From 0e9f830f646ee97bff578771e127c3781886b92c Mon Sep 17 00:00:00 2001
From: aran-yogesh <yogesh.mahendran@langchain.dev>
Date: Tue, 24 Feb 2026 10:44:17 -0800
Subject: [PATCH] refactor: extract recent comment logic and add tests

---
 apps/agent/agent/utils/comments.py       | 40 ++++++++++++++++++++++++
 apps/agent/agent/webapp.py               | 21 ++-----------
 apps/agent/tests/test_recent_comments.py | 27 ++++++++++++++++
 3 files changed, 69 insertions(+), 19 deletions(-)
 create mode 100644 apps/agent/agent/utils/comments.py
 create mode 100644 apps/agent/tests/test_recent_comments.py

diff --git a/apps/agent/agent/utils/comments.py b/apps/agent/agent/utils/comments.py
new file mode 100644
index 00000000..0c20e8db
--- /dev/null
+++ b/apps/agent/agent/utils/comments.py
@@ -0,0 +1,40 @@
+"""Helpers for Linear comment processing."""
+
+from __future__ import annotations
+
+from typing import Any, Sequence
+
+
+def get_recent_comments(
+    comments: Sequence[dict[str, Any]], bot_message_prefixes: Sequence[str]
+) -> list[dict[str, Any]] | None:
+    """Return user comments since the last agent response, or None if none.
+
+    Args:
+        comments: Linear issue comments.
+        bot_message_prefixes: Prefixes that identify agent/bot responses.
+
+    Returns:
+        Chronological list of comments since the last agent response, or None.
+    """
+    if not comments:
+        return None
+
+    sorted_comments = sorted(
+        comments,
+        key=lambda comment: comment.get("createdAt", ""),
+        reverse=True,
+    )
+
+    recent_user_comments: list[dict[str, Any]] = []
+    for comment in sorted_comments:
+        body = comment.get("body", "")
+        if any(body.startswith(prefix) for prefix in bot_message_prefixes):
+            break  # Everything after this is from before the last agent response
+        recent_user_comments.append(comment)
+
+    if not recent_user_comments:
+        return None
+
+    recent_user_comments.reverse()
+    return recent_user_comments
diff --git a/apps/agent/agent/webapp.py b/apps/agent/agent/webapp.py
index a872a9f7..15a51571 100644
--- a/apps/agent/agent/webapp.py
+++ b/apps/agent/agent/webapp.py
@@ -15,6 +15,7 @@ from langgraph_sdk import get_client
 
 # Local import for encryption
 from .encryption import encrypt_token
+from .utils.comments import get_recent_comments
 
 logger = logging.getLogger(__name__)
 
@@ -586,25 +587,7 @@ async def process_linear_issue(  # noqa: PLR0912, PLR0915
     )
 
     if comments:
-        # Sort newest-first so we can collect forward until we hit the last agent response
-        sorted_comments = sorted(
-            comments,
-            key=lambda c: c.get("createdAt", ""),
-            reverse=True,
-        )
-
-        # Collect user comments since the last agent response.
-        # Iterate newest-first and stop as soon as we see a bot message.
-        recent_user_comments = []
-        for comment in sorted_comments:
-            body = comment.get("body", "")
-            if any(body.startswith(prefix) for prefix in bot_message_prefixes):
-                break  # Everything after this is from before the last agent response
-            recent_user_comments.append(comment)
-
-        # Reverse to restore chronological (oldest-first) order for the prompt
-        recent_user_comments.reverse()
-
+        recent_user_comments = get_recent_comments(comments, bot_message_prefixes)
         if recent_user_comments:
             comments_text = "\n\n## Comments:\n"
             for comment in recent_user_comments:
diff --git a/apps/agent/tests/test_recent_comments.py b/apps/agent/tests/test_recent_comments.py
new file mode 100644
index 00000000..750bbad3
--- /dev/null
+++ b/apps/agent/tests/test_recent_comments.py
@@ -0,0 +1,27 @@
+from agent.utils.comments import get_recent_comments
+
+
+def test_get_recent_comments_returns_none_for_empty() -> None:
+    assert get_recent_comments([], ("🤖 **Agent Response**",)) is None
+
+
+def test_get_recent_comments_returns_none_when_newest_is_bot_message() -> None:
+    comments = [
+        {"body": "🤖 **Agent Response** latest", "createdAt": "2024-01-03T00:00:00Z"},
+        {"body": "user comment", "createdAt": "2024-01-02T00:00:00Z"},
+    ]
+
+    assert get_recent_comments(comments, ("🤖 **Agent Response**",)) is None
+
+
+def test_get_recent_comments_collects_since_last_bot_message() -> None:
+    comments = [
+        {"body": "first user", "createdAt": "2024-01-01T00:00:00Z"},
+        {"body": "🤖 **Agent Response** done", "createdAt": "2024-01-02T00:00:00Z"},
+        {"body": "follow up 1", "createdAt": "2024-01-03T00:00:00Z"},
+        {"body": "follow up 2", "createdAt": "2024-01-04T00:00:00Z"},
+    ]
+
+    result = get_recent_comments(comments, ("🤖 **Agent Response**",))
+    assert result is not None
+    assert [comment["body"] for comment in result] == ["follow up 1", "follow up 2"]