Tiles now sit with zero gap (their 1px borders are the only seam) and the
grid runs edge to edge. Wherever two tiles share a vertical edge, an
invisible strip sits on the seam; hovering reveals a small grab pill
(split-view style) and dragging it moves the shared edge, trading width
between the two tiles. The combined span is preserved, both tiles' min
sizes are honored, and a third tile sitting behind part of the seam
blocks the drag instead of being overlapped. Pills hide during tile
drags/resizes and rebuild for the new geometry on release; seam sizes
persist with the layout. Also fixes cellMetrics treating a 0px grid gap
as falsy and falling back to 10px.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RNYUv9EyrGSFmCnmH7WYKH
Claude
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