Proxy Harness Credits

Coding harnesses can use chat.dev platform credits through metered provider proxies when the matching platform key is configured. The server mints a chatdev-* session token for the worker and routes calls through the provider-specific proxy URL so token usage is counted and charged to the user's chat.dev balance.

Direct provider keys still bypass the proxy. Selecting an OpenAI, Anthropic, OpenRouter, or Poolside key injects the provider's normal environment variable for that harness.

If the matching platform key is not configured, the launch path should ask the user to select a provider key instead of starting a harness that will fail later inside the worker.

Current proxy behavior:

• Codex uses PLATFORM_OPENAI_API_KEY through /proxy/v1 unless the agent is using ChatGPT subscription auth.
• ChatGPT+Tools uses platform OpenAI credits inside chat.dev.
• Claude Code and OpenClaw use PLATFORM_ANTHROPIC_API_KEY through the Anthropic proxy when configured.
• Poolside uses PLATFORM_POOLSIDE_API_KEY through the Poolside proxy when configured.
• OpenCode chooses the proxy from the selected model provider: OpenAI, Anthropic, OpenRouter, or Poolside.

Provider keys remain available for users who want billing to happen directly at the upstream provider instead of through chat.dev credits.