(Rosie is a code janitor program at Google that takes a change that affects files all across the tree and automatically cuts it into individual changes that can

(Rosie is a code janitor program at Google that takes a change that affects files all across the tree and automatically cuts it into individual changes that can be mailed out to the individual teams as CLs/PRs for their approval.) Rosie existed but very much wanted to break up the CL into independent per-directory CLs, and since I was editing one file in every directory in the entire tree, that would have been 200,000 independent CLs. I broke the list up by top-level directory or sub-directory and hit 100+ directories at a time. Rosie also really wants to run each affected directory's tests, and I did not, because at scale flaky tests and such would be a significant source of false positives. The bit-for-bit check on the internal parsed representation of the meaning of the BUILD file proved that the changes were no-ops. That was better than any tests of the code in the directory. I was already automating everything else, including deciding which files to change, reverting edits in files that were concurrently modified (they got swept into the next attempt), and the testing. Running a shell command to actually make the CLs was not difficult. And it generating the approval script trivial too. Rosie is great but it wasn't the right tool for this job.