Official release note (2026-07-06)
GPT-5.5 Instant Mini is now the fallback model after GPT-5.5 Instant / Auto rate limits; it replaces GPT-5.3 Instant Mini, is not shown in the model picker, and is not available via API or Codex. A robots.txt update also blocks AdsBot-Google from /s/cb_ and /g/.
Flag changes by theme
Voice / microphone eligibility
microphone_permission_eligibility_enabled– gates whether microphone permission UI is offered.recent_voice_window_days– defines the look-back window used to decide voice eligibility.
New-user targeting
new_user_eligibility_enabled– turns new-user-specific logic on or off.new_user_window_days– sets how many days after signup a user is still considered “new.”
Timing / caching parameters
cache_ttl_ms– controls cache lifetime in milliseconds.period_ms– sets the interval for a periodic background task.
Prompt landing / prefill experiments
prefilled_prompt_landing_arm– assigns users to an experiment variant for prefilled prompts on first landing.
Paid-ads prompt experiments (removed)
Removal of auto_send_paid_ad_prompt, model_speaks_first_paid_ad_prompt, and paid_ads_prompt_landing_arm indicates the paid-ads prompt tests have been turned down.