>> "Hey claude, I get this error message: <X>", and it'll often find the root cause quicker than I could.

Back in the day, we would just do this with a search engine.

It's not the same. Recently Opus 4.5 diagnosed and fixed a bug in the F# compiler for me, for example (https://github.com/dotnet/fsharp/pull/19123). The root cause is pretty subtle and very non-obvious, and of course the critical snippet of the stack trace `at FSharp.Compiler.Symbols.FSharpExprConvert.GetWitnessArgs` has no hits on Google other than my own bug report. I would have been completely lost fixing it.