diff --git a/CLAUDE.md b/CLAUDE.md
index 0c96d48..785e93e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -40,7 +40,7 @@ Each host in `hosts/<hostname>/` contains:
 - `fleet.nix` → symlink to root `fleet.nix` (SFTP user provisioning)
 - `utils/` → symlink to root `utils/` (shared modules)
 
-Current hosts: `fw` (firewall/router), `nb` (notebook), `web-arm`, `mail`, `amzebs-01`
+Current hosts: `fw` (firewall/router), `nb` (notebook), `web-arm`, `mail`, `amzebs-01`, `nas`
 
 ### Shared Components (`utils/`)
 - `modules/` - Reusable NixOS modules (nginx, sops, borgbackup, lego, promtail, etc.)
@@ -90,3 +90,4 @@ utils/pkgs/<package-name>/
 - Commits: Conventional Commits format (`fix:`, `feat:`, `chore:`), scope by host when relevant (`fix(mail):`). Do not add "Generated with Claude Code" or "Co-Authored-By: Claude" footers.
 - Modules import via explicit paths, not wildcards
 - Comments explain non-obvious decisions (open ports, unusual service options)
+- **Never update `system.stateVersion`** - it should remain at the original installation version. To upgrade NixOS, update the `channel` file instead.