Codex CLI rejects DOCX attachments with unknown file variant

What version of Codex is running?

codex-cli 0.152.1

What operating system are you using?

Windows

What happened?

Attaching a .docx file in the Codex CLI chat fails before the message is sent. The UI displays the staged upload path, then returns:

Invalid request: unknown variant `file`, expected one of `text`, `image`, `localImage`, `audio`, `localAudio`, `skill`, `mention`

The upload was attempted twice and failed identically both times. Image attachments work, and pasting the document content as plain text works.

Steps to reproduce

1. Open a Codex CLI chat on Windows.
2. Attach a Microsoft Word .docx document.
3. Add a short message such as Here's the doc.
4. Send the message.

Expected behavior

The document should be attached and made available to the conversation. If .docx attachments are unsupported, the client should reject the selection locally with a clear supported-file-types message rather than serializing an unsupported file content variant.

Additional context

The error suggests the client emits a generic file content item while the receiving request schema does not accept that variant.

Start by tracing how Codex CLI serializes attachments into the chat request, focusing on the generic file content variant reported by the error. Reproduce the failure with a .docx on Windows and compare it with image and pasted-text attachments. Done means DOCX is supported by the receiving schema or rejected locally with a clear supported-file-types message.