From b55d6de636f285d291e91d17a5fac24542f0b881 Mon Sep 17 00:00:00 2001
From: rope <fredrik@nordhammer.it>
Date: Sun, 9 Aug 2026 11:26:09 +0100
Subject: [PATCH] prebuild: nightly macbook closure build on mediaserver

---
 common.nix            |  1 +
 services/prebuild.nix | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 services/prebuild.nix

diff --git a/common.nix b/common.nix
index 6330900..a3ca361 100644
--- a/common.nix
+++ b/common.nix
@@ -55,6 +55,7 @@ in
     ./services/memos.nix
     ./services/hardware-health.nix
     ./services/wan-watchdog.nix
+    ./services/prebuild.nix
   ];
 
   ### Make build time quicker
diff --git a/services/prebuild.nix b/services/prebuild.nix
new file mode 100644
index 0000000..6ed7f94
--- /dev/null
+++ b/services/prebuild.nix
@@ -0,0 +1,39 @@
+# services/prebuild.nix — nightly pre-build of the Macbook's system closure.
+#
+# The Macbook runs with max-jobs = 0 and offloads every build to this host
+# (nix.buildMachines in common.nix). Realising its toplevel here ahead of time
+# turns `update` on the laptop into a pure copy: the offloaded build finds the
+# path already in this store and just ships it back over SSH.
+#
+# --out-link doubles as the gc root, so `clean` doesn't reap the closure
+# before the laptop ever asks for it.
+{ config, lib, pkgs, ... }:
+
+{
+  config = lib.mkIf (config.networking.hostName == "FredOS-Mediaserver") {
+    systemd.services.prebuild-macbook = {
+      description = "Pre-build the FredOS-Macbook system closure";
+      after = [ "network-online.target" ];
+      wants = [ "network-online.target" ];
+      path = [ pkgs.git ];
+      environment.HOME = "/root";
+      serviceConfig = {
+        Type = "oneshot";
+        StateDirectory = "prebuild";
+      };
+      script = ''
+        ${config.nix.package}/bin/nix build --refresh --out-link /var/lib/prebuild/FredOS-Macbook \
+          'git+https://forg.gregersen.it/rope/nixos#nixosConfigurations.FredOS-Macbook.config.system.build.toplevel'
+      '';
+    };
+
+    systemd.timers.prebuild-macbook = {
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnCalendar = "04:00";
+        Persistent = true;
+        RandomizedDelaySec = "30m";
+      };
+    };
+  };
+}