What I got wrong building a browser extension with an AI assistant

First hour with Claude's browser extension: I pointed it at our LLC registration and watched it work through the forms, finding the right pages, filling the fields, moving on. I sat there holding a coffee, contributing nothing. I thought: I'm going to ship so many products. I shipped one. Here's what happened in between. Everything below was caught before launch. None of it was caught by being clever. It was caught by a process that got built slowly, mostly after being burned. What went wrong The idea wasn't the hard part. Once I went looking, I found several products with some of the same features. Nobody had the exact combination, but the idea was never the moat. Good implementation and distribution seem to be. You design the product while building it. Referral behaviour, what happens when a trial expires mid-session, how translations work across a page, none of it was in my head at the start. Each became a decision made under pressure, halfway through something else. Write as much of the workflow down as possible first. It says it did things it didn't do. Confidently. I deployed more than once to find the fix I'd been told about was never written. Treat every claim of completion as unverified. The rule that came out of it: make it prove the code is right before it theorises about what you did wrong. Bullet points, not paragraphs. Long replies made it hard to tell which of my five points got addressed. Numbering my instructions, and making it map answers back to the same numbers, turned "did you do item 3" into a question with an answer. It blames you first, and argues with facts. Two landing page changes; one appeared, one didn't. Its verdict: "you didn't deploy." I said one change was live, which is only possible if I had deployed. It repeated that I hadn't. It never asked which change I could see, and never reopened its own code, where the bug was. I swore at it. It stopped guessing, checked, and found the error. Many times, escalation seemed to be the only thi