pane/new takes rows from a pane in another column before refusing ENOSPC, as acme's placement does

A pane/new whose column had no room was refused "no space for a pane in
that column", even with another column holding a tall pane that could
give rows. acme takes rows wherever a window has them before saying
there are none. pane/new now tries the other columns as +Errors already
did: an empty one, else its tallest pane's bottom half, last column
first. It is refused only when no pane anywhere can give the rows.

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

1 files changed, 21 insertions, 0 deletions

diff --git a/src/ninep/cols.zig b/src/ninep/cols.zig
index 9185a2bc..c4ee83eb 100644
--- a/src/ninep/cols.zig
+++ b/src/ninep/cols.zig
@@ -228,6 +228,27 @@ test "New written to a column's exec makes its scratch in the session's director
     try testing.expectEqualStrings("/project/src/+New", p.panes[p.active].?.file.?.path);
 }
 
+test "pane/new takes rows from a pane in another column before refusing ENOSPC" {
+    const p = try pardes.Pardes.init(testing.allocator, .{ .tty_only = true, .cols = 160, .rows = 16 });
+    defer p.deinit();
+    while (p.nextEffect()) |_| {}
+    const first = p.panes[p.active].?.serial;
+    // A second column holding one tall pane.
+    try testing.expectEqual(tree.Status.ok, th.wr(p, @intFromEnum(tree.TopFile.ctl), "Newcol\n").reply.status);
+    const tall = try th.newPane(p);
+    const tall_col = layout.findPane(p, p.paneBySerial(tall).?).?.col;
+    const focus = @intFromEnum(tree.TopFile.focus);
+    var digits: [16]u8 = undefined;
+    // From the first column, until pane/new is refused.
+    var moved = false;
+    for (0..pardes.MAX_PANES) |_| {
+        _ = th.wr(p, focus, try std.fmt.bufPrint(&digits, "{d}\n", .{first}));
+        const made = th.newPane(p) catch break;
+        if (layout.findPane(p, p.paneBySerial(made).?).?.col == tall_col) moved = true;
+    }
+    try testing.expect(moved);
+}
+
 test "a Newcol refused because the tags would not fit logs its err alone and spends no column serial" {
     const p = try pardes.Pardes.init(testing.allocator, .{ .tty_only = true, .cols = 160, .rows = 14 });
     defer p.deinit();