fix(anthropic): omit tool-streaming beta on MiniMax endpoints

MiniMax's Anthropic-compatible endpoints reject requests that include
the fine-grained-tool-streaming beta header — every tool-use message
triggers a connection error (~18s timeout). Regular chat works fine.

Add _common_betas_for_base_url() that filters out the tool-streaming
beta for Bearer-auth (MiniMax) endpoints while keeping all other betas.
All four client-construction branches now use the filtered list.

Based on #6528 by @HiddenPuppy.
Original cherry-picked from PR #6688 by kshitijk4poor.
Fixes #6510, fixes #6555.

agent/anthropic_adapter.py

@@ -95,6 +95,10 @@ _COMMON_BETAS = [
     "interleaved-thinking-2025-05-14",
     "fine-grained-tool-streaming-2025-05-14",
 ]
+# MiniMax's Anthropic-compatible endpoints fail tool-use requests when
+# the fine-grained tool streaming beta is present.  Omit it so tool calls
+# fall back to the provider's default response path.
+_TOOL_STREAMING_BETA = "fine-grained-tool-streaming-2025-05-14"
 
 # Additional beta headers required for OAuth/subscription auth.
 # Matches what Claude Code (and pi-ai / OpenCode) send.
@@ -204,6 +208,19 @@ def _requires_bearer_auth(base_url: str | None) -> bool:
     return normalized.startswith(("https://api.minimax.io/anthropic", "https://api.minimaxi.com/anthropic"))
 
 
+def _common_betas_for_base_url(base_url: str | None) -> list[str]:
+    """Return the beta headers that are safe for the configured endpoint.
+
+    MiniMax's Anthropic-compatible endpoints (Bearer-auth) reject requests
+    that include Anthropic's ``fine-grained-tool-streaming`` beta — every
+    tool-use message triggers a connection error.  Strip that beta for
+    Bearer-auth endpoints while keeping all other betas intact.
+    """
+    if _requires_bearer_auth(base_url):
+        return [b for b in _COMMON_BETAS if b != _TOOL_STREAMING_BETA]
+    return _COMMON_BETAS
+
+
 def build_anthropic_client(api_key: str, base_url: str = None):
     """Create an Anthropic client, auto-detecting setup-tokens vs API keys.
 
@@ -222,6 +239,7 @@ def build_anthropic_client(api_key: str, base_url: str = None):
     }
     if normalized_base_url:
         kwargs["base_url"] = normalized_base_url
+    common_betas = _common_betas_for_base_url(normalized_base_url)
 
     if _requires_bearer_auth(normalized_base_url):
         # Some Anthropic-compatible providers (e.g. MiniMax) expect the API key in
@@ -231,21 +249,21 @@ def build_anthropic_client(api_key: str, base_url: str = None):
         # not use Anthropic's sk-ant-api prefix and would otherwise be misread as
         # Anthropic OAuth/setup tokens.
         kwargs["auth_token"] = api_key
-        if _COMMON_BETAS:
+        if common_betas:
-            kwargs["default_headers"] = {"anthropic-beta": ",".join(_COMMON_BETAS)}
+            kwargs["default_headers"] = {"anthropic-beta": ",".join(common_betas)}
     elif _is_third_party_anthropic_endpoint(base_url):
         # Third-party proxies (Azure AI Foundry, AWS Bedrock, etc.) use their
         # own API keys with x-api-key auth. Skip OAuth detection — their keys
         # don't follow Anthropic's sk-ant-* prefix convention and would be
         # misclassified as OAuth tokens.
         kwargs["api_key"] = api_key
-        if _COMMON_BETAS:
+        if common_betas:
-            kwargs["default_headers"] = {"anthropic-beta": ",".join(_COMMON_BETAS)}
+            kwargs["default_headers"] = {"anthropic-beta": ",".join(common_betas)}
     elif _is_oauth_token(api_key):
         # OAuth access token / setup-token → Bearer auth + Claude Code identity.
         # Anthropic routes OAuth requests based on user-agent and headers;
         # without Claude Code's fingerprint, requests get intermittent 500s.
-        all_betas = _COMMON_BETAS + _OAUTH_ONLY_BETAS
+        all_betas = common_betas + _OAUTH_ONLY_BETAS
         kwargs["auth_token"] = api_key
         kwargs["default_headers"] = {
             "anthropic-beta": ",".join(all_betas),
@@ -255,8 +273,8 @@ def build_anthropic_client(api_key: str, base_url: str = None):
     else:
         # Regular API key → x-api-key header + common betas
         kwargs["api_key"] = api_key
-        if _COMMON_BETAS:
+        if common_betas:
-            kwargs["default_headers"] = {"anthropic-beta": ",".join(_COMMON_BETAS)}
+            kwargs["default_headers"] = {"anthropic-beta": ",".join(common_betas)}
 
     return _anthropic_sdk.Anthropic(**kwargs)
 

tests/agent/test_anthropic_adapter.py

@@ -81,6 +81,9 @@ class TestBuildAnthropicClient:
             build_anthropic_client("sk-ant-api03-x", base_url="https://custom.api.com")
             kwargs = mock_sdk.Anthropic.call_args[1]
             assert kwargs["base_url"] == "https://custom.api.com"
+            assert kwargs["default_headers"] == {
+                "anthropic-beta": "interleaved-thinking-2025-05-14,fine-grained-tool-streaming-2025-05-14"
+            }
 
     def test_minimax_anthropic_endpoint_uses_bearer_auth_for_regular_api_keys(self):
         with patch("agent.anthropic_adapter._anthropic_sdk") as mock_sdk:
@@ -92,7 +95,20 @@ class TestBuildAnthropicClient:
             assert kwargs["auth_token"] == "minimax-secret-123"
             assert "api_key" not in kwargs
             assert kwargs["default_headers"] == {
-                "anthropic-beta": "interleaved-thinking-2025-05-14,fine-grained-tool-streaming-2025-05-14"
+                "anthropic-beta": "interleaved-thinking-2025-05-14"
+            }
+
+    def test_minimax_cn_anthropic_endpoint_omits_tool_streaming_beta(self):
+        with patch("agent.anthropic_adapter._anthropic_sdk") as mock_sdk:
+            build_anthropic_client(
+                "minimax-cn-secret-123",
+                base_url="https://api.minimaxi.com/anthropic",
+            )
+            kwargs = mock_sdk.Anthropic.call_args[1]
+            assert kwargs["auth_token"] == "minimax-cn-secret-123"
+            assert "api_key" not in kwargs
+            assert kwargs["default_headers"] == {
+                "anthropic-beta": "interleaved-thinking-2025-05-14"
             }
 
 

tests/agent/test_minimax_provider.py

@@ -1,4 +1,6 @@
-"""Tests for MiniMax provider hardening — context lengths, thinking guard, catalog."""
+"""Tests for MiniMax provider hardening — context lengths, thinking guard, catalog, beta headers."""
+
+from unittest.mock import patch
 
 
 class TestMinimaxContextLengths:
@@ -103,3 +105,100 @@ class TestMinimaxModelCatalog:
             models = _PROVIDER_MODELS[provider]
             assert "MiniMax-M2.7-highspeed" not in models
             assert "MiniMax-M2.5-highspeed" not in models
+
+
+class TestMinimaxBetaHeaders:
+    """MiniMax Anthropic-compat endpoints reject fine-grained-tool-streaming beta.
+
+    Verify that build_anthropic_client omits the tool-streaming beta for MiniMax
+    (both global and China domains) while keeping it for native Anthropic and
+    other third-party endpoints.  Covers the fix for #6510 / #6555.
+    """
+
+    _TOOL_BETA = "fine-grained-tool-streaming-2025-05-14"
+    _THINKING_BETA = "interleaved-thinking-2025-05-14"
+
+    # -- helper ----------------------------------------------------------
+
+    def _build_and_get_betas(self, api_key, base_url=None):
+        """Build client, return the anthropic-beta header string."""
+        from agent.anthropic_adapter import build_anthropic_client
+        with patch("agent.anthropic_adapter._anthropic_sdk") as mock_sdk:
+            build_anthropic_client(api_key, base_url=base_url)
+            kwargs = mock_sdk.Anthropic.call_args[1]
+            headers = kwargs.get("default_headers", {})
+            return headers.get("anthropic-beta", "")
+
+    # -- MiniMax global --------------------------------------------------
+
+    def test_minimax_global_omits_tool_streaming(self):
+        betas = self._build_and_get_betas(
+            "mm-key-123", base_url="https://api.minimax.io/anthropic"
+        )
+        assert self._TOOL_BETA not in betas
+        assert self._THINKING_BETA in betas
+
+    def test_minimax_global_trailing_slash(self):
+        betas = self._build_and_get_betas(
+            "mm-key-123", base_url="https://api.minimax.io/anthropic/"
+        )
+        assert self._TOOL_BETA not in betas
+
+    # -- MiniMax China ---------------------------------------------------
+
+    def test_minimax_cn_omits_tool_streaming(self):
+        betas = self._build_and_get_betas(
+            "mm-cn-key-456", base_url="https://api.minimaxi.com/anthropic"
+        )
+        assert self._TOOL_BETA not in betas
+        assert self._THINKING_BETA in betas
+
+    def test_minimax_cn_trailing_slash(self):
+        betas = self._build_and_get_betas(
+            "mm-cn-key-456", base_url="https://api.minimaxi.com/anthropic/"
+        )
+        assert self._TOOL_BETA not in betas
+
+    # -- Non-MiniMax keeps full betas ------------------------------------
+
+    def test_native_anthropic_keeps_tool_streaming(self):
+        betas = self._build_and_get_betas("sk-ant-api03-real-key-here")
+        assert self._TOOL_BETA in betas
+        assert self._THINKING_BETA in betas
+
+    def test_third_party_proxy_keeps_tool_streaming(self):
+        betas = self._build_and_get_betas(
+            "custom-key", base_url="https://my-proxy.example.com/anthropic"
+        )
+        assert self._TOOL_BETA in betas
+
+    def test_custom_base_url_keeps_tool_streaming(self):
+        betas = self._build_and_get_betas(
+            "custom-key", base_url="https://custom.api.com"
+        )
+        assert self._TOOL_BETA in betas
+
+    # -- _common_betas_for_base_url unit tests ---------------------------
+
+    def test_common_betas_none_url(self):
+        from agent.anthropic_adapter import _common_betas_for_base_url, _COMMON_BETAS
+        assert _common_betas_for_base_url(None) == _COMMON_BETAS
+
+    def test_common_betas_empty_url(self):
+        from agent.anthropic_adapter import _common_betas_for_base_url, _COMMON_BETAS
+        assert _common_betas_for_base_url("") == _COMMON_BETAS
+
+    def test_common_betas_minimax_url(self):
+        from agent.anthropic_adapter import _common_betas_for_base_url, _TOOL_STREAMING_BETA
+        betas = _common_betas_for_base_url("https://api.minimax.io/anthropic")
+        assert _TOOL_STREAMING_BETA not in betas
+        assert len(betas) > 0  # still has other betas
+
+    def test_common_betas_minimax_cn_url(self):
+        from agent.anthropic_adapter import _common_betas_for_base_url, _TOOL_STREAMING_BETA
+        betas = _common_betas_for_base_url("https://api.minimaxi.com/anthropic")
+        assert _TOOL_STREAMING_BETA not in betas
+
+    def test_common_betas_regular_url(self):
+        from agent.anthropic_adapter import _common_betas_for_base_url, _COMMON_BETAS
+        assert _common_betas_for_base_url("https://api.anthropic.com") == _COMMON_BETAS