agent: Fix "open thread as markdown" button (#28962)

Just now realized that the reason this button wasn't working reliably is
because we weren't passing the index to it. It's now fixed.

Release Notes:

- N/A
022a110f8eDanilo Leal committed on 4/17/2025, 1:20:24 PM· committed by GitHubparentb0200c4
1 file changedLine totals unavailable