The LWW skip path compared only annotation content (text, color, note,
percentages) — locator columns were not part of 'changed'. A device echo
with identical content therefore resolved to skip, and the freshly
re-derived canonical CFIs were discarded in the same request that
computed them: a highlight whose stored start anchor had been corrupted
by the old percentage-exact bug could never heal, because every
subsequent echo carried the same text and was skipped before the
locator columns were written. Observed live: a push converted the
cross-block highlight's anchors correctly (structural, heading to
paragraph) yet the row kept its garbage start CFI and the highlight
stayed unpaintable on the web.
Echo saves now treat a non-empty incoming locator that differs from the
stored one as a change (locatorRefresher): empty locators still coalesce
(no drift), and once healed the echo produces identical CFIs, so the
steady state remains skip — no write churn. Highlights check
epubcfi_start/end; bookmarks check cfi_position/position.
applyBookmarkLWW also gains the empty-locator coalescing the highlight
path already had: web bookmark edits carry no device locators, and a
title/note edit must not wipe the stored device-native position.
john-okeefe
ae87c0cd6a