For the "harder tech" part: I played around with a "vibe code" project to see how far it gets. It's a cargo workspace linter that does things like find unused feature flags, unused pub, etc. Guiding it only on high-level feature-set requirements, it ended up doing workspace-wide lints backed by rustc's name resolution, not a parser. Something I would never have done myself. I picked that project because a missed lint costs nothing - I still wouldn't work this way on anything where a wrong answer hurts - yet.