What a subscribe writes — the memory ids are server-minted (never a client body).
Optional
Tenant-salted resourceId (${tenantId}_${key}) — the thread's owner.
${tenantId}_${key}
Tenant-salted threadId (${tenantId}_${uuid}) the caller owns (path-checked upstream).
${tenantId}_${uuid}
What a subscribe writes — the memory ids are server-minted (never a client body).