I kept running into the same split.
Companion AI has a face and a voice, and does nothing. Agent tools do things, but you sit there watching a spinner, and the moment you ask for something long you have lost the conversation.
So Kotoba runs one agentic loop with two modes. Companion mode is the conversation you are in — full toolset every turn, no keyword router deciding what you "meant". Work mode is a background job that outlives the turn that started it: she goes off to research, run code and write files, and you keep talking to her meanwhile. Its output does not interrupt you; only the final summary comes back.
Honest limits: this is v0.10.0 and I built it alone. The Live2D avatar needs a model you supply, the llm and the voice costs money if you use the good engine, and background work will happily burn tokens if you let it.
Would genuinely like to hear where it breaks.