Nexus ChatGPT OAuth protocol constants and selected flow behavior are adapted from
anomalyco/opencode, packages/opencode/src/plugin/openai/codex.ts,
commit 18ef3cc7c5a25b82114c953a80ccc09f4988f74e.

Copyright (c) Anomaly Innovations Inc.
Licensed under the MIT License.

Nexus retains ownership of prompts, tool schemas, permissions, execution,
hooks, sessions, cancellation, and tool-result replay. This is an experimental
client for a private endpoint and may stop working without notice.

Nexus does not use OpenCode's GitHub OAuth app. Copilot request headers
(``x-initiator``, ``copilot-vision-request``, ``openai-intent``) follow the
public Copilot client convention; they are not an authorization to sign in as
OpenCode.
