line ranges are always collapsed to ``start_line``."""
     captured: list[Any] = []
 
     async def fake_append(thread_id: str, finding: Any) -> Any:
@@ -219,15 +192,14 @@ def test_add_finding_keeps_small_range() -> None:
             severity="low",
             category="style",
             file="foo.py",
-            description="five lines",
+            description="anchor on start_line",
             start_line=15,
-            end_line=19,  # 5 lines — within the cap
+            end_line=19,
         )
 
     assert result["success"] is True
-    assert "range_collapsed" not in result
     assert captured[0]["start_line"] == 15
-    assert captured[0]["end_line"] == 19
+    assert captured[0]["end_line"] == 15
 
 
 def test_update_finding_rejects_long_suggestion_without_clobbering() -> None: