11 essays
Notes on building AI systems that hold up.
The index tells you what exists. These essays cover the decisions behind it — what to reach for first, what looks like an optimisation and is actually a rewrite, and where the failure modes live.
Choosing an inference runtime
7 minThe wrong runtime costs you throughput you never knew you were leaving on the table. The right one is usually decided by traffic shape, not model size. Inference & ServingThe gateway is the product
8 minThe interesting engineering is not calling a model. It is deciding which model, failing over safely, and staying inside a budget while you do it. Routing & GatewaysFix the ranking, not the prompt
9 minWhen a RAG system gives a bad answer, the instinct is to rewrite the prompt. Nine times out of ten the prompt is fine and the context was never there. Retrieval & Vector Stores Evaluation & ObservabilityEvals are the asset, not the logging
8 minTraces tell you what happened. Evals tell you whether it got better. Most teams build the first and mistake it for the second. Evaluation & ObservabilityAgents need a durable host
8 minThe loop is a weekend project. The part where it keeps working at three in the morning is the actual product, and almost nobody budgets for it. Workflow Orchestration Agent FrameworksPrompt, or fine-tune?
7 minAlmost every 'the model does not know this' problem is a retrieval problem wearing a hat. Here is how to tell the difference before you spend a week on a training run. Fine-tuning & Training Prompt EngineeringWhere guardrails belong
8 minSafety is not a layer you add. It is a set of controls at specific points in a request's path, and each one catches a different class of failure. Guardrails & SafetyContext is a budget, not a container
7 minThe instinct is to keep everything in case it is needed. The models are not filing systems, and past a certain length the middle of your context is doing nothing but costing money. Inference & Serving Prompt EngineeringBuild a cost model before you optimise
7 minTeams optimise the thing they can see in the dashboard. The dashboard shows tokens. The number that matters is cost per successful outcome, and nobody is measuring it. Routing & Gateways Evaluation & ObservabilityChoosing a model is a routing problem
8 minThere is no best model. There is a best model for a task, at a quality bar, within a latency and cost budget — and that decision is a routing policy, not a benchmark. Routing & Gateways Inference & ServingObservability is not logging
7 minA log line with a status code is not a trace. The difference is whether it can reconstruct a decision after the model that made it has been replaced twice. Evaluation & Observability