Codex integration is completely broken for me as well (it did work in the past though). Every prompt fails with the message “The data couldn’t be read because it isn’t in the correct format.” macOS 26.5.1 Only Xcode 26.5 installed (also tried on 26.6RC and did the same thing) Logged out/in to codex (via ChatGPT account - NOT API Key) - No problems with login. Tried all the available models (Default, 5.5, 5.4, 5.4mini) Note: Custom codex ACP integration on Xcode 26.6RC works! (github.com/zed-industries/codex-acp) Already submitted a bug report with sysdiagnose.

Thank you once again 🙏 I managed to get it to work (there is very little information indeed).

Thank you Quinn (big fan btw), I have tried to do it with an extension, which works surprisingly well, but for some reason the only way to get it to truly work was to present the remote view (tried both NSView/Controller representables) inside a popup. Trying to directly include it in the hierarchy results in a stale view (shows up the content but cannot be interacted with).

Disregard. This was an issue on my end.

Archiving & uploading with Xcode 13.2RC also resolves the issue.