I'll put it out there that if you provide an API, others will no doubt build the apps for you.
For me:
- native, or as close as possible (drag and drop text, images and files, integrated, snappy, looks like it belongs, menubar/taskbar launcher)
- Global shortcut to launch a quick conversation
- integrated with macOS services menu so it works most places without copy/pasting
I had the openAI app, and I miss it. A main part of your workflow being hidden in a browser tab or clunk wrapper is the main bit of friction for me. So maybe the bar's not that high.
Total pivot: I do feel like a general Kagi app could be something to consider. Blur the lines between search, assistant and other enquiries to provide a general smart assistant where others have failed. Mac knows when I'm asking maths/conversions in search and solves for me, or provides a dictionary definition, or web lookup etc. But fails to be smart when I ask a complicated question. I have to separately use Siri for that, and it can't do anything really challenging. Kagi has all the parts, maybe a really basic onboard LLM could route the request to assistant or search based on the query. Like Wolfram alpha-esque?