-`services.mattermost.listenAddress` has been split into {option}`services.mattermost.host` and {option}`services.mattermost.port`. If your `listenAddress` contained a port, you will need to edit your configuration.
- Mattermost now supports peer authentication on both MySQL and Postgres database backends. Updating {option}`system.stateVersion` to 25.05 or later will result in peer authentication being used by default if the Mattermost server would otherwise be connecting to localhost. This is the recommended configuration.
- The Mattermost module will produce eval warnings if a database password would end up in the Nix store, and recommend alternatives such as peer authentication or using the environment file.
- Mattermost's entire test suite is now enabled by default, which will extend build time from sources by up to an hour. A `withoutTests` passthru has been added in case you want to skip it.
- We now support `mmctl` for Mattermost administration if both {option}`services.mattermost.socket.enable` and {option}`services.mattermost.socket.export` are set, which export the Mattermost control socket path into the system environment.
- A new `pkgs.mattermost.buildPlugin` function has been added, which allows plugins to be built from source, including webapp frontends with a supported package-lock.json. See the Mattermost NixOS test and [manual](https://nixos.org/manual/nixpkgs/unstable/#sec-mattermost-plugins-build) for an example.
- Note that the Mattermost module will create an account _without_ a well-known UID if the username differs from the default (`mattermost`). If you used Mattermost with a nonstandard username, you may want to review the module changes before upgrading.
