From GitHub

In the Inbox and Issues, pick items with space (or a range with v), then:

Key
`s`	Start one session from the picked items: Start work opens with a prompt built from them
`a`	Add them to the current session: typed into its agent (not while it is blocked or asking)

With nothing picked, the item under the cursor is used. The panel on the right shows the prompt that will be used.

Two issues picked, and the prompt Start work will open with

Start work opened from them: the prompt written, the repo guessed from the issues