bug: Firefox module is not updating policies.json

[GideonWolfe]

Are you following the right branch?

• My Nixpkgs and Home Manager versions are in sync

Is there an existing issue for this?

• I have searched the existing issues

Issue description

I have declared many settings in my firefox.nix file. Most of them work just fine. userChrome and userContent, along with various options for about:config work great.

The issue is with programs.firefox.policies. I have primarily utilized the ExtensionSettings policy to declare a set of plugins that should be installed, but also browsed https://mozilla.github.io/policy-templates/ for other policies which I added.

The problem is that this file does not seem to be consistently regenerated/built when the file is changed. My symptoms are

1. when I first installed on bare metal, it took many tries of nuking ~/.mozilla and random other fixes to get it to "recognize" the plugins and install. This is after I got everything working in a VM, so my config was "good"
2. When I edit the file now, kill firefox, rebuild home manager, and restart firefox, no new plugins are added

I was able to find /nix/store/<pathtofirefox>/lib/firefox/distribution/policies.json, which seemed to contain some policies that I had defined at one point, such as plugins.

But this file isn't a symlink. I can remove every single value from programs.firefox.policies and this file is not modified at all. I can add policies and it isn't updated.

When I open Firefox and visit about:policies, none of the policies I have declared appear.

I'm not seeing any sort of errors anywhere, what am I doing wrong?

Maintainer CC

@rycee

System information

- system: `"x86_64-linux"`
 - host os: `Linux 6.6.72, NixOS, 24.11 (Vicuna), 24.11.20250119.107d5ef`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.24.11`
 - channels(root): `"home-manager-24.05.tar.gz, nixos-24.05"`
 - nixpkgs: `/nix/store/sbnwhhx7zjp45n53bkmnj4whg79aw8pq-source`