Ask from the keyboard which neighbour a closed pane's rows go to

Del takes a side: `Del k` gives the closed pane's rows to the nearest
expanded pane above it, `Del j` to the one below, each falling back to the
other side when it has none. DelAbove and DelBelow are those two lines, with
no path of their own under SPC.

A bare Del started from a key -- SPC d, Enter on the tag word, a row run from
an output buffer -- on a pane with expanded panes both above and below asks
instead of guessing. The question is a prompt like Save's or a search's
(Pane.Prompt.del_side), so it is painted on the pane's notice band by the
same path, and the next key answers it before any mode sees it: k or Up,
j or Down, anything else keeps the pane, as does a click. Only a key press
sets Pardes.can_ask, so a click, a 9P ctl or event write, a startup line, a
restore and a shell exiting all close the pane at once, the rows going
where layout.absorbVWeight has always sent them. A collapsed pane is not
asked about (it has only a tag row to give), and collapsed neighbours are
passed over (layout.expandedNeighbor, which Collapse now uses too).

removePane and absorbVWeight take the recipient; every other caller passes
null. Three scripts that closed a middle pane with SPC d answer k, which
is where the rows went before, and their goldens are unchanged. delask.snap
covers the question, Esc, j, a clicked DelBelow and a clicked Del.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

1 files changed, 71 insertions, 0 deletions

diff --git a/test/snapshots/delask.snap b/test/snapshots/delask.snap
new file mode 100644
index 00000000..04bc850c
--- /dev/null
+++ b/test/snapshots/delask.snap
@@ -0,0 +1,71 @@
+# Del from the keyboard on a pane with open panes above AND below asks, on the
+# pane's notice band, which one takes its rows: k above, j below, anything else
+# keeps the pane. A click, and DelAbove/DelBelow (Del k / Del j), never ask.
+file top.txt top-marker
+start 36 100 top.txt
+wait 8000 top-marker
+stable 700 20000
+# two scratch panes below the file, each saying which it is, then focus the
+# middle one
+key space f n
+stable 400 5000
+key i
+text middle-pane
+key esc
+settle 100
+key space f n
+stable 400 5000
+key i
+text bottom-pane
+key esc
+settle 100
+key c-w k
+stable 400 5000
+snap three
+# asked, and nothing closes yet
+key space d
+stable 400 5000
+snap asked
+# Esc takes the question back: the pane stays
+key esc
+settle 100
+stable 400 5000
+snap kept
+# j: the pane below grows over the middle one's rows, the file keeps its own
+key space d
+stable 400 5000
+key j
+stable 700 10000
+snap below-took
+# a pane under it, and DelBelow (Del j) appended to the middle one's text and
+# executed with a click: no question, the pane below takes the rows
+key space f n
+stable 400 5000
+key i
+text third-pane
+key esc
+settle 100
+key c-w k
+stable 400 5000
+key A
+send \x20DelBelow
+key esc
+settle 100
+stable 400 5000
+snap typed
+press middle @DelBelow 21
+release middle @DelBelow 21
+stable 700 10000
+snap below-took-click
+# a fresh pane between the file and the third one, closed by a middle click
+# on its tag's Del: no question, and the rows go up as they always have
+press left 10 5
+release left 10 5
+stable 400 5000
+key space f n
+stable 400 5000
+snap four
+press middle @Del 12
+release middle @Del 12
+stable 700 10000
+snap mouse-del