Propose GNOME desktop for NixOS hosts

Planning artifacts only (proposal, spec, design, tasks) — GDM+GNOME,
NetworkManager, PipeWire, and CUPS+Avahi printing, applied
unconditionally to every NixOS host via modules/nixos/common.nix. Not
yet implemented.

1 files changed, 23 insertions, 0 deletions

diff --git a/openspec/changes/add-gnome-desktop/tasks.md b/openspec/changes/add-gnome-desktop/tasks.md
new file mode 100644
index 0000000..e30615d
--- /dev/null
+++ b/openspec/changes/add-gnome-desktop/tasks.md
@@ -0,0 +1,23 @@
+## 1. GNOME desktop and login manager
+
+- [ ] 1.1 In `modules/nixos/common.nix`, add `services.xserver.enable = true;` — verify by reading the file
+- [ ] 1.2 Add `services.displayManager.gdm.enable = true;` and `services.desktopManager.gnome.enable = true;` — verify by reading the added block, and flag the option-path uncertainty from design.md (post-migration `services.displayManager.*`/`services.desktopManager.*` vs. older `services.xserver.displayManager.*`/`services.xserver.desktopManager.*`) as a known risk to re-check once `nix flake check` can run
+
+## 2. Networking and audio companions
+
+- [ ] 2.1 Add `networking.networkmanager.enable = true;` — verify by reading the added line
+- [ ] 2.2 Add `services.pipewire = { enable = true; pulse.enable = true; };` and `security.rtkit.enable = true;` — verify by reading the added block
+
+## 3. Printing
+
+- [ ] 3.1 Add `services.printing.enable = true;` — verify by reading the added line
+- [ ] 3.2 Add `services.avahi = { enable = true; nssmdns4 = true; openFirewall = true; };` — verify by reading the added block, and confirm `openFirewall = true` is present so mDNS/printer discovery isn't blocked by the firewall enabled in `add-developer-environment`
+
+## 4. Documentation
+
+- [ ] 4.1 Update `README.md` to document that NixOS hosts from this flake now boot into GNOME (GDM login) by default, with NetworkManager, PipeWire, and CUPS+Avahi printing enabled as necessary companions — verify by reading the updated section for consistency with the actual module changes
+
+## 5. Validation
+
+- [ ] 5.1 Run `nix flake check` and confirm `modules/nixos/common.nix` still evaluates without error with the new services added, resolving the option-path question from task 1.2 (blocked — Nix is not installed on this machine, and there's still no live NixOS host to boot; run this once Nix/a real host are available — this is the real acceptance gate, not the individual checkboxes above)
+- [ ] 5.2 Manually trace through each spec scenario in `specs/gnome-desktop/spec.md` against the implemented module, confirming each is satisfied by inspection given #5.1 cannot run locally