docs(subagent): name parent session lineage

packages/subagent/subagent/src/types.ts

@@ -135,8 +135,8 @@ export interface SubagentResult {
 export interface SubagentRun {
   /**
    * Parent-scoped run id. For a local run, this MUST equal the published child
-   * session id, whose `parentSession` records `request.parent`; a remote
-   * provider mints an id unique in the parent namespace.
+   * session id, whose `parentSession` records `request.parent.session.id`; a
+   * remote provider mints an id unique in the parent namespace.
    */
   readonly id: SessionId
   /**