refactor(provider): simplify litellm capabilities

src/langbot/pkg/pipeline/preproc/preproc.py

@@ -109,7 +109,7 @@ class PreProcessor(stage.PipelineStage):
             if llm_model:
                 query.use_llm_model_uuid = llm_model.model_entity.uuid
 
-                if llm_model.model_entity.abilities.__contains__('func_call'):
+                if 'func_call' in (llm_model.model_entity.abilities or []):
                     # Get bound plugins and MCP servers for filtering tools
                     bound_plugins = query.variables.get('_pipeline_bound_plugins', None)
                     bound_mcp_servers = query.variables.get('_pipeline_bound_mcp_servers', None)
@@ -162,7 +162,7 @@ class PreProcessor(stage.PipelineStage):
         if (
             selected_runner == 'local-agent'
             and llm_model
-            and not llm_model.model_entity.abilities.__contains__('vision')
+            and 'vision' not in (llm_model.model_entity.abilities or [])
         ):
             for msg in query.messages:
                 if isinstance(msg.content, list):
@@ -181,7 +181,7 @@ class PreProcessor(stage.PipelineStage):
                 plain_text += me.text
             elif isinstance(me, platform_message.Image):
                 if selected_runner != 'local-agent' or (
-                    llm_model and llm_model.model_entity.abilities.__contains__('vision')
+                    llm_model and 'vision' in (llm_model.model_entity.abilities or [])
                 ):
                     if me.base64 is not None:
                         content_list.append(provider_message.ContentElement.from_image_base64(me.base64))
@@ -202,7 +202,7 @@ class PreProcessor(stage.PipelineStage):
                         content_list.append(provider_message.ContentElement.from_text(msg.text))
                     elif isinstance(msg, platform_message.Image):
                         if selected_runner != 'local-agent' or (
-                            llm_model and llm_model.model_entity.abilities.__contains__('vision')
+                            llm_model and 'vision' in (llm_model.model_entity.abilities or [])
                         ):
                             if msg.base64 is not None:
                                 content_list.append(provider_message.ContentElement.from_image_base64(msg.base64))

src/langbot/pkg/provider/modelmgr/modelmgr.py

@@ -37,16 +37,39 @@ class ModelManager:
         self.requester_components = []
         self.requester_dict = {}
 
+    @staticmethod
+    def _get_litellm_provider_from_manifest(component: engine.Component | None) -> str | None:
+        if component is None:
+            return None
+
+        spec = getattr(component, 'spec', None) or {}
+        litellm_provider = None
+
+        if isinstance(spec, dict):
+            litellm_provider = spec.get('litellm_provider')
+        else:
+            getter = getattr(spec, 'get', None)
+            if callable(getter):
+                try:
+                    litellm_provider = getter('litellm_provider')
+                except Exception:
+                    litellm_provider = None
+
+        if isinstance(litellm_provider, str) and litellm_provider:
+            return litellm_provider
+        return None
+
     async def initialize(self):
         self.requester_components = self.ap.discover.get_components_by_kind('LLMAPIRequester')
 
         requester_dict: dict[str, type[requester.ProviderAPIRequester]] = {}
         for component in self.requester_components:
             # Skip components that use litellm_provider (they will use litellmchat.py instead)
-            if component.spec.get('litellm_provider'):
+            litellm_provider = self._get_litellm_provider_from_manifest(component)
+            if litellm_provider:
                 self.ap.logger.debug(
                     f'Skipping Python class loading for {component.metadata.name} '
-                    f'(uses litellm_provider={component.spec.get("litellm_provider")})'
+                    f'(uses litellm_provider={litellm_provider})'
                 )
                 continue
             requester_dict[component.metadata.name] = component.get_python_component_class()
@@ -303,17 +326,18 @@ class ModelManager:
 
         # Get requester manifest to check for litellm_provider
         requester_manifest = self.get_available_requester_manifest_by_name(provider_entity.requester)
+        litellm_provider = self._get_litellm_provider_from_manifest(requester_manifest)
 
         # Build config from base_url
         config = {'base_url': provider_entity.base_url}
 
         # Check if requester manifest specifies litellm_provider
-        if requester_manifest and requester_manifest.spec.get('litellm_provider'):
+        if litellm_provider:
             from .requesters import litellmchat
 
             # Use unified LiteLLMRequester with provider prefix
             # Map litellm_provider (YAML spec) to custom_llm_provider (config)
-            config['custom_llm_provider'] = requester_manifest.spec['litellm_provider']
+            config['custom_llm_provider'] = litellm_provider
             requester_inst = litellmchat.LiteLLMRequester(
                 ap=self.ap,
                 config=config,

src/langbot/pkg/provider/modelmgr/requesters/litellmchat.py

@@ -16,6 +16,9 @@ import langbot_plugin.api.entities.builtin.provider.message as provider_message
 class LiteLLMRequester(requester.ProviderAPIRequester):
     """LiteLLM unified API requester supporting chat, embedding, and rerank."""
 
+    _EMBEDDING_MODEL_HINTS = ('embedding', 'embed', 'bge-', 'e5-', 'm3e', 'gte-', 'text-embedding')
+    _RERANK_MODEL_HINTS = ('rerank', 're-rank', 're_rank')
+
     default_config: dict[str, typing.Any] = {
         'base_url': '',
         'timeout': 120,
@@ -36,10 +39,90 @@ class LiteLLMRequester(requester.ProviderAPIRequester):
         provider = custom_llm_provider or self.requester_cfg.get('custom_llm_provider', '')
         if provider:
             # LiteLLM format: provider/model_name
+            if model_name.startswith(f'{provider}/'):
+                return model_name
             return f'{provider}/{model_name}'
         # If no custom provider, assume model_name already includes prefix or is OpenAI-compatible
         return model_name
 
+    def _get_custom_llm_provider(self) -> str | None:
+        return self.requester_cfg.get('custom_llm_provider') or None
+
+    def _safe_litellm_bool_helper(self, helper_name: str, model_name: str) -> bool:
+        """Call a LiteLLM boolean capability helper without letting metadata gaps fail requests."""
+        helper = getattr(litellm, helper_name, None)
+        if not callable(helper):
+            return False
+
+        provider = self._get_custom_llm_provider()
+        candidates: list[tuple[str, str | None]] = [(model_name, provider)]
+        litellm_model_name = self._build_litellm_model_name(model_name)
+        if litellm_model_name != model_name:
+            candidates.append((litellm_model_name, None))
+
+        for candidate_model, candidate_provider in candidates:
+            try:
+                if bool(helper(model=candidate_model, custom_llm_provider=candidate_provider)):
+                    return True
+            except Exception:
+                continue
+        return False
+
+    def _safe_context_length(self, model_name: str) -> int | None:
+        helper = getattr(litellm, 'get_max_tokens', None)
+        if not callable(helper):
+            return None
+
+        candidates = [model_name]
+        litellm_model_name = self._build_litellm_model_name(model_name)
+        if litellm_model_name != model_name:
+            candidates.append(litellm_model_name)
+
+        for candidate in candidates:
+            try:
+                max_tokens = helper(candidate)
+            except Exception:
+                continue
+            if isinstance(max_tokens, int) and max_tokens > 0:
+                return max_tokens
+        return None
+
+    def _supports_function_calling(self, model_name: str) -> bool:
+        return self._safe_litellm_bool_helper('supports_function_calling', model_name)
+
+    def _supports_vision(self, model_name: str) -> bool:
+        return self._safe_litellm_bool_helper('supports_vision', model_name)
+
+    def _infer_model_type(self, model_id: str) -> str:
+        normalized_id = (model_id or '').lower()
+        if any(kw in normalized_id for kw in self._RERANK_MODEL_HINTS):
+            return 'rerank'
+        if any(kw in normalized_id for kw in self._EMBEDDING_MODEL_HINTS):
+            return 'embedding'
+        return 'llm'
+
+    def _enrich_scanned_model(self, model_id: str) -> dict[str, typing.Any]:
+        model_type = self._infer_model_type(model_id)
+        scanned_model: dict[str, typing.Any] = {
+            'id': model_id,
+            'name': model_id,
+            'type': model_type,
+        }
+
+        if model_type == 'llm':
+            abilities = []
+            if self._supports_function_calling(model_id):
+                abilities.append('func_call')
+            if self._supports_vision(model_id):
+                abilities.append('vision')
+            scanned_model['abilities'] = abilities
+
+            context_length = self._safe_context_length(model_id)
+            if context_length is not None:
+                scanned_model['context_length'] = context_length
+
+        return scanned_model
+
     def _convert_messages(self, messages: typing.List[provider_message.Message]) -> list[dict]:
         """Convert LangBot messages to LiteLLM/OpenAI format."""
         req_messages = []
@@ -121,6 +204,64 @@ class LiteLLMRequester(requester.ProviderAPIRequester):
         """Extract usage info from a non-streaming LiteLLM response."""
         return self._normalize_usage(getattr(response, 'usage', None))
 
+    @staticmethod
+    def _as_dict(value: typing.Any) -> dict:
+        if value is None:
+            return {}
+        if isinstance(value, dict):
+            return value
+        if hasattr(value, 'model_dump'):
+            return value.model_dump()
+        return {}
+
+    def _normalize_stream_tool_calls(
+        self,
+        raw_tool_calls: typing.Any,
+        tool_call_state: dict[int, dict[str, str]],
+    ) -> list[dict] | None:
+        """Fill OpenAI-style streaming tool-call deltas so MessageChunk can validate them."""
+        if not raw_tool_calls:
+            return None
+
+        normalized = []
+        for fallback_index, raw_tool_call in enumerate(raw_tool_calls):
+            tool_call = self._as_dict(raw_tool_call)
+            index = tool_call.get('index')
+            if not isinstance(index, int):
+                index = fallback_index
+
+            state = tool_call_state.setdefault(index, {'id': '', 'type': 'function', 'name': ''})
+            if tool_call.get('id'):
+                state['id'] = tool_call['id']
+            if tool_call.get('type'):
+                state['type'] = tool_call['type']
+
+            function = self._as_dict(tool_call.get('function'))
+            if function.get('name'):
+                state['name'] = function['name']
+
+            arguments = function.get('arguments')
+            if arguments is None:
+                arguments = ''
+            elif not isinstance(arguments, str):
+                arguments = str(arguments)
+
+            if not state['id'] or not state['name']:
+                continue
+
+            normalized.append(
+                {
+                    'id': state['id'],
+                    'type': state['type'] or 'function',
+                    'function': {
+                        'name': state['name'],
+                        'arguments': arguments,
+                    },
+                }
+            )
+
+        return normalized or None
+
     def _build_common_args(self, args: dict, include_retry_params: bool = True) -> dict:
         """Apply common requester config to args dict."""
         if self.requester_cfg.get('base_url'):
@@ -189,6 +330,7 @@ class LiteLLMRequester(requester.ProviderAPIRequester):
             tools = await self.ap.tool_mgr.generate_tools_for_openai(funcs)
             if tools:
                 args['tools'] = tools
+                args.setdefault('tool_choice', 'auto')
 
         return args
 
@@ -240,6 +382,7 @@ class LiteLLMRequester(requester.ProviderAPIRequester):
 
         chunk_idx = 0
         role = 'assistant'
+        tool_call_state: dict[int, dict[str, str]] = {}
 
         try:
             response = await acompletion(**args)
@@ -283,14 +426,16 @@ class LiteLLMRequester(requester.ProviderAPIRequester):
                         # Use reasoning_content as the displayed content
                         delta_content = reasoning_content
 
-                if chunk_idx == 0 and not delta_content and not delta.get('tool_calls'):
+                tool_calls = self._normalize_stream_tool_calls(delta.get('tool_calls'), tool_call_state)
+
+                if chunk_idx == 0 and not delta_content and not tool_calls:
                     chunk_idx += 1
                     continue
 
                 chunk_data = {
                     'role': role,
                     'content': delta_content if delta_content else None,
-                    'tool_calls': delta.get('tool_calls'),
+                    'tool_calls': tool_calls,
                     'is_final': bool(finish_reason),
                 }
 
@@ -412,18 +557,7 @@ class LiteLLMRequester(requester.ProviderAPIRequester):
                 if not model_id:
                     continue
 
-                # Infer model type
-                normalized_id = (model_id or '').lower()
-                embedding_keywords = ('embedding', 'embed', 'bge-', 'e5-', 'm3e', 'gte-', 'text-embedding')
-                model_type = 'embedding' if any(kw in normalized_id for kw in embedding_keywords) else 'llm'
-
-                models.append(
-                    {
-                        'id': model_id,
-                        'name': model_id,
-                        'type': model_type,
-                    }
-                )
+                models.append(self._enrich_scanned_model(model_id))
 
             models.sort(key=lambda x: (x['type'] != 'llm', x['name'].lower()))
 

src/langbot/pkg/provider/runners/localagent.py

@@ -41,6 +41,64 @@ SANDBOX_EXEC_SYSTEM_GUIDANCE = (
 MAX_TOOL_CALL_ROUNDS = 128
 
 
+def _model_has_ability(model: modelmgr_requester.RuntimeLLMModel, ability: str) -> bool:
+    return ability in (model.model_entity.abilities or [])
+
+
+class _StreamAccumulator:
+    """Accumulate streamed content and fragmented OpenAI-style tool calls."""
+
+    def __init__(self, msg_sequence: int = 0, initial_content: str | None = None):
+        self.tool_calls_map: dict[str, provider_message.ToolCall] = {}
+        self.msg_idx = 0
+        self.accumulated_content = initial_content or ''
+        self.last_role = 'assistant'
+        self.msg_sequence = msg_sequence
+
+    def add(self, msg: provider_message.MessageChunk) -> provider_message.MessageChunk | None:
+        self.msg_idx += 1
+
+        if msg.role:
+            self.last_role = msg.role
+
+        if msg.content:
+            self.accumulated_content += msg.content
+
+        if msg.tool_calls:
+            for tool_call in msg.tool_calls:
+                if tool_call.id not in self.tool_calls_map:
+                    self.tool_calls_map[tool_call.id] = provider_message.ToolCall(
+                        id=tool_call.id,
+                        type=tool_call.type,
+                        function=provider_message.FunctionCall(
+                            name=tool_call.function.name if tool_call.function else '',
+                            arguments='',
+                        ),
+                    )
+                if tool_call.function and tool_call.function.arguments:
+                    self.tool_calls_map[tool_call.id].function.arguments += tool_call.function.arguments
+
+        if self.msg_idx % 8 == 0 or msg.is_final:
+            self.msg_sequence += 1
+            return provider_message.MessageChunk(
+                role=self.last_role,
+                content=self.accumulated_content,
+                tool_calls=list(self.tool_calls_map.values()) if (self.tool_calls_map and msg.is_final) else None,
+                is_final=msg.is_final,
+                msg_sequence=self.msg_sequence,
+            )
+
+        return None
+
+    def final_message(self) -> provider_message.MessageChunk:
+        return provider_message.MessageChunk(
+            role=self.last_role,
+            content=self.accumulated_content,
+            tool_calls=list(self.tool_calls_map.values()) if self.tool_calls_map else None,
+            msg_sequence=self.msg_sequence,
+        )
+
+
 @runner.runner_class('local-agent')
 class LocalAgentRunner(runner.RequestRunner):
     """Local agent request runner"""
@@ -105,7 +163,7 @@ class LocalAgentRunner(runner.RequestRunner):
                     query,
                     model,
                     messages,
-                    funcs if model.model_entity.abilities.__contains__('func_call') else [],
+                    funcs if _model_has_ability(model, 'func_call') else [],
                     extra_args=model.model_entity.extra_args,
                     remove_think=remove_think,
                 )
@@ -135,7 +193,7 @@ class LocalAgentRunner(runner.RequestRunner):
                     query,
                     model,
                     messages,
-                    funcs if model.model_entity.abilities.__contains__('func_call') else [],
+                    funcs if _model_has_ability(model, 'func_call') else [],
                     extra_args=model.model_entity.extra_args,
                     remove_think=remove_think,
                 )
@@ -302,11 +360,7 @@ class LocalAgentRunner(runner.RequestRunner):
             final_msg = msg
         else:
             # Streaming: invoke with fallback
-            tool_calls_map: dict[str, provider_message.ToolCall] = {}
-            msg_idx = 0
-            accumulated_content = ''
-            last_role = 'assistant'
-            msg_sequence = 1
+            stream_accumulator = _StreamAccumulator(msg_sequence=1)
 
             stream_src, use_llm_model = await self._invoke_stream_with_fallback(
                 query,
@@ -316,44 +370,12 @@ class LocalAgentRunner(runner.RequestRunner):
                 remove_think,
             )
             async for msg in stream_src:
-                msg_idx = msg_idx + 1
-
-                if msg.role:
-                    last_role = msg.role
-
-                if msg.content:
-                    accumulated_content += msg.content
-
-                if msg.tool_calls:
-                    for tool_call in msg.tool_calls:
-                        if tool_call.id not in tool_calls_map:
-                            tool_calls_map[tool_call.id] = provider_message.ToolCall(
-                                id=tool_call.id,
-                                type=tool_call.type,
-                                function=provider_message.FunctionCall(
-                                    name=tool_call.function.name if tool_call.function else '', arguments=''
-                                ),
-                            )
-                        if tool_call.function and tool_call.function.arguments:
-                            tool_calls_map[tool_call.id].function.arguments += tool_call.function.arguments
-
-                if msg_idx % 8 == 0 or msg.is_final:
-                    msg_sequence += 1
-                    yield provider_message.MessageChunk(
-                        role=last_role,
-                        content=accumulated_content,
-                        tool_calls=list(tool_calls_map.values()) if (tool_calls_map and msg.is_final) else None,
-                        is_final=msg.is_final,
-                        msg_sequence=msg_sequence,
-                    )
+                chunk = stream_accumulator.add(msg)
+                if chunk:
+                    yield chunk
                     initial_response_emitted = True
 
-            final_msg = provider_message.MessageChunk(
-                role=last_role,
-                content=accumulated_content,
-                tool_calls=list(tool_calls_map.values()) if tool_calls_map else None,
-                msg_sequence=msg_sequence,
-            )
+            final_msg = stream_accumulator.final_message()
 
         pending_tool_calls = final_msg.tool_calls
         first_content = final_msg.content
@@ -438,69 +460,36 @@ class LocalAgentRunner(runner.RequestRunner):
             )
 
             if is_stream:
-                tool_calls_map = {}
-                msg_idx = 0
-                accumulated_content = ''
-                last_role = 'assistant'
-                msg_sequence = first_end_sequence
+                stream_accumulator = _StreamAccumulator(
+                    msg_sequence=first_end_sequence,
+                    initial_content=first_content,
+                )
 
                 tool_stream_src = use_llm_model.provider.invoke_llm_stream(
                     query,
                     use_llm_model,
                     req_messages,
-                    query.use_funcs if use_llm_model.model_entity.abilities.__contains__('func_call') else [],
+                    query.use_funcs
+                    if _model_has_ability(use_llm_model, 'func_call')
+                    else [],
                     extra_args=use_llm_model.model_entity.extra_args,
                     remove_think=remove_think,
                 )
                 async for msg in tool_stream_src:
-                    msg_idx += 1
+                    chunk = stream_accumulator.add(msg)
+                    if chunk:
+                        yield chunk
 
-                    if msg.role:
-                        last_role = msg.role
-
-                    # Prepend first-round content on first chunk of tool-call round
-                    if msg_idx == 1:
-                        accumulated_content = first_content if first_content is not None else accumulated_content
-
-                    if msg.content:
-                        accumulated_content += msg.content
-
-                    if msg.tool_calls:
-                        for tool_call in msg.tool_calls:
-                            if tool_call.id not in tool_calls_map:
-                                tool_calls_map[tool_call.id] = provider_message.ToolCall(
-                                    id=tool_call.id,
-                                    type=tool_call.type,
-                                    function=provider_message.FunctionCall(
-                                        name=tool_call.function.name if tool_call.function else '', arguments=''
-                                    ),
-                                )
-                            if tool_call.function and tool_call.function.arguments:
-                                tool_calls_map[tool_call.id].function.arguments += tool_call.function.arguments
-
-                    if msg_idx % 8 == 0 or msg.is_final:
-                        msg_sequence += 1
-                        yield provider_message.MessageChunk(
-                            role=last_role,
-                            content=accumulated_content,
-                            tool_calls=list(tool_calls_map.values()) if (tool_calls_map and msg.is_final) else None,
-                            is_final=msg.is_final,
-                            msg_sequence=msg_sequence,
-                        )
-
-                final_msg = provider_message.MessageChunk(
-                    role=last_role,
-                    content=accumulated_content,
-                    tool_calls=list(tool_calls_map.values()) if tool_calls_map else None,
-                    msg_sequence=msg_sequence,
-                )
+                final_msg = stream_accumulator.final_message()
             else:
                 # Non-streaming: use committed model directly (no fallback in tool loop)
                 msg = await use_llm_model.provider.invoke_llm(
                     query,
                     use_llm_model,
                     req_messages,
-                    query.use_funcs if use_llm_model.model_entity.abilities.__contains__('func_call') else [],
+                    query.use_funcs
+                    if _model_has_ability(use_llm_model, 'func_call')
+                    else [],
                     extra_args=use_llm_model.model_entity.extra_args,
                     remove_think=remove_think,
                 )

tests/unit_tests/provider/test_litellmchat.py

@@ -68,6 +68,12 @@ class TestBuildLiteLLMModelName:
         result = requester._build_litellm_model_name('gpt-4o')
         assert result == 'openai/gpt-4o'
 
+    def test_avoid_duplicate_provider_prefix(self):
+        """Test model name with an existing matching provider prefix."""
+        requester = litellmchat.LiteLLMRequester(ap=Mock(), config={'custom_llm_provider': 'openai'})
+        result = requester._build_litellm_model_name('openai/gpt-4o')
+        assert result == 'openai/gpt-4o'
+
     def test_override_provider(self):
         """Test override provider via parameter"""
         requester = litellmchat.LiteLLMRequester(ap=Mock(), config={'custom_llm_provider': 'openai'})
@@ -151,7 +157,7 @@ class TestInvokeLLMStreamUsage:
     calls record 0 tokens.
     """
 
-    def _make_chunk(self, *, content=None, finish_reason=None, usage=None, has_choice=True):
+    def _make_chunk(self, *, content=None, tool_calls=None, finish_reason=None, usage=None, has_choice=True):
         chunk = Mock()
         if usage is not None:
             chunk.usage = usage
@@ -161,7 +167,7 @@ class TestInvokeLLMStreamUsage:
             choice = Mock()
             delta = Mock()
             delta.model_dump = Mock(
-                return_value={'role': 'assistant', 'content': content, 'tool_calls': None}
+                return_value={'role': 'assistant', 'content': content, 'tool_calls': tool_calls}
             )
             choice.delta = delta
             choice.finish_reason = finish_reason
@@ -250,6 +256,78 @@ class TestInvokeLLMStreamUsage:
 
         assert query.variables['_stream_usage']['total_tokens'] == 12
 
+    @pytest.mark.asyncio
+    async def test_stream_tool_call_delta_missing_id_and_name(self):
+        """LiteLLM may stream tool-call argument deltas with id/name set to None."""
+        import langbot_plugin.api.entities.builtin.pipeline.query as pipeline_query
+        import langbot_plugin.api.entities.builtin.provider.message as provider_message
+
+        mock_ap = Mock()
+        mock_ap.tool_mgr = Mock()
+        mock_ap.tool_mgr.generate_tools_for_openai = AsyncMock(
+            return_value=[{'type': 'function', 'function': {'name': 'qa_plugin_echo'}}]
+        )
+        requester = litellmchat.LiteLLMRequester(ap=mock_ap, config={})
+        model = MockRuntimeModel('gpt-4o', 'test-api-key')
+
+        chunks = [
+            self._make_chunk(
+                tool_calls=[
+                    {
+                        'index': 0,
+                        'id': 'call_123',
+                        'type': 'function',
+                        'function': {'name': 'qa_plugin_echo', 'arguments': ''},
+                    }
+                ]
+            ),
+            self._make_chunk(
+                tool_calls=[
+                    {
+                        'index': 0,
+                        'id': None,
+                        'type': None,
+                        'function': {'name': None, 'arguments': '{"text":'},
+                    }
+                ]
+            ),
+            self._make_chunk(
+                tool_calls=[
+                    {
+                        'index': 0,
+                        'function': {'arguments': '"plugin-tool-ok"}'},
+                    }
+                ]
+            ),
+            self._make_chunk(finish_reason='tool_calls'),
+        ]
+
+        async def _aiter(*args, **kwargs):
+            for c in chunks:
+                yield c
+
+        query = Mock(spec=pipeline_query.Query)
+        query.variables = {}
+        messages = [provider_message.Message(role='user', content='Call the tool')]
+        funcs = [Mock()]
+
+        with patch.object(litellmchat, 'acompletion', new=AsyncMock(side_effect=lambda **kw: _aiter())):
+            collected = [
+                chunk async for chunk in requester.invoke_llm_stream(
+                    query=query,
+                    model=model,
+                    messages=messages,
+                    funcs=funcs,
+                )
+            ]
+
+        tool_chunks = [chunk for chunk in collected if chunk.tool_calls]
+        assert len(tool_chunks) == 3
+        assert tool_chunks[1].tool_calls[0].id == 'call_123'
+        assert tool_chunks[1].tool_calls[0].function.name == 'qa_plugin_echo'
+        assert tool_chunks[1].tool_calls[0].function.arguments == '{"text":'
+        assert tool_chunks[2].tool_calls[0].function.arguments == '"plugin-tool-ok"}'
+
 
 class TestProcessThinkingContent:
     """Test _process_thinking_content method"""
@@ -499,6 +577,32 @@ class TestInvokeLLM:
             )
 
             assert result_msg.tool_calls is not None
+            called_kwargs = litellmchat.acompletion.await_args.kwargs
+            assert called_kwargs['tools'] == [{'type': 'function', 'function': {'name': 'get_weather'}}]
+            assert called_kwargs['tool_choice'] == 'auto'
+
+    @pytest.mark.asyncio
+    async def test_build_completion_args_preserves_explicit_tool_choice(self):
+        """Model extra args can override the default auto tool choice."""
+        mock_ap = Mock()
+        mock_ap.tool_mgr = Mock()
+        mock_ap.tool_mgr.generate_tools_for_openai = AsyncMock(
+            return_value=[{'type': 'function', 'function': {'name': 'get_weather'}}]
+        )
+
+        requester = litellmchat.LiteLLMRequester(ap=mock_ap, config={})
+        model = MockRuntimeModel('gpt-4o', 'test-api-key')
+        model.model_entity.extra_args = {'tool_choice': 'required'}
+
+        import langbot_plugin.api.entities.builtin.resource.tool as resource_tool
+        import langbot_plugin.api.entities.builtin.provider.message as provider_message
+
+        funcs = [Mock(spec=resource_tool.LLMTool)]
+        messages = [provider_message.Message(role='user', content='What is the weather?')]
+
+        args = await requester._build_completion_args(model, messages, funcs)
+
+        assert args['tool_choice'] == 'required'
 
     @pytest.mark.asyncio
     async def test_invoke_llm_error_handling(self):
@@ -754,6 +858,44 @@ class TestScanModels:
             embedding_models = [m for m in result['models'] if m['type'] == 'embedding']
             assert len(embedding_models) == 1
 
+    @pytest.mark.asyncio
+    async def test_scan_models_enriches_llm_abilities_and_context_length(self):
+        """Scanned LLM models get LiteLLM-derived abilities and context length."""
+        requester = litellmchat.LiteLLMRequester(
+            ap=Mock(),
+            config={
+                'base_url': 'https://api.openai.com/v1',
+                'timeout': 60,
+            },
+        )
+        requester._supports_function_calling = Mock(side_effect=lambda model_id: model_id == 'gpt-4o')
+        requester._supports_vision = Mock(side_effect=lambda model_id: model_id == 'gpt-4o')
+        requester._safe_context_length = Mock(side_effect=lambda model_id: 128000 if model_id == 'gpt-4o' else None)
+
+        mock_response = Mock()
+        mock_response.json = Mock(
+            return_value={
+                'data': [
+                    {'id': 'gpt-4o'},
+                    {'id': 'text-embedding-3-small'},
+                    {'id': 'bge-reranker-v2'},
+                ]
+            }
+        )
+        mock_response.raise_for_status = Mock()
+
+        with patch('httpx.AsyncClient') as mock_client:
+            mock_client.return_value.__aenter__ = AsyncMock(return_value=Mock())
+            mock_client.return_value.__aenter__.return_value.get = AsyncMock(return_value=mock_response)
+
+            result = await requester.scan_models(api_key='test-key')
+
+        by_id = {model['id']: model for model in result['models']}
+        assert by_id['gpt-4o']['abilities'] == ['func_call', 'vision']
+        assert by_id['gpt-4o']['context_length'] == 128000
+        assert by_id['text-embedding-3-small']['type'] == 'embedding'
+        assert by_id['bge-reranker-v2']['type'] == 'rerank'
+
     @pytest.mark.asyncio
     async def test_scan_models_no_base_url(self):
         """Test scan_models without base_url raises error"""

tests/unit_tests/provider/test_localagent_sandbox_exec.py

@@ -10,7 +10,7 @@ import langbot_plugin.api.entities.builtin.pipeline.query as pipeline_query
 import langbot_plugin.api.entities.builtin.provider.message as provider_message
 import langbot_plugin.api.entities.builtin.provider.session as provider_session
 
-from langbot.pkg.provider.runners.localagent import LocalAgentRunner
+from langbot.pkg.provider.runners.localagent import LocalAgentRunner, _StreamAccumulator
 
 
 class RecordingProvider:
@@ -124,6 +124,45 @@ def make_query() -> pipeline_query.Query:
     )
 
 
+def test_stream_accumulator_merges_fragmented_tool_call_arguments():
+    accumulator = _StreamAccumulator(msg_sequence=1)
+
+    assert (
+        accumulator.add(
+            provider_message.MessageChunk(
+                role='assistant',
+                tool_calls=[
+                    provider_message.ToolCall(
+                        id='call-1',
+                        type='function',
+                        function=provider_message.FunctionCall(name='exec', arguments='{"command":'),
+                    )
+                ],
+            )
+        )
+        is None
+    )
+
+    emitted = accumulator.add(
+        provider_message.MessageChunk(
+            role='assistant',
+            tool_calls=[
+                provider_message.ToolCall(
+                    id='call-1',
+                    type='function',
+                    function=provider_message.FunctionCall(name='exec', arguments='"pwd"}'),
+                )
+            ],
+            is_final=True,
+        )
+    )
+
+    assert emitted is not None
+    final_msg = accumulator.final_message()
+    assert final_msg.tool_calls[0].function.name == 'exec'
+    assert final_msg.tool_calls[0].function.arguments == '{"command":"pwd"}'
+
+
 @pytest.mark.asyncio
 async def test_localagent_uses_exec_for_exact_calculation():
     provider = RecordingProvider()

web/src/app/home/components/models-dialog/components/AddModelPopover.tsx

@@ -130,32 +130,6 @@ export default function AddModelPopover({
     setScanLoading(true);
     try {
       const result = await onScanModels(trigger ? undefined : tab);
-
-      const debugData = (
-        result.debug?.response as { data?: Record<string, unknown>[] }
-      )?.data;
-      if (Array.isArray(debugData)) {
-        const debugMap = new Map<string, Record<string, unknown>>();
-        for (const item of debugData) {
-          if (typeof item?.id === 'string') {
-            debugMap.set(item.id, item);
-          }
-        }
-        for (const model of result.models) {
-          const debugItem = debugMap.get(model.id);
-          if (!debugItem) continue;
-          const features = debugItem.features as
-            | Record<string, unknown>
-            | undefined;
-          const tools = features?.tools as Record<string, unknown> | undefined;
-          if (tools?.function_calling === true) {
-            const nextAbilities = new Set(model.abilities || []);
-            nextAbilities.add('func_call');
-            model.abilities = [...nextAbilities];
-          }
-        }
-      }
-
       setScannedModels(result.models);
       setSelectedScannedModels({});
     } finally {