Reporting Home Manager Package Changes During Updates

nix

Use nvd with Home Manager's activation hook to report package changes during updates.

Example output:

<<< .../.local/state/nix/profiles/home-manager-65-link
>>> .../.local/state/nix/profiles/home-manager-66-link
Version changes:
[U.]  #1  claude-code  2.1.7 -> 2.1.9
[U.]  #2  codex        0.84.0 -> 0.86.0
[U.]  #3  opencode     1.1.20 -> 1.1.23
Closure size: 408 -> 408 (9 paths added, 9 paths removed, delta +0, disk usage +1,011.2KiB).

Add this home.activation block to your home.nix configuration:

{ config, pkgs, ... }:

{
  # ... existing configuration ...

  home.activation.report-changes = config.lib.dag.entryAnywhere ''
    if [[ -n "$oldGenPath" && "$oldGenPath" != "$newGenPath" ]]; then
      ${pkgs.nvd}/bin/nvd diff "$oldGenPath" "$newGenPath"
    fi
  '';
}

Key Points:

  • nvd (Nix/NixOS package version diff tool) provides human-readable package summaries.
  • The $oldGenPath and $newGenPath variables are provided automatically by Home Manager during activation.
  • Using ${pkgs.nvd} ensures the tool is available without adding it to your global environment.
  • The if statement guards against the first activation and no-change scenarios.