diff --git a/packages/opencode/src/session/message-v2.ts b/packages/opencode/src/session/message-v2.ts
index 650fda6e94..6358c6c5e9 100644
--- a/packages/opencode/src/session/message-v2.ts
+++ b/packages/opencode/src/session/message-v2.ts
@@ -176,6 +176,8 @@ export namespace MessageV2 {
       })
       .optional(),
     command: z.string().optional(),
+  }).meta({
+    ref: "SubtaskPart",
   })
   export type SubtaskPart = z.infer<typeof SubtaskPart>