[robertandrewp]

AstroBen's framing matches my experience — "well-specified + verification harness" really is the sweet spot. Financial math is about as well-specified as a domain gets: the amortization formula is unambiguous, expected outputs are known to the cent, and you can write tests that catch rounding errors in the third decimal place.

I shipped a REST API (8 financial calculator endpoints) from idea to live in about a week of evenings with Claude Code. The 33-test suite was essential — EdNutting's "convincing-but-wrong code" problem is acute in this domain specifically because an IRR calculation that's off by 0.01% looks completely plausible until a test catches it.

But the thing that surprised me wasn't the speed — it was the shift in which projects are worth building at all. Infrastructure that used to take days (Dockerfile, Nginx config, deployment scripts) now takes a few hours. That changes the viability calculation for small projects. Things I'd have considered too small to bother productionising before now cross the threshold. That feels like a different kind of career change than "writes code faster" — more like a change in what's worth attempting.