diff --git a/apps/api/migrations/032_room_id_bare_form.sql b/apps/api/migrations/032_room_id_bare_form.sql
new file mode 100644
index 0000000..e8f2ced
--- /dev/null
+++ b/apps/api/migrations/032_room_id_bare_form.sql
@@ -0,0 +1,11 @@
+-- 032: accept homeservers that mint room IDs without the :server suffix.
+--
+-- tuwunel 1.9.4 returns BARE room IDs from createRoom ("!localpart") and its
+-- client API only accepts that bare form for those rooms (the suffixed form
+-- 500s with "no forward extremities"). The 030 check demanded the full
+-- "!localpart:server" spec form, which made every provisioned collective fail.
+-- Accept both forms; the homeserver is the authority on its own IDs.
+
+ALTER TABLE group_rooms DROP CONSTRAINT group_rooms_room_id_check;
+ALTER TABLE group_rooms ADD CONSTRAINT group_rooms_room_id_check
+  CHECK (room_id ~ '^![^:\s]+(:[^:\s]+)?$');
diff --git a/apps/api/src/collectives/provisioner.config.ts b/apps/api/src/collectives/provisioner.config.ts
index d62483f..5f5148b 100644
--- a/apps/api/src/collectives/provisioner.config.ts
+++ b/apps/api/src/collectives/provisioner.config.ts
@@ -115,13 +115,7 @@ export class MatrixHttpClient implements MatrixAdminPort {
     if (typeof body.room_id !== "string" || body.room_id === "") {
       throw new ProvisionerUnavailableError("createRoom response missing room_id");
     }
-    // Some homeservers return the bare localpart; the full room ID carries the
-    // server name, and every downstream consumer (DB checks, invites, joins)
-    // requires the complete form.
-    const roomId = body.room_id.includes(":")
-      ? body.room_id
-      : `${body.room_id}:${this.config.homeserverUrl.host}`;
-    return { roomId };
+    return { roomId: body.room_id };
   }
 
   async sendStateEvent(