Copilot code review gains API access and Balanced default effort level

GitHub Copilot code review can now be requested through the REST and GraphQL APIs, with an optional review effort level set per request.

Balanced became the default review effort level for new and existing repositories and organizations as of September 28, 2026, while users who explicitly selected Lite keep that setting.

The changes are generally available to Copilot Pro, Pro+, Max, Business, and Enterprise plans.