Cache keys from git’s index
On a clean tree, vx keys your tasks without reading your sources.
A cache key needs a hash of every input file. Git already keeps one for every tracked file in its index, so vx walks the index once per run and builds keys from those hashes.
Only files that are modified or untracked are read and hashed. On a clean checkout that is none of them, which is why keying thousands of tasks takes milliseconds.
No daemon keeps this warm between runs. The work is small enough to do from scratch every time.
