Source-led inclusion
The canonical board favors public-health agencies, standing guidance, disease outbreak notices, surveillance references, and reputable reporting with clear attribution. Each feed item must keep a source URL so readers can inspect the original record.
Trust hints, not proof
Source rank separates primary public-health sources from reputable news and lower-trust candidate lanes. Rank helps triage attention; it does not turn a summary into clinical guidance or a confirmed case count.
Material changes
The changes artifact reports recently added, removed, or materially updated feed records between promoted versions. It is a latest-delta aid, not a permanent incident history.