Great minds think alike? Two months ago I created an agent called 'zop' [1] that's also a static Go app. It's not a code harness, it's a cli tool for quick one-liners (faster and less memory than opencode --prompt) with canned system messages. With compile tags you can strip it down to just prompt execution and the binary's less than 3MB.
....But also because feature creep, you can compile-in text-to-speech, speech-to-text, an interactive mode, an Android app, MCP/tool calling, multiple provider support, and now a really crappy web interface that only half works. It turns out vibe coding is harder/more time-consuming than it seems... Creating an alternative to beads made it more manageable, but I need multi-agent orchestration to code it so I don't have to babysit it and manually QA it (because just installing playwright and telling the AI to write tests doesn't really work).
Kind of a waste of time, but interesting learning experience. Now I know why there aren't a hundred magically awesome user tools out there... they're still not that easy to make.