A column takes panes until their minimums fill it, not until none can be halved

Placement halved the tallest pane or refused, so 11 panes filled 48 rows
that hold 16 at their tag and two rows each: the refusal did not match
the documented arithmetic. When no pane can be halved but the minimums
with the new pane's fit, the column's rows are shared out again; and a
refused pane's removal leaves no pane under its minimum.

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

1 files changed, 12 insertions, 1 deletions

diff --git a/src/exec.zig b/src/exec.zig
index 79717963..60c4172d 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -977,9 +977,12 @@ pub fn placeNew(p: *Pardes, from: usize, origin: ?usize, id: usize, kind: NewPan
         layout.snapColWeights(p, f.col);
         if (!layout.splitTallest(p, f.col, id) or !layout.placedRoomy(p, id, &before)) {
             if (layout.findPane(p, id) == null) layout.insert(p, f.col, p.col_n[f.col], id);
+            // No pane to halve, but the column holds every pane's minimum
+            // with the new one's: the rows are shared out again, so what is
+            // refused is only what the documented arithmetic cannot hold.
             // +Errors goes wherever there is room, last column first; with
             // none, its maker says the text some other way (appendErrors).
-            if (kind == .errors) {
+            if (layout.shareColumn(p, f.col)) {} else if (kind == .errors) {
                 layout.removePane(p, id);
                 var c = p.ncol;
                 while (c > 0) {
@@ -999,12 +1002,20 @@ pub fn placeNew(p: *Pardes, from: usize, origin: ?usize, id: usize, kind: NewPan
                     return;
                 }
             } else {
+                // Refused, it closes at the step's end holding no weight, so
+                // its column's rows come back as they were, none rounded off.
+                p.panes[id].?.vweight = 0;
                 p.unplaced.set(id);
                 p.reportError(from, "placement", error.NoPaneRoom);
                 return;
             }
         }
     };
+    // Placed: no pane of its column left under its minimum by the rows
+    // rounding or an earlier placement gave it; shared out again if so.
+    if (layout.findPane(p, id)) |f| if (!layout.columnAtMinimums(p, f.col)) {
+        _ = layout.shareColumn(p, f.col);
+    };
     if (kind == .command) return;
     tagline.exitHeader(p);
     p.active = id;