ActiveFilterChips (feed applied-filter row) and ChannelTagsControl both
hand-rolled the same single-line chip-fit measurer: a hidden mirror + a
layout-effect + ResizeObserver reading chip right edges, the real rem gap,
the pill width and the lane width. The policy half was already extracted
(decideChipLayout); the DOM-measurement half was still duplicated.
Promote that half to useChipOverflowFit(rowRef, chipsRef, pillRef, deps,
decide, initial): it owns the effect + observer + initial measure and reads
the common geometry, then hands it to each caller's own policy. The feed
row layers its leading label + trailing "Clear all" reservation on top and
keeps decideChipLayout; the tag cell's chips-only policy is extracted as
fitChipsWithPill (pure, unit-tested) alongside it. Add a jsdom test for the
hook (stubbed offsets, re-measure on deps). Behaviour unchanged — verified
in the browser: feed all/count modes + popover, tag "+N" fit + hover reveal.
- test_feed_views: extend _seed_tagged so a channel carries 2+ tags in a
non-topic category, and add language-AND / other-AND equivalence cases — the
per-category any/all generalization was only exercised for topic.
- tagModes.test: coerceTagModes migration (legacy global tagMode -> topic),
per-category preservation, invalid-value coercion, defaults.
- urlState.dom.test: per-category tag-mode URL round-trip + legacy ?tagmode=and
migration into the topic slot.
- Combobox.dom.test: the any/all match footer (hidden below 2 selections, reports
a mode change at 2+).
- chipOverflow.test: the all/some/count fit boundaries and the +N reservation.
peter