SharePoint datasource context stops resolving files by name after switching model from Claude 4.6 to GPT-5.2

[bonequinha]

Description

When switching the assistant model from Claude Sonnet 4.6 to GPT-5.2 (2025-12-11) while using an assistant with a configured SharePoint datasource, the assistant loses the ability to resolve files by filename inside the chat.

Instead of accessing files from the datasource context by the nabe, the system starts requesting:

• direct URLs to each file, or
• manual upload of each file into the conversation.

Switching the model back to Claude Sonnet 4.6 directly in the chat - immediately restores normal behavior, and files can again be referenced by filename only. This indicates that the SharePoint datasource itself remains functional and the issue is model-switch related.

Steps to Reproduce

1. Configure a SharePoint datasource context.
2. Start a conversation using Claude Sonnet 4.6.
3. Reference a file by filename in chat (without direct URL or upload).
4. Verify that the assistant correctly finds and accesses the file from the datasource.
5. Clean the session.
6. Switch the model to GPT-5.2 (2025-12-11).
7. Reference the same file again by filename only.

Actual Result

The assistant no longer resolves the file from the SharePoint datasource context and instead asks for:

• a direct file link, or
• manual file upload.

Expected Result

The assistant should continue using the existing SharePoint datasource context after model switching and should still be able to resolve files by filename without requiring direct links or uploads.

Additional Notes

• Switching back to Claude Sonnet 4.6 restores correct datasource behavior immediately.
• The issue appears to be related specifically to datasource context persistence or retrieval after switching to GPT-5.2.
• The SharePoint datasource configuration itself remains valid and operational.