Dim prompts use the documented dim exec form

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

bin/omarchy-agent

@@ -108,8 +108,12 @@ deepcode)
   [[ -n ${prompt:-} ]] && command+=("$prompt")
   ;;
 dim)
-  command=(dim)
+  # `dim exec` is the documented one-shot prompt form
-  [[ -n ${prompt:-} ]] && command+=("$prompt")
+  if [[ -n ${prompt:-} ]]; then
+    command=(dim exec "$prompt")
+  else
+    command=(dim)
+  fi
   ;;
 *)
   echo "Unsupported default agent: $agent" >&2