fix(bedrock): route non-Claude auxiliary models through Converse API

Auxiliary Bedrock resolution always used the Anthropic Bedrock SDK, which
only works for Claude foundation-model IDs. Non-Claude models such as
openai.gpt-oss-20b-1:0 now use a Bedrock Converse adapter, matching the
main agent's bedrock_converse transport.

agent/auxiliary_client.py

@@ -1356,6 +1356,74 @@ class AsyncAnthropicAuxiliaryClient:
         self._real_client = sync_wrapper._real_client
 
 
+class _BedrockCompletionsAdapter:
+    """Translates ``chat.completions.create(**kwargs)`` into Bedrock Converse."""
+
+    def __init__(self, region: str, model: str):
+        self._region = region
+        self._model = model
+
+    def create(self, **kwargs) -> Any:
+        from agent.bedrock_adapter import call_converse
+
+        messages = kwargs.get("messages", [])
+        model = kwargs.get("model", self._model)
+        max_tokens = kwargs.get("max_tokens") or kwargs.get("max_completion_tokens")
+        return call_converse(
+            region=self._region,
+            model=model,
+            messages=messages,
+            tools=kwargs.get("tools"),
+            max_tokens=int(max_tokens) if max_tokens else 4096,
+            temperature=kwargs.get("temperature"),
+            top_p=kwargs.get("top_p"),
+            stop_sequences=kwargs.get("stop"),
+        )
+
+
+class _BedrockChatShim:
+    def __init__(self, adapter: "_BedrockCompletionsAdapter"):
+        self.completions = adapter
+
+
+class BedrockAuxiliaryClient:
+    """OpenAI-client-compatible wrapper over AWS Bedrock Converse API."""
+
+    def __init__(self, region: str, model: str):
+        self._region = region
+        self._model = model
+        adapter = _BedrockCompletionsAdapter(region, model)
+        self.chat = _BedrockChatShim(adapter)
+        self.api_key = "aws-sdk"
+        self.base_url = f"https://bedrock-runtime.{region}.amazonaws.com"
+
+    def close(self):
+        pass
+
+
+class _AsyncBedrockCompletionsAdapter:
+    def __init__(self, sync_adapter: _BedrockCompletionsAdapter):
+        self._sync = sync_adapter
+
+    async def create(self, **kwargs) -> Any:
+        import asyncio
+        return await asyncio.to_thread(self._sync.create, **kwargs)
+
+
+class _AsyncBedrockChatShim:
+    def __init__(self, adapter: _AsyncBedrockCompletionsAdapter):
+        self.completions = adapter
+
+
+class AsyncBedrockAuxiliaryClient:
+    def __init__(self, sync_wrapper: "BedrockAuxiliaryClient"):
+        sync_adapter = sync_wrapper.chat.completions
+        async_adapter = _AsyncBedrockCompletionsAdapter(sync_adapter)
+        self.chat = _AsyncBedrockChatShim(async_adapter)
+        self.api_key = sync_wrapper.api_key
+        self.base_url = sync_wrapper.base_url
+
+
 def _endpoint_speaks_anthropic_messages(base_url: str) -> bool:
     """True if the endpoint at ``base_url`` speaks the Anthropic Messages
     protocol instead of OpenAI chat.completions.
@@ -1411,6 +1479,8 @@ def _maybe_wrap_anthropic(
     # Already wrapped — don't double-wrap.
     if _safe_isinstance(client_obj, AnthropicAuxiliaryClient):
         return client_obj
+    if _safe_isinstance(client_obj, BedrockAuxiliaryClient):
+        return client_obj
     # Other specialized adapters we should never re-dispatch.
     if _safe_isinstance(client_obj, CodexAuxiliaryClient):
         return client_obj
@@ -4204,6 +4274,8 @@ def _to_async_client(sync_client, model: str, is_vision: bool = False):
         return AsyncCodexAuxiliaryClient(sync_client), model
     if isinstance(sync_client, AnthropicAuxiliaryClient):
         return AsyncAnthropicAuxiliaryClient(sync_client), model
+    if isinstance(sync_client, BedrockAuxiliaryClient):
+        return AsyncBedrockAuxiliaryClient(sync_client), model
     try:
         from agent.gemini_native_adapter import GeminiNativeClient, AsyncGeminiNativeClient
 
@@ -4943,10 +5015,14 @@ def resolve_provider_client(
                 else (client, final_model))
 
     elif pconfig.auth_type == "aws_sdk":
-        # AWS SDK providers (Bedrock) — use the Anthropic Bedrock client via
-        # boto3's credential chain (IAM roles, SSO, env vars, instance metadata).
+        # AWS SDK providers (Bedrock) — Claude models use the Anthropic Bedrock
+        # SDK (prompt caching, thinking); non-Claude models use Converse API.
         try:
-            from agent.bedrock_adapter import has_aws_credentials, resolve_bedrock_region
+            from agent.bedrock_adapter import (
+                has_aws_credentials,
+                is_anthropic_bedrock_model,
+                resolve_bedrock_region,
+            )
             from agent.anthropic_adapter import build_anthropic_bedrock_client
         except ImportError:
             logger.warning("resolve_provider_client: bedrock requested but "
@@ -4961,17 +5037,26 @@ def resolve_provider_client(
         region = resolve_bedrock_region()
         default_model = "anthropic.claude-haiku-4-5-20251001-v1:0"
         final_model = _normalize_resolved_model(model or default_model, provider)
-        try:
-            real_client = build_anthropic_bedrock_client(region)
-        except ImportError as exc:
-            logger.warning("resolve_provider_client: cannot create Bedrock "
-                           "client: %s", exc)
-            return None, None
-        client = AnthropicAuxiliaryClient(
-            real_client, final_model, api_key="aws-sdk",
-            base_url=f"https://bedrock-runtime.{region}.amazonaws.com",
-        )
-        logger.debug("resolve_provider_client: bedrock (%s, %s)", final_model, region)
+        base_url = f"https://bedrock-runtime.{region}.amazonaws.com"
+
+        if is_anthropic_bedrock_model(final_model):
+            try:
+                real_client = build_anthropic_bedrock_client(region)
+            except ImportError as exc:
+                logger.warning("resolve_provider_client: cannot create Bedrock "
+                               "client: %s", exc)
+                return None, None
+            client = AnthropicAuxiliaryClient(
+                real_client, final_model, api_key="aws-sdk",
+                base_url=base_url,
+            )
+            logger.debug("resolve_provider_client: bedrock anthropic (%s, %s)",
+                         final_model, region)
+        else:
+            client = BedrockAuxiliaryClient(region, final_model)
+            logger.debug("resolve_provider_client: bedrock converse (%s, %s)",
+                         final_model, region)
+
         return (_to_async_client(client, final_model, is_vision=is_vision) if async_mode
                 else (client, final_model))