http://x.com/i/article/2082133743893204992
Pragmatic Leverage in the Software Factory
This one is a bit of an addendum / side-quest to the recent series. It didn't fit cleanly into the main post so I'm publishing it standalone. It is referenced briefly in Why Software Factories Fail part 2： Turning the lights back on.
Seeking Leverage
Even before AI， only 25-50% of the time to ship a feature was writing the code itself. The rest was aligning/planning， code-review/rework， and testing/verifying the solution.
If you're only using AI to write the code， then you're taking the 2-4 hours of coding time down to 10-20 minutes， but you haven't accelerated anything else here.
But if you use AI to help you plan and align， then you actually get closer to 2-3x faster.
The 80/20 rule in AI coding leverage
Lets assume if you yolo a two-sentence prompt into your factory， your chance of getting a fully-mergeable result is ~50%， the chance you have to rework it is 50%.
Now lets say you are a principal engineer with 10 years of experience. You have the whole codebase across 100 repos downloaded into your head. So you spend an afternoon writing a perfectly detailed spec by hand. Now your odds are better， but you probably still have about a 10% chance that you'll have to redo *something* significant.
And at the far end： write every line yourself. Nothing's left for the agent to get wrong， so the rework chance goes to zero.
note For this example I'm gonna blur
"chance you'll have to change something" weighted by "how painful the change will be"