Reject null agent registry fields

adapter/matrix/agent_registry.py

@@ -29,6 +29,16 @@ class AgentRegistry:
             raise AgentRegistryError(f"unknown agent id: {agent_id}") from exc
 
 
+def _required_text(entry: Mapping[str, object], key: str) -> str:
+    value = entry.get(key)
+    if value is None:
+        raise AgentRegistryError("each agent entry requires id and label")
+    text = str(value).strip()
+    if not text:
+        raise AgentRegistryError("each agent entry requires id and label")
+    return text
+
+
 def _load_registry_data(path: str | Path) -> dict[str, object]:
     try:
         raw = yaml.safe_load(Path(path).read_text(encoding="utf-8"))
@@ -52,10 +62,8 @@ def load_agent_registry(path: str | Path) -> AgentRegistry:
     for entry in entries:
         if not isinstance(entry, Mapping):
             raise AgentRegistryError("each agent entry requires id and label")
-        agent_id = str(entry.get("id", "")).strip()
-        label = str(entry.get("label", "")).strip()
-        if not agent_id or not label:
-            raise AgentRegistryError("each agent entry requires id and label")
+        agent_id = _required_text(entry, "id")
+        label = _required_text(entry, "label")
         if agent_id in seen:
             raise AgentRegistryError(f"duplicate agent id: {agent_id}")
         seen.add(agent_id)

tests/adapter/matrix/test_agent_registry.py

@@ -117,3 +117,22 @@ def test_load_agent_registry_rejects_malformed_yaml(tmp_path: Path):
 
     with pytest.raises(AgentRegistryError, match="invalid agent registry YAML"):
         load_agent_registry(path)
+
+
+@pytest.mark.parametrize(
+    "content",
+    [
+        "agents:\n"
+        "  - id: null\n"
+        "    label: Analyst\n",
+        "agents:\n"
+        "  - id: agent-1\n"
+        "    label: null\n",
+    ],
+)
+def test_load_agent_registry_rejects_null_id_or_label(tmp_path: Path, content: str):
+    path = tmp_path / "agents.yaml"
+    path.write_text(content, encoding="utf-8")
+
+    with pytest.raises(AgentRegistryError, match="each agent entry requires id and label"):
+        load_agent_registry(path)