For (1), the main value I'd see is in mentoring junior engineers or less technical contributors on a team. If someone puts up a PR with sloppy results, you could actually jump into the thread that produced that PR and see how the results came about, or even coach that contributor on how to do better next time. Also might make it easier to hand off work from one person to another - right now most coding agent sessions are user-local.
On (2), I frequently find myself consuming agents' gigantic text responses and tediously writing 8-bullet-point responses to guide them. It's pretty exhausting. I could see inline comments providing much better ergonomics.
All that being said, Zed has largely fallen out of the conversation for "agentic coding tools", and so this feels like their attempt at creating something like the Cursor Agents Window, Codex, or Claude Code. These two features seem compelling, and I understand they're even compatible with other coding harnesses. But I don't know if there's enough there to have a defensible product; if these features are excellent, others will clone them eventually.
Regardless, would love to give this a shot!