browser-use/browser_use/agent/prompts.py

import importlib.resources
from datetime import datetime
from typing import TYPE_CHECKING, Optional

from langchain_core.messages import HumanMessage, SystemMessage

if TYPE_CHECKING:
	from browser_use.agent.views import ActionResult, AgentStepInfo
	from browser_use.browser.views import BrowserStateSummary


class SystemPrompt:
	def __init__(
		self,
		action_description: str,
		max_actions_per_step: int = 10,
		override_system_message: str | None = None,
		extend_system_message: str | None = None,
	):
		self.default_action_description = action_description
		self.max_actions_per_step = max_actions_per_step
		prompt = ''
		if override_system_message:
			prompt = override_system_message
		else:
			self._load_prompt_template()
			prompt = self.prompt_template.format(max_actions=self.max_actions_per_step)

		if extend_system_message:
			prompt += f'\n{extend_system_message}'

		self.system_message = SystemMessage(content=prompt)

	def _load_prompt_template(self) -> None:
		"""Load the prompt template from the markdown file."""
		try:
			# This works both in development and when installed as a package
			with importlib.resources.files('browser_use.agent').joinpath('system_prompt.md').open('r') as f:
				self.prompt_template = f.read()
		except Exception as e:
			raise RuntimeError(f'Failed to load system prompt template: {e}')

	def get_system_message(self) -> SystemMessage:
		"""
		Get the system prompt for the agent.

		Returns:
		    SystemMessage: Formatted system prompt
		"""
		return self.system_message


# Functions:
# {self.default_action_description}

# Example:
# {self.example_response()}
# Your AVAILABLE ACTIONS:
# {self.default_action_description}


class AgentMessagePrompt:
	def __init__(
		self,
		browser_state_summary: 'BrowserStateSummary',
		result: list['ActionResult'] | None = None,
		include_attributes: list[str] | None = None,
		step_info: Optional['AgentStepInfo'] = None,
	):
		self.state: 'BrowserStateSummary' = browser_state_summary
		self.result = result
		self.include_attributes = include_attributes or []
		self.step_info = step_info
		assert self.state

	def get_user_message(self, use_vision: bool = True) -> HumanMessage:
		elements_text = self.state.element_tree.clickable_elements_to_string(include_attributes=self.include_attributes)

		has_content_above = (self.state.pixels_above or 0) > 0
		has_content_below = (self.state.pixels_below or 0) > 0

		if elements_text != '':
			if has_content_above:
				elements_text = (
					f'... {self.state.pixels_above} pixels above - scroll or extract content to see more ...\n{elements_text}'
				)
			else:
				elements_text = f'[Start of page]\n{elements_text}'
			if has_content_below:
				elements_text = (
					f'{elements_text}\n... {self.state.pixels_below} pixels below - scroll or extract content to see more ...'
				)
			else:
				elements_text = f'{elements_text}\n[End of page]'
		else:
			elements_text = 'empty page'

		if self.step_info:
			step_info_description = f'Current step: {self.step_info.step_number + 1}/{self.step_info.max_steps}'
		else:
			step_info_description = ''
		time_str = datetime.now().strftime('%Y-%m-%d %H:%M')
		step_info_description += f'Current date and time: {time_str}'

		state_description = f"""
[Task history memory ends]
[Current state starts here]
The following is one-time information - if you need to remember it write it to memory:
Current url: {self.state.url}
Available tabs:
{self.state.tabs}
Interactive elements from top layer of the current page inside the viewport:
{elements_text}
{step_info_description}
"""

		if self.result:
			for i, result in enumerate(self.result):
				if result.extracted_content:
					state_description += f'\nAction result {i + 1}/{len(self.result)}: {result.extracted_content}'
				if result.error:
					# only use last line of error
					error = result.error.split('\n')[-1]
					state_description += f'\nAction error {i + 1}/{len(self.result)}: ...{error}'

		if self.state.screenshot and use_vision is True:
			# Format message for vision model
			return HumanMessage(
				content=[
					{'type': 'text', 'text': state_description},
					{
						'type': 'image_url',
						'image_url': {'url': f'data:image/png;base64,{self.state.screenshot}'},  # , 'detail': 'low'
					},
				]
			)

		return HumanMessage(content=state_description)


class PlannerPrompt(SystemPrompt):
	def __init__(self, available_actions: str):
		self.available_actions = available_actions

	def get_system_message(
		self, is_planner_reasoning: bool, extended_planner_system_prompt: str | None = None
	) -> SystemMessage | HumanMessage:
		"""Get the system message for the planner.

		Args:
		    is_planner_reasoning: If True, return as HumanMessage for chain-of-thought
		    extended_planner_system_prompt: Optional text to append to the base prompt

		Returns:
		    SystemMessage or HumanMessage depending on is_planner_reasoning
		"""

		planner_prompt_text = """
You are a planning agent that helps break down tasks into smaller steps and reason about the current state.
Your role is to:
1. Analyze the current state and history
2. Evaluate progress towards the ultimate goal
3. Identify potential challenges or roadblocks
4. Suggest the next high-level steps to take

Inside your messages, there will be AI messages from different agents with different formats.

Your output format should be always a JSON object with the following fields:
{{
    "state_analysis": "Brief analysis of the current state and what has been done so far",
    "progress_evaluation": "Evaluation of progress towards the ultimate goal (as percentage and description)",
    "challenges": "List any potential challenges or roadblocks",
    "next_steps": "List 2-3 concrete next steps to take",
    "reasoning": "Explain your reasoning for the suggested next steps"
}}

Ignore the other AI messages output structures.

Keep your responses concise and focused on actionable insights.
"""

		if extended_planner_system_prompt:
			planner_prompt_text += f'\n{extended_planner_system_prompt}'

		if is_planner_reasoning:
			return HumanMessage(content=planner_prompt_text)
		else:
			return SystemMessage(content=planner_prompt_text)