diff --git a/configs/nixos/AGENTS.md b/configs/nixos/AGENTS.md
index 064dc22..c127e3a 100644
--- a/configs/nixos/AGENTS.md
+++ b/configs/nixos/AGENTS.md
@@ -50,7 +50,10 @@
   directories already exist inside the read-only source.
   For aggregate Copyparty volumes such as `/srv` with nested `/srv/inbox`, keep the guest bind mount
   writable and enforce read-only behavior through Copyparty access plus service `ReadWritePaths`.
-- `deploy-to` builds from the source checkout and activates a copied closure on the target.
+- `deploy-to` builds from the source checkout and activates an imported closure on the target.
   Do not rely on a target-local monorepo checkout for remote deployment.
+- On Pikachu, `nix copy --to ssh://pikachu` accepted a small `nix store add-file` probe,
+  but rejected locally built system paths that lacked trusted signatures.
+  Use a sudo `nix-store --import` path for unsigned deploy closures.
 - Do not hand-author `hardware-configuration.nix` for a host that has not been generated on that machine.
   Generate it on the target system or live ISO, then stage it before evaluating the flake.
diff --git a/configs/nixos/modules/shell/fish/default.nix b/configs/nixos/modules/shell/fish/default.nix
index 42de91d..7808133 100644
--- a/configs/nixos/modules/shell/fish/default.nix
+++ b/configs/nixos/modules/shell/fish/default.nix
@@ -99,7 +99,7 @@ in
           };
 
           deploy-to = {
-            description = "Build the current checkout locally, copy it to a host, and activate it";
+            description = "Build the current checkout locally, import it on a host, and activate it";
             body = builtins.readFile ./functions/deploy-to.fish;
           };
 
diff --git a/configs/nixos/modules/shell/fish/functions/deploy-to.fish b/configs/nixos/modules/shell/fish/functions/deploy-to.fish
index 09503d7..4e3c043 100644
--- a/configs/nixos/modules/shell/fish/functions/deploy-to.fish
+++ b/configs/nixos/modules/shell/fish/functions/deploy-to.fish
@@ -34,10 +34,40 @@ if test (count $system_path) -ne 1
     return 1
 end
 
-echo "deploy-to: copying $system_path to $host" >&2
-nix copy --to ssh://$host $system_path
+set nar_file (mktemp --suffix=.nar)
+or return $status
+set remote_nar "/tmp/deploy-to-$host-"(date +%s)"-$fish_pid.nar"
+
+set closure_paths (nix-store -qR $system_path)
 or begin
-    echo "deploy-to: copy failed for $host" >&2
+    set query_status $status
+    rm -f $nar_file
+    echo "deploy-to: closure query failed for $host" >&2
+    return $query_status
+end
+
+echo "deploy-to: exporting closure for $system_path" >&2
+nix-store --export $closure_paths >$nar_file
+or begin
+    set export_status $status
+    rm -f $nar_file
+    echo "deploy-to: closure export failed for $host" >&2
+    return $export_status
+end
+
+echo "deploy-to: copying closure archive to $host:$remote_nar" >&2
+scp $nar_file $host:$remote_nar
+set scp_status $status
+rm -f $nar_file
+if test $scp_status -ne 0
+    echo "deploy-to: closure archive copy failed for $host" >&2
+    return $scp_status
+end
+
+echo "deploy-to: importing closure on $host" >&2
+ssh -t $host "sudo sh -c 'nix-store --import < $remote_nar' && rm -f $remote_nar"
+or begin
+    echo "deploy-to: closure import failed for $host" >&2
     return $status
 end