feat(builders): enable aquamarine on remaining physical hosts (#500)

Enable the existing remote-builder module on shoryu, shushou and
youko, and authorize their SSH host keys on aquamarine.

Kana and Ruby are VM guests with no need to build; leave their local
store and build behavior unchanged.

Assisted-by: DeepSeek Harness (deepseek-flash)

hosts/12kingdoms-shoryu/default.nix

@@ -24,6 +24,10 @@ in
     coreModule
   ];
 
+  # Use the shared Aquamarine builder for heavy derivations; local builds
+  # remain available as a fallback.
+  modules.remote-builders.enable = true;
+
   modules.btrbk.enable = true;
   modules.security.audit.enable = true;
 

hosts/12kingdoms-shushou/default.nix

@@ -23,6 +23,10 @@ in
     coreModule
   ];
 
+  # Use the shared Aquamarine builder for heavy derivations; local builds
+  # remain available as a fallback.
+  modules.remote-builders.enable = true;
+
   modules.btrbk.enable = true;
   modules.security.audit.enable = true;
 

hosts/12kingdoms-youko/default.nix

@@ -57,6 +57,10 @@ in
     ];
   };
 
+  # Use the shared Aquamarine builder for heavy derivations; local builds
+  # remain available as a fallback.
+  modules.remote-builders.enable = true;
+
   modules.btrbk.enable = true;
   modules.security.audit.enable = true;
 

outputs/aarch64-linux/tests/remote-builders/expected.nix

@@ -0,0 +1,4 @@
+{
+  distributedBuilds = true;
+  aquamarineConfigured = true;
+}

outputs/aarch64-linux/tests/remote-builders/expr.nix

@@ -0,0 +1,14 @@
+{
+  outputs,
+  ...
+}:
+let
+  name = "shoukei-niri";
+  cfg = outputs.nixosConfigurations.${name}.config;
+in
+{
+  distributedBuilds = cfg.nix.distributedBuilds;
+  aquamarineConfigured = builtins.any (
+    machine: machine.hostName == "aquamarine" && machine.sshUser == "root"
+  ) cfg.nix.buildMachines;
+}

outputs/x86_64-linux/tests/remote-builders/expected.nix

@@ -0,0 +1,16 @@
+{
+  lib,
+  ...
+}:
+let
+  yes = lib.genAttrs [
+    "ai-niri"
+    "shoryu"
+    "shushou"
+    "youko"
+  ] (_: true);
+in
+{
+  distributedBuilds = yes;
+  aquamarineConfigured = yes;
+}

outputs/x86_64-linux/tests/remote-builders/expr.nix

@@ -0,0 +1,22 @@
+{
+  lib,
+  outputs,
+  ...
+}:
+let
+  builderHosts = [
+    "ai-niri"
+    "shoryu"
+    "shushou"
+    "youko"
+  ];
+  cfg = name: outputs.nixosConfigurations.${name}.config;
+  usesAquamarine =
+    name:
+    builtins.any (machine: machine.hostName == "aquamarine" && machine.sshUser == "root")
+      (cfg name).nix.buildMachines;
+in
+{
+  distributedBuilds = lib.genAttrs builderHosts (name: (cfg name).nix.distributedBuilds);
+  aquamarineConfigured = lib.genAttrs builderHosts usesAquamarine;
+}

vars/default.nix

@@ -38,5 +38,8 @@
   remoteBuilderClientKeys = [
     "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINHZtzeaQyXwuRMLzoOAuTu8P9bu5yc5MBwo5LI3iWBV root@ai"
     "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILDkbOwOeuAem8BKbyTDliRiTfHVAFdiVpAKh1bhs2s0 root@shoukei"
+    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGSSw4Oa8CaAeYXq2+O/SHHICaoUTFTGYjW5R9MzZ9Nj root@shoryu"
+    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIK4Po3tzTPVKEE5fAk4RQfhTvA4h+AurnkEiM7RYdND9 root@shushou"
+    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEs8b3CmxM+utXZVKvJBssXBupBXvvzjHP40HcY7PSyZ root@youko"
   ];
 }