Keep the retry marker until delivery settles and reuse deferred missed-run
history across low-budget turns. Update the integration expectation so an
oversized handoff allows the turn to complete while preserving its context.

Co-Authored-By: GPT-6.1-Sol at high effort <noreply@openai.com>
Co-Authored-By: GPT-6.1-Sol at high effort, review subagent for deferred handoff recovery <noreply@openai.com>
Co-Authored-By: GPT-6.1-Sol at xhigh effort, review subagent for PR 19414 maintenance rebase <noreply@openai.com>