Offline-verifiable building blocks for GitHub Copilot; network paths are the
flagged live-verification risk and are covered by pure unit tests only.
- copilot/device_flow.rs: OAuth device flow (RFC 8628). No hardcoded client id —
ai-harness must register its own GitHub OAuth app and pass it in. Pure
parse_poll_response (pending/slow_down/success/failed) + slow_down interval bump;
request_device_code/poll_once/poll_for_token (injected sleep).
- copilot/token.rs: copilot_internal/v2/token exchange with cache + single-flight
refresh (tokio::Mutex) and direct-Bearer fallback on 401/403/404; needs_refresh
honors a 120s skew and expires_at==0 = never.
- copilot/provider.rs: CopilotProvider over api.githubcopilot.com, routing each
model to chat/responses/anthropic codec by its /models supported_endpoints
(parse_models + codec_for_endpoints); headers (X-GitHub-Api-Version, Openai-Intent,
x-initiator, Copilot-Vision-Request, anthropic-beta for anthropic models).
- 11 unit tests (device-flow parsing, token refresh math, codec routing, /models
parsing).
Deferred (needs live API + TUI work): EngineHandle::login device-flow modal,
startup /models fetch, auth.json-backed registry wiring.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
