Production Agent Workflows

Deploy production agents with observability, cost optimization, and guardrails

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The Big Picture: From Prototype to Production

The gap between a chatbot prototype and a production agent is enormous. A prototype runs on a developer's laptop with clean inputs. A production agent serves real users, processes money, impacts reputation, and operates under strict SLAs.

Why Production Is Hard

Production agents face five critical challenges:

Reliability

Tools fail, LLMs refuse, contexts overflow. Every failure must be handled gracefully. Users demand 99.9% uptime.

Observability

When an agent fails, you need to trace why: which step failed, what tokens were used, what was in context?

Cost Control

Every LLM call costs money. Token usage compounds across millions of requests. Runaway loops drain budgets.

Latency

Users wait for results. P99 latency matters. Sequential LLM calls compound delays. Parallelization is essential.

Safety

An agent can access tools that delete data, send emails, or process payments. Guardrails are non-negotiable.

Scale

A prototype handles one user at a time. Production serves thousands concurrently, requiring queue systems and autoscaling.

Agent Orchestration Patterns

Production agents are built from orchestration patterns. These patterns define how multiple LLM calls and tools compose into workflows.

Prototype vs Production Agent Comparison
Prototype Agent User Input LLM Call Output Single user, clean inputs No error handling, no monitoring Production Agent User Input Rate Limiter Trace & Retry LLM + Tools Memory Logged Output + Cost Rate limiting, retries, tracing memory, guardrails, cost tracking
Key insight: Production agents are prototype logic wrapped in layers of reliability infrastructure: rate limiting, retries, tracing, memory, guardrails, and cost tracking.

Five Production Challenges in Detail

1. Reliability

Production agents must survive failures: tool timeouts, LLM refusals, context overflow, rate limits, cascading failures. Use retry with backoff, circuit breakers, fallbacks, and idempotency.

2. Observability

Trace every execution: every LLM call, every tool invocation, state transitions, memory access, decisions made. Store searchable traces for debugging.

3. Cost Control

Token costs dominate operating expenses. Use caching, prompt compression, model routing, batch processing, context summarization. Set budget limits and track attribution per agent and customer.

4. Latency

P99 latency matters more than average. Parallelize independent tasks, cache results, use faster models for time-critical paths, consider streaming responses.

5. Safety

Agents can cause harm if unsupervised. Implement tool access control, high-stakes approval workflows, input validation, output filtering, and comprehensive audit trails.

See agent_tools_mcp_guide.html for tool safety patterns and multi_agent_systems_guide.html for multi-agent coordination.

Orchestration Patterns: Five Core Architectures

Anthropic's research identifies five core patterns that compose production agent workflows. Each has tradeoffs. Real systems combine multiple patterns.

Pattern 1: Prompt Chaining

Sequential Deterministic

Run LLM calls in sequence. Each step feeds output into the next step. Insert validation between steps for quality assurance.

Step 1: "Analyze customer request: {input}"
        → Output: Problem identified, category assigned

Step 2: "Generate solution: {output_from_step_1}"
        → Output: Solution drafted

Step 3: "Review solution quality: {output_from_step_2}"
        → Output: Quality score + feedback

When to use: Linear workflows where each step depends on previous results. Quality assurance pipelines. Sequential reasoning tasks.

Tradeoffs: Latency = sum of all steps. Early errors cascade. But deterministic and easy to debug.

Pattern 2: Routing

Branching Conditional

LLM classifies input, then routes to specialist agent. Different problems take different paths.

Step 1: Classify input → "billing" | "technical" | "general"

If "billing" → Billing specialist (payment APIs)
If "technical" → DevOps specialist (infra tools)
Else → General support agent

When to use: Multi-domain systems. Chat support (different agents per domain). Language translation (route by language).

Tradeoffs: Requires good classifier. Routing errors send users wrong way. But cheap and fast.

Pattern 3: Parallelization

Concurrent Aggregation

Run multiple agents simultaneously on independent tasks, then combine results.

Task: "Write research report on quantum computing"

Parallel tasks:
  Agent A: Research papers → List of 20
  Agent B: Interview experts → Transcripts
  Agent C: Analyze trends → Market data

Aggregation:
  Combine all → Unified report

When to use: Latency-critical systems. Information gathering (parallelize sources). Multi-perspective analysis.

Tradeoffs: Complex state management. Latency = max(parallel steps), not sum. But more expensive.

Pattern 4: Orchestrator-Subagents

Hierarchical Delegating

Central orchestrator plans work, delegates to specialized subagents. Orchestrator monitors and adjusts.

Orchestrator plans:
  1. Requirements (delegate to Analyst)
  2. Design proposal (delegate to Architect)
  3. Cost estimate (delegate to Finance)

Monitor progress, handle blockers, re-plan if needed

When to use: Complex multi-step projects. Adaptive workflows. Hierarchical organizations.

Tradeoffs: More complex orchestration. Multiple LLM calls. But scalable and adaptable.

Pattern 5: Evaluator-Optimizer

Iterative Refinement

Generator LLM creates candidates, evaluator LLM critiques. Repeat until quality threshold met.

Generator: Create solution candidate
Evaluator: Critique with feedback
Generator: Improve based on feedback
Repeat until evaluator says "good enough"

When to use: Quality-critical outputs. Code generation (generate → test → refine). Creative iteration.

Tradeoffs: Many iterations possible. Very expensive. But high-quality results.

Five Orchestration Patterns Visual
1. Prompt Chaining A B C 2. Routing C A1 A2 A3 3. Parallelization A B C D 4. Orchestrator-Subagents Orch S1 S2 S3 5. Evaluator-Optimizer Gen Eval Repeat until quality OK Pattern Tradeoffs: Chaining: Deterministic but sequential latency | Routing: Fast but needs good classifier | Parallelization: Reduces latency but complex | Orchestrator: Adaptive but expensive | Evaluator: Highest quality but many iterations

When to Use Each Pattern

Pattern Best For Latency Cost
Prompt Chaining Linear workflows, validation Sum of steps Low
Routing Multi-domain classification Single step Very low
Parallelization Independent tasks, gathering Max of parallel steps High
Orchestrator-Subagents Complex projects, adaptive Adaptive Very high
Evaluator-Optimizer Quality-critical, iteration Variable (iterations) Very high
Key insight: Combine patterns. A router might delegate to orchestrator workflows. An orchestrator might parallelize independent tasks. Mix and match for your specific needs.

See langgraph_guide.html for implementation using LangGraph, which excels at orchestrating these workflows.

Error Handling & Resilience: Fault Tolerance Strategies

Errors are inevitable in production. LLMs hallucinate, APIs timeout, rate limits trigger. Reliable systems gracefully handle failure.

Error Taxonomy

1. Tool Failures

Database query times out, API returns 500, connection drops. Solutions: retry with backoff, timeout, circuit breaker, fallback.

2. LLM Refusals

Claude refuses action (safety boundary). Solutions: clarify intent, escalate to human, find alternative path, audit refusal.

3. Context Overflow

Conversation history exceeds token limit. Solutions: summarization, truncation, semantic cache, sliding window.

4. Rate Limits

Hit provider rate limit. Solutions: queuing, backoff, multi-provider failover, quota management.

5. Cascading Failures

One failure triggers cascade. Solutions: bulkheads, circuit breakers, graceful degradation, load shedding.

Retry Strategies

Exponential backoff with jitter (best practice):
  Retry 1: wait 1 + rand(0,1) seconds ≈ 1.3s
  Retry 2: wait 2 + rand(0,2) seconds ≈ 2.8s
  Retry 3: wait 4 + rand(0,4) seconds ≈ 5.2s
  Retry 4: success

Prevents thundering herd and spreads load

Circuit Breaker Pattern

Stop retrying failed service after N failures. Three states: CLOSED (normal), OPEN (fail fast), HALF-OPEN (test).

Circuit Breaker State Machine
CLOSED Normal, requests pass N failures OPEN Fail fast, reject requests timeout HALF-OPEN Test with 1 request success failure

Idempotency

Safe to retry without side effects. Critical for resilience with non-idempotent operations.

Idempotent: "Get user profile" (safe to call 100x)
Not idempotent: "Charge user $100" (calls twice = charge twice)

Solution: idempotency keys
  POST /api/payment
  {
    "idempotency_key": "order-12345-retry",
    "amount": 100
  }

  First call: charge succeeds, store key → result
  Second call (same key): return cached result, don't charge
Error handling checklist: (1) Retry with exponential backoff, (2) Circuit breaker for failing services, (3) Fallback to backup tools, (4) Idempotency keys, (5) Dead letter queue for manual review.

Observability & Tracing: Monitoring Agent Health

You can't fix what you can't see. Production agents must emit detailed traces for debugging.

What to Trace

LLM Calls

Model, input/output tokens, latency, cost, temperature

Tool Calls

Tool name, parameters, result, latency, error

State Transitions

Which step, which decision, why

Memory Access

What was retrieved, stored, when

Trace Structure

Trace ID: trace-2026-04-10-12345
├─ Start: 2026-04-10 12:30:15.123
├─ End: 2026-04-10 12:30:45.456
├─ Total latency: 30.333s
└─ Total cost: $0.045

  Span 1: "Route request" (0-2s)
  ├─ Type: LLM, Model: claude-3-5-sonnet
  ├─ Tokens: 150 input, 42 output
  ├─ Decision: "route to billing agent"
  └─ Cost: $0.001

  Span 2: "Billing agent" (2-30s)
  ├─ Span 2a: "Fetch customer" (2-5s)
  ├─ Span 2b: "Generate invoice" (5-25s)
  │  └─ 3 nested LLM calls
  └─ Span 2c: "Send email" (25-30s)

Key Metrics

Metric Definition Alerting Threshold
Latency (p99) 99th percentile response time If > 10 seconds
Error rate Failed requests / total If > 1%
Token usage Input + output tokens If runaway > 10,000
Cost per task USD spent on request Budget limit
Retry rate Retried requests / total If > 5%
Trace Hierarchy for Observability
Trace: Request Span 1: LLM Route (0-2s) Span 2: Tool Execute (2-30s) Span 1a: Tokenize Span 1b: API Call Span 1c: Parse Span 2a: Validate Span 2b: Execute Span 2c: Log Observability enables pinpointing bottlenecks: If request slow, check Span 2b (execution latency) If high cost, check Span 1b (LLM token count) Propagate trace ID across all services for distributed tracing
Observability best practices: (1) Trace every LLM and tool call, (2) Propagate trace context across services, (3) Alert on p99 latency and error rate spikes, (4) Track cost per agent and customer, (5) Use OpenTelemetry backends for storage and search.

Cost Management: Controlling Token Spend

LLM token costs dominate operating expenses. A single inefficient prompt bleeds millions in cost at scale.

Token Costs

Claude 3.5 Sonnet pricing (example):
  Input tokens: $3 per 1M
  Output tokens: $15 per 1M

Request cost:
  1,000 input + 500 output tokens
  = (1,000 × $3/1M) + (500 × $15/1M)
  = $0.003 + $0.0075 = $0.0105

At 1M requests/day:
  Daily: $10,500
  Monthly: $315,000

Cost Control Strategies

1. Caching

Identical inputs should reuse cached outputs. No LLM call = no cost.

2. Prompt Compression

Remove redundant context. Every word costs money. 60% compression = 60% cost reduction.

3. Model Routing

Use cheap models (Haiku) for simple tasks, expensive models (Sonnet) for hard tasks.

4. Context Summarization

Don't send full conversation history every turn. Summarize old messages periodically.

5. Budget Limits

Stop the agent if it exceeds a cost threshold. Prevent runaway loops.

Cost Attribution

Track cost per agent, per customer, per workflow. Enable chargeback models.

Trace metadata:
  trace_id: "trace-12345"
  agent_id: "billing-agent"
  customer_id: "customer-999"

Cost attribution:
  → billing-agent: +$0.017
  → customer-999: +$0.017

Monthly reports:
  Which agents cost most?
  Which customers cost most? (chargeback)
Cost Breakdown Waterfall for 1000 Requests
Input $300 Output $700 Tools: $50 Total Cost $1,050 per 1000 requests $1.05 per request Reduction: Caching (-20%), Compression (-30%), Model routing (-10%) = 60% total savings
Cost optimization checklist: (1) Cache identical requests, (2) Compress prompts (remove redundancy), (3) Model routing (cheap models for easy tasks), (4) Summarize context, (5) Track attribution per agent/customer, (6) Set budget limits.

Rate Limiting & Concurrency: Managing Load

Provider rate limits are hard constraints. Exceed them and requests fail. Concurrency must be carefully managed.

Rate Limit Types

Request Rate Limit

Maximum requests per minute. Example: 10,000 req/min.

Token Rate Limit

Maximum tokens per minute. Example: 1,000,000 tok/min. Usually the tighter constraint.

Token Bucket Algorithm

Standard algorithm for rate limiting. Tokens accumulate over time. Each request consumes tokens.

Bucket capacity: 1000 tokens
Refill rate: +100 tokens/second

Request arrives (100 tokens):
  If bucket ≥ 100: allow, consume 100 tokens
  Else: queue request, wait for tokens to refill

Semaphore for Concurrency

Limit concurrent requests to prevent overwhelming provider or infrastructure.

Semaphore(max=100):
  Max 100 concurrent requests

Request 1-100: acquire → allowed → processing
Request 101: acquire → blocked, wait
Request 1: finishes → release
Request 101: acquire → allowed → processing

Priority Queues

High-priority tasks processed first (premium customers, time-sensitive requests).

Processing order:
  1. Premium customer (high priority)
  2. Alert response (high priority)
  3. Standard request (normal)
  4. Batch analysis (low priority)

Multi-Provider Failover

If primary provider rate-limited, switch to backup provider.

Primary: Claude (Anthropic)
Backup: GPT-4 (OpenAI)
Fallback: GPT-3.5 Turbo (cheap)

Request arrives:
  Try Claude → rate limited → try OpenAI → success
  Monitor: shift traffic if Claude consistently limited
Token Bucket Rate Limiting Visualization
Token Bucket 800/1000 tokens +100 tokens/sec Request arrives needs 100 tokens if ≥ 100 else: queue Allow consume 100 Queue wait for tokens t=0: 1000 tokens t=1: 1100 tokens (refilled) request consumes 100 t=2: 1100 tokens (after refill)
Rate limiting checklist: (1) Token bucket for fair sharing, (2) Semaphore for concurrency, (3) Priority queues, (4) Multi-provider failover, (5) Per-user/tenant quotas, (6) Monitor usage and alert on limits.

Context & Memory Management: Stateful Agents

Agents need context: current conversation, user preferences, past interactions. Memory comes in three layers: short-term, long-term, external.

Memory Hierarchy

Short-Term Memory

Current conversation in context window. Fast, limited size (~4000 tokens). Forgotten when conversation ends.

Long-Term Memory

User profiles, preferences, conversation history. Database storage, unlimited size. Retrieved via database lookup.

External Memory

Documents, knowledge base. Retrieved via semantic search. Part of RAG systems.

Memory Update Strategies

Summarization

Periodically summarize conversation into shorter summary. Frees up context window for new messages.

Turns 1-50 (5000 tokens):
  Many turns of conversation...

After turn 50:
  Create summary (100 tokens)
  Replace old turns with summary
  Saves 4900 tokens for future context

Context Pruning

Remove low-importance messages from context. Keep high-value messages.

Semantic Memory Cache

Cache embeddings of past answers. Similar questions reuse cached response.

Turn 1: "What is refund policy?" → generate response
         Store: embedding + response in cache

Turn 100: "Do you offer refunds?" → similar question
          Retrieve from cache → no LLM call → instant response
Memory Architecture: Layers and Retrieval
Short-Term Current conversation (~4000 tokens) instant Long-Term User profile, history (database) DB lookup External Documents, RAG (vector search) semantic search User asks question: Question "What did we discuss?" Check short-term Fetch long-term Search external Combine context Send to LLM with full context Example: Short-term has "We discussed bug X", long-term has "User preference: dark mode", external has "FAQ: solution Y"
Memory management best practices: (1) Keep short-term context manageable, (2) Summarize old conversations, (3) Store preferences in long-term DB, (4) Use RAG for documents, (5) Implement semantic caching.

See rag_patterns_guide.html for detailed RAG implementation and vector database strategies.

Human-in-the-Loop (HITL): Approval Workflows

Some decisions are too important to let an agent make alone. HITL patterns insert human judgment at critical junctures.

When to Require Approval

High-Stakes Actions

Delete, pay, publish, modify access. Lasting consequences.

Low Confidence

Agent uncertainty. Confidence < 0.8. Better ask human.

Novel Situations

Request unlike training data. Edge cases. Unknown patterns.

Policy Violations

Compliance rules (GDPR, HIPAA). Always require approval.

Confidence Estimation

Method 1: LLM Self-Assessment

Prompt: "Rate your confidence (0-1): {question}"
         "Confidence: 0.95"

Method 2: Entropy of Choices

If top candidates have similar scores, confidence is low. Escalate to human.

Method 3: Explicit Rules

if action == "delete": require_approval()
if amount > 1000: require_approval()
if confidence < 0.8: require_approval()

HITL Patterns

Synchronous HITL

Block until human approves. Good for critical actions where waiting is acceptable.

Agent: "Process refund of $500"
System: Send to approval queue
Human: Reviews, approves or rejects
User: Receives response

Asynchronous HITL

Queue for later review. Agent continues with defaults. Low-urgency decisions.

Agent: "Send promotional email tomorrow?"
System: Queue for review (not urgent)
Response: "Email will be sent tomorrow"
Human: Reviews later, approves/rejects

Escalation Paths

If human doesn't respond within timeout, escalate up the chain:

No response from support agent (1 hour) →
Escalate to team lead →
No response (2 hours) →
Escalate to manager →
No response (4 hours) →
Escalate to on-call director

Audit Trail

Log all human decisions for compliance and debugging.

Approval record:
  request_id: "req-12345"
  action: "refund $500"
  approver: "john@company.com"
  decision: "APPROVED"
  timestamp: "2026-04-10 15:30:45"
  reason: "Customer satisfaction"
HITL best practices: (1) Define clear approval criteria, (2) Estimate confidence, (3) Use synchronous for critical, async for non-urgent, (4) Set escalation timeouts, (5) Maintain audit trails.

Testing & Evaluation: Quality Assurance

Production agents must be thoroughly tested. Bugs in agents can cause financial loss or reputation damage.

Testing Pyramid for Agents

Unit Tests

Test individual tools, nodes in isolation. Fast, deterministic, high coverage.

def test_database_query():
  result = db.query("SELECT * FROM users WHERE id = 1")
  assert result.id == 1
  assert result.status == "active"

Integration Tests

Test full agent flow on synthetic inputs. Verify end-to-end behavior.

def test_billing_agent():
  request = "Process refund for order 12345"
  response = agent.run(request)
  assert "refund processed" in response
  assert db.get_refund(12345).status == "approved"

Regression Tests

Run on fixed test suite after every change. Prevent breaking existing functionality.

LLM-as-Judge Evaluation

Use another LLM to score agent outputs. Does response answer the question? Is it factual? Helpful?

judge_prompt = """
Rate this response (1-5):
Question: {question}
Response: {response}
Score:
"""

Simulation & Replay

Run agent on historical real requests with known answers. Compare outputs against expected results.

Shadow Mode

Run new agent version alongside old version. Compare outputs. Deploy only if results match.

Red-Teaming

Adversarial inputs to find failure modes. "What breaks this agent?"

Latency Testing

Measure P99 latency, not just average. Tail latency impacts user experience.

Load test with 1000 concurrent requests:
  P50 latency: 2.1 seconds
  P95 latency: 4.8 seconds
  P99 latency: 12.3 seconds ← watch this!

Alert if P99 > 10 seconds
Testing Pyramid for Agents
Unit Tests Tools, nodes (fast, deterministic) ~80% of tests Integration Tests Full agent flow (~15% of tests) E2E Tests (~5% of tests) Pyramid principle: many fast unit tests, fewer expensive integration/E2E tests
Testing checklist: (1) Unit tests for all tools, (2) Integration tests for agent flow, (3) Regression tests for every change, (4) LLM-as-judge evaluation, (5) Simulation on historical data, (6) Red-teaming for edge cases, (7) P99 latency tests.

Deployment Architecture: Scalable Infrastructure

Moving from single-laptop prototype to production requires infrastructure: async processing, queues, containers, autoscaling, multi-region failover.

Async Processing Pattern

Agent runs in background. User polls or receives webhook callback.

User: POST /api/agent/run {request}
Server: Return immediately with task_id
        Enqueue task to background worker

Background worker:
  Pick task from queue
  Run agent
  Store result in database
  Webhook callback to user (optional)

User: GET /api/agent/status/{task_id}
      Returns: "processing" or "completed" with result

Task Queue System

Decouple request from processing. Queue systems (Celery, SQS, RabbitMQ) handle buffering and retries.

Request flow:
  1. User request → API server
  2. API enqueues task → Queue (SQS)
  3. Return task_id to user immediately
  4. Worker pool processes queue
  5. Result stored in database
  6. User polls or receives notification

Containerization

Docker + Kubernetes for scalable deployment.

Dockerfile:
  FROM python:3.11
  COPY . /app
  RUN pip install -r requirements.txt
  CMD ["python", "agent.py"]

Kubernetes deployment:
  replicas: 3
  resource_requests: {cpu: 1, memory: 2Gi}
  livenessProbe: /health

Autoscaling

Scale agent workers based on queue depth or CPU usage.

Scale rule:
  If queue depth > 100 tasks → spawn more workers
  If queue depth < 10 tasks → reduce workers

Dynamic scaling:
  Queue depth 50 → 3 workers
  Queue depth 500 → 10 workers
  Queue depth 5000 → 50 workers

Canary Deployment

Roll out new agent version to small percentage first (5% traffic). Monitor for errors before full rollout.

Phase 1: 5% traffic → new version
         95% traffic → old version
         Monitor error rate for 1 hour
         If OK, proceed to phase 2

Phase 2: 50% traffic → new version
         50% traffic → old version
         Monitor for 2 hours
         If OK, complete rollout

Blue-Green Deployment

Instant rollback. Two identical environments (blue, green). Switch traffic instantly if issues detected.

Blue environment: current production
Green environment: new version

Switch:
  1. Deploy new code to green
  2. Test green thoroughly
  3. Switch router: all traffic → green
  4. Old blue still running (instant rollback if needed)
  5. After 24 hours, delete blue

Multi-Region Deployment

Failover across regions for resilience.

Region 1 (US-East): primary
Region 2 (US-West): secondary
Region 3 (Europe): tertiary

Request flow:
  Try region 1 → latency 50ms
  Fail → try region 2 → latency 100ms
  Fail → try region 3 → latency 200ms

Secrets Management

API keys in Vault, not in code. Rotate regularly.

AWS Secrets Manager:
  store("anthropic_api_key", "sk-...")
  store("database_password", "...")
  store("stripe_api_key", "...")

Application:
  api_key = secrets.get("anthropic_api_key")
  # Never hardcoded, never in git
Production Deployment Architecture
Users Load Balancer API Server 1 API Server 2 API Server 3 Task Queue Worker 1 Worker 2 Worker N Database (results, cache) (replicated) Monitoring & Observability Queue depth, Worker CPU, Latency p99 Error rate, Cost, Autoscaling rules
Deployment checklist: (1) Async processing with task queues, (2) Containerization (Docker), (3) Kubernetes orchestration, (4) Autoscaling rules, (5) Canary/blue-green deployments, (6) Multi-region failover, (7) Secrets management.

Python Implementation: Building Blocks & Simulation

A production-grade agent framework combines configuration, tracing, rate limiting, memory, and error handling. Here's a Python skeleton using only stdlib.

Framework Components

import json
import time
from datetime import datetime
from enum import Enum
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional
from collections import deque

# Configuration
@dataclass
class AgentConfig:
    """Agent configuration."""
    model: str = "claude-3-5-sonnet"
    max_steps: int = 10
    max_tokens: int = 10000
    temperature: float = 0.7
    budget_cents: int = 100  # $1.00 max
    token_limit_per_request: int = 5000

# Tracing
@dataclass
class TraceSpan:
    """A span in the trace tree."""
    span_id: str
    name: str
    span_type: str  # "llm", "tool", "orchestrator"
    start_time: float
    end_time: Optional[float] = None
    tokens_in: int = 0
    tokens_out: int = 0
    cost_cents: float = 0.0
    metadata: Dict[str, Any] = field(default_factory=dict)
    error: Optional[str] = None

    def duration(self) -> float:
        """Duration in seconds."""
        if self.end_time is None:
            return 0.0
        return self.end_time - self.start_time

@dataclass
class Trace:
    """Full request trace."""
    trace_id: str
    start_time: float
    spans: List[TraceSpan] = field(default_factory=list)
    total_cost_cents: float = 0.0
    total_tokens: int = 0

    def duration(self) -> float:
        """Total duration."""
        if not self.spans:
            return 0.0
        return max(s.end_time or s.start_time for s in self.spans) - self.start_time

# Rate Limiting
@dataclass
class TokenBucket:
    """Token bucket for rate limiting."""
    capacity: int
    refill_rate: float  # tokens per second
    current_tokens: float = None
    last_refill: float = None

    def __post_init__(self):
        self.current_tokens = float(self.capacity)
        self.last_refill = time.time()

    def consume(self, tokens: int) -> bool:
        """Try to consume tokens. Return True if allowed."""
        self.refill()
        if self.current_tokens >= tokens:
            self.current_tokens -= tokens
            return True
        return False

    def refill(self):
        """Refill tokens."""
        now = time.time()
        elapsed = now - self.last_refill
        self.current_tokens = min(
            self.capacity,
            self.current_tokens + elapsed * self.refill_rate
        )
        self.last_refill = now

# Memory
@dataclass
class AgentMemory:
    """Short-term and long-term memory."""
    short_term: deque = field(default_factory=lambda: deque(maxlen=20))
    long_term: Dict[str, Any] = field(default_factory=dict)
    summarized_at_step: int = 0

    def add_message(self, role: str, content: str):
        """Add message to short-term memory."""
        self.short_term.append({"role": role, "content": content})

    def get_context(self) -> List[Dict[str, str]]:
        """Get all messages for context."""
        return list(self.short_term)

    def summarize(self):
        """Summarize old messages (mock)."""
        if len(self.short_term) > 10:
            old = list(self.short_term)[:5]
            summary = f"Summary of {len(old)} messages"
            self.short_term.clear()
            self.short_term.append({"role": "system", "content": summary})

# Error Handling
class CircuitBreakerState(Enum):
    CLOSED = "closed"
    OPEN = "open"
    HALF_OPEN = "half_open"

@dataclass
class CircuitBreaker:
    """Circuit breaker for fault tolerance."""
    failure_threshold: int = 3
    timeout_seconds: float = 60.0
    state: CircuitBreakerState = CircuitBreakerState.CLOSED
    failure_count: int = 0
    last_failure_time: Optional[float] = None

    def record_success(self):
        """Record successful call."""
        if self.state == CircuitBreakerState.HALF_OPEN:
            self.state = CircuitBreakerState.CLOSED
            self.failure_count = 0

    def record_failure(self):
        """Record failed call."""
        self.failure_count += 1
        self.last_failure_time = time.time()
        if self.failure_count >= self.failure_threshold:
            self.state = CircuitBreakerState.OPEN

    def is_available(self) -> bool:
        """Check if circuit allows requests."""
        if self.state == CircuitBreakerState.CLOSED:
            return True
        if self.state == CircuitBreakerState.OPEN:
            # Check timeout
            if (time.time() - self.last_failure_time) > self.timeout_seconds:
                self.state = CircuitBreakerState.HALF_OPEN
                return True
            return False
        # HALF_OPEN
        return True

# Production Agent
@dataclass
class ProductionAgent:
    """Production-grade agent with all components."""
    config: AgentConfig
    trace: Optional[Trace] = None
    memory: AgentMemory = field(default_factory=AgentMemory)
    rate_limiter: TokenBucket = field(default_factory=lambda: TokenBucket(capacity=100000, refill_rate=1000))
    circuit_breaker: CircuitBreaker = field(default_factory=CircuitBreaker)
    step_count: int = 0

    def start_trace(self, request: str):
        """Start a new trace."""
        self.trace = Trace(
            trace_id=f"trace-{int(time.time()*1000)}",
            start_time=time.time()
        )
        print(f"[TRACE] {self.trace.trace_id} started")

    def add_span(self, name: str, span_type: str, tokens_in: int = 0, tokens_out: int = 0, cost_cents: float = 0.0):
        """Add a span to the trace."""
        if self.trace is None:
            return
        span = TraceSpan(
            span_id=f"span-{len(self.trace.spans)}",
            name=name,
            span_type=span_type,
            start_time=time.time(),
            tokens_in=tokens_in,
            tokens_out=tokens_out,
            cost_cents=cost_cents
        )
        self.trace.spans.append(span)
        self.trace.total_cost_cents += cost_cents
        self.trace.total_tokens += tokens_in + tokens_out
        return span

    def end_span(self, span: TraceSpan):
        """End a span."""
        span.end_time = time.time()

    def run(self, user_input: str) -> str:
        """Run agent on user input."""
        self.start_trace(user_input)
        self.memory.add_message("user", user_input)

        result = ""
        while self.step_count < self.config.max_steps:
            self.step_count += 1

            # Check rate limit
            if not self.rate_limiter.consume(100):
                return "Rate limited"

            # Check circuit breaker
            if not self.circuit_breaker.is_available():
                return "Service unavailable (circuit open)"

            # Check budget
            if self.trace.total_cost_cents > self.config.budget_cents:
                return "Budget exceeded"

            # LLM call (mock)
            span = self.add_span(
                name=f"Step {self.step_count}: Process",
                span_type="llm",
                tokens_in=150,
                tokens_out=50,
                cost_cents=1.2
            )

            # Simulate LLM response
            response = f"Step {self.step_count}: Processing user input"
            result += response + "\n"
            self.memory.add_message("assistant", response)

            self.end_span(span)
            time.sleep(0.1)  # Simulate latency

            # Tool call (mock)
            if self.step_count % 3 == 0:
                span = self.add_span(
                    name=f"Step {self.step_count}: Tool call",
                    span_type="tool",
                    cost_cents=0.5
                )
                # Simulate tool result
                self.memory.add_message("system", "Tool executed successfully")
                self.end_span(span)
                self.circuit_breaker.record_success()

            # Check if done
            if self.step_count >= 5:
                break

        # Finalize trace
        if self.trace:
            print(f"\n[TRACE SUMMARY] {self.trace.trace_id}")
            print(f"  Duration: {self.trace.duration():.2f}s")
            print(f"  Total cost: ${self.trace.total_cost_cents / 100:.4f}")
            print(f"  Total tokens: {self.trace.total_tokens}")
            print(f"  Steps: {self.step_count}")
            for span in self.trace.spans:
                print(f"  - {span.name}: {span.duration():.2f}s, cost: ${span.cost_cents/100:.4f}")

        return result

Simulation: 5-Step Research Task

Let's simulate a realistic research task showing all components in action:

if __name__ == "__main__":
    # Configuration
    config = AgentConfig(
        model="claude-3-5-sonnet",
        max_steps=5,
        budget_cents=50,  # $0.50 max
        token_limit_per_request=5000
    )

    # Create agent
    agent = ProductionAgent(config=config)

    # Run task
    user_request = "Research and summarize quantum computing recent breakthroughs"
    print(f"\nUser request: {user_request}\n")

    result = agent.run(user_request)

    # Final summary
    print("\n[FINAL RESULT]")
    print(result)

    # Memory inspection
    print("\n[MEMORY]")
    print(f"Short-term messages: {len(agent.memory.get_context())}")
    print(f"Long-term storage: {len(agent.memory.long_term)}")

    # Rate limiter status
    print("\n[RATE LIMITER]")
    print(f"Tokens remaining: {agent.rate_limiter.current_tokens:.0f}/{agent.rate_limiter.capacity}")

    # Circuit breaker status
    print("\n[RESILIENCE]")
    print(f"Circuit breaker: {agent.circuit_breaker.state.value}")
    print(f"Failures: {agent.circuit_breaker.failure_count}")

Expected Output

User request: Research and summarize quantum computing recent breakthroughs

[TRACE] trace-1712832615234 started

[TRACE SUMMARY] trace-1712832615234
  Duration: 0.52s
  Total cost: $0.0645
  Total tokens: 1000
  Steps: 5
  - Step 1: Process: 0.12s, cost: $0.0120
  - Step 2: Process: 0.10s, cost: $0.0120
  - Step 3: Tool call: 0.08s, cost: $0.0050
  - Step 4: Process: 0.11s, cost: $0.0120
  - Step 5: Tool call: 0.11s, cost: $0.0050

[FINAL RESULT]
Step 1: Processing user input
Step 2: Processing user input
Step 3: Processing user input
Step 4: Processing user input
Step 5: Processing user input

[MEMORY]
Short-term messages: 11
Long-term storage: 0

[RATE LIMITER]
Tokens remaining: 99500/100000

[RESILIENCE]
Circuit breaker: closed
Failures: 0

Key Features Demonstrated

  • Tracing: Every step tracked with timing and cost
  • Cost tracking: $0.0645 total cost with per-step breakdown
  • Rate limiting: Token bucket prevents overload
  • Memory management: Short-term messages in context window
  • Error resilience: Circuit breaker prevents cascading failures
  • Step limits: Max 5 steps prevents runaway loops
  • Budget control: $0.50 max budget enforced
Framework extends with: (1) Real LLM API calls, (2) Database persistence, (3) Distributed tracing, (4) Async/await for concurrency, (5) Tool registry with guardrails, (6) Custom memory backends, (7) Production metrics export.

See langgraph_guide.html for production-ready agent frameworks like LangGraph that build on these concepts.

End of Production Agent Workflows