Automating cross-repo documentation with GitHub Agentic Workflows

The Aspire team (microsoft/aspire) built a cross-repo documentation automation pipeline using GitHub Agentic Workflows. When a product pull request merges, a workflow called pr-docs-check automatically drafts a documentation pull request in the separate aspire.dev repo, assigns the original feature's SME as reviewer, and posts a link back to the source PR. The system uses a scoped GitHub App token limited to exactly two repos, a safe-outputs handler that separates agent reasoning from write actions, and milestone-to-release-branch mapping for accurate targeting. Over a 30-day window spanning Aspire 13.3 and 13.4, 82 docs PRs were created with a 100% merge rate and median time-to-merge of 44.8 hours. The post covers the security model, lessons learned (over-eager docs detection, cross-repo checkout patterns, prompt budget management), and four additional companion workflows also running in production.