[Windows Desktop] Non-image attachments are rejected and long pasted instructions can freeze the composer

What version of the Codex App are you using?

Codex Desktop: 26.820.7780.0

Codex CLI installed on the same machine: codex-cli 0.150.0-alpha.8

Platform

Windows desktop, using a local project/workspace (not Remote SSH).

What issue are you seeing?

There appear to be two composer/attachment problems in Codex Desktop on Windows:

1. Non-image file attachments are rejected or fail to attach.

   • Image attachments work.
   • Attempts to attach normal development files (text/source/document-style files) are rejected or do not complete normally.
   • This makes it difficult to provide source files or project artifacts directly to a Codex task.

2. Pasting a long structured instruction can freeze the composer.

   • When a long multi-section prompt is pasted into the composer, the UI can remain stuck in the paste-processing state (localized as an "adding/pasting text" state).
   • The pasted text may never finish materializing in the editor and the composer becomes unusable.
   • A restart or a new thread may be required.
   • Short text messages work normally.

The second symptom is similar to the "Adding pasted text…" behavior reported in #37671, but this reproduction is on a local Windows project, not a Remote SSH project. It may also be related to other paste-path issues such as #40246 and #25865.

Steps to reproduce

A. Non-image attachment failure

1. Open Codex Desktop on Windows.
2. Open a normal local project task.
3. Use the attachment control to attach a normal non-image development file (for example a text/source/document file).
4. Observe that the file is rejected or fails to attach, while image files can be attached normally.

B. Long pasted-text freeze

1. Open a Codex task in a local Windows project.
2. Copy a long structured instruction containing many sections, headings, code-style blocks, and several thousand characters.
3. Paste it into the composer.
4. Observe that the composer can remain stuck processing the paste instead of completing quickly.
5. The task UI may need to be restarted or abandoned.

Expected behavior

• Supported non-image development files should attach normally, or Codex should clearly explain which file types are intentionally unsupported.
• Pasting a large plain-text instruction should complete without blocking the renderer/composer.
• If pasted content is large, it would be preferable to convert it to a text attachment or process it asynchronously rather than freeze the composer.

Actual behavior

• Image files attach successfully, while non-image files can be rejected/fail.
• Large structured text pastes can leave the composer stuck in the paste-processing state.

Impact

This affects normal coding workflows where long implementation instructions and source/document attachments are common. Splitting a task into multiple smaller messages is a workaround for the paste issue, but it is inconvenient and changes the intended task context.

Related issues

• #37671 — Windows Desktop + Remote SSH: multi-minute composer latency / "Adding pasted text…"
• #40246 — Windows: pasting files from Explorer freezes Codex
• #25865 — composer freeze on certain pasted structured text

Additional information

• The problem occurs in Codex Desktop while working with a local project.
• Image attachment remains usable.
• Short text input remains usable.
• No system security settings or Codex configuration were changed as a workaround.
• Screenshots / a screen recording and more precise reproduction data can be provided if maintainers request them.

No files or tests are named. Start by reproducing both the non-image attachment failure and the long-paste freeze in a Windows local project, then trace the Desktop composer’s attachment and paste-processing paths. Done means supported files attach or receive a clear rejection, and large plain-text pastes complete without blocking the composer.