OpenAI released Codex CLI 0.155.1 on September 18 with a compatibility fix for new local terminal sessions. Its changelog says reasoning summaries are now disabled by default because some providers reject requests that include them.
Explicit settings for reasoning summaries still take effect. That makes the patch relevant to developers investigating provider request failures, while limiting what they should expect from a default-setting change.
For a team maintaining a Codex integration, the useful checks are the installed CLI version and any explicit summary configuration. The release note addresses this particular cause of rejected requests; it does not claim to fix every connection or authentication problem.