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, 5 insertions, 1 deletions

diff --git a/src/panes.zig b/src/panes.zig
index 0b565676..0b4204aa 100644
--- a/src/panes.zig
+++ b/src/panes.zig
@@ -94,6 +94,9 @@ pub const Pane = struct {
         pipe: struct { at: u16, how: modal.Normal.PipeBehavior },
         /// Save on a scratch buffer or a terminal: the tail is a path to write to.
         save: u16,
+        /// Del from the keyboard with open panes both above and below: which
+        /// one takes the rows. Nothing is typed; one key answers.
+        del_side,
     };
 
     pub const Cwd = union(enum) { none, inherited: *Pane, owned: []u8 };
@@ -338,7 +341,7 @@ pub const Pane = struct {
     }
     pub fn promptAt(p: *const Pane) ?u16 {
         return switch (p.prompt) {
-            .none => null,
+            .none, .del_side => null,
             .search, .save => |at| at,
             .pipe => |pipe| pipe.at,
         };
@@ -347,6 +350,7 @@ pub const Pane = struct {
     /// What an open prompt shows on its notice band: the one answer every
     /// painter of the band reads.
     pub fn promptText(p: *const Pane) ?[]const u8 {
+        if (p.prompt == .del_side) return config.del_question;
         const at = p.promptAt() orelse return null;
         return p.tagSlice()[@min(at, p.tag_tail_len)..];
     }