Add gpt-6.1-sol to the Codex model registry and allowlist #169

OpenAI released GPT-6.1 Sol for Codex today (September 29, 2026). The proxy does not accept it yet. v0.1.42 has no gpt-6.1 entry in the registry or the Codex allowlist, and /v1/models does not list it.

Requested change

• Add gpt-6.1-sol and gpt-6.1-sol-fast to src/registry.rs and src/providers/codex/translate/model_allowlist.rs.
• Put them on the Responses Lite lane, like gpt-6-sol and gpt-6-astra.
• List both in /v1/models.

PR #165 added gpt-6-sol the same way, so it should serve as a template.

Open question for the maintainer

Should the opus and fable aliases move from gpt-6-sol to gpt-6.1-sol? I have no opinion. Adding the model without changing any defaults would already unblock me.

Environment

• claude-code-proxy 0.1.42 on Linux x86-64
• Used through Claude Code with a ChatGPT subscription login