Focus on a closed pane goes to the pane that takes its place, never to the one focused before

Dogfood closed a pane in one column and focus jumped to another column, only because that pane was focused last. Now removePane decides for every route (Del, a ctl del, a command pane's end, a 9P remove, a stillborn scratch replaced): the pane that grew into the rows, or the scratch standing in an emptied column; removeColumn gives it to the pane level with it in the column that takes the width. Closing an unfocused pane leaves focus alone. The per-caller focus lines in Del and replaceStillborn are gone, and so is prevFocus.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 9 insertions, 5 deletions

diff --git a/src/layout.zig b/src/layout.zig
index 8e44f1d9..855a3eb9 100644
--- a/src/layout.zig
+++ b/src/layout.zig
@@ -1000,7 +1000,7 @@ pub fn splitColumn(p: *Pardes, source_id: usize, id: usize, before: bool) bool {
     if (needs_rebase) old_weight *= 2;
     if (id == source_id) {
         if (p.col_n[source_col] <= 1) return false;
-        absorbVWeight(p, id, null);
+        _ = absorbVWeight(p, id, null);
         removePane(p, id);
     } else if (findPane(p, id) != null) return false;
 
@@ -1041,9 +1041,11 @@ pub fn snapColWeights(p: *Pardes, c: usize) void {
 /// Hand a closing pane's rows to `to`. With none named they go up: past any
 /// results listing to the nearest pane above that is not one, or to the
 /// pane below when the closing one is first in its column.
-pub fn absorbVWeight(p: *Pardes, id: usize, to: ?usize) void {
-    const f = findPane(p, id) orelse return;
-    if (p.col_n[f.col] <= 1) return;
+/// Give a closing pane's rows to `to`, or to the nearest document above it
+/// (the pane below for the top one); the pane that got them is returned.
+pub fn absorbVWeight(p: *Pardes, id: usize, to: ?usize) ?usize {
+    const f = findPane(p, id) orelse return null;
+    if (p.col_n[f.col] <= 1) return null;
     snapColWeights(p, f.col);
     var sib = to orelse if (f.idx > 0) p.col_panes[f.col][f.idx - 1] else p.col_panes[f.col][f.idx + 1];
     var k = f.idx;
@@ -1051,7 +1053,9 @@ pub fn absorbVWeight(p: *Pardes, id: usize, to: ?usize) void {
         sib = p.col_panes[f.col][k - 1];
         if (p.panes[sib]) |pp| if (if (pp.file) |ff| panes.Output.fileTraits(ff.output).doc else true) break;
     }
-    if (p.panes[sib]) |s| s.vweight += @as(f32, @floatFromInt(@max(1, p.rects[id].h)));
+    const s = p.panes[sib] orelse return null;
+    s.vweight += @as(f32, @floatFromInt(@max(1, p.rects[id].h)));
+    return sib;
 }
 
 pub fn splitParent(p: *Pardes, want: usize) usize {