Codex chat: "Add element to chat" always routes to wrong chat/thread

Bug Report

Summary:
In VS Code, when using Codex chat, the "Add element to chat" feature consistently attaches the element to a different chat/thread than the currently active Codex session — specifically, it always routes to the Copilot chat instead of the active Codex chat.

This happens every time, across all sessions and workspaces. It is not a workspace-specific issue or a one-off glitch.

Steps to Reproduce

1. Open VS Code with the Codex extension active.
2. Open Codex chat and start a new session.
3. Open Simple Browser or have a file/element ready.
4. Use "Add element to chat."
5. Element is sent to Copilot chat, not the active Codex chat.

Expected Behaviour

"Add element to chat" should attach the element to the currently active Codex chat session.

Actual Behaviour

"Add element to chat" always routes to the Copilot chat thread instead of the active Codex chat session.

Environment

• OS: Windows 11
• VS Code version: [please fill in]
• Codex extension version: [please fill in]
• Copilot extension version: [please fill in]

Additional Notes

This appears to be a routing/thread-binding bug in the Codex VS Code extension. The active Codex session is not being recognised as the target for element attachment. Please investigate session mapping and context attachment routing in Codex for VS Code.

Related potential issues: #14234