> This may be the largest AI-generated codebase right now, by a lot.

I'm sure there's lots of other large scale applications of AI, just not many/any projects that are open source and so high profile - with the changes being done so far.

Personally, in the past 3 months I've shipped about 2.3M lines of a legacy project migration, though the new codebase is Java + Oracle ADF because of reasons™ and instead of being an interesting codebase, it's more forms heavy and essentially acts as a front end for a large Oracle instance, think more CRUD than application runtime (with an upsetting amount of XML).

The difference also is that it wasn't migrated by using AI on every file, but rather dumped the DB schema into JSON, and converted the old form contents to a YAML intermediate format that describes what's in the forms and have been iterating ever since of creating code that generates code - basically AI assisted development of a codegen solution + AI assisted sidecars that get merged with the generated code based on markers, when something can't be automated that way and often times also AI controlled browser based testing (since Playwright is in the cards for everything, but not yet).

Seems to be going pretty okay so far, will probably take months more of iteration and fixes, currently the automated testing is taking a while because let me tell you - not only Oracle ADF is shit, but so is WebLogic, like fuck I'd be so closer to being done if I was allowed to pick Python + HTMX or even Java + Thymeleaf. That's still better than a team spending a year on the migration and getting like 10% of the way there.

Obviously there's no more details to publicly share, but the overall vibe is clear: as long as you can test any changes, you can iterate faster than without AI - and the code ends up being more readable that colleagues would often write. The problem is that people would squint at the suggestion of 100% test coverage previously so most code is even written in a way that is straight up not testable (and often nothing is decoupled from the framework properly and tests take way too long, both time and resources).