[macOS] In-app Browser backend disappears after update; 26.721.41059 restores it

Summary

On macOS, the Codex in-app Browser backend was unavailable after updating ChatGPT/Codex Desktop to 26.721.81911. The Browser skill and Node runtime were present, but no browser backend was registered.

Installing the previous official OpenAI app build 26.721.41059 restored the backend immediately. This blocked browser-dependent workflows such as web research and local/visual validation.

Environment

• Platform: macOS 26.2, Apple Silicon
• Affected app build: ChatGPT/Codex Desktop 26.721.81911 (bundle 5973)
• Affected bundled CLI observed after reinstalling the official build: codex-cli 0.146.0-alpha.3.1
• Working app build: ChatGPT/Codex Desktop 26.721.41059 (bundle 5848)
• Browser plugin: bundled browser/26.721.81911 when affected; browser/26.721.41059 when working
• Auth: ChatGPT subscription

Actual behavior on 26.721.81911

The official Browser bootstrap completed, but browser discovery returned an empty list:

await setupBrowserRuntime({ globals: globalThis });
await agent.browsers.list();
// []

Selecting a URL then failed before navigation with:

No browser is available

This was not a target-site, login, cookie, or network failure: it occurred before opening any page.

Expected behavior

A Codex Desktop task should discover the in-app browser backend after the bundled Browser skill initializes, for example:

Codex In-app Browser
type: iab

The browser should remain available across app updates.

Working comparison: 26.721.41059

I installed the official archived OpenAI app bundle for 26.721.41059, fully quit/reopened the app, and repeated the same bootstrap.

Discovery then returned the in-app backend successfully, including its normal capabilities:

Codex In-app Browser
type: iab
capabilities: visibility, viewport

So the observed A/B is:

| App version | Browser discovery |
|---|---|
| 26.721.81911 | []; no browser available |
| 26.721.41059 | Codex In-app Browser available |

Reproduction

1. Install/update to ChatGPT/Codex Desktop 26.721.81911 on macOS.
2. Start a new Codex Desktop task.
3. Invoke the bundled Browser skill for any URL.
4. Initialize the documented browser runtime and list backends.
5. Observe [] / No browser is available.
6. Quit the app completely and install the official 26.721.41059 build.
7. Start a new task and repeat the same steps.
8. Observe the iab backend.

Impact

There is no clear in-app recovery path. Users can see the Browser skill but cannot use the browser backend, so browser tasks fail after spending time on bootstrap/troubleshooting. Downgrading the entire desktop app is an impractical workaround and updates reintroduce the regression.

Related reports

This looks related to the broader class of macOS reports where the Browser skill is present but the iab backend is missing, including #20579, #20678, #22852, and #25247.