Joincol is refused, as Newcol is, when the joined column cannot give each pane its tag and 2 rows

Joincol moved every pane of the keyboard's column into the next one
whether they fit or not. Two columns of two panes in a 12-row window
became one column of four, wanting 12 rows where 10 were free, a layout
that `size` then refused as it stood. Joincol now tries the join in place
first (layout.joinFits: the panes and width moved, minimaFit asked,
everything put back, nothing dropped or logged). A join that does not
fit is refused, "Joincol: no space: the joined column cannot give each
pane its tag and 2 rows".

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

1 files changed, 3 insertions, 0 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index 6688d05f..27a1d36d 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -1271,6 +1271,9 @@ pub const Joincol = struct {
         // The keyboard's column joins the one to its right; the last has none.
         const col = c.p.keyboardColumn(c.p.active) orelse return;
         if (col + 1 >= c.p.ncol) return c.p.reportFailure(c.id, "Joincol: no column to the right");
+        // As Newcol is refused: a column that could not give each pane its
+        // tag and 2 rows would leave a layout `size` refuses as it is.
+        if (!layout.joinFits(c.p, col)) return c.p.reportFailure(c.id, "Joincol: no space: the joined column cannot give each pane its tag and 2 rows");
         layout.joinCol(c.p, col);
     }
 };