garry tan is so right about not building massive rails factories for agents but nobody talks about what actually goes in its place

after building this way for a while the shift is actually super simple

1. your backend code should just be dumb hands and feet. no complex business logic, no nested if/else loops trying to predict what the model will do. just clean deterministic apis, db reads, auth, and sandboxes. the plumbing.

2. all the actual brains and workflow procedures live in markdown skills. the first time an agent solves a weird problem, it takes a minute. but instead of throwing that away you freeze the procedure by stripping out the specific data. next time someone asks for the same shape you serve it instantly and deterministically. zero agent latency, zero model cost.

3. and the golden rule for keeping the agent from burning your house down is that you never trust its self report. if the agent says tests passed or the write succeeded, you don't believe it. you rerun the check in your dumb code. you let go of control on the way out but you buy it back on the way in.

build the harness, not the factory