diff --git a/modules/ncli.nix b/modules/ncli.nix
old mode 100755
new mode 100644
index 854f25d..a31ffd6
--- a/modules/ncli.nix
+++ b/modules/ncli.nix
@@ -91,7 +91,32 @@ in
         echo -e "''${YELLOW}[->]''${NOCOLOR} $1"
     }
 
-    # --- Main Logic ---
+    handle_build_error() {
+        local exit_code=$?
+        # Exit code 137 = 128+9 = SIGKILL, almost always OOM killer
+        if [ "$exit_code" -eq 137 ]; then
+            echo ""
+            echo -e "''${RED}╔══════════════════════════════════════════════════════════╗''${NOCOLOR}"
+            echo -e "''${RED}║  BUILD KILLED — Signal 9 (SIGKILL) detected              ║''${NOCOLOR}"
+            echo -e "''${RED}╚══════════════════════════════════════════════════════════╝''${NOCOLOR}"
+            echo ""
+            echo -e "''${YELLOW}What happened:''${NOCOLOR}"
+            echo "  The build process was forcefully terminated by the OS."
+            echo "  This is almost always the Linux kernel OOM killer running out"
+            echo "  of RAM + swap during Nix evaluation or compilation."
+            echo ""
+            echo -e "''${YELLOW}Suggested fixes (try in order):''${NOCOLOR}"
+            echo ""
+            echo -e "  ''${GREEN}1. Reduce parallel jobs''${NOCOLOR} (lowest RAM usage):"
+            echo "     sudo nixos-rebuild switch --flake . --max-jobs 1 --cores 1"
+            echo ""
+            echo -e "  ''${GREEN}2. Confirm OOM killer fired:''${NOCOLOR}"
+            echo "     journalctl -k --since '5 minutes ago' | grep -i oom"
+            echo ""
+        fi
+    }
+
+        # --- Main Logic ---
     if [ "$#" -eq 0 ]; then
       echo "Error: No command provided." >&2
       print_help
@@ -164,7 +189,8 @@ in
           current=$(cat /etc/nixos-tags)
         fi
 
-        if sudo nixos-rebuild switch --flake .; then
+        sudo nixos-rebuild switch --flake . ; _rebuild_exit=$?
+        if [ "$_rebuild_exit" -eq 0 ]; then
           echo "✓ Rebuild finished successfully for $HOST"
 
           if [ -n "$current" ]; then
@@ -177,6 +203,7 @@ in
           echo -e "Running on new generation: $YELLOW $geno $NOCOLOR-> $GREEN$genn$NOCOLOR"
 
         else
+          ( exit "$_rebuild_exit" ); handle_build_error
           echo "✗ Rebuild failed for $HOST" >&2
           exit 1
         fi
@@ -258,7 +285,8 @@ in
           echo "Rebuilding system... Staying on current specialization"
         fi
 
-        if sudo nixos-rebuild switch --flake .; then
+        sudo nixos-rebuild switch --flake . ; _rebuild_exit=$?
+        if [ "$_rebuild_exit" -eq 0 ]; then
           echo "✓ Update and rebuild finished successfully for $HOST"
 
           if [ -n "$current" ]; then
@@ -271,6 +299,7 @@ in
           echo -e "Running on new generation: $YELLOW $geno $NOCOLOR-> $GREEN$genn$NOCOLOR"
 
         else
+          ( exit "$_rebuild_exit" ); handle_build_error
           echo "✗ Update and rebuild failed for $HOST" >&2
           exit 1
         fi