A focus write makes its pane's column the active one, and layout's active is it

Writing a serial to /focus gave that pane the keyboard but left the active
column where it was, so pane/new under Placement acme went elsewhere, and
/layout's active named the keyboard's column rather than where a new pane
would go. A focus write now sets the active column as the user's click
there would, under either Placement, and /layout's active names the active
column, which pane/new and a look place into.

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

1 files changed, 23 insertions, 2 deletions

diff --git a/src/ninep/cols.zig b/src/ninep/cols.zig
index 682c2a02..79943b1b 100644
--- a/src/ninep/cols.zig
+++ b/src/ninep/cols.zig
@@ -27,7 +27,8 @@ pub fn activeColumn(p: *const Pardes) ?usize {
 /// it, which stays while it lives), its index left to right, x and width in
 /// cells, `current` or `notcurrent` (rio's words, for the column with the
 /// keyboard), `empty` or `full`, and its panes' serials, top to bottom;
-/// then `active <serial>`.
+/// then `active <serial>`: the active column, where pane/new and a look
+/// place a pane next (acme's activecol), not always the keyboard's.
 pub fn writeLayout(p: *Pardes, w: *std.Io.Writer) !void {
     const active = activeColumn(p);
     for (0..p.ncol) |c| {
@@ -38,7 +39,7 @@ pub fn writeLayout(p: *Pardes, w: *std.Io.Writer) !void {
         for (p.col_panes[c][0..p.col_n[c]]) |id| if (p.panes[id]) |pane| try w.print(" {d}", .{pane.serial});
         try w.writeByte('\n');
     }
-    if (active) |c| try w.print("active {d}\n", .{layout.columnSerial(p, c)}) else try w.writeAll("active -\n");
+    if (p.activeColumn() orelse active) |c| try w.print("active {d}\n", .{layout.columnSerial(p, c)}) else try w.writeAll("active -\n");
 }
 
 pub fn layoutLen(p: *Pardes) u64 {
@@ -179,3 +180,23 @@ test "a column's tag and the workspace's read, replace and append as a pane tag
     _ = th.wr(p, top, "Newcol Exit\n");
     try testing.expectEqualStrings("Newcol Exit", tagline.topbar(p));
 }
+
+test "a focus write makes its pane's column the active one: layout says so and pane/new goes there" {
+    for ([_][]const u8{ "Placement acme", "Placement pardes" }) |placement| {
+        const p = try th.withFile(testing.allocator, "x\n");
+        defer p.deinit();
+        try testing.expect(p.executeBuiltinLine(p.active, placement));
+        const left = p.panes[0].?.serial;
+        p.newColumn(p.active);
+        p.newScratchFor(p.active, .fs); // fills the new, right column
+        p.sync();
+        try testing.expectEqual(@as(usize, 1), layout.findPane(p, p.active).?.col);
+        var digits: [16]u8 = undefined;
+        _ = th.wr(p, @intFromEnum(tree.TopFile.focus), try std.fmt.bufPrint(&digits, "{d}\n", .{left}));
+        var want: [32]u8 = undefined;
+        const text = th.rd(p, @intFromEnum(tree.TopFile.layout), 0, 4096).bytes;
+        try testing.expect(std.mem.endsWith(u8, text, try std.fmt.bufPrint(&want, "active {d}\n", .{layout.columnSerial(p, 0)})));
+        const made = th.call(p, .{ .tag = 1, .op = .open, .node = @intFromEnum(tree.TopFile.new) }).reply.handle;
+        try testing.expectEqual(@as(usize, 0), layout.findPane(p, p.paneBySerial(made).?).?.col);
+    }
+}