chore: import upstream snapshot with attribution

examples/models/langchain/serializer.py

@@ -0,0 +1,149 @@
+import json
+from typing import overload
+
+from langchain_core.messages import (  # pyright: ignore
+	AIMessage,
+	HumanMessage,
+	SystemMessage,
+)
+from langchain_core.messages import (  # pyright: ignore
+	ToolCall as LangChainToolCall,
+)
+from langchain_core.messages.base import BaseMessage as LangChainBaseMessage  # pyright: ignore
+
+from browser_use.llm.messages import (
+	AssistantMessage,
+	BaseMessage,
+	ContentPartImageParam,
+	ContentPartRefusalParam,
+	ContentPartTextParam,
+	ToolCall,
+	UserMessage,
+)
+from browser_use.llm.messages import (
+	SystemMessage as BrowserUseSystemMessage,
+)
+
+
+class LangChainMessageSerializer:
+	"""Serializer for converting between browser-use message types and LangChain message types."""
+
+	@staticmethod
+	def _serialize_user_content(
+		content: str | list[ContentPartTextParam | ContentPartImageParam],
+	) -> str | list[str | dict]:
+		"""Convert user message content for LangChain compatibility."""
+		if isinstance(content, str):
+			return content
+
+		serialized_parts = []
+		for part in content:
+			if part.type == 'text':
+				serialized_parts.append(
+					{
+						'type': 'text',
+						'text': part.text,
+					}
+				)
+			elif part.type == 'image_url':
+				# LangChain format for images
+				serialized_parts.append(
+					{'type': 'image_url', 'image_url': {'url': part.image_url.url, 'detail': part.image_url.detail}}
+				)
+
+		return serialized_parts
+
+	@staticmethod
+	def _serialize_system_content(
+		content: str | list[ContentPartTextParam],
+	) -> str:
+		"""Convert system message content to text string for LangChain compatibility."""
+		if isinstance(content, str):
+			return content
+
+		text_parts = []
+		for part in content:
+			if part.type == 'text':
+				text_parts.append(part.text)
+
+		return '\n'.join(text_parts)
+
+	@staticmethod
+	def _serialize_assistant_content(
+		content: str | list[ContentPartTextParam | ContentPartRefusalParam] | None,
+	) -> str:
+		"""Convert assistant message content to text string for LangChain compatibility."""
+		if content is None:
+			return ''
+		if isinstance(content, str):
+			return content
+
+		text_parts = []
+		for part in content:
+			if part.type == 'text':
+				text_parts.append(part.text)
+			# elif part.type == 'refusal':
+			# 	# Include refusal content as text
+			# 	text_parts.append(f'[Refusal: {part.refusal}]')
+
+		return '\n'.join(text_parts)
+
+	@staticmethod
+	def _serialize_tool_call(tool_call: ToolCall) -> LangChainToolCall:
+		"""Convert browser-use ToolCall to LangChain ToolCall."""
+		# Parse the arguments string to a dict for LangChain
+		try:
+			args_dict = json.loads(tool_call.function.arguments)
+		except json.JSONDecodeError:
+			# If parsing fails, wrap in a dict
+			args_dict = {'arguments': tool_call.function.arguments}
+
+		return LangChainToolCall(
+			name=tool_call.function.name,
+			args=args_dict,
+			id=tool_call.id,
+		)
+
+	# region - Serialize overloads
+	@overload
+	@staticmethod
+	def serialize(message: UserMessage) -> HumanMessage: ...
+
+	@overload
+	@staticmethod
+	def serialize(message: BrowserUseSystemMessage) -> SystemMessage: ...
+
+	@overload
+	@staticmethod
+	def serialize(message: AssistantMessage) -> AIMessage: ...
+
+	@staticmethod
+	def serialize(message: BaseMessage) -> LangChainBaseMessage:
+		"""Serialize a browser-use message to a LangChain message."""
+
+		if isinstance(message, UserMessage):
+			content = LangChainMessageSerializer._serialize_user_content(message.content)
+			return HumanMessage(content=content, name=message.name)
+
+		elif isinstance(message, BrowserUseSystemMessage):
+			content = LangChainMessageSerializer._serialize_system_content(message.content)
+			return SystemMessage(content=content, name=message.name)
+
+		elif isinstance(message, AssistantMessage):
+			# Handle content
+			content = LangChainMessageSerializer._serialize_assistant_content(message.content)
+
+			# For simplicity, we'll ignore tool calls in LangChain integration
+			# as requested by the user
+			return AIMessage(
+				content=content,
+				name=message.name,
+			)
+
+		else:
+			raise ValueError(f'Unknown message type: {type(message)}')
+
+	@staticmethod
+	def serialize_messages(messages: list[BaseMessage]) -> list[LangChainBaseMessage]:
+		"""Serialize a list of browser-use messages to LangChain messages."""
+		return [LangChainMessageSerializer.serialize(m) for m in messages]