AI & LLM Engineering for .NET Architects

LLM Cost Estimation: Token accounting and budget strategies

1 Views Updated 5/4/2026

AI Unit Economics

Cloud compute is cheap. AI compute is Expensive. A single GPT-4 call can cost $0.03. If you have 1 million users, that's $30,000 per request. You must be an architect of costs as much as code.

1. Token Accounting

Always track tokens programmatically. Use libraries like Tiktoken to calculate the token count *before* sending the request. If a user tries to upload a 500-page PDF, block it at the gateway to prevent a $50 bill for a single call.

2. The "Model Tier" Strategy

Don't use GPT-4 for everything.

  • GPT-3.5 / Llama-3-8B ($): For simple summarization, classification, or formatting.
  • GPT-4 / Claude 3 Opus ($$$): For complex reasoning, coding, and multi-step math.
**Architect Tip:** Use a "Classifier" model to determine the difficulty of a task, then route it to the cheapest model that can handle it.

4. Interview Mastery

Q: "What is 'Prompt Caching' and how does it save money?"

Architect Answer: "In a RAG system, you often send the same 10,000-word 'Knowledge Base' with every request. Prompt caching (available in Azure OpenAI) allows the provider to 'Keep' that prefix in memory. You only pay for the full 10,000 tokens once; subsequent calls only pay for the 'New' user message. This can reduce your AI bill by up to **90%** for repetitive enterprise tasks."

AI & LLM Engineering for .NET Architects
1. AI Foundations & Prompt Engineering
The LLM Landscape: Transformers, Attention, and Tokens Advanced Prompt Engineering: Few-shot, Chain-of-Thought, and ReAct Prompt Versioning & Management in Production LLM Cost Estimation: Token accounting and budget strategies
2. Semantic Kernel & Integration
Introduction to Microsoft Semantic Kernel (SK) Skills & Plugins: Extending the LLM with native C# functions Planner & Orchestration: Automating complex multi-step AI tasks Connectors: Switching between OpenAI, Azure OpenAI, and HuggingFace
3. Vector Databases & RAG
The RAG Pattern: Solving the 'Static Knowledge' problem Embeddings Deep Dive: Converting text to math Vector DBs: Azure AI Search vs Pinecode vs Milvus Hybrid Search: Combining Keyword and Semantic search for accuracy
4. Advanced RAG Techniques
Document Chunking Strategies: Overlap, Slidewindow, and Semantic splitting Recursive Document Processing for massive knowledge bases Context Window Management: Summarization vs Truncation Citations & Grounding: Ensuring the AI doesn't hallucinate
5. AI Safety & Guardrails
Content Moderation: Azure AI Content Safety integration Prompt Injection: Defending against adversarial attacks Punitiveness & Bias: Evaluating and mitigating model behavior Self-Correction Patterns: Letting the AI check its own work
6. Small Language Models (SLMs) & Local AI
The rise of SLMs: Phi-3, Llama-3-8B, and Mistral Running AI Locally with ONNX and LocalLLM Quantization: Running 70B models on 16GB RAM Edge AI: Deploying models to local devices and private clouds
7. Multimodal & Agentic AI
Multimodal AI: Processing Images, PDFs, and Audio in C# Agentic Workflows: Multi-agent collaboration with AutoGen Function Calling: Letting the LLM use your SQL and API tools Memory Management: Ephemeral vs Long-term Semantic memory
8. FAANG AI Engineer Interview
Case Study: Designing a Global Enterprise AI Knowledge Assistant Case Study: Building an Autonomous AI Agent for Software Dev