[kaens]

Believe it or not, it was a large (~1M lines) in-house "CMS-generator for different clients" type of thing written in perl, this was right around the time 2nd-gen rails clones were starting to be a thing, a fair bit after perl was the popular weblang of choice.

The people who wrote it were competent at writing maintainable software. It was well thought out in terms of design and discoverability and tooling, it was well tested, and the authors cared a lot about not obfuscating purpose.

It had good dev ramp-up docs and a pretty clean commit history.

I think probably the largest differentiating factor for this particular codebase was that it wasn't developed under duress of time-pressure and the previous authors were past the point in their programming careers where they learned how to not overestimate their own ability or underestimate unknowns in their domain. The company was relatively small, technically competent at the top, and culturally less concerned with inflating profits than making enough money to live comfortably and do their thing.