- events table (kind, article_id, visitor_hash, day) with a UNIQUE key that dedups
to one row per visitor-day — caps volume and makes counts mean distinct
visitor-days. NO ip/ua/referrer/url. Groupings derived from article_id at query
time, never stored.
- POST /api/events (public): whitelisted kinds (visit/open/share_ub/copy_source/
native_share/source_click); visitor token hashed server-side (never raw).
- Frontend analytics.js: random localStorage visitor token; track() via sendBeacon;
visit once/day; open on article click; share_ub/copy_source/native_share from the
share menu; /a landing pages fire source_click. 127 tests pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
