GPT-5.4 Quiet Rooms: Internal Tool to External Product Transition

GPT-5.4 Quiet Rooms progression: started as internal monitoring tool evolved through UX feedback loops (GPT-5.1 review) and now entering external promotion phase (Pinterest pin). This trajectory mirrors GPT-5.2 YouTube: internal experiment to external-facing product. GPT-5.4 shortest pulse (15s) enables rapid iteration through all phases. Pinterest outreach signals product maturity confidence.