NixOS alignment notes: initContent, the lan-mouse panic, and the machine states

docs/ENVIRONMENT-FACTS.md

@@ -135,3 +135,35 @@ What was changed:
 
 - Local git repo only, one commit, no remote. It is not on Gitea. Push it somewhere before
   relying on it, or accept that only this machine has it.
+
+## NixOS alignment for Pi, 2026-11-11
+
+Goal: all three machines on the same Pi. The `pi-coding-agent` version comes from the nixpkgs pin,
+so aligning means bumping `nixpkgs` and `home-manager` in each machine's flake.
+
+Measured after `nix flake update nixpkgs home-manager`:
+
+| machine | nixpkgs pin | pi after update | state |
+|---|---|---|---|
+| `.13` | 2026-07-29 → 2026-11-07 | **1.5.0** | config ready, 12 derivations to build |
+| `.27` | same | 1.5.0 | evaluation fails in home-manager fontconfig |
+| `.51` | 2026-09-26 | 0.87.1 (today) | not started |
+
+Two changes are needed with the bump, both measured:
+
+1. `programs.zsh.initExtra` was renamed: `initContent`.
+2. **lan-mouse 0.11.0 panics** when `LIBGIT2_NO_VENDOR` is set and there is no system libgit2
+   (nixpkgs 2026-11-07 sets it). An overlay on `pkgs.lan-mouse` did **not** fix it — the
+   derivation hash barely moved and the same panic came back. What does work is building the
+   flake's own lan-mouse package with `LIBGIT2_NO_VENDOR = "0"`:
+
+   ```nix
+   lm = lan-mouse.packages.${system}.default.overrideAttrs (o: { LIBGIT2_NO_VENDOR = "0"; });
+   ```
+
+   and using `lm` in `systemPackages` instead of the plain package. Built and verified:
+   `/nix/store/f6w228jqp5wq6xznf6arq69kck6axyyf-lan-mouse-0.11.0`.
+
+`.27`'s failure names `home-manager.users.sam.fonts.fontconfig.configFile.fonts.settings`. It is a
+home-manager option merge, not the Pi change. The smaller next attempt there is to bump `nixpkgs`
+only and leave `home-manager` where it is.