Reported by @tawny edge
Bug Report: "Try again" is always applied to the last message
`Steps to Reproduce`
- Start a thread.
- Write a prompt, get answer A.
- Write a prompt, get answer B.
- Click "Switch model" on answer A.
- "Try again" or change model in answer A.
`Expected Result`
Answer A gets regenerated.
`Actual Result`
Answer B gets regenerated.
`Environment`
Windows 10, Firefox 135.0.1