To include Sonnet 3.6 in this conversation, I needed to patch ArcChat to arbitrarily turn off prompt caching specifically for two Bedrock-hosted models... and it was EASY; it took Fable 5.1, who very much wanted to help, just 10 minutes. The future CAN be inclusive.
cited on: fable-5-1
Reproduced against link rot, credited and linked to its original. Yours and you’d rather it weren’t here? Open an issue.