Robust Agent Design Patterns

A design methodology based on loose coupling, state-driven architecture, and fault-tolerance-first principles.

Core Design Principles

1. Node-Based vs Function-Based

• Each functional unit is encapsulated as an independent Agent
• Agents communicate via messages/state rather than function calls
• Each Agent has its own lifecycle and state management

2. State-Driven vs Flow-Driven

• System state is explicitly stored and managed
• Decisions are based on state rather than hardcoded flows
• Supports checkpoint recovery and state restoration

3. Fault-Tolerance-First vs Success-First

• Assume all components can fail
• Design recovery strategies for each failure scenario
• "Failure is the norm, success requires guarantees"

Three-Level Fault Handling Mechanism

Agent Design Template

Basic Agent Class Structure

class RobustAgent:
    def __init__(self, config):
        self.id = generate_uuid()
        self.state = 'initialized'  # initialized|waiting|processing|completed|failed
        self.input_queue = []
        self.output_queue = []
        self.retry_count = 0
        self.max_retries = config.get('max_retries', 3)
        self.compensation_actions = config.get('compensation_actions', [])
        self.state_persistence = config.get('state_persistence', 'file')  # file|db|memory
    
    async def execute(self, task):
        """Main execution entry point"""
        try:
            # 1. State transition
            self.state = 'processing'
            self._persist_state()
            
            # 2. Execute work
            result = await self._do_work(task)
            
            # 3. Validate result
            await self._validate_result(result)
            
            # 4. Complete state
            self.state = 'completed'
            self._persist_state()
            return result
            
        except Exception as error:
            # 5.