Automating cross-repo documentation with GitHub Agentic Workflows

This post details the implementation of GitHub Agentic Workflows for automating cross-repo documentation generation. Key contributions include: a markdown-based workflow definition with YAML frontmatter and English prompts; a secure output handler that materializes agent intent (JSON blob) into GitHub actions via a scoped GitHub App; a deterministic target branch resolver mapping product repo milestones to docs repo release branches; and the use of a draft-only pull request strategy with the feature's SME as the reviewer. It also addresses challenges like prompt budget limitations for large diffs by pre-extracting metadata and the need for a mirrored checkout pattern for cross-repo operations.