Reasoning Models in Production

January 20, 2025

Reasoning models represent a paradigm shift. Instead of generating tokens quickly, they “think” before responding. The result is dramatically better performance on complex tasks—but with different tradeoffs than standard models.

Here’s how to use reasoning models effectively in production.

Understanding Reasoning Models

How They Differ

reasoning_model_characteristics:
  standard_models:
    approach: "Generate tokens sequentially"
    latency: "Fast (1-3 seconds typical)"
    quality: "Good for straightforward tasks"
    cost: "Per token, predictable"

  reasoning_models:
    approach: "Think, then generate"
    latency: "Slower (10-60+ seconds)"
    quality: "Excellent for complex tasks"
    cost: "Thinking tokens add up"

  tradeoff:
    - More thinking = better answers
    - Latency and cost increase together
    - Not always worth the tradeoff

When to Use

reasoning_model_use_cases:
  good_fit:
    - Complex multi-step problems
    - Code review and debugging
    - Mathematical reasoning
    - Strategic analysis
    - Research synthesis

  poor_fit:
    - Simple Q&A
    - Real-time chat
    - High-volume, low-complexity
    - Latency-sensitive applications

  decision_framework:
    - Is accuracy critical?
    - Is the problem complex?
    - Can users wait 30+ seconds?
    - Does the value justify the cost?

Production Patterns

Async Processing

class ReasoningModelService:
    """Handle reasoning model requests asynchronously."""

    async def submit_request(
        self,
        request: ReasoningRequest
    ) -> str:
        """Submit request, return job ID."""
        job_id = generate_job_id()

        await self.queue.publish(
            topic="reasoning-requests",
            message={
                "job_id": job_id,
                "request": request.dict(),
                "submitted_at": datetime.utcnow().isoformat()
            }
        )

        # Notify user of expected wait
        await self.notify_user(
            request.user_id,
            f"Processing your request. Expected wait: 30-60 seconds."
        )

        return job_id

    async def process_request(self, message: dict):
        """Worker that processes reasoning requests."""
        request = ReasoningRequest.parse(message["request"])

        response = await self.reasoning_model.generate(
            prompt=request.prompt,
            max_thinking_tokens=request.max_thinking
        )

        await self.result_store.set(
            message["job_id"],
            {
                "response": response.content,
                "thinking_tokens": response.thinking_tokens,
                "completion_tokens": response.completion_tokens,
                "completed_at": datetime.utcnow().isoformat()
            }
        )

        await self.notify_user(
            request.user_id,
            "Your analysis is ready."
        )

Routing Based on Complexity

class ModelRouter:
    """Route to reasoning model only when needed."""

    async def route_request(
        self,
        request: GenerateRequest,
        context: RequestContext
    ) -> GenerateResponse:
        # Classify complexity
        complexity = await self._assess_complexity(request)

        if complexity == "simple":
            return await self.fast_model.generate(request)

        elif complexity == "medium":
            return await self.capable_model.generate(request)

        else:  # complex
            if context.can_wait:
                return await self.reasoning_model.generate(request)
            else:
                # Fall back with disclaimer
                response = await self.capable_model.generate(request)
                response.add_note("For deeper analysis, use extended thinking mode")
                return response

    async def _assess_complexity(self, request: GenerateRequest) -> str:
        indicators = [
            "analyze" in request.prompt.lower(),
            "step by step" in request.prompt.lower(),
            len(request.prompt) > 2000,
            "prove" in request.prompt.lower(),
            "debug" in request.prompt.lower(),
        ]

        complexity_score = sum(indicators)

        if complexity_score >= 3:
            return "complex"
        elif complexity_score >= 1:
            return "medium"
        return "simple"

UX Considerations

reasoning_model_ux:
  set_expectations:
    - Show estimated wait time
    - Explain why it takes longer
    - Provide progress indicators

  handle_long_waits:
    - Allow user to continue other tasks
    - Send notification when complete
    - Don't block the UI

  show_value:
    - Display thinking summary
    - Highlight confidence
    - Show reasoning steps (when helpful)

Cost Management

reasoning_cost_management:
  strategies:
    - Route carefully (not everything needs reasoning)
    - Set thinking token limits
    - Cache complex analyses
    - Batch similar requests

  monitoring:
    - Track thinking vs completion tokens
    - Measure cost per successful task
    - Compare to standard model outcomes

Key Takeaways

Reasoning models are powerful. Use them strategically.