diff --git a/litellm/__init__.py b/litellm/__init__.py
index d5a6af8173f..e36e94e10d1 100644
--- a/litellm/__init__.py
+++ b/litellm/__init__.py
@@ -644,7 +644,7 @@ snowflake_models: Set = set()
 gradient_ai_models: Set = set()
 llama_models: Set = set()
 nscale_models: Set = set()
-apodex_models: Set = set()
+apodex_models: Set = set()  # mutable-ok: provider model registry is populated during initialization
 nebius_models: Set = set()
 nebius_embedding_models: Set = set()
 aiml_models: Set = set()
diff --git a/litellm/llms/anthropic/experimental_pass_through/responses_adapters/streaming_iterator.py b/litellm/llms/anthropic/experimental_pass_through/responses_adapters/streaming_iterator.py
index 2a310fe4c1a..834d7437c43 100644
--- a/litellm/llms/anthropic/experimental_pass_through/responses_adapters/streaming_iterator.py
+++ b/litellm/llms/anthropic/experimental_pass_through/responses_adapters/streaming_iterator.py
@@ -74,7 +74,7 @@ class AnthropicResponsesStreamWrapper:
         if self._open_block_index is None:
             return
         self._chunk_queue.append(
-            {
+            {  # mutable-ok: queued Anthropic event payload
                 "type": "content_block_stop",
                 "index": self._open_block_index,
             }
@@ -88,7 +88,7 @@ class AnthropicResponsesStreamWrapper:
             {
                 "type": "content_block_start",
                 "index": block_idx,
-                "content_block": dict(content_block),
+                "content_block": dict(content_block),  # mutable-ok: queued Anthropic event payload
             }
         )
         self._open_block_index = block_idx
@@ -143,7 +143,11 @@ class AnthropicResponsesStreamWrapper:
                 block_idx = self._next_block_index()
                 if item_id:
                     self._item_id_to_block_index[item_id] = block_idx
-                self._start_block(block_idx, "text", {"type": "text", "text": ""})
+                self._start_block(
+                    block_idx,
+                    "text",
+                    {"type": "text", "text": ""},  # mutable-ok: Anthropic content block payload
+                )
             elif item_type == "function_call":
                 call_id: Final = (
                     getattr(item, "call_id", None) or (item.get("call_id") if isinstance(item, dict) else None) or ""
@@ -172,7 +176,7 @@ class AnthropicResponsesStreamWrapper:
             text_block_idx: Final = self._get_or_start_block(
                 item_id=item_id,
                 block_type="text",
-                content_block={"type": "text", "text": ""},
+                content_block={"type": "text", "text": ""},  # mutable-ok: Anthropic content block payload
             )
             self._chunk_queue.append(
                 {
@@ -192,7 +196,11 @@ class AnthropicResponsesStreamWrapper:
             thinking_block_idx: Final = self._get_or_start_block(
                 item_id=item_id,
                 block_type="thinking",
-                content_block={"type": "thinking", "thinking": "", "signature": ""},
+                content_block={  # mutable-ok: Anthropic content block payload
+                    "type": "thinking",
+                    "thinking": "",
+                    "signature": "",
+                },
             )
             self._chunk_queue.append(
                 {
diff --git a/litellm/llms/apodex/chat/transformation.py b/litellm/llms/apodex/chat/transformation.py
index 5b7e1e8ee6b..6287aedeebb 100644
--- a/litellm/llms/apodex/chat/transformation.py
+++ b/litellm/llms/apodex/chat/transformation.py
@@ -125,13 +125,15 @@ class ApodexChatConfig(OpenAIGPTConfig):
     def transform_request(
         self,
         model: str,
-        messages: list[AllMessageValues],
+        messages: list[AllMessageValues],  # mutable-ok: matches the base-class signature
         optional_params: dict,  # mutable-ok: matches the base-class signature
         litellm_params: dict,  # mutable-ok: matches the base-class signature
         headers: dict,  # mutable-ok: matches the base-class signature
     ) -> dict:  # mutable-ok: JSON request body
         pin_non_streaming: Final = bool(optional_params.get(_PIN_NON_STREAMING, False))
-        forwarded_params: Final = {key: value for key, value in optional_params.items() if key != _PIN_NON_STREAMING}
+        forwarded_params: Final = {  # mutable-ok: base transformer requires a request dict
+            key: value for key, value in optional_params.items() if key != _PIN_NON_STREAMING
+        }
         transformed: Final = super().transform_request(
             model=model,
             messages=messages,
diff --git a/litellm/llms/apodex/responses/transformation.py b/litellm/llms/apodex/responses/transformation.py
index 1e6d2fbd1f4..86357e118be 100644
--- a/litellm/llms/apodex/responses/transformation.py
+++ b/litellm/llms/apodex/responses/transformation.py
@@ -117,13 +117,13 @@ class ApodexResponsesConfig(OpenAIResponsesAPIConfig):
             status_code=raw_response.status_code,
             # Content-Encoding and Content-Length describe the body being replaced here;
             # carrying them over makes httpx try to decompress plain JSON on read.
-            headers={
+            headers={  # mutable-ok: httpx requires mutable response headers
                 name: value for name, value in raw_response.headers.items() if name.lower() not in _BODY_FRAMING_HEADERS
             },
-            json={
+            json={  # mutable-ok: httpx requires a JSON-compatible response dict
                 **payload,
                 "created_at": payload.get("created_at", int(time())),
-                "output": payload.get("output", []),
+                "output": payload.get("output", []),  # mutable-ok: Responses payload requires an array default
             },
         )
         return super().transform_cancel_response_api_response(
diff --git a/tests/test_litellm/llms/anthropic/experimental_pass_through/responses_adapters/test_responses_adapters_streaming_iterator.py b/tests/test_litellm/llms/anthropic/experimental_pass_through/responses_adapters/test_responses_adapters_streaming_iterator.py
index d0da2056e84..28339143b72 100644
--- a/tests/test_litellm/llms/anthropic/experimental_pass_through/responses_adapters/test_responses_adapters_streaming_iterator.py
+++ b/tests/test_litellm/llms/anthropic/experimental_pass_through/responses_adapters/test_responses_adapters_streaming_iterator.py
@@ -245,10 +245,16 @@ class TestProcessEventTextDeltaWithoutOutputItemAdded:
         assert chunks[1]["delta"] == {"type": "text_delta", "text": "Hel"}
 
     def test_process_event_delta_without_item_id_never_yields_negative_index(self):
-        chunks = _process_all([{"type": "response.output_text.delta", "delta": "Hi"}])
+        chunks = _process_all(
+            [
+                {"type": "response.output_text.delta", "delta": "Hi"},
+                {"type": "response.output_text.delta", "delta": " again"},
+            ]
+        )
         assert [(c["type"], c["index"]) for c in chunks] == [
             ("content_block_start", 0),
             ("content_block_delta", 0),
+            ("content_block_delta", 0),
         ]
 
     def test_process_event_unregistered_item_id_opens_new_text_block(self):
diff --git a/tests/test_litellm/llms/apodex/test_apodex_chat_transformation.py b/tests/test_litellm/llms/apodex/test_apodex_chat_transformation.py
index 7cfbefca047..75bb3068ca3 100644
--- a/tests/test_litellm/llms/apodex/test_apodex_chat_transformation.py
+++ b/tests/test_litellm/llms/apodex/test_apodex_chat_transformation.py
@@ -72,6 +72,13 @@ def _chat_config(model: str):
 
 
 class TestProviderResolution:
+    def test_openai_compatible_provider_info_uses_apodex_credentials(self):
+        config = _chat_config("apodex-1.1")
+        assert config._get_openai_compatible_provider_info("https://override.test/v1", "sk-override") == (
+            "https://override.test/v1",
+            "sk-override",
+        )
+
     def test_prefixed_model_resolves_to_the_default_base(self):
         model, provider, api_key, api_base = litellm.get_llm_provider(model=CORE_MODEL)
         assert (model, provider, api_key, api_base) == (
diff --git a/tests/test_litellm/llms/apodex/test_apodex_messages_transformation.py b/tests/test_litellm/llms/apodex/test_apodex_messages_transformation.py
index 0e4fb368cc5..ed6da35bba6 100644
--- a/tests/test_litellm/llms/apodex/test_apodex_messages_transformation.py
+++ b/tests/test_litellm/llms/apodex/test_apodex_messages_transformation.py
@@ -55,6 +55,7 @@ class TestNativePassthroughRouting:
         assert config is not None
         assert type(config).__name__ == "ApodexAnthropicMessagesConfig"
         assert config.custom_llm_provider == "apodex"
+        assert config.should_strip_billing_metadata() is True
 
     @pytest.mark.parametrize("model", DEEP_RESEARCH_MODELS)
     def test_deep_research_models_fall_back_to_translation(self, model: str):
diff --git a/tests/test_litellm/llms/apodex/test_apodex_responses_transformation.py b/tests/test_litellm/llms/apodex/test_apodex_responses_transformation.py
index 032fb99db67..252a07bf607 100644
--- a/tests/test_litellm/llms/apodex/test_apodex_responses_transformation.py
+++ b/tests/test_litellm/llms/apodex/test_apodex_responses_transformation.py
@@ -367,6 +367,18 @@ class TestDeepResearchKeepsState:
 
         assert event.type == "response.swarm.llm_delta"
 
+    def test_non_string_delta_is_not_claimed(self):
+        config = _responses_config("apodex-1-1-deep-research")
+        assert (
+            config._map_swarm_delta(
+                {
+                    "type": "response.swarm.llm_delta",
+                    "swarm": {"data": {"channel": "output_text", "delta": None}},
+                }
+            )
+            is None
+        )
+
     @pytest.mark.parametrize(
         "event_type",
         (