Founder of the agent company HumanLayer, author of the 12-factor agents principles, and the engineer who put the name "context engineering" on the practice.
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Dex HorthyFounder of the agent company HumanLayerAnd the plan doc, what was bad about it is it didn't give you leverage. The plan was every single line of code that was going to change like in diff blocks and like all the new stuff to write. And so like people would review these plans. We recommended this. We told people to read the plans. We read all our plans. And then eventually I found myself like I just kind of skimmed the plans.↗Context engineering with Dex Horthyyoutube.com · 15 Jul 2026 · 1:02:53 into the videoAll korrents from this video
Their wordsAnd the plan doc, what was bad about it is it didn't give you leverage. The plan was every single line of code that was going to change like in diff blocks and like all the new stuff to write. And so like people would review these plans. We recommended this. We told people to read the plans. We read all our plans. And then eventually I found myself like I just kind of skimmed the plans.
Their wordsthe problem with training models on maintainability is like the cost function of bad architecture and bad program design can't be evaluated by running the unit test because it hits you 3 to 6 months later
Their wordsif you want to do loops engineering, you should build one loop at a time and you should keep them small and contained. Basically, I think everything except stop reading the code is really good advice.
Their wordsWe tried this. We built a lights off software factory in July of 2025 and by November we had shut it down. I think it takes about three to six months of you shipping all the time with nobody reading the code before you realize like, wow, this is getting way worse and it's easier to start over than it is to fix it.
Their wordsAnd at the end of the day, they're all like different ways to pass tokens into a model and ask it to produce usually some structured output. And understanding that is a lot more powerful than trying to learn memory and trying to pick some agent framework off the shelf and some memory framework off the shelf.
Their wordsWell, harness engineering just is like how do I raise the floor so that every single turn of this thing, the results are as good as possible.