Column collapse did not survive flipping away from the browser and back,
because it was the one piece of state still held outside the config:
applySplitDepth restored a *truncated* split_by, and a rebuilt view took its
split_by from the config while the levels it had dropped lived only in
splitFull.
split_by_depth is the config-level equivalent, and it works now that
apply_update applies it -- server.cpp does
ctx2->set_depth(HEADER_COLUMN, column_pivot_depth - 1), so it is 1-based
exactly like group_by_depth.
Everything that existed to support truncation goes with it:
- splitFull no longer has to outlive split_by, because split_by keeps every
level. It is just the live axis, for rendering the buttons.
- split_full is no longer persisted beside the config. Still read on load,
for layouts saved by the old scheme.
- collapsingRef and the prefix test are gone. They existed to tell our own
collapse from the user rearranging the pivot, which only mattered because
a collapse looked like a shorter split_by.
- The selection survives a collapse. It was cleared because slices name the
split_by dimensions they were cut from and the axis was changing shape;
with a depth those dimensions are all still there.
CLAUDE.md's §Column hierarchy describes the old mechanism throughout, and is
now wrong; updating it separately.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Paul Trowbridge
607dac221d