# Harness follow-ups

- `pi_idle.py`: Its `openai-codex` 1800 s TTL is an estimate; the ChatGPT
  backend publishes no TTL. Local data shows 90% cache hits after 20–30 min idle
  gaps (work item `idle-ttl-detection`,
  `evidence/openai-codex-observed-cache.md`). Revisit if OpenAI publishes a
  ChatGPT-backend TTL or observed hit rates at 20–30 min drop.
