alt Hacker NewsSomething being simultaneously described as a "30 sheet, mind-numbingly complex Excel model" and "testable" seems somewhat unlikely, even before we get into whether Claude will be able to test such a thing before it runs into context length issues. I've seen Claude hallucinate running test suites before.
It compacted at least twice but continued with no real issues.
Anyway, please try it if you find it unbelievable. I didn't expect it to work FWIW like it did. Opus 4.5 is pretty amazing at long running tasks like this.