[FR] Algorithm for unique ID generation

Start with the Firestore add example and review the linked requests for custom IDs in beforeUserCreated and Firestore blocking functions. Clarify whether the scope covers authentication, Firestore, or both, then define acceptance criteria for ordered IDs, length and character rules, and server-generated fields before implementation.

Is your feature request related to a problem? Please describe.
When there is a time we rely on firebase to generate unique ID for firestore or authentication, sometimes we don't want complete random ID. There should be some option to control the ID generation algorithm

I wish I could generate ID that can be always sorted. At least incremental or any monotonic function should be allow to prepend to the generated ID, such as base64 encoded unix timestamp

Additionally it should allow specifying the length of id, and the allowed encode character such as, is it case-sensitive, only numeric or alphanumeric, is it allow symbol, so on. So we have

Describe the solution you'd like
For authentication, maybe it could have option at the firebase console to specify the detailed algorithm as checkbox/radio

For firestore. Actually I wish I could have ability to do servervalue string formatting. So I could have firestore server generate any field, include ID, with the string I want

For this particular case I think we should have

db.collection("users").add({ // Should allow push new document with __name__ as id
    "__name__": ServerValue.calculate("string(request.time.toMillis(),16).reverse() + hashing.crc32(request.path).toHexString()"), // use firebase rule syntax for server generate value
    data : "anydata"
});

The above example generate reverse hex string from time and hash of the path. This function guaranteed incremental from server timestamp but also seemingly random at start and the end

(Also I want to request that string() function in firebase rule system should have base argument for int value, and also reverse function)

Describe alternatives you've considered

There is a request to allow set custom ID in beforeUserCreated as requested in https://github.com/firebase/firebase-tools/issues/5675

Same go for firestore blocking function https://github.com/firebase/firebase-admin-node/issues/2077

Additional context
Is it possible to have firebase server issue request in github too?