How can I restrict commits to a specific branch in Mercurial?

Question

I'm essentially seeking for a way to manage write permissions to specific branches.

This can be either before committing (local), or after committing but before pushing (remote).

I need to protect certain branches from being written to in order to enforce a workflow where the release branch can only be edited by some.

Answer 1

Enabled and properly configured ACL Extension can be an answer in your case

Answer 2

ACL Extension would do it

regarding branches however:

You cannot limit read access to a subset of a repository with a read rule and a file condition: any user who has access to a repository can read all of it and its full history. 

But you can disallow push.