diff --git a/app.py b/app.py
index 063ec95..b0511c7 100644
--- a/app.py
+++ b/app.py
@@ -2561,7 +2561,7 @@ def fetch_available_workspaces_for_organization(organization_id: str):
         with conn.cursor() as cur:
             cur.execute(
                 """
-                SELECT id, key, name, description
+                SELECT id, key, name, description, organization_id
                 FROM workspaces
                 WHERE organization_id IS NULL OR organization_id = %s
                 ORDER BY (organization_id IS NULL) DESC, name
@@ -2569,8 +2569,18 @@ def fetch_available_workspaces_for_organization(organization_id: str):
                 (organization_id,),
             )
             return [
-                {"id": str(wid), "key": key, "name": name, "description": description}
-                for wid, key, name, description in cur.fetchall()
+                {
+                    "id": str(wid),
+                    "key": key,
+                    "name": name,
+                    "description": description,
+                    # GUI-Umbau Phase 3 (11.09.2026, Kunden-Workspace-Creator):
+                    # ist_global steuert, ob der Kunde die Zusammensetzung
+                    # bearbeiten darf (eigener Workspace) oder nur lesend
+                    # sieht (globaler, schreibgeschützter Standard).
+                    "ist_global": ws_org_id is None,
+                }
+                for wid, key, name, description, ws_org_id in cur.fetchall()
             ]
 
 def create_workspace(key: str, name: str, description: str | None, organization_id: str | None):