Agents window: pasted content from another workspace's response is not visible in the target input

## Bug Description

When copying output from an agent response in workspace A and pasting it into the chat input of workspace B (in the Agents window), workspace B's input does not display or recognize the pasted content.

## Steps to Reproduce

1. Open two workspaces (A and B) with the Agents window active
2. In workspace A, get a response from an agent
3. Select and copy text from that response
4. Switch to workspace B's Agents window
5. Paste into the chat input field

## Expected Behavior

The copied text appears in workspace B's input field and can be submitted as part of a prompt.

## Actual Behavior

The pasted content is not visible in workspace B's input — the agent responds with "I can see you referenced a pasted text attachment, but I'm not able to see its content in your message."