Windows: codex exec image generation produces no image artifact

Summary

On Windows 11, Codex image generation stopped producing image artifacts after updating to the 0.149.x CLI line. The CLI/app integration can finish without a usable error, but no PNG or manifest is written.

Environment

• Codex CLI: 0.149.0-alpha.4.3
• OS: Windows 11
• Authentication: ChatGPT account through the VS Code extension CLI

Expected behavior

A normal image-generation request should write a valid PNG to the requested working directory, or return a clear non-zero error if the image tool or artifact delivery is unavailable.

Actual behavior

• A standalone one-image request ran for about three minutes and then exited without creating the requested PNG.
• The desktop app's four-image integration repeatedly observed: exit code 0, 0/4 valid PNGs, and a missing manifest.json.
• No usable image artifact was published to the requested staging directory.

Regression window

Image output was last confirmed working with 0.148.0-alpha.21 on August 20, 2026. The failure began around August 22, after updates in the 0.149.0-alpha.4.x line.

Minimal reproduction

1. Create a new writable empty directory on Windows.
2. Run codex exec with an ordinary request that requires the image-generation tool to save a PNG in that directory.
3. Wait for completion.
4. Observe that no PNG is created; in the multi-image integration the process can report exit code 0 with no artifacts.

No account identifiers, prompts, credentials, or application logs are included here. This appears related to existing reports of image-tool exposure and artifact-delivery failures, but the behavior above is reproducible as a Windows CLI regression.

Start by reproducing the failure with codex exec on Windows 11 using the minimal empty-directory setup described in the issue, and inspect whether the command exits successfully without a PNG or manifest.json. Trace the image-generation and artifact-delivery entry points involved in that command. Done means a valid PNG is written to the requested directory, or a clear non-zero error is returned when delivery is unavailable.