hermes - 💡(How to fix) Fix [Bug]: Desktop dragged images become unsupported binary files and disappear after chat switch

Bug Description

Dragging/pasting PNG screenshots into Hermes Desktop produces inconsistent attachment handling. The composer can show image chips/previews, but the submitted context can also report the same screenshots as unsupported binary files.

Observed warning text looked like:

--- Context Warnings ---
- @file:`...\Pictures\Screenshots\Screenshot 2026-06-05 190653.png`: binary files are not supported
- @file:`...\Pictures\Screenshots\Screenshot 2026-06-05 190423.png`: binary files are not supported

At the same time, at least one image was available through the Desktop composer-image cache path, e.g.:

...\AppData\Roaming\Hermes\composer-images\composer_2026-06-05_16-07-58-015_11aa16.png

This makes it look like dragged images may enter both a generic file-attachment path and the composer-image path.

Steps to Reproduce

1. Open Hermes Desktop.
2. Drag multiple PNG screenshots into the composer.
3. Observe that image chips/previews appear in the composer.
4. Switch to another chat and back before sending, or send the prompt with the images attached.
5. Observe whether attachments disappear visually after switching.
6. Observe whether the message context contains binary files are not supported warnings for the PNG screenshots.

Expected Behavior

• Dragged/pasted image files should be treated as image attachments, not unsupported binary files.
• The app should not send duplicate/conflicting representations of the same image.
• If images are too large/too many/unsupported, Desktop should show which files were rejected and why.
• Unsent image attachments should persist per chat when switching chats, or the user should be warned before they are cleared.

Actual Behavior

• PNG screenshots appeared as composer image attachments visually.
• The context also warned that the same screenshot files were unsupported binary files.
• Selected image attachments could disappear visually after switching chats.

Affected Component

Other (Hermes Desktop UI)
Tools (terminal, file ops, web, code execution, etc.)

Messaging Platform (if gateway-related)

N/A

Debug Report

Not available yet. This was observed in the Desktop composer/attachment UI. Screenshot evidence exists locally and can be uploaded through the GitHub web UI if needed.

Operating System

Windows 10

Python Version

3.11.15

Hermes Version

Hermes Agent v0.15.1 (2026.5.29)
Hermes Desktop visible build: v0.15.1 (+8) af8b917
Model/session context: Codex GPT-5.5

Additional Logs / Traceback (optional)

Context warning text included: `binary files are not supported` for PNG screenshot paths.

Root Cause Analysis (optional)

Possible duplicate path handling: dragged images may be registered as both generic file attachments and Desktop composer-image attachments.

Proposed Fix (optional)

Normalize drag/drop handling so image MIME types/extensions go through the image attachment pipeline only, with clear accept/reject state and per-chat draft persistence.

Are you willing to submit a PR for this?

• I'd like to fix this myself and submit a PR