ci: scoped 100% coverage gates + policy doc

backend/tests/test_mentions.py

@@ -12,6 +12,21 @@ def test_matches_agent_mention_matches_first_name():
     assert matches_agent_mention(agent, {"cooper"}) is False
 
 
+def test_matches_agent_mention_no_mentions_is_false():
+    agent = Agent(name="Alice")
+    assert matches_agent_mention(agent, set()) is False
+
+
+def test_matches_agent_mention_empty_agent_name_is_false():
+    agent = Agent(name="   ")
+    assert matches_agent_mention(agent, {"alice"}) is False
+
+
+def test_matches_agent_mention_matches_full_normalized_name():
+    agent = Agent(name="Alice Cooper")
+    assert matches_agent_mention(agent, {"alice cooper"}) is True
+
+
 def test_matches_agent_mention_supports_reserved_lead_shortcut():
     lead = Agent(name="Riya", is_board_lead=True)
     other = Agent(name="Lead", is_board_lead=False)