diff --git a/stacks.sh b/stacks.sh
index f81140f..21e2ef9 100755
--- a/stacks.sh
+++ b/stacks.sh
@@ -379,6 +379,24 @@ cmd_compose() {
 
 # ─── Update Service ───────────────────────────────────────────────────────────
 
+# Resolve each service's image tag to its current local SHA256 ID.
+# Reads from the local image store (updated by 'docker compose pull'),
+# NOT from running containers — so the comparison reflects the pulled image.
+_stack_image_ids() {
+  local stack_dir="$1"; shift
+  local -a env_flag=("$@")
+  local images
+  # 'config --images' (compose v2.19+) outputs one image name per line;
+  # fall back to parsing the resolved config yaml for older versions.
+  if images=$(cd "$stack_dir" && docker compose "${env_flag[@]}" config --images 2>/dev/null) \
+      && [[ -n "$images" ]]; then
+    echo "$images"
+  else
+    cd "$stack_dir" && docker compose "${env_flag[@]}" config 2>/dev/null \
+      | awk '/^\s+image:/{print $2}' | sort -u
+  fi | xargs -r docker image inspect --format '{{.Id}}' 2>/dev/null | sort
+}
+
 _update_run() {
   load_root_env
 
@@ -398,9 +416,9 @@ _update_run() {
     ((checked++)) || true
 
     local before after
-    before=$(cd "$stack_dir" && docker compose "${env_flag[@]}" images -q 2>/dev/null | sort || true)
+    before=$(_stack_image_ids "$stack_dir" "${env_flag[@]+"${env_flag[@]}"}")
     (cd "$stack_dir" && docker compose "${env_flag[@]}" pull 2>&1) || true
-    after=$(cd "$stack_dir" && docker compose "${env_flag[@]}" images -q 2>/dev/null | sort || true)
+    after=$(_stack_image_ids "$stack_dir" "${env_flag[@]+"${env_flag[@]}"}")
 
     if [[ "$before" != "$after" ]]; then
       info "  Updates found — recreating $stack"