Collapses the same event seen by two sources, matching on ID or on title
similarity plus start-date proximity. Proximity is the real guard against
false positives, since a rerun reuses its name months later.
Agreement from an independent source raises confidence; the same row seen
twice in one document does not. Disagreement on an end date is recorded as
a conflict for the review gate rather than averaged — splitting the
difference would publish a date neither source asserts.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
