Document how a restore-key cache is chosen

I don't see any documentation that describes which partial cache match will be chosen when there are multiple options.

Consider the following case:

Cache key pattern: {branch-name}-{content-hash}
My cache key: rob-branch--5555
My cache restore keys: rob-branch--
Available caches:

• rob-branch--11111, created 1 day ago
• rob-branch--3333, created 1 minute ago
• rob-branch--4444, created 10 minutes ago

All of these match the restore pattern.

If the fallback match is based on the newest matching cache file, rob-branch--3333 will be restored.
If the fallback match is based on alphabetic sorting, rob-branch--1111 will be restored.
If the fallback match is based on reverse alphabetic sorting, rob-branch--4444 will be restored.

I need this information to deliver the best partial matches for incremental builds. Thanks for your help.

The issue names no documentation file or test. Start by locating the existing restore-key documentation and the cache matching implementation, then verify which matching cache is selected; the work is done when the selection rule and the supplied example are documented clearly.