providers: plumb anthropic base_url + surface MiniMax-M3

coworker/providers/anthropic_provider.py

@@ -345,15 +345,20 @@ def __init__(
         *,
         default_model: str = "claude-sonnet-4-6",
         api_key: Optional[str] = None,
+        base_url: Optional[str] = None,
         secrets: Any = None,
         thinking_budget: Optional[int] = None,
     ):
         # Mirrors OpenAIProvider: the SDK client is built lazily so engines can be assembled
         # before any key exists; the key resolves at call time (explicit → env → SecretStore).
         # Tests inject a `client` directly. `thinking_budget` (tokens, from the provider
         # profile's optional field) opts every request into extended thinking.
+        # `base_url` points the same SDK at any Anthropic-protocol-compatible gateway (e.g.
+        # a third-party Claude/MiniMax endpoint at https://api.<vendor>/anthropic). When None,
+        # behavior is identical to stock Anthropic (api.anthropic.com).
         self._client = client
         self._api_key = api_key
+        self._base_url = base_url
         self._secrets = secrets
         self.default_model = default_model
         self.thinking_budget = thinking_budget or 0
@@ -369,7 +374,10 @@ def _ensure_client(self) -> Any:
                     "No Anthropic API key configured. Set ANTHROPIC_API_KEY in the environment, "
                     "or add your key in Manage → Configure Models."
                 )
-            self._client = Anthropic(api_key=key)
+            kwargs: dict[str, Any] = {"api_key": key}
+            if self._base_url:
+                kwargs["base_url"] = self._base_url
+            self._client = Anthropic(**kwargs)
         return self._client
 
     def _request_kwargs(

coworker/providers/matrix.py

@@ -85,6 +85,7 @@ class ModelEntry:
     "deepseek:deepseek-v4-pro": ModelEntry("DeepSeek V4 Pro · DeepSeek"),
     "kimi:kimi-k2.6": ModelEntry("Kimi K2.6 · Moonshot"),
     "minimax:MiniMax-M2.5": ModelEntry("MiniMax M2.5 · MiniMax"),
+    "minimax:MiniMax-M3": ModelEntry("MiniMax M3 · MiniMax"),
     "qwen:qwen3-max": ModelEntry("Qwen3 Max · Alibaba"),
     "xai:grok-4.3": ModelEntry("Grok 4.3 · xAI"),
     "mistral:mistral-large-latest": ModelEntry("Mistral Large · Mistral"),

coworker/providers/registry.py

@@ -108,15 +108,21 @@ def _build_anthropic(profile: dict[str, Any], secrets: Any) -> ProviderClient:
     # deferred to first call so the provider can be built before a key exists.
     # thinking_budget: hidden profile override — absent/invalid → the default (ON),
     # explicit 0 → off (see DEFAULT_THINKING_BUDGET).
+    # base_url (optional): points the same Anthropic SDK at any Anthropic-protocol gateway
+    # (e.g. a third-party Claude/MiniMax endpoint). None → stock api.anthropic.com.
     from .anthropic_provider import DEFAULT_THINKING_BUDGET
 
     api_key = ((profile or {}).get("api_key") or "").strip() or None
+    base_url = ((profile or {}).get("base_url") or "").strip() or None
     try:
         thinking_budget = int(str((profile or {}).get("thinking_budget") or "").strip())
     except ValueError:
         thinking_budget = DEFAULT_THINKING_BUDGET
     return AnthropicProvider(
-        api_key=api_key, secrets=secrets, thinking_budget=thinking_budget
+        api_key=api_key,
+        base_url=base_url,
+        secrets=secrets,
+        thinking_budget=thinking_budget,
     )
 
 
@@ -229,6 +235,14 @@ def _compat(
                 secret=True,
                 placeholder="sk-ant-…",
             ),
+            ProviderField(
+                "base_url",
+                "Endpoint (optional)",
+                secret=False,
+                required=False,
+                placeholder="https://api.anthropic.com",
+                help="Leave blank for api.anthropic.com, or point at any Anthropic-protocol-compatible gateway (e.g. a third-party Claude/MiniMax endpoint).",
+            ),
             # No thinking_budget field (owner call 2026-07-23): extended thinking is
             # on by default; the profile key stays a hidden override (0 = off).
         ],
@@ -410,8 +424,13 @@ def verify_provider_key(
     key = (api_key or "").strip()
     try:
         if name == "anthropic":
+            # Honor a custom `base_url` so Settings → Test can probe third-party
+            # Anthropic-protocol gateways (e.g. a MiniMax-Claude endpoint). Strip a
+            # trailing slash and rely on the SDK's /v1 path default; fall back to
+            # stock api.anthropic.com when no override is set.
+            base = ((base_url or "").strip().rstrip("/") or "https://api.anthropic.com")
             resp = httpx.get(
-                "https://api.anthropic.com/v1/models",
+                base + "/v1/models",
                 headers={"x-api-key": key, "anthropic-version": "2023-06-01"},
                 timeout=timeout,
             )