Lessons

Why "the same request twice should produce the same result" is one of the most useful properties you can give an API, the standard patterns for implementing it (keys, dedupe tables, natural idempotency), and what goes wrong when you don't.

Commands tell, events announce. How event-driven systems decouple producers from consumers, when CQRS and event sourcing earn their complexity, and the eventual-consistency tax you pay either way.

The honest case for each. When a monolith is correct, what microservices actually buy you (and what they cost), Conway's law, and how to spot a fake microservices architecture that's actually a distributed monolith.

Why your assets should never come from your origin. How a CDN's edge cache, geographic routing, and invalidation actually work, plus the cases where a CDN doesn't help (or quietly hurts).

How to keep one client from breaking the system for everyone else. The four canonical algorithms (fixed window, sliding window, token bucket, leaky bucket), distributed limiting with Redis, and the polite way to tell a client "slow down".

Async work between services without one tripping the other. Point-to-point vs pub/sub, the three delivery guarantees and what they cost, dead letter queues, and how to pick between Kafka, RabbitMQ, SQS, and friends.

The named caching patterns (cache-aside, read-through, write-through, write-behind), when each makes sense, and the failure modes that bite even experienced teams (thundering herd, stale invalidation, the second-hardest problem).

Why every distributed system has to give up something when the network splits. CAP, the trade-offs in real databases, and the PACELC extension that's usually more useful in practice.

When one database isn't enough. How sharding splits data across nodes, the trade-offs of different sharding keys, and the operational headaches (hot spots, rebalancing, cross-shard queries) you sign up for.

How load balancers spread traffic across servers, what L4 and L7 actually mean, the routing algorithms in real use, and the failure modes you need to design around.

How to cut LLM bills 50-90% without sacrificing freshness. Covers the three caching layers (response, prefix, semantic), what each costs to build, and the cases where caching subtly breaks correctness.

Not every AI feature should be fully autonomous. Here's where to insert humans for the biggest reliability win, the UX patterns that scale (confidence-gated review, sample audits, escalation), and the anti-patterns that turn HITL into a meeting factory.

Why traditional software testing falls apart on LLMs, the four evaluation regimes that work in practice (golden sets, LLM-as-judge, human review, online metrics), and how to wire them together without drowning in ungrounded scores.

What LangGraph adds over plain LangChain, how its nodes-and-edges model maps to real agent patterns (loops, branches, human approvals), and when to reach for it versus a simpler control flow.

What the context window actually is, why 1M-token marketing doesn't mean what you think, the cost and accuracy curves that bend as you stuff more in, and the strategies (compaction, caching, retrieval) that keep long-context apps sane.

Why LLM apps are uniquely vulnerable to attacks delivered as plain text, the difference between direct and indirect injection, and the defences that actually help (plus the ones that don't).

What modern AI dev tools actually do, where they sit on a spectrum from inline completion to autonomous agents, and the workflow habits that separate developers who 2x their output from developers who ship subtly broken code.

OpenAI released CLIP. LAION and friends released OpenCLIP — a reproducible, openly-trained re-implementation that has quietly become the default vision-language embedding backbone. Here's what it is, why it won, and how to drop it into a project.

How diffusion-based video models turn a text prompt into a moving image, why consistency is so hard, and the practical patterns you need to know before generating anything longer than a few seconds.

What "multimodal" actually means once you get past marketing copy. How modern models like GPT-4o, Gemini, and Claude blend modalities, and the design trade-offs (early vs late fusion, native vs adapted) you'll meet when building with them.

How models like CLIP, GPT-4V, and Claude visual learn to talk about pictures. Cover the contrastive trick behind CLIP, the difference between embedding models and generative VLMs, and where each one shines.

What separates an agent from a plain chatbot, the perceive-think-act loop they all share, and how to design one that doesn't loop forever or burn through your token budget.

Learn how to combine data from different tables in a relational database using the four fundamental SQL JOIN types: INNER, LEFT, RIGHT, and FULL OUTER. We'll explore what each join does, when to use it, and how they differ, using clear examples and diagrams.

Dive deep into the world of PostgreSQL indexes. Understand the core mechanics of B-tree, Hash, GIN, and GiST indexes, their optimal use cases, and how to choose the right indexing strategy to dramatically accelerate your database queries.