Codex thread/fork is sent without excludeTurns, so the app server serializes
every historical turn into the fork response even though the adapter only uses
thread metadata. Large histories can exceed the transport bound. This test
expects the inclusive lastTurnId boundary plus excludeTurns: true and fails
until the adapter sends it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>