This article is published in English.
Practical notes: Agentic Architectures — Article 6: Multi-Agent Orchestration
Operable walkthrough of Practical notes: Agentic Architectures — Article 6: Multi-Agent Orchestration: contracts, checks, and drop-in code slots for teams shipping this pattern.
The following notes reconstruct a practical path around “Agentic Architectures — Article 6: Multi-Agent Orchestration Patterns”. Emphasis stays on contracts, checks, and drop-in code placeholders rather than motivational framing. When working through the Overview stage, write down the contract first: required inputs, success signal, and what happens on partial failure. That checklist keeps later code changes honest. Record timings and token or query cost next to functional results. Cost visibility early prevents surprise bills when the path moves from demo to shared environments.
What You’ll Find Here
The What You ll Find stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Keep configuration outside application code. Environment files, secret stores, and feature flags belong in one place operators can audit without reading the whole graph. Keep graph state flat and typed. Nested blobs hide which node wrote which field and break resume after interrupts.
Why a Single Agent Hits a Ceiling
The Why a Single Agent stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Document the happy path and the recovery path together. Retries, human gates, and dead-letter handling are part of the product, not later polish. Keep graph state flat and typed. Nested blobs hide which node wrote which field and break resume after interrupts.
A Taxonomy of Multi-Agent Patterns
The A Taxonomy of Multi-Agent stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Prefer small, testable units over sprawling scripts. When a step fails, the failure should point at a single responsibility rather than a tangled pipeline. Keep graph state flat and typed. Nested blobs hide which node wrote which field and break resume after interrupts. The A Taxonomy of Multi-Agent stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Record timings and token or query cost next to functional results. Cost visibility early prevents surprise bills when the path moves from demo to shared environments.
+--------------------+--------------------------------------------------+------------------+
| Pattern | Structure | Best For |
+--------------------+--------------------------------------------------+------------------+
| Supervisor-Worker | One orchestrator decomposes + delegates | Complex tasks |
| | N workers execute specialized subtasks | needing expert |
| | | decomposition |
+--------------------+--------------------------------------------------+------------------+
| Pipeline | Agent A -> Agent B -> Agent C (sequential) | Transformation |
| | Each processes the previous output | chains, ETL-like |
| | | workflows |
+--------------------+--------------------------------------------------+------------------+
| Parallel Fan-out | Orchestrator sends same/related task to N agents | Research, |
| | Results aggregated into single output | analysis tasks |
| | | that parallelize |
+--------------------+--------------------------------------------------+------------------+
| Debate / Critique | Agent A produces solution, Agent B critiques | High-stakes |
| | Agent C synthesizes or adjudicates | outputs needing |
| | | adversarial QA |
+--------------------+--------------------------------------------------+------------------+
Pattern 1: Supervisor-Worker
For the Pattern 1 Supervisor-Worker stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Keep configuration outside application code. Environment files, secret stores, and feature flags belong in one place operators can audit without reading the whole graph. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
┌─────────────────────────────┐
│ SUPERVISOR AGENT │
│ (task decomposition + │
│ result synthesis) │
└──────┬───────────┬──────────┘
│ │
┌────────▼──┐ ┌────▼──────────┐ ┌──────────────┐
│ Worker A │ │ Worker B │ │ Worker C │
│ (code │ │ (security │ │ (test │
│ analysis)│ │ review) │ │ coverage) │
└────────────┘ └───────────────┘ └──────────────┘
# harness/multi_agent/supervisor.py
from typing import Literal, TypedDict, Annotated, List
from langgraph.graph import StateGraph, END, START
from langgraph.graph.message import add_messages
from langchain_core.messages import BaseMessage, HumanMessage, SystemMessage
from langchain_aws import ChatBedrock
from pydantic import BaseModel
import boto3
class SupervisorState(TypedDict):
messages: Annotated[List[BaseMessage], add_messages]
task_spec: str
subtasks: List[dict] # decomposed work items
worker_results: dict # keyed by subtask ID
current_worker: str # which worker is active
synthesis_complete: bool
agent_run_id: str
class SubtaskAssignment(BaseModel):
"""Structured output from supervisor decomposition."""
subtask_id: str
worker_type: Literal["code_analyst", "security_reviewer", "test_evaluator"]
description: str
depends_on: List[str] # subtask IDs this depends on
priority: int
SUPERVISOR_SYSTEM_PROMPT = """
You are an orchestrator agent. You do not write code or perform analysis yourself.
Your job is to:
1. Break the task into discrete subtasks
2. Assign each subtask to the correct specialist worker
3. Track dependencies between subtasks
4. Synthesize worker outputs into a coherent final result
Available workers:
- code_analyst: Reads and analyzes code structure, dependencies, patterns
- security_reviewer: Evaluates security implications, checks against CVEs
- test_evaluator: Assesses test coverage, identifies gaps
When decomposing, be specific. A subtask description like "analyze the auth module"
is useful. "analyze the code" is not.
Respond in JSON when asked to decompose. Respond in prose when asked to synthesize.
"""
def build_supervisor(region: str = "us-east-1") -> callable:
bedrock = boto3.client("bedrock-runtime", region_name=region)
# Supervisor uses the heavier model — it's doing strategic reasoning
supervisor_model = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-3-7-sonnet-20250219-v1:0",
model_kwargs={
"temperature": 0.2,
"max_tokens": 8000,
"thinking": {"type": "enabled", "budget_tokens": 5000}
}
)
def supervisor_node(state: SupervisorState) -> SupervisorState:
if not state.get("subtasks"):
# First pass: decompose the task
response = supervisor_model.invoke([
SystemMessage(content=SUPERVISOR_SYSTEM_PROMPT),
HumanMessage(content=f"Decompose this task into subtasks:\n{state['task_spec']}")
])
import json
try:
subtasks = json.loads(response.content)
if isinstance(subtasks, dict) and "subtasks" in subtasks:
subtasks = subtasks["subtasks"]
except json.JSONDecodeError:
subtasks = []
return {**state, "subtasks": subtasks}
# All workers done: synthesize
results_summary = "\n\n".join([
f"=== {worker} ===\n{result}"
for worker, result in state["worker_results"].items()
])
synthesis_prompt = f"""
Original task: {state['task_spec']}
Worker results:
{results_summary}
Synthesize these into a coherent final report. Highlight conflicts between
worker findings and make clear recommendations.
"""
response = supervisor_model.invoke([
SystemMessage(content=SUPERVISOR_SYSTEM_PROMPT),
HumanMessage(content=synthesis_prompt)
])
return {
**state,
"messages": state["messages"] + [response],
"synthesis_complete": True,
}
return supervisor_node
def route_to_worker(state: SupervisorState) -> str:
"""
Routes to the next worker with unfinished subtasks.
Returns END when all subtasks are complete and synthesis is done.
"""
if state.get("synthesis_complete"):
return END
# Find next unfinished subtask whose dependencies are met
completed = set(state.get("worker_results", {}).keys())
for subtask in state.get("subtasks", []):
sid = subtask["subtask_id"]
if sid in completed:
continue
deps = set(subtask.get("depends_on", []))
if deps.issubset(completed):
return subtask["worker_type"] # route to this worker
# All subtasks done, back to supervisor for synthesis
return "supervisor"
# harness/multi_agent/workers.py
from langchain_aws import ChatBedrock
from langchain_core.messages import SystemMessage, HumanMessage
import boto3
CODE_ANALYST_PROMPT = """
You are a code analysis specialist. You receive specific, bounded analysis tasks.
Focus only on what you were asked to analyze. Do not expand scope.
Return structured findings: what you found, confidence level, and specific evidence.
"""
SECURITY_REVIEWER_PROMPT = """
You are a security review specialist. You look for vulnerabilities, insecure patterns,
and CVE-relevant code. Reference specific CWE numbers when applicable.
Return structured findings with severity levels (CRITICAL, HIGH, MEDIUM, LOW).
"""
TEST_EVALUATOR_PROMPT = """
You are a test coverage specialist. You assess test quality and identify gaps.
Focus on: coverage percentage where available, missing edge cases, and untested paths.
Return structured findings with specific test gaps and suggested test cases.
"""
WORKER_PROMPTS = {
"code_analyst": CODE_ANALYST_PROMPT,
"security_reviewer": SECURITY_REVIEWER_PROMPT,
"test_evaluator": TEST_EVALUATOR_PROMPT,
}
def build_worker(worker_type: str, region: str = "us-east-1") -> callable:
bedrock = boto3.client("bedrock-runtime", region_name=region)
# Workers use the faster model — they execute a specific, bounded task
worker_model = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-3-5-sonnet-20241022-v2:0",
model_kwargs={"temperature": 0, "max_tokens": 4000}
)
system_prompt = WORKER_PROMPTS[worker_type]
def worker_node(state: SupervisorState) -> SupervisorState:
# Find the subtask assigned to this worker type
completed = set(state.get("worker_results", {}).keys())
current_subtask = None
for subtask in state["subtasks"]:
if subtask["worker_type"] == worker_type and subtask["subtask_id"] not in completed:
deps = set(subtask.get("depends_on", []))
if deps.issubset(completed):
current_subtask = subtask
break
if not current_subtask:
return state
# Pass relevant prior results as context if this task has dependencies
context = ""
if current_subtask.get("depends_on"):
for dep_id in current_subtask["depends_on"]:
if dep_id in state.get("worker_results", {}):
context += f"\nPrevious analysis ({dep_id}):\n{state['worker_results'][dep_id]}\n"
prompt = f"Task: {current_subtask['description']}"
if context:
prompt = f"Prior context:{context}\n\n{prompt}"
response = worker_model.invoke([
SystemMessage(content=system_prompt),
HumanMessage(content=prompt)
])
updated_results = {**state.get("worker_results", {})}
updated_results[current_subtask["subtask_id"]] = response.content
return {**state, "worker_results": updated_results}
return worker_node
# harness/multi_agent/supervisor_graph.py
from langgraph.graph import StateGraph, END, START
from langgraph.checkpoint.memory import MemorySaver
from harness.multi_agent.supervisor import SupervisorState, build_supervisor, route_to_worker
from harness.multi_agent.workers import build_worker
def build_supervisor_graph(region: str = "us-east-1"):
graph = StateGraph(SupervisorState)
graph.add_node("supervisor", build_supervisor(region))
graph.add_node("code_analyst", build_worker("code_analyst", region))
graph.add_node("security_reviewer", build_worker("security_reviewer", region))
graph.add_node("test_evaluator", build_worker("test_evaluator", region))
graph.add_edge(START, "supervisor")
graph.add_conditional_edges(
"supervisor",
route_to_worker,
{
"code_analyst": "code_analyst",
"security_reviewer": "security_reviewer",
"test_evaluator": "test_evaluator",
END: END,
}
)
# All workers route back to supervisor after completing their subtask
for worker in ["code_analyst", "security_reviewer", "test_evaluator"]:
graph.add_edge(worker, "supervisor")
return graph.compile(checkpointer=MemorySaver())
Pattern 2: Pipeline Orchestration
For the Pattern 2 Pipeline Orchestration stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Document the happy path and the recovery path together. Retries, human gates, and dead-letter handling are part of the product, not later polish. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
┌───────────────┐ ┌───────────────┐ ┌───────────────┐
│ Agent A │ │ Agent B │ │ Agent C │
│ (extraction) │────>│ (enrichment) │────>│ (validation) │
└───────────────┘ └───────────────┘ └───────────────┘
output A output B output C
becomes input B becomes input C final result
# harness/multi_agent/pipeline.py
from typing import TypedDict, Annotated, List, Optional, Any
from langgraph.graph import StateGraph, END, START
from langchain_core.messages import BaseMessage, HumanMessage, SystemMessage
from langchain_aws import ChatBedrock
import boto3
class PipelineState(TypedDict):
original_input: str
stage_outputs: List[dict] # accumulates each stage's compressed result
current_stage: int
final_output: Optional[str]
agent_run_id: str
def compress_for_handoff(full_output: str, model: ChatBedrock) -> str:
"""
Compresses a stage's full output into a structured handoff summary.
This is the core of pipeline context management — the next agent gets
the substance, not the reasoning trace.
"""
response = model.invoke([
SystemMessage(content="""
Compress the following agent output into a structured handoff summary.
Include: key findings, decisions made, artifacts produced, and what the
next stage needs to know. Discard reasoning traces and intermediate steps.
Target length: 20% of original. Use bullet points for clarity.
"""),
HumanMessage(content=f"Compress this:\n\n{full_output}")
])
return response.content
def build_pipeline_stage(
stage_name: str,
system_prompt: str,
region: str = "us-east-1"
) -> callable:
bedrock = boto3.client("bedrock-runtime", region_name=region)
model = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-3-5-sonnet-20241022-v2:0",
model_kwargs={"temperature": 0, "max_tokens": 6000}
)
# Cheaper model for compression — this is mechanical, not creative
compressor = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-haiku-3-5",
model_kwargs={"temperature": 0, "max_tokens": 2000}
)
def stage_node(state: PipelineState) -> PipelineState:
# Build context from compressed prior stage outputs only
prior_context = ""
for past_stage in state.get("stage_outputs", []):
prior_context += f"\n### {past_stage['stage']} output:\n{past_stage['compressed_output']}\n"
prompt = f"Original task: {state['original_input']}\n"
if prior_context:
prompt += f"\nPrior stage results:\n{prior_context}\n"
prompt += f"\nNow perform your stage: {stage_name}"
response = model.invoke([
SystemMessage(content=system_prompt),
HumanMessage(content=prompt)
])
full_output = response.content
# Compress before storing — next stage won't see raw output
compressed = compress_for_handoff(full_output, compressor)
updated_outputs = list(state.get("stage_outputs", []))
updated_outputs.append({
"stage": stage_name,
"full_output": full_output,
"compressed_output": compressed,
})
return {
**state,
"stage_outputs": updated_outputs,
"current_stage": state.get("current_stage", 0) + 1,
}
return stage_node
Pattern 3: Parallel Fan-out / Fan-in
For the Pattern 3 Parallel Fan-out stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Prefer small, testable units over sprawling scripts. When a step fails, the failure should point at a single responsibility rather than a tangled pipeline. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness. For the Pattern 3 Parallel Fan-out stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Record timings and token or query cost next to functional results. Cost visibility early prevents surprise bills when the path moves from demo to shared environments.
┌──────────────────┐
│ ORCHESTRATOR │
│ (task splitter) │
└──┬───┬───┬───┬──┘
│ │ │ │
┌──────────▼┐ ┌▼─┐ ┌▼──┐ ┌▼──────────┐
│ Agent 1 │ │A2│ │A3 │ │ Agent 4 │
│ (region A)│ │ │ │ │ │ (region D)│
└──────────┬┘ └┬─┘ └┬──┘ └┬──────────┘
│ │ │ │
┌──▼───▼────▼─────▼──┐
│ AGGREGATOR │
│ (result merger) │
└────────────────────┘
# harness/multi_agent/fanout.py
import asyncio
from typing import List, TypedDict, Annotated, Optional
from langchain_aws import ChatBedrock
from langchain_core.messages import SystemMessage, HumanMessage
import boto3
class FanoutResult(TypedDict):
agent_id: str
input_slice: str
output: str
success: bool
error: Optional[str]
async def run_agent_async(
agent_id: str,
input_slice: str,
system_prompt: str,
model: ChatBedrock,
) -> FanoutResult:
"""Run a single agent asynchronously."""
try:
response = await model.ainvoke([
SystemMessage(content=system_prompt),
HumanMessage(content=input_slice)
])
return FanoutResult(
agent_id=agent_id,
input_slice=input_slice,
output=response.content,
success=True,
error=None,
)
except Exception as e:
return FanoutResult(
agent_id=agent_id,
input_slice=input_slice,
output="",
success=False,
error=str(e),
)
async def fan_out(
task_slices: List[str],
system_prompt: str,
region: str = "us-east-1",
max_concurrent: int = 5, # don't hammer Bedrock rate limits
) -> List[FanoutResult]:
"""
Runs agents concurrently with a semaphore to cap parallelism.
max_concurrent protects against Bedrock throttling — you
will hit rate limits if you fire 20 concurrent requests.
"""
bedrock = boto3.client("bedrock-runtime", region_name=region)
model = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-3-5-sonnet-20241022-v2:0",
model_kwargs={"temperature": 0, "max_tokens": 4000}
)
semaphore = asyncio.Semaphore(max_concurrent)
async def bounded_run(agent_id, slice_content):
async with semaphore:
return await run_agent_async(agent_id, slice_content, system_prompt, model)
tasks = [
bounded_run(f"agent_{i}", slice_content)
for i, slice_content in enumerate(task_slices)
]
return await asyncio.gather(*tasks)
def aggregate_results(
results: List[FanoutResult],
aggregator_model: ChatBedrock,
aggregation_strategy: str = "synthesize",
) -> str:
"""
Merges parallel agent outputs.
aggregation_strategy options:
- "synthesize": ask a model to merge findings coherently
- "concat": simple concatenation (fast, no model call needed)
- "vote": majority-vote for classification tasks
"""
if aggregation_strategy == "concat":
successful = [r for r in results if r["success"]]
return "\n\n---\n\n".join(r["output"] for r in successful)
failed = [r for r in results if not r["success"]]
successful = [r for r in results if r["success"]]
if failed:
# Log partial failures but don't crash — partial results are usually useful
for f in failed:
print(f"Agent {f['agent_id']} failed: {f['error']}")
outputs_for_synthesis = "\n\n".join([
f"[Agent {r['agent_id']}]:\n{r['output']}"
for r in successful
])
response = aggregator_model.invoke([
SystemMessage(content="""
You are a results aggregator. You receive outputs from multiple parallel agents
that each analyzed a different slice of the same problem. Your job is to:
1. Identify common findings across agents
2. Surface unique findings from individual agents
3. Flag any contradictions between agents and explain which to trust
4. Produce a single coherent output as if one expert had analyzed everything
Do not simply concatenate. Actively synthesize.
"""),
HumanMessage(content=f"Synthesize these {len(successful)} agent outputs:\n\n{outputs_for_synthesis}")
])
return response.content
# Convenience wrapper for synchronous callers
def run_parallel_analysis(
task_slices: List[str],
system_prompt: str,
region: str = "us-east-1",
) -> str:
results = asyncio.run(fan_out(task_slices, system_prompt, region))
bedrock = boto3.client("bedrock-runtime", region_name=region)
aggregator = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-3-7-sonnet-20250219-v1:0",
model_kwargs={"temperature": 0, "max_tokens": 8000}
)
return aggregate_results(results, aggregator)
Pattern 4: Debate / Critique
When working through the Pattern 4 Debate Critique stage, write down the contract first: required inputs, success signal, and what happens on partial failure. That checklist keeps later code changes honest. Keep configuration outside application code. Environment files, secret stores, and feature flags belong in one place operators can audit without reading the whole graph. Checkpoint after expensive steps. Resume should not re-bill the same LLM call when an operator retries a later node.
┌─────────────┐ ┌─────────────┐
│ Proposer │ │ Challenger │
│ (solution │ │ (solution │
│ attempt 1)│ │ attempt 2)│
└──────┬──────┘ └──────┬──────┘
│ │
└──────────┬─────────────┘
▼
┌─────────────────┐
│ ADJUDICATOR │
│ (critique + │
│ synthesis) │
└─────────────────┘
# harness/multi_agent/debate.py
from dataclasses import dataclass
from typing import Optional
from langchain_aws import ChatBedrock
from langchain_core.messages import SystemMessage, HumanMessage
import boto3
@dataclass
class DebateResult:
proposer_solution: str
challenger_solution: str
adjudication: str
final_recommendation: str
agreement_level: str # HIGH | MEDIUM | LOW | CONTRADICTION
PROPOSER_PROMPT = """
You are a solution proposer. Approach the problem carefully and produce your best
solution. Explain your reasoning. Do not hedge excessively — commit to a specific answer.
"""
CHALLENGER_PROMPT = """
You are a solution challenger. You will receive a problem that another agent has
already attempted. Produce your own independent solution WITHOUT seeing their work.
Approach this fresh. Your goal is not to contradict — it's to find the best solution.
"""
ADJUDICATOR_PROMPT = """
You are an adjudicator reviewing two independent solutions to the same problem.
Your job:
1. Identify where the two solutions agree (these are likely correct)
2. Identify where they diverge (these need careful evaluation)
3. For each divergence, evaluate which solution is better and why
4. Produce a final synthesis that takes the best of both
Be direct about contradictions. Do not smooth over genuine disagreements —
surface them clearly so the human reviewer can make a judgment call.
Rate the agreement level: HIGH (minor differences), MEDIUM (some significant
divergences), LOW (fundamentally different approaches), or CONTRADICTION
(mutually exclusive conclusions).
"""
def run_debate(
problem: str,
region: str = "us-east-1",
) -> DebateResult:
bedrock = boto3.client("bedrock-runtime", region_name=region)
heavy_model = ChatBedrock(
client=bedrock,
model_id="anthropic.claude-3-7-sonnet-20250219-v1:0",
model_kwargs={
"temperature": 0.3, # slight temperature for independent solutions
"max_tokens": 6000,
"thinking": {"type": "enabled", "budget_tokens": 4000}
}
)
# Proposer works the problem
proposer_response = heavy_model.invoke([
SystemMessage(content=PROPOSER_PROMPT),
HumanMessage(content=problem)
])
proposer_solution = proposer_response.content
# Challenger works the same problem independently
# Note: Challenger does NOT see Proposer's solution
challenger_response = heavy_model.invoke([
SystemMessage(content=CHALLENGER_PROMPT),
HumanMessage(content=problem)
])
challenger_solution = challenger_response.content
# Adjudicator sees both and synthesizes
adjudicator_response = heavy_model.invoke([
SystemMessage(content=ADJUDICATOR_PROMPT),
HumanMessage(content=f"""
Problem: {problem}
Solution A (Proposer):
{proposer_solution}
Solution B (Challenger):
{challenger_solution}
Adjudicate and synthesize.
""")
])
adjudication = adjudicator_response.content
# Extract agreement level from adjudication
agreement_level = "MEDIUM"
for level in ["CONTRADICTION", "LOW", "HIGH", "MEDIUM"]:
if level in adjudication.upper():
agreement_level = level
break
return DebateResult(
proposer_solution=proposer_solution,
challenger_solution=challenger_solution,
adjudication=adjudication,
final_recommendation=adjudication,
agreement_level=agreement_level,
)
Inter-Agent Handoff and Context Passing
When working through the Inter-Agent Handoff and Context stage, write down the contract first: required inputs, success signal, and what happens on partial failure. That checklist keeps later code changes honest. Document the happy path and the recovery path together. Retries, human gates, and dead-letter handling are part of the product, not later polish. Checkpoint after expensive steps. Resume should not re-bill the same LLM call when an operator retries a later node.
# harness/multi_agent/handoff.py
from dataclasses import dataclass, field
from typing import Any, Optional
from langchain_core.messages import HumanMessage
@dataclass
class AgentHandoff:
"""
Structured context passed between agents.
The split between result and trace is deliberate: downstream agents
need the result, not the full reasoning history. Keeping them separate
lets each agent decide how much context it wants to consume.
"""
source_agent: str
task_completed: str
result_summary: str # compressed, structured result
artifacts: dict = field(default_factory=dict) # files, code, structured data
reasoning_trace: Optional[str] = None # full trace, passed only if downstream needs it
confidence: str = "MEDIUM" # HIGH | MEDIUM | LOW
flags: list = field(default_factory=list) # NEEDS_REVIEW, PARTIAL_RESULT, etc.
def to_context_message(self, include_trace: bool = False) -> HumanMessage:
"""
Converts handoff to a HumanMessage for injection into next agent's context.
include_trace=True only when the downstream agent genuinely needs the reasoning.
"""
content = f"""
[HANDOFF FROM: {self.source_agent}]
Task completed: {self.task_completed}
Confidence: {self.confidence}
Flags: {', '.join(self.flags) if self.flags else 'none'}
Result summary:
{self.result_summary}
"""
if self.artifacts:
content += f"\nArtifacts available:\n"
for key, value in self.artifacts.items():
if isinstance(value, str) and len(value) < 500:
content += f" {key}: {value}\n"
else:
content += f" {key}: [available, {type(value).__name__}]\n"
if include_trace and self.reasoning_trace:
content += f"\nFull reasoning trace:\n{self.reasoning_trace}"
return HumanMessage(content=content)
Production Hardening
When working through the Production Hardening stage, write down the contract first: required inputs, success signal, and what happens on partial failure. That checklist keeps later code changes honest. Prefer small, testable units over sprawling scripts. When a step fails, the failure should point at a single responsibility rather than a tangled pipeline. Checkpoint after expensive steps. Resume should not re-bill the same LLM call when an operator retries a later node. When working through the Production Hardening stage, write down the contract first: required inputs, success signal, and what happens on partial failure. That checklist keeps later code changes honest. Record timings and token or query cost next to functional results. Cost visibility early prevents surprise bills when the path moves from demo to shared environments.
Cost Explosion Prevention
The Cost Explosion Prevention stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Keep configuration outside application code. Environment files, secret stores, and feature flags belong in one place operators can audit without reading the whole graph. Keep graph state flat and typed. Nested blobs hide which node wrote which field and break resume after interrupts.
# harness/multi_agent/budget.py
import boto3
import time
from decimal import Decimal
class AgentBudgetGuard:
"""
Tracks cumulative cost and agent count per run.
Hard-stops execution when limits are exceeded.
"""
def __init__(
self,
max_agents_per_run: int = 10,
max_total_tokens: int = 500_000,
table_name: str = "agent-budget-state",
region: str = "us-east-1",
):
self.max_agents = max_agents_per_run
self.max_tokens = max_total_tokens
self.table = boto3.resource("dynamodb", region_name=region).Table(table_name)
def register_agent_spawn(self, run_id: str, agent_id: str) -> bool:
"""
Returns True if spawn is allowed, False if budget exceeded.
Call this before spawning any sub-agent.
"""
response = self.table.update_item(
Key={"run_id": run_id},
UpdateExpression="SET agent_count = if_not_exists(agent_count, :z) + :inc",
ExpressionAttributeValues={":z": 0, ":inc": 1},
ReturnValues="UPDATED_NEW",
)
new_count = int(response["Attributes"]["agent_count"])
if new_count > self.max_agents:
raise AgentBudgetExceededError(
f"Run {run_id} attempted to spawn agent #{new_count}, "
f"but max_agents_per_run is {self.max_agents}. "
f"Either the supervisor is over-decomposing, or there is a spawn loop."
)
return True
def record_token_usage(self, run_id: str, tokens_used: int):
response = self.table.update_item(
Key={"run_id": run_id},
UpdateExpression="SET total_tokens = if_not_exists(total_tokens, :z) + :inc",
ExpressionAttributeValues={":z": 0, ":inc": tokens_used},
ReturnValues="UPDATED_NEW",
)
total = int(response["Attributes"]["total_tokens"])
if total > self.max_tokens:
raise AgentBudgetExceededError(
f"Run {run_id} consumed {total:,} tokens, exceeding limit of {self.max_tokens:,}."
)
class AgentBudgetExceededError(Exception):
pass
Deadlock Detection
The Deadlock Detection stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Document the happy path and the recovery path together. Retries, human gates, and dead-letter handling are part of the product, not later polish. Keep graph state flat and typed. Nested blobs hide which node wrote which field and break resume after interrupts.
# harness/multi_agent/deadlock.py
import boto3
import time
from typing import List
class DeadlockDetector:
"""
Tracks the delegation chain per run and detects cycles.
Stored in DynamoDB so it works across parallel agent branches.
"""
def __init__(self, table_name: str = "agent-delegation-chain", region: str = "us-east-1"):
self.table = boto3.resource("dynamodb", region_name=region).Table(table_name)
def record_delegation(self, run_id: str, from_agent: str, to_agent: str):
"""
Records a delegation event and checks for cycles.
Raises DeadlockDetectedError if a cycle is found.
"""
self.table.put_item(Item={
"run_id": run_id,
"delegation_id": f"{from_agent}->{to_agent}-{int(time.time())}",
"from_agent": from_agent,
"to_agent": to_agent,
"timestamp": int(time.time()),
})
chain = self._get_delegation_chain(run_id)
if self._has_cycle(chain):
cycle_description = self._describe_cycle(chain)
raise DeadlockDetectedError(
f"Delegation cycle detected in run {run_id}: {cycle_description}. "
f"Check supervisor decomposition logic for circular dependencies."
)
def _get_delegation_chain(self, run_id: str) -> List[tuple]:
response = self.table.query(
KeyConditionExpression="run_id = :rid",
ExpressionAttributeValues={":rid": run_id}
)
return [(item["from_agent"], item["to_agent"]) for item in response.get("Items", [])]
def _has_cycle(self, chain: List[tuple]) -> bool:
graph = {}
for from_a, to_a in chain:
graph.setdefault(from_a, set()).add(to_a)
visited, rec_stack = set(), set()
def dfs(node):
visited.add(node)
rec_stack.add(node)
for neighbor in graph.get(node, []):
if neighbor not in visited:
if dfs(neighbor): return True
elif neighbor in rec_stack:
return True
rec_stack.discard(node)
return False
return any(dfs(node) for node in graph if node not in visited)
def _describe_cycle(self, chain: List[tuple]) -> str:
return " -> ".join(f"{f}->{t}" for f, t in chain[-5:])
class DeadlockDetectedError(Exception):
pass
Cross-Agent Observability
The Cross-Agent Observability stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Prefer small, testable units over sprawling scripts. When a step fails, the failure should point at a single responsibility rather than a tangled pipeline. Keep graph state flat and typed. Nested blobs hide which node wrote which field and break resume after interrupts. The Cross-Agent Observability stage works best when treated as a measurable surface. Capture one golden transcript, one failure case, and the rollback note before expanding scope. Record timings and token or query cost next to functional results. Cost visibility early prevents surprise bills when the path moves from demo to shared environments.
# harness/multi_agent/observability.py
import os
from contextlib import contextmanager
from langsmith import Client
from langsmith.run_trees import RunTree
class MultiAgentTracer:
"""
Maintains a run tree across all agents in a multi-agent system.
Pass the parent_run_id to each agent so their traces nest correctly.
"""
def __init__(self):
self.client = Client()
@contextmanager
def agent_span(self, parent_run_id: str, agent_name: str, inputs: dict):
"""
Context manager for an individual agent's trace span.
Usage:
with tracer.agent_span(parent_run_id, "security_reviewer", {...}) as span:
result = run_security_review(...)
span.end(outputs={"result": result})
"""
run = self.client.create_run(
name=agent_name,
run_type="chain",
inputs=inputs,
parent_run_id=parent_run_id,
)
try:
yield run
except Exception as e:
self.client.update_run(run.id, error=str(e))
raise
finally:
self.client.update_run(run.id, end_time=None) # auto-sets end time
Production Reality Check
For the Production Reality Check stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Keep configuration outside application code. Environment files, secret stores, and feature flags belong in one place operators can audit without reading the whole graph. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
Reference Architecture
For the Reference Architecture stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Document the happy path and the recovery path together. Retries, human gates, and dead-letter handling are part of the product, not later polish. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
┌───────────────────────────────────────────┐
│ User Request │
└──────────────────┬────────────────────────┘
│
┌──────────────────▼────────────────────────┐
│ AgentHarness Runtime │
│ (budget guard, deadlock detector, tracer)│
└──────────────────┬────────────────────────┘
│
┌──────────────────▼────────────────────────┐
│ SUPERVISOR / ORCHESTRATOR │
│ Claude 3.7 + extended thinking │
│ Task decomposition + result synthesis │
└────┬──────────────┬──────────────┬────────┘
│ │ │
┌───────────▼──┐ ┌────────▼──┐ ┌───────▼───────┐
│ Worker A │ │ Worker B │ │ Worker C │
│ Claude 3.5 │ │ Claude 3.5 │ │ Claude 3.5 │
│ specialist │ │ specialist │ │ specialist │
└───────┬──────┘ └─────┬─────┘ └──────┬────────┘
│ │ │
┌───────▼───────────────▼────────────────▼────────┐
│ Tool Execution Layer │
│ (auth, retry, circuit breaker from Art.5) │
└───────────────────────┬─────────────────────────┘
│
┌───────────────────────▼──────────────────────────┐
│ AWS Services │
│ Bedrock │ DynamoDB (budget+deadlock+loop+circ) │
│ Secrets Manager │ Knowledge Bases │
└──────────────────────────────────────────────────┘
Observability: LangSmith run trees — full hierarchy per user request
Reference Infrastructure Stack
For the Reference Infrastructure Stack stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Prefer small, testable units over sprawling scripts. When a step fails, the failure should point at a single responsibility rather than a tangled pipeline. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
+-----------------------------+---------------------+------------------------------+
| Component | Technology | Role |
+-----------------------------+---------------------+------------------------------+
| Orchestration | LangGraph 0.2+ | Multi-agent graph, routing, |
| | | supervisor-worker topology |
+-----------------------------+---------------------+------------------------------+
| Supervisor Model | Claude 3.7 Sonnet | Task decomposition, |
| | (extended thinking) | result synthesis |
+-----------------------------+---------------------+------------------------------+
| Worker Models | Claude 3.5 Sonnet | Specialized execution, |
| | | bounded tasks |
+-----------------------------+---------------------+------------------------------+
| Parallel Execution | asyncio + Bedrock | Concurrent agent runs with |
| | | semaphore-gated concurrency |
+-----------------------------+---------------------+------------------------------+
| Context Compression | Claude Haiku 3.5 | Pipeline stage handoffs, |
| | | summary generation |
+-----------------------------+---------------------+------------------------------+
| Budget Guard | DynamoDB | Agent count + token limits |
| | | per run |
+-----------------------------+---------------------+------------------------------+
| Deadlock Detection | DynamoDB | Delegation cycle detection |
+-----------------------------+---------------------+------------------------------+
| Loop Detection | DynamoDB (Art. 5) | Per-resource edit tracking |
+-----------------------------+---------------------+------------------------------+
| Circuit Breaker State | DynamoDB (Art. 5) | Shared across all agents |
| | | in a run |
+-----------------------------+---------------------+------------------------------+
| Cross-Agent Observability | LangSmith run trees | Full hierarchy per request |
+-----------------------------+---------------------+------------------------------+
| Auth Propagation | CredentialManager | JWT passed to all workers |
| | (Art. 5) | via execution context |
+-----------------------------+---------------------+------------------------------+
| Local Dev Alternative | Ollama + Docker | All patterns testable |
| | Compose | without Bedrock costs |
+-----------------------------+---------------------+------------------------------+
| Infrastructure as Code | Terraform | DynamoDB tables, IAM roles |
+-----------------------------+---------------------+------------------------------+
A Note on Where We’re Headed
For the A Note on Where stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state. Treat this stage as a contract between inputs and validated outputs. Name the artifacts, define success checks, and refuse silent partial completion. Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
Operational checklist
For the Operational checklist stage, define the inputs, the owner of the step, and the exit criteria before changing code. Operators should be able to re-run the step from a known checkpoint without guessing hidden state.
Treat this stage as a contract between inputs and validated outputs. Name the artifacts, define success checks, and refuse silent partial completion.
Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
Write a short runbook: how to rotate keys, how to drain the queue, how to roll back the last ingest.
Record timings and token or query cost next to functional results. Cost visibility early prevents surprise bills when the path moves from demo to shared environments.
Put human approval on edges that spend money or change production data. Compile-time wiring does not equal business completeness.
Before promoting the stack, freeze versions, capture a golden transcript for the critical path, and confirm rollback steps. Shared environments need rate limits, tenancy checks, and a clear owner for secret rotation. Prefer boring reliability over clever one-off demos.
Batch note for a0dc7ff1211b: keep provider keys out of the repo, set a per-session token ceiling, and store transcripts next to the eval fixtures so later model swaps stay comparable.