feat(dashscope): add Anthropic Messages support

Add DashScopeAnthropicMessagesConfig to route /v1/messages calls to
DashScope's Anthropic-compatible endpoint at
https://dashscope.aliyuncs.com/apps/anthropic/v1/messages (and the
international ...dashscope-intl... mirror).

The config extends AnthropicMessagesConfig (the same pattern used by
MinimaxMessagesConfig and DeepSeekAnthropicMessagesConfig) and is
wired into ProviderConfigManager.get_provider_anthropic_messages_config
for the existing LlmProviders.DASHSCOPE enum entry.

Two DashScope-specific behaviors:
- URL rewriting: recognize the OpenAI-compatible base URLs
  (.../compatible-mode/v1[, /chat/completions]) and rewrite them to the
  Anthropic Messages endpoint, since callers commonly reuse the
  chat-completions base URL.
- Header normalization: strip anthropic-version / anthropic-beta
  headers, which DashScope's endpoint does not accept. Pull api_key
  from DASHSCOPE_API_KEY when not provided.

litellm/llms/dashscope/messages/__init__.py

@@ -0,0 +1,3 @@
+from .transformation import DashScopeAnthropicMessagesConfig
+
+__all__ = ["DashScopeAnthropicMessagesConfig"]

litellm/llms/dashscope/messages/transformation.py

@@ -0,0 +1,99 @@
+"""
+DashScope Anthropic transformation config - extends AnthropicMessagesConfig for
+DashScope's Anthropic-compatible Messages API.
+"""
+
+from typing import Any, List, Optional, Tuple
+
+from litellm.llms.anthropic.experimental_pass_through.messages.transformation import (
+    AnthropicMessagesConfig,
+)
+from litellm.secret_managers.main import get_secret_str
+
+DEFAULT_DASHSCOPE_ANTHROPIC_MESSAGES_API_BASE = "https://dashscope.aliyuncs.com/apps/anthropic/v1/messages"
+_COMPATIBLE_MODE_CHAT_COMPLETIONS_SUFFIX = "/compatible-mode/v1/chat/completions"
+_COMPATIBLE_MODE_SUFFIX = "/compatible-mode/v1"
+_ANTHROPIC_MESSAGES_SUFFIX = "/apps/anthropic"
+_MESSAGES_SUFFIX = "/v1/messages"
+
+
+class DashScopeAnthropicMessagesConfig(AnthropicMessagesConfig):
+    """
+    DashScope Anthropic configuration that extends AnthropicMessagesConfig.
+
+    DashScope (Alibaba Cloud) exposes an Anthropic-compatible Messages API at:
+    - China:         https://dashscope.aliyuncs.com/apps/anthropic/v1/messages
+    - International: https://dashscope-intl.aliyuncs.com/apps/anthropic/v1/messages
+
+    The OpenAI-compatible base URLs (``.../compatible-mode/v1`` and
+    ``.../compatible-mode/v1/chat/completions``) are also recognized and
+    rewritten to the Anthropic Messages endpoint, since callers commonly reuse
+    the chat-completions base URL.
+
+    Supported models: any DashScope-hosted model that is exposed via the
+    Anthropic Messages endpoint (e.g. ``qwen3-max``, ``qwen-plus``,
+    ``qwen-max``).
+    """
+
+    @property
+    def custom_llm_provider(self) -> Optional[str]:
+        return "dashscope"
+
+    @staticmethod
+    def _get_api_key(api_key: Optional[str] = None) -> Optional[str]:
+        return api_key or get_secret_str("DASHSCOPE_API_KEY")
+
+    @staticmethod
+    def _get_anthropic_messages_api_base(api_base: Optional[str] = None) -> str:
+        if not api_base:
+            return DEFAULT_DASHSCOPE_ANTHROPIC_MESSAGES_API_BASE
+
+        base_url = api_base.rstrip("/")
+        if base_url.endswith(_MESSAGES_SUFFIX):
+            return base_url
+        if base_url.endswith(_COMPATIBLE_MODE_CHAT_COMPLETIONS_SUFFIX):
+            root = base_url[: -len(_COMPATIBLE_MODE_CHAT_COMPLETIONS_SUFFIX)]
+            return f"{root}{_ANTHROPIC_MESSAGES_SUFFIX}{_MESSAGES_SUFFIX}"
+        if base_url.endswith(_COMPATIBLE_MODE_SUFFIX):
+            root = base_url[: -len(_COMPATIBLE_MODE_SUFFIX)]
+            return f"{root}{_ANTHROPIC_MESSAGES_SUFFIX}{_MESSAGES_SUFFIX}"
+        if base_url.endswith(f"{_ANTHROPIC_MESSAGES_SUFFIX}/v1"):
+            return f"{base_url}/messages"
+        if base_url.endswith(_ANTHROPIC_MESSAGES_SUFFIX):
+            return f"{base_url}{_MESSAGES_SUFFIX}"
+
+        return f"{base_url}{_MESSAGES_SUFFIX}"
+
+    def get_complete_url(
+        self,
+        api_base: Optional[str],
+        api_key: Optional[str],
+        model: str,
+        optional_params: dict,
+        litellm_params: dict,
+        stream: Optional[bool] = None,
+    ) -> str:
+        return self._get_anthropic_messages_api_base(api_base=api_base)
+
+    def validate_anthropic_messages_environment(
+        self,
+        headers: dict,
+        model: str,
+        messages: List[Any],
+        optional_params: dict,
+        litellm_params: dict,
+        api_key: Optional[str] = None,
+        api_base: Optional[str] = None,
+    ) -> Tuple[dict, Optional[str]]:
+        dynamic_api_key = self._get_api_key(api_key=api_key)
+        if dynamic_api_key and "x-api-key" not in headers:
+            headers["x-api-key"] = dynamic_api_key
+        if "content-type" not in headers:
+            headers["content-type"] = "application/json"
+
+        # DashScope's Anthropic-compatible endpoint does not accept Anthropic
+        # version/beta headers. Keep this provider-specific so other Anthropic
+        # Messages providers retain their existing behavior.
+        headers.pop("anthropic-version", None)
+        headers.pop("anthropic-beta", None)
+        return headers, api_base

litellm/utils.py

@@ -8301,6 +8301,12 @@ class ProviderConfigManager:
             )
 
             return DeepSeekAnthropicMessagesConfig()
+        elif litellm.LlmProviders.DASHSCOPE == provider:
+            from litellm.llms.dashscope.messages.transformation import (
+                DashScopeAnthropicMessagesConfig,
+            )
+
+            return DashScopeAnthropicMessagesConfig()
         elif litellm.LlmProviders.TENCENT == provider:
             from litellm.llms.tencent.messages.transformation import (
                 TencentAnthropicMessagesConfig,

tests/test_litellm/llms/dashscope/test_dashscope_messages_transformation.py

@@ -0,0 +1,92 @@
+"""
+Unit tests for DashScope Anthropic-compatible Messages support.
+"""
+
+from litellm.llms.dashscope.messages.transformation import (
+    DEFAULT_DASHSCOPE_ANTHROPIC_MESSAGES_API_BASE,
+    DashScopeAnthropicMessagesConfig,
+)
+from litellm.types.utils import LlmProviders
+from litellm.utils import ProviderConfigManager
+
+
+def test_should_map_dashscope_compatible_base_to_anthropic_messages_endpoint():
+    config = DashScopeAnthropicMessagesConfig()
+
+    assert (
+        config.get_complete_url(
+            api_base=None,
+            api_key=None,
+            model="qwen3-max",
+            optional_params={},
+            litellm_params={},
+        )
+        == DEFAULT_DASHSCOPE_ANTHROPIC_MESSAGES_API_BASE
+    )
+    assert (
+        config.get_complete_url(
+            api_base="https://dashscope.aliyuncs.com/compatible-mode/v1",
+            api_key=None,
+            model="qwen3-max",
+            optional_params={},
+            litellm_params={},
+        )
+        == "https://dashscope.aliyuncs.com/apps/anthropic/v1/messages"
+    )
+    assert (
+        config.get_complete_url(
+            api_base="https://dashscope-intl.aliyuncs.com/compatible-mode/v1/chat/completions",
+            api_key=None,
+            model="qwen3-max",
+            optional_params={},
+            litellm_params={},
+        )
+        == "https://dashscope-intl.aliyuncs.com/apps/anthropic/v1/messages"
+    )
+    assert (
+        config.get_complete_url(
+            api_base="https://dashscope.aliyuncs.com/apps/anthropic",
+            api_key=None,
+            model="qwen3-max",
+            optional_params={},
+            litellm_params={},
+        )
+        == "https://dashscope.aliyuncs.com/apps/anthropic/v1/messages"
+    )
+
+
+def test_should_prepare_dashscope_anthropic_messages_headers():
+    config = DashScopeAnthropicMessagesConfig()
+
+    headers, api_base = config.validate_anthropic_messages_environment(
+        headers={
+            "anthropic-version": "2023-06-01",
+            "anthropic-beta": "prompt-caching-2024-07-31",
+        },
+        model="qwen3-max",
+        messages=[{"role": "user", "content": "hello"}],
+        optional_params={},
+        litellm_params={},
+        api_key="dashscope-key",
+        api_base="https://dashscope.aliyuncs.com/compatible-mode/v1",
+    )
+
+    assert headers["x-api-key"] == "dashscope-key"
+    assert headers["content-type"] == "application/json"
+    assert "anthropic-version" not in headers
+    assert "anthropic-beta" not in headers
+    assert api_base == "https://dashscope.aliyuncs.com/compatible-mode/v1"
+
+
+def test_should_route_dashscope_provider_to_native_messages_config():
+    qwen_max_config = ProviderConfigManager.get_provider_anthropic_messages_config(
+        model="qwen3-max",
+        provider=LlmProviders.DASHSCOPE,
+    )
+    qwen_plus_config = ProviderConfigManager.get_provider_anthropic_messages_config(
+        model="qwen-plus",
+        provider=LlmProviders.DASHSCOPE,
+    )
+
+    assert isinstance(qwen_max_config, DashScopeAnthropicMessagesConfig)
+    assert isinstance(qwen_plus_config, DashScopeAnthropicMessagesConfig)