fix: keep resumed CLI sessions in sidebar cap

CHANGELOG.md

@@ -3,6 +3,9 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Keep capped CLI/agent sidebar scans ordered by latest message activity as well as session start time, so long-lived CLI sessions that were resumed recently stay visible in the sidebar window.
 
 ## [v0.51.100] — 2026-05-20 — Release BX (stage-393 — 3-PR deep-review batch — lazy journal recovery retry + faster profile-switch + cross-tab session list SSE sync)
 

api/agent_sessions.py

@@ -433,10 +433,13 @@ def read_importable_agent_session_rows(
             if result_limit == 0:
                 return []
             # The sidebar only needs a small visible window. Bound the expensive
-            # messages join to a recent-session candidate set instead of
+            # messages join to a recent-activity candidate set instead of
             # aggregating every historical Hermes state.db session before
-            # slicing in Python. Oversampling preserves room for hidden
-            # compression segments or other rows filtered after projection.
+            # slicing in Python. The candidate ordering must include the latest
+            # message timestamp, not only ``started_at``: long-lived CLI sessions
+            # can be resumed days later and should still surface at the top.
+            # Oversampling preserves room for hidden compression segments or
+            # other rows filtered after projection.
             candidate_limit = max(result_limit * 8, result_limit)
             cur.execute(
                 f"""
@@ -444,7 +447,11 @@ def read_importable_agent_session_rows(
                     SELECT s.id
                     FROM sessions s
                     WHERE {' AND '.join(where_clauses)}
-                    ORDER BY s.started_at DESC
+                    ORDER BY COALESCE(
+                        (SELECT MAX(mx.timestamp) FROM messages mx WHERE mx.session_id = s.id),
+                        s.started_at
+                    ) DESC,
+                    s.started_at DESC
                     LIMIT ?
                 )
                 {select_sql}

tests/test_issue2628_cli_sessions_perf.py

@@ -71,9 +71,43 @@ def test_importable_agent_rows_push_sidebar_limit_into_sql(tmp_path):
     src = (REPO_ROOT / "api" / "agent_sessions.py").read_text()
     assert "WITH candidates AS" in src
     assert "JOIN candidates c ON c.id = s.id" in src
+    assert "SELECT MAX(mx.timestamp) FROM messages mx WHERE mx.session_id = s.id" in src
     assert "candidate_limit = max(result_limit * 8, result_limit)" in src
 
 
+def test_importable_agent_rows_limit_includes_resumed_old_session(tmp_path):
+    """The capped candidate window must not hide old sessions resumed recently."""
+    db = tmp_path / "state.db"
+    _make_state_db(db, sessions=200, messages_per_session=1)
+
+    old_started = time.time() - 60 * 60 * 24 * 30
+    recent_activity = time.time() + 60
+    conn = sqlite3.connect(str(db))
+    conn.execute(
+        """
+        INSERT INTO sessions
+        (id, source, session_source, title, model, started_at, message_count, parent_session_id, ended_at, end_reason)
+        VALUES ('cli_resumed_old', 'cli', 'cli', 'Old resumed session', 'openai/gpt-5', ?, 2, NULL, NULL, NULL)
+        """,
+        (old_started,),
+    )
+    conn.execute(
+        "INSERT INTO messages (id, session_id, role, content, timestamp) VALUES ('old_msg_1', 'cli_resumed_old', 'user', 'old hello', ?)",
+        (old_started,),
+    )
+    conn.execute(
+        "INSERT INTO messages (id, session_id, role, content, timestamp) VALUES ('old_msg_2', 'cli_resumed_old', 'assistant', 'recent reply', ?)",
+        (recent_activity,),
+    )
+    conn.commit()
+    conn.close()
+
+    rows = agent_sessions.read_importable_agent_session_rows(db, limit=20, exclude_sources=("webui",))
+
+    assert rows[0]["id"] == "cli_resumed_old"
+    assert rows[0]["actual_message_count"] == 2
+
+
 def test_importable_agent_rows_zero_limit_skips_query_work(tmp_path):
     db = tmp_path / "state.db"
     _make_state_db(db, sessions=5, messages_per_session=1)