diff --git a/apps/gui/src/components/builder/EntitiesTab.tsx b/apps/gui/src/components/builder/EntitiesTab.tsx
index 8002c83..fa4cafb 100644
--- a/apps/gui/src/components/builder/EntitiesTab.tsx
+++ b/apps/gui/src/components/builder/EntitiesTab.tsx
@@ -59,6 +59,7 @@ export function EntitiesTab({
                   attributes: [],
                   aliases: {},
                   initialMemories: [],
+                  isAgent: true,
                 },
               ]);
               setSelectedEntIndex(entities.length);
@@ -140,6 +141,27 @@ export function EntitiesTab({
               </select>
             </div>
 
+            <div className="space-y-1.5 pt-1 pb-2">
+              <div className="flex items-center gap-2">
+                <Label className="text-muted-foreground cursor-pointer flex items-center gap-1.5 text-sm font-semibold">
+                  <Checkbox
+                    checked={selectedEnt.isAgent !== false}
+                    onCheckedChange={(checked) => {
+                      const copy = [...entities];
+                      copy[selectedEntIndex].isAgent = !!checked;
+                      setEntities(copy);
+                    }}
+                  />
+                  Is Agent?
+                </Label>
+              </div>
+              <p className="text-[11px] text-muted-foreground/75 pl-5 select-none leading-normal">
+                When enabled, this entity will run an autonomous LLM loop to
+                perceive its environment, update its memories, and generate
+                prose narrative actions.
+              </p>
+            </div>
+
             {/* Attributes */}
             <div className="pt-2">
               <AttributeEditor
diff --git a/apps/gui/src/components/builder/types.ts b/apps/gui/src/components/builder/types.ts
index 337f356..c617710 100644
--- a/apps/gui/src/components/builder/types.ts
+++ b/apps/gui/src/components/builder/types.ts
@@ -46,4 +46,5 @@ export interface EntityData {
   attributes: AttributeData[];
   aliases: Record<string, string>;
   initialMemories: MemoryData[];
+  isAgent?: boolean;
 }