implement nix rbuild nushell command

.config/nushell/conf.d/99-attic.nu

@@ -1,14 +0,0 @@
-def "attic bpush" [
-    cache:string,      # The Attic cache to push to
-    flake:string,      # The flake reference to build
-    ...nixargs:string, # Extra arguments for Nix
-    --nom(-n),         # Use Nom
-] {
-    let outpath = (^(if $nom { "nom" } else { "nix" })
-                   build
-                   --no-link
-                   --print-out-paths
-                   $flake
-                   ...$nixargs)
-    attic push $cache $outpath
-}

.config/nushell/conf.d/99-nix.nu

@@ -0,0 +1,51 @@
+# Build a flake reference on a remote host. Creates a `result` symlink.
+# The nix-command and flakes experimental features must be active both locally and on the target host.
+def "nix rbuild" [
+    host:string,       # The remote host to build on
+    flakeref:string,   # A flake reference to build
+    ...nixargs:string, # Additional arguments to pass to the eval command
+    --no-link(-n),     # Don't create a `result` link
+    --nom,             # Invoke `nom` on the remote machine instead of `nix`
+    --remote-eval(-r), # Evaluate the derivation on the remote. Note that this will incorrectly handle path-based flake references.
+]: nothing -> list<string> {
+    let outpaths = if $remote_eval {
+        print "Eval & Build on Remote..."
+        ssh $host $"(if $nom { "nom" } else { "nix" }) build --no-link --print-out-paths '($flakeref)' ($nixargs | str join ' ')" | lines
+    } else {
+        print "Eval..."
+        let eval_output = nix eval $flakeref ...$nixargs
+        if $eval_output =~ "error:" {
+            error make {
+                msg: "Derivation evaluation failed!",
+                help: $eval_output,
+            } | return $in
+        }
+        let drv_path = $eval_output | parse "«derivation {drv}»" | get 0.drv
+
+        print "Copy drv to Remote..."
+        nix copy --substitute-on-destination --derivation --to $"ssh://($host)" $drv_path
+
+        print "Build on Remote..."
+        ssh $host $"(if $nom { "nom" } else { "nix" }) build --no-link --print-out-paths '($drv_path)^*'" | lines
+    }
+
+    print "Copy from Remote..."
+    nix copy --substitute-on-destination --no-check-sigs --from $"ssh://($host)" ...$outpaths
+
+    $outpaths
+}
+
+def "attic bpush" [
+    cache:string,      # The Attic cache to push to
+    flake:string,      # The flake reference to build
+    ...nixargs:string, # Extra arguments for Nix
+    --nom(-n),         # Use Nom
+] {
+    let outpath = (^(if $nom { "nom" } else { "nix" })
+                   build
+                   --no-link
+                   --print-out-paths
+                   $flake
+                   ...$nixargs)
+    attic push $cache $outpath
+}

flake.lock

@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1722062969,
-        "narHash": "sha256-QOS0ykELUmPbrrUGmegAUlpmUFznDQeR4q7rFhl8eQg=",
+        "lastModified": 1722630782,
+        "narHash": "sha256-hMyG9/WlUi0Ho9VkRrrez7SeNlDzLxalm9FwY7n/Noo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "b73c2221a46c13557b1b3be9c2070cc42cf01eb3",
+        "rev": "d04953086551086b44b6f3c6b7eeb26294f207da",
         "type": "github"
       },
       "original": {