diff --git a/bump-coldairnetworks.sh b/bump-coldairnetworks.sh
new file mode 100755
index 0000000..0804641
--- /dev/null
+++ b/bump-coldairnetworks.sh
@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+LINUX=/root/petersweb-infra/nixos/linux.nix
+
+usage() {
+  echo "Usage: $0 <sha256-digest>"
+  echo "  e.g. $0 sha256:2e2d92abae0ba68be780fff581523480ac05444690dbf38bf4330f1dda099e2a"
+  exit 1
+}
+
+[[ $# -eq 1 ]] || usage
+
+NEW_DIGEST="${1#sha256:}"   # strip leading "sha256:" if provided
+
+# Validate: hex string of the right length
+if ! [[ "$NEW_DIGEST" =~ ^[0-9a-f]{64}$ ]]; then
+  echo "Error: digest must be a 64-character lowercase hex string (got: $NEW_DIGEST)" >&2
+  exit 1
+fi
+
+OLD_LINE=$(grep -n 'coldairnetworks-com@sha256:' "$LINUX")
+echo "Current: $OLD_LINE"
+
+sed -i -E "s|(coldairnetworks-com@sha256:)[0-9a-f]{64}|\1${NEW_DIGEST}|" "$LINUX"
+
+NEW_LINE=$(grep -n 'coldairnetworks-com@sha256:' "$LINUX")
+echo "Updated: $NEW_LINE"
+
+echo "Applying NixOS configuration..."
+nixos-rebuild switch --flake /root/petersweb-infra/nixos#mainframe
+echo "Done. Tail logs with: podman logs -f coldairnetworks"