Understand the system.Build with fewer assumptions.

Original, practical notes that connect backend code, computer systems, and AI engineering—from first principles to production trade-offs.

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01 · BACKEND

Backend engineering

API design, Go services, data consistency, authentication, deployment, and the boundaries that keep systems maintainable.

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02 · SYSTEMS

Computer systems

Follow real requests through DNS, TCP, TLS, proxies, operating systems, databases, and distributed components.

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03 · AI

AI engineering

Embeddings, retrieval, ranking, agents, evaluation, and the practical difference between a demo and a reliable product.

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04 · PRACTICE

Working knowledge

Compact explanations, runnable examples, failure modes, and checklists designed to be reused while building real software.

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Learn across boundaries

A production bug rarely stays inside one abstraction. An API timeout may begin with DNS, a proxy route, a connection pool, or a database lock. A weak search result may come from the embedding model, filters, chunking, or ranking—not “AI” in general.