Multi-Agent Orchestration

Coordinate multiple specialized agents for complex tasks.

When to Use

• Tasks requiring multiple expertise areas
• Parallel analysis from different perspectives
• Complex workflows with agent handoffs
• Synthesis of multiple agent outputs

Fan-Out/Fan-In Pattern

async def multi_agent_analysis(content: str) -> dict:
    """Fan-out to specialists, fan-in to synthesize."""
    agents = [
        ("security", security_agent),
        ("performance", performance_agent),
        ("code_quality", quality_agent),
        ("architecture", architecture_agent),
    ]

    # Fan-out: Run all agents in parallel
    tasks = [agent(content) for _, agent in agents]
    results = await asyncio.gather(*tasks, return_exceptions=True)

    # Filter successful results
    findings = [
        {"agent": name, "result": result}
        for (name, _), result in zip(agents, results)
        if not isinstance(result, Exception)
    ]

    # Fan-in: Synthesize findings
    return await synthesize_findings(findings)

Supervisor Pattern

class Supervisor:
    """Central coordinator that routes to specialists."""

    def __init__(self, agents: dict):
        self.agents = agents  # {"security": agent, "performance": agent}
        self.completed = []

    async def run(self, task: str) -> dict:
        """Route task through appropriate agents."""
        # 1. Determine which agents to use
        plan = await self.plan_routing(task)

        # 2. Execute in dependency order
        results = {}
        for agent_name in plan.execution_order:
            if plan.can_parallelize(agent_name):
                # Run parallel batch
                batch = plan.get_parallel_batch(agent_name)
                batch_results = await asyncio.gather(*[
                    self.agents[name](task, context=results)
                    for name in batch
                ])
                results.update(dict(zip(batch, batch_results)))
            else:
                # Run sequential
                results[agent_name] = await self.agents[agent_name](
                    task, context=results
                )

        return results

    async def plan_routing(self, task: str) -> RoutingPlan:
        """Use LLM to determine agent routing."""
        response = await llm.chat([{
            "role": "user",
            "content": f"""Task: {task}

Available agents: {list(self.agents.keys())}

Which agents should handle this task?
What order? Can any run in parallel?"""
        }])
        return parse_routing_plan(response.content)

Conflict Resolution

async def resolve_conflicts(findings: list[dict]) -> list[dict]:
    """When agents disagree, resolve by confidence or LLM."""
    conflicts = detect_conflicts(findings)

    if not conflicts:
        return findings

    for conflict in conflicts:
        # Option 1: Higher confidence wins
        winner = max(conflict.agents, key=lambda a: a.confidence)

        # Option 2: LLM arbitration
        resolution = await llm.chat([{
            "role": "user",
            "content": f"""Two agents disagree:

Agent A ({conflict.agent_a.name}): {conflict.agent_a.finding}
Agent B ({conflict.agent_b.name}): {conflict.agent_b.finding}

Which is more likely correct and why?"""
        }])

        # Record resolution
        conflict.resolution = parse_resolution(resolution.content)

    return apply_resolutions(findings, conflicts)

Synthesis Pattern

async def synthesize_findings(findings: list[dict]) -> dict:
    """Combine multiple agent outputs into coherent result."""
    # Group by category
    by_category = {}
    for f in findings:
        cat = f.get("category", "general")
        by_category.setdefault(cat, []).append(f)

    # Synthesize each category
    synthesis = await llm.chat([{
        "role": "user",
        "content": f"""Synthesize these agent findings into a coherent summary:

{json.dumps(by_category, indent=2)}

Output format:
- Executive summary (2-3 sentences)
- Key findings by category
- Recommendations
- Confidence score (0-1)"""
    }])

    return parse_synthesis(synthesis.content)

Agent Communication Bus

class AgentBus:
    """Message passing between agents."""

    def __init__(self):
        self.messages = []
        self.subscribers = {}

    def publish(self, from_agent: str, message: dict):
        """Broadcast message to all agents."""
        msg = {"from": from_agent, "data": message, "ts": time.time()}
        self.messages.append(msg)

        for callback in self.subscribers.values():
            callback(msg)

    def subscribe(self, agent_id: str, callback):
        """Register agent to receive messages."""
        self.subscribers[agent_id] = callback

    def get_history(self, agent_id: str = None) -> list:
        """Get message history, optionally filtered."""
        if agent_id:
            return [m for m in self.messages if m["from"] == agent_id]
        return self.messages

Key Decisions

Common Mistakes

• No timeout per agent (one slow agent blocks all)
• No error isolation (one failure crashes workflow)
• Over-coordination (too much overhead)
• Missing synthesis (raw agent outputs not useful)

Related Skills

• langgraph-supervisor - LangGraph supervisor pattern
• langgraph-parallel - Fan-out/fan-in with LangGraph
• agent-loops - Single agent patterns