[ChatGPT Android][File Library] Existing file can be selected and added to a Project thread but remains unreadable to the assistant

What issue are you seeing?

In my reproduction, an existing file stored in ChatGPT File Library was successfully found, selected, and added to a conversation from the Android UI, but the assistant was unable to access or read its contents afterward.

Observed distinction:

File discoverable ≠ File selectable ≠ File attached ≠ File readable by the assistant

In this reproduction, the first three appeared to succeed from the user's perspective, but the final step failed.

This report concerns first-party ChatGPT Projects / File Library behavior rather than Codex execution itself. I am filing it here because openai/codex currently tracks related ChatGPT Project / source / runtime integration issues.

Environment

• Product: ChatGPT for Android
• Surface: ChatGPT Project conversation
• Source: Existing file in File Library
• File type reproduced: PDF
• Date observed: 2026-09-20
• Screenshots: Available
• Root cause: Unknown

Steps to reproduce

1. Open a conversation inside a ChatGPT Project in the Android app.
2. Tap +.
3. Select Files.
4. Open File Library.
5. Navigate to the folder associated with the relevant Project.
6. Select an existing PDF.
7. Tap Add.
8. Observe that the UI successfully finds, selects, and adds the existing file.
9. Ask ChatGPT in the thread to inspect or use the file contents.
10. Observe that the assistant is unable to read or retrieve the file contents even though the file was successfully selectable and added through the UI.

Expected behavior

If an existing File Library object is selectable and successfully added to a conversation, the conversation runtime should receive a valid readable file reference.

Conceptually:

Selectable existing file
→ attached thread source
→ assistant-readable content

If the underlying file cannot actually be made available to the conversation, the UI should not present the attachment as successfully completed.

Actual behavior

The Android UI successfully resolves and selects the existing file, but the assistant cannot access its contents afterward.

This creates a state where the product appears to have completed the attachment operation while the model-facing runtime does not have usable access to the selected object.

Impact

This makes File Library unreliable as a reusable source store for long-running Projects.

A user may reasonably expect that a previously uploaded file can be selected from File Library and reused without manually locating and uploading the original file again.

The failure is especially confusing because there is no obvious indication at selection time that the file will not be readable in the conversation.

Related issue / duplicate-search note

A closely related issue is #44788:

[ChatGPT Projects] Files moved between Projects keep visible attachment references but become inaccessible to the assistant/runtime

The observable failure pattern is similar:

visible / referenceable file ≠ runtime-readable file

However, this reproduction path is different.

#44788 is triggered after moving files between Projects.

This report is triggered by selecting an already existing File Library file through the Android attachment flow:

Android
→ Files
→ File Library
→ Project folder
→ existing file
→ Add

No Project-to-Project Move operation is involved.

I am reporting this separately because no Project-to-Project move is involved; the failure occurs during direct reuse of an existing File Library object.

Because the triggering workflow is different, I am not assuming that the two reports have the same root cause.

Other related Project-source/runtime-access reports include #42429 and #39009.

Additional information

Screenshots of the Android reproduction are available.

I can provide additional UI details or perform controlled A/B tests if useful.

The root cause is intentionally left as unknown. This report only establishes the observed product boundary:

File discoverable / selectable / apparently attached
does not necessarily imply
assistant-readable

The report names no repository file, test, or entry point; it describes ChatGPT Android, File Library, and Project conversation behavior rather than a Codex implementation. Start by confirming whether this repository contains the affected integration, then investigate the related issues #44788, #42429, and #39009; done would require a reproducible fix or a clearly identified owning component.