PDF upload fails with GPT-5: "Item not found" error due to Zero Data Retention

Steps to Reproduce:

1. Use GPT-5 (o1) model in Chipp
2. Upload a PDF file to the chat
3. Attempt to send a message/generate a response

Expected Behavior: PDF should be processed and the assistant should respond based on the file content

Actual Behavior: Error message appears: "Failed to generate response. Please try again." Detailed error: Item with id 'rs_...' not found. Items are not persisted for Zero Data Retention organizations. Remove this item from your input and try again.

Environment:

• Model: GPT-5 (o1)
• Feature: PDF upload and processing
• Note: PDF upload and processing works correctly on most other LLMs - this issue is specific to GPT-5

Root Cause: The error indicates that uploaded files are being referenced by resource ID (rs_…), but these items are not persisted in Zero Data Retention organizations, causing the request to fail.

Original Report:

• Featurebase submission: https://updates.chipp.ai/p/continually-getting-this-error
• Reporter: Jake Galloway
• Testing/replication confirmed from Discord discussion

Screenshots:

• https://files.slack.com/files-pri/T03UEBJ9PGW-F0A6FGUBSUE/screenshot2026-01-02at_14.31.13.png
• https://files.slack.com/files-pri/T03UEBJ9PGW-F0A6FHNDV2A/screenshot2026-01-02at_14.35.22.png