Codex CLI cannot set Bedrock explicit prompt-cache controls, and a reported production workload spent 85 percent of its model cost on cache writes

Sources: Codex issue 37674, HN discussion
Summary: The issue is an open enhancement request rather than a defect report. It states that the Codex CLI exposes no way to place explicit prompt-cache control points when it runs against Amazon Bedrock, so the stable prefix of a conversation is written to the cache on each turn instead of being read from it, and the reporter puts cache-write tokens at about 85 percent of one production workload's model cost. That figure is the reporter's AWS Cost Explorer estimate rather than an invoice, the issue text states that not every cache write is a defect, and the Hacker News title's claim of a bug causing 10x charges appears nowhere in the issue.
Why it matters: An agent that rewrites its whole stable prefix on every turn pays full price for a prompt cache it never reads, and no client-side setting can turn it off.
Follow-up: Track whether explicit cache-control support lands in the Codex CLI for Bedrock.