Codex on AWS bedrock bug causing 10x charges

A bug in AWS Bedrock's Codex integration is causing users to be charged approximately 10x more than expected because the system lacks explicit cache controls for the GPT-5.6 Sol model. The issue prevents agentic coding workloads from utilizing prompt caching, resulting in cache-write tokens comprising 85% of estimated costs—with one user reporting $1,386 in charges over four days where caching could have significantly reduced expenses. The problem requires adding support for serializing prompt cache options in the native Amazon Bedrock provider to enable the cost-saving caching feature AWS designed specifically for agentic workflows.