[macOS] Writing block magic-edit fails on submit with “ChatGPT couldn't update this writing block”

What version of the Codex App are you using (from “About Codex”)?

26.814.41407 (build 6720)

What platform is your computer?

• macOS 26.5.2 (build 25F84)
• Apple Silicon (arm64)
• App bundle ID: com.openai.codex
• UI locale: zh-CN

What issue are you seeing?

In the macOS Codex app, the writing-block magic-edit UI opens normally and accepts an edit instruction, but submitting the instruction does not update the block.

The floating edit prompt appears and the submit-arrow button is enabled. Clicking the button triggers the request, but the app then shows:

ChatGPT couldn't update this writing block

In the zh-CN interface:

ChatGPT 无法更新此写作块

The writing block remains unchanged. This workflow worked previously.

Because the same failure occurs when clicking the enabled submit button, this does not appear to be only an Enter-key or CJK IME handling problem.

Steps to reproduce

1. Open a conversation containing a writing block.
2. Click the writing block's edit / magic-edit action.
3. Confirm that the floating edit prompt appears.
4. Enter a short instruction. An ASCII-only instruction can be used to avoid IME ambiguity.
5. Click the enabled submit-arrow button.
6. Observe the error toast and unchanged writing block.

Expected behavior

The submitted instruction should generate a proposed revision that can be reviewed and accepted, or apply the requested update according to the normal writing-block workflow.

Actual behavior

The request fails immediately after submission. No proposed edit is shown, the writing block stays unchanged, and the app displays “ChatGPT couldn't update this writing block.”

Diagnostic evidence

Local Codex desktop logs contain repeated failures for:

POST /conversation/message/writing-blocks/magic-edit

During a reproducible failure window on 2026-08-19 (local time), seven POST attempts were logged with:

• errorMessage=net::ERR_CONNECTION_CLOSED
• routePattern=/conversation/message/writing-blocks/magic-edit
• status=500
• hasRequestBody=true

Other ChatGPT endpoints also showed connection closures during part of that window, so the current evidence does not isolate whether the root cause is a writing-block client regression, the endpoint, or the connection path. However, the magic-edit UI consistently surfaced only the generic writing-block error and offered no retry or diagnostic detail.

A later UI attempt showed the same toast, although the available logs cannot be matched to that latest screenshot on a one-to-one basis.

Possible relation to #33489

This may be adjacent to #33489 because both affect writing-block updates, but the failure stage and platform are different:

• this report is from the macOS app;
• it fails when the magic-edit instruction is submitted;
• no proposed edit reaches an Accept/Reject stage;
• an explicit update-failure toast is shown.

Privacy note

No conversation IDs, writing-block IDs, authorization data, local filesystem paths, account identifiers, request bodies, or document content are included here.

A tightly cropped screenshot showing only the floating editor and error toast is available if useful.

Start by reproducing the macOS writing-block magic-edit flow and inspect POST /conversation/message/writing-blocks/magic-edit alongside the reported net::ERR_CONNECTION_CLOSED and status 500 logs. Compare the behavior with issue #33489, then determine whether the client, endpoint, or connection path is responsible; done means a submitted instruction produces a proposed revision or normal update instead of the generic error toast.