alt Hacker NewsWith Anthropic, you either pay per token with an API key (expensive), or use their subscription, but only with the tools that they provide you - Claude, Claude Cowork and Claude Code (both GUI and CLI variants). Individuals generally get to use the subscriptions, companies, especially the ones building services on top of their models, are expected to pay per token. Same applies to various third party tools.
The belief is that the subscriptions are subsidized by them (or just heavily cut into profit margins) so for whatever reason they're trying to maintain control over the harness - maybe to gather more usage analytics and gain an edge over competitors and improve their models better to work with it, or perhaps to route certain requests to Haiku or Sonnet instead of using Opus for everything, to cut down on the compute.
Given the ample usage limits, I personally just use Claude Code now with their 100 USD per month subscription because it gives me the best value - kind of sucks that they won't support other harnesses though (especially custom GUIs for managing parallel tasks/projects). OpenCode never worked well for me on Windows though, also used Codex and Gemini CLI.
>or perhaps to route certain requests to Haiku or Sonnet instead of using Opus for everything, to cut down on the compute
You can point Claude Code at a local inference server (e.g. llama.cpp, vLLM) and see which model names it sends each request to. It's not hard to do a MITM against it either. Claude Code does send some requests to Haiku, but not the ones you're making with whatever model you have it set to - these are tool result processing requests, conversation summary / title generation requests, etc - low complexity background stuff.
Now, Anthropic could simply take requests to their Opus model and internally route them to Sonnet on the server side, but then it wouldn't really matter which harness was used or what the client requests anyway, as this would be happening server-side.