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, 3 insertions, 0 deletions

diff --git a/test/snapshots/lspdebug.snap b/test/snapshots/lspdebug.snap
index 23a95db0..ab330a76 100644
--- a/test/snapshots/lspdebug.snap
+++ b/test/snapshots/lspdebug.snap
@@ -46,7 +46,10 @@ wait 10000 definition             z.zig
 # report one row short of its second query: step the cursor past it.
 key j j j
 wait 10000 explain                z.zig
+# the report sits between the source and the results, so Del asks where its
+# rows go: k, back to the source above
 key space d
+key k
 key space w j
 key space d
 stable 700 15000