Under the hood
Repository-diff computation now happens lazily and is cached instead of running eagerly upfront
What
The internal helper that computes repository diffs no longer eagerly computes the git baseline it needs as soon as it runs. Instead, it computes and caches that baseline only when fetchDiff is actually called. A related function, headKeyOf, now explicitly passes a null baseline rather than a computed one.
Why
This avoids doing potentially unnecessary work computing a git baseline when it isn't needed, improving efficiency for code paths that don't end up calling fetchDiff.