[FEATURE] Allow a non-Anthropic model provider alongside the subscription in a Remote Control session

Problem Statement

Remote Control requires claude.ai subscription auth, and ANTHROPIC_BASE_URL / ANTHROPIC_AUTH_TOKEN replace the provider for the entire process. A session can therefore be remotely controllable, or it can talk to a different provider, never both. Setting a custom base URL flips the session to API billing and Remote Control refuses to attach ("Remote Control requires a claude.ai subscription").

That leaves no way to use any other model from the phone or web. The only thing that works today is wrapping the other provider in an MCP server, which means an Anthropic turn has to run on every single call just to relay the request, so the subscription is billed for work it is not doing.

Proposed Solution

Let a session hold a second provider next to the subscription one, configured in settings:

"providers": {
  "my-gateway": {
    "baseUrl": "https://gateway.example.com",
    "apiKeyEnv": "MY_GATEWAY_KEY",
    "models": ["gpt-x", "gemini-y"]
  }
}

Those models appear as extra entries in /model and in the model picker on web and mobile. The subscription login keeps owning the Remote Control connection, the session, and everything around it. Choosing an external model changes only where inference requests go, so the session stays remotely usable the whole time.

Remote Control can keep requiring an active claude.ai subscription exactly as it does now. Nothing here asks for the remote layer to be usable without one. The request is only that a valid subscription stops being cancelled out by the presence of a second inference endpoint.

Alternative Solutions

• MCP server wrapping the other provider: works, but every call costs an Anthropic turn on top of the external tokens, and the external model cannot drive the session, it can only answer questions.
• Second local session with ANTHROPIC_BASE_URL set to LiteLLM or a router: the other models work, but that session is invisible to Remote Control, so it can only be used while sitting at the machine.

Priority

Medium - Would be very helpful

Feature Category

API and model interactions

Use Case Example

1. Remote Control session running on my home Linux box, driven from my phone.
2. A task comes up where a different model fits better, either on cost or because it is stronger at that one thing.
3. Today I have to be physically at the machine and start a separate session with a custom base URL, and that session has no Remote Control at all.
4. With this, I pick the other model from the phone and the session keeps running where it is.

Further cases, mostly from teams rather than individuals:

• A company on Bedrock or Vertex for compliance reasons cannot use Remote Control today, because routing inference through their own cloud account disables it. Their developers keep paying for seats and still cannot reach their sessions from outside the office. With this, every one of those seats becomes a remote-capable seat.
• An internal gateway that logs and audits every model call is mandatory in a lot of regulated environments. Right now that gateway and Remote Control are mutually exclusive, so the teams who most need session oversight are the ones who have to give up the feature.
• Work on data that is contractually not allowed to leave a self-hosted model can still be driven from a Claude session, with Claude doing the reasoning, orchestration and tool use, and the restricted model only touching the restricted content.
• Long mechanical batches (bulk renames, mass translation, log triage) can run on a cheap model while Claude stays the driver, which makes it easier to justify keeping the subscription for the parts that actually need it.

Additional Context

Related but different asks: #72749 covers a transparent local proxy that still ends at api.anthropic.com with the same models, and #28795 covers Bedrock with AWS SSO for the remote-control command.