diff --git a/headroom/ccr/tool_calls.py b/headroom/ccr/tool_calls.py
index 16fa18878..46e5feacb 100644
--- a/headroom/ccr/tool_calls.py
+++ b/headroom/ccr/tool_calls.py
@@ -73,8 +73,8 @@ def is_ccr_tool_call(tool_call: dict[str, Any]) -> bool:
     """Return true when a provider-native tool call names the CCR retrieval tool."""
     return (
         tool_call.get("name") == CCR_TOOL_NAME
-        or tool_call.get("function", {}).get("name") == CCR_TOOL_NAME
-        or tool_call.get("functionCall", {}).get("name") == CCR_TOOL_NAME
+        or (tool_call.get("function") or {}).get("name") == CCR_TOOL_NAME
+        or (tool_call.get("functionCall") or {}).get("name") == CCR_TOOL_NAME
     )
 
 
diff --git a/headroom/ccr/tool_injection.py b/headroom/ccr/tool_injection.py
index 90a83c9a6..20337285d 100644
--- a/headroom/ccr/tool_injection.py
+++ b/headroom/ccr/tool_injection.py
@@ -467,7 +467,10 @@ def parse_tool_call(
         name = tool_call.get("name")
         input_data = tool_call.get("input", {})
     elif provider == "openai":
-        function = tool_call.get("function", {})
+        # `get("function", {})` returns None for an explicit {"function": null}
+        # (the default only applies to a missing key), so `.get` below would
+        # raise AttributeError on a malformed/partial tool call. Coalesce to {}.
+        function = tool_call.get("function") or {}
         name = function.get("name")
         # OpenAI passes args as JSON string
         args_str = function.get("arguments", "{}")
@@ -478,7 +481,8 @@ def parse_tool_call(
             input_data = {}
     elif provider == "google":
         # Google/Gemini format: {"functionCall": {"name": "...", "args": {...}}}
-        function_call = tool_call.get("functionCall", {})
+        # Coalesce to {} so an explicit {"functionCall": null} does not crash.
+        function_call = tool_call.get("functionCall") or {}
         name = function_call.get("name")
         input_data = function_call.get("args", {})
     elif provider == "openai_responses":
diff --git a/tests/test_ccr_tool_calls.py b/tests/test_ccr_tool_calls.py
index b70b16320..bf2522b42 100644
--- a/tests/test_ccr_tool_calls.py
+++ b/tests/test_ccr_tool_calls.py
@@ -58,6 +58,36 @@ def test_has_ccr_tool_calls_uses_provider_native_names() -> None:
     )
 
 
+def test_ccr_detection_survives_null_function_tool_call() -> None:
+    # A partial/streamed OpenAI tool call with an explicit {"function": null}
+    # must not crash detection: dict.get("function", {}) returns None for a
+    # present-but-null key, and .get on None raises AttributeError.
+    response = {
+        "choices": [
+            {
+                "message": {
+                    "tool_calls": [
+                        {"id": "call_1", "type": "function", "function": None},
+                        {
+                            "id": "call_2",
+                            "type": "function",
+                            "function": {
+                                "name": CCR_TOOL_NAME,
+                                "arguments": '{"hash": "' + HASH + '"}',
+                            },
+                        },
+                    ]
+                }
+            }
+        ]
+    }
+
+    assert has_ccr_tool_calls(response, "openai")
+    ccr_calls, other_calls = parse_ccr_tool_calls(response, "openai")
+    assert ccr_calls == [CCRToolCall(tool_call_id="call_2", hash_key=HASH)]
+    assert other_calls == [{"id": "call_1", "type": "function", "function": None}]
+
+
 def test_parse_ccr_tool_calls_splits_retrievals_from_other_tools() -> None:
     response = {
         "content": [
diff --git a/tests/test_ccr_tool_injection.py b/tests/test_ccr_tool_injection.py
index d4506bc33..6bf2ccc13 100644
--- a/tests/test_ccr_tool_injection.py
+++ b/tests/test_ccr_tool_injection.py
@@ -310,6 +310,12 @@ class TestParseToolCall:
 
         assert hash_key == "def456abc123def456abc123"
 
+    def test_parse_null_function_returns_none_without_crashing(self):
+        """A tool call with an explicit {"function": null} / {"functionCall": null}
+        must return None, not raise AttributeError."""
+        assert parse_tool_call({"id": "c1", "function": None}, "openai") is None
+        assert parse_tool_call({"functionCall": None}, "google") is None
+
     def test_parse_normalises_uppercase_hash_to_lowercase(self):
         """An uppercase hash echoed by the model must be lowercased so it
         matches the store (which keys entries by a lowercase hash)."""