Notes from the middle layer.

I cloned a shipping coding agent and read it the way I read a paper — to see which design decisions survive contact with production. Here are the ones worth stealing.

When an agent misses a case, the reflex is to teach it that case in the system prompt. That's whack-a-mole. The fix is structural.

Loop engineering took off in coding because coding ships with a free oracle. Everywhere else, you have to build one.

A daily digest agent reported "all sources fetched" — while quietly dropping one. The bug wasn't the fetch. It was the missing guardrail.

The thing worth getting right keeps moving up a level — prompt, context, harness, loop. The hard part was never the while-loop.

Stop adding a tool for every request. Autonomy is a stack of composition types with two layers of glue, not a single trick.

I migrated a production agent onto a server runtime, ran the whole playbook, then rolled it all back. Sometimes the senior move is not adopting the thing.

Standard tool-calling can't express composition. So stop picking tools — let the model write the code that calls them.

Reliable agent UX isn't about preventing errors — it's about making the wrong answer cheap to notice and undo.

Everyone treats agent memory as one framework, and compares the options as if they're rivals. They answer different questions — here's the map.

Vector RAG, RAGFlow, GraphRAG, PageIndex, an LLM wiki, Obsidian — they get lumped together as rivals. They aren't even at the same layer. A field guide to which one fits which job.

I scored two agent frameworks across eleven dimensions. Strip the weights and they tie. The gap was never about quality — it was about who I am.

Everyone is racing to build a smarter index. The labs that build the models quietly went the other way — toward plain text the agent reads and tidies itself.

A bigger context window buys you a better goldfish. Persistence is a different problem — and most of the work happens between the prompts.

Every retry feels free in isolation. Stacked across a session, they are where latency, cost, and confusion quietly accumulate.