test(anthropic): cover identity-strip drop and non-text block branches

Close the Codecov gaps on strip_claude_code_identity_from_system:
identity+content same-block rewrite, non-text blocks, non-dict list
items, non-str/non-list payload, and the identity-only system-pop path.

tests/test_litellm/llms/anthropic/chat/test_anthropic_chat_transformation.py

@@ -6565,3 +6565,26 @@ def test_eager_input_streaming_reaches_anthropic_request_tools():
 
     assert result["tools"][0]["eager_input_streaming"] is True
     assert result["tools"][0]["name"] == "write_file"
+
+
+def test_messages_request_strips_identity_only_system_for_minimax():
+    """Identity-only system drops the whole system param (pop path)."""
+    from litellm.llms.minimax.messages.transformation import MinimaxMessagesConfig
+    from litellm.types.router import GenericLiteLLMParams
+
+    config = MinimaxMessagesConfig()
+    optional_params = {
+        "max_tokens": 16,
+        "system": [
+            {"type": "text", "text": "You are Claude Code, Anthropic's official CLI for Claude."},
+        ],
+    }
+    result = config.transform_anthropic_messages_request(
+        model="MiniMax-M2",
+        messages=[{"role": "user", "content": "hi"}],
+        anthropic_messages_optional_request_params=optional_params,
+        litellm_params=GenericLiteLLMParams(),
+        headers={},
+    )
+
+    assert "system" not in result

tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py

@@ -108,6 +108,20 @@ CLAUDE_CODE_IDENTITY = "You are Claude Code, Anthropic's official CLI for Claude
             ],
             [{"type": "text", "text": "real system prompt", "cache_control": {"type": "ephemeral"}}],
         ),
+        # List form: identity + real content in the same block -> rewritten block.
+        (
+            [{"type": "text", "text": f"{CLAUDE_CODE_IDENTITY}\nreal system prompt"}],
+            [{"type": "text", "text": "real system prompt"}],
+        ),
+        # List form: a non-text block (type "other") is kept as-is.
+        (
+            [{"type": "text", "text": CLAUDE_CODE_IDENTITY}, {"type": "other", "foo": "bar"}],
+            [{"type": "other", "foo": "bar"}],
+        ),
+        # List form: non-dict items are kept as-is.
+        ([{"type": "text", "text": CLAUDE_CODE_IDENTITY}, "loose item"], ["loose item"]),
+        # Non-string, non-list system payload is passed through untouched.
+        (None, None),
     ],
 )
 def test_strip_claude_code_identity_from_system(system_param, expected):