Make the column and workspace tags Texts with the pane tag's keys

The headers had their own one-line editor with its own keys: Enter always
executed, h/l and J/K moved between headers and panes, Ctrl-c/x/v cut and
pasted, and TagLine refused a newline that 9P accepted. They are now Texts
like a pane's tag, with no prefix and a default until edited, so normal and
insert mode, undo and the look and execute keys are the body's. Moving
between them is the window keys' job: Up from a pane with nothing above it
reaches its column's tag and then the workspace's, Down comes back, and
Left and Right walk the column tags.

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

1 files changed, 33 insertions, 4 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index 743573e4..74645376 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -735,27 +735,56 @@ pub const Grep = struct {
 
 // ---- the window group ----
 
+// The headers are above the panes in the same layout: Up from a pane with
+// nothing above it reaches its column's tag, then the workspace's, and Down
+// comes back the same way. Left and Right walk the column tags.
+
 pub const Left = struct {
     pub fn run(c: Ctx) void {
-        layout.focusDir(c.p, c.id, .left);
+        if (c.p.header_focus) {
+            if (c.p.header_column) |column| if (column > 0) c.p.enterHeader(column - 1);
+            return;
+        }
+        _ = layout.focusDir(c.p, c.id, .left);
     }
 };
 
 pub const Down = struct {
     pub fn run(c: Ctx) void {
-        layout.focusDir(c.p, c.id, .down);
+        if (c.p.header_focus) {
+            const column = layout.findPane(c.p, c.id);
+            if (c.p.header_column == null and c.p.columnBarHeight() > 0)
+                return c.p.enterHeader(if (column) |at| at.col else 0);
+            // Onto the top pane of the column the header stands over.
+            const col = c.p.header_column orelse if (column) |at| at.col else return;
+            c.p.exitHeader();
+            if (col < c.p.ncol and c.p.col_n[col] > 0) c.p.active = c.p.col_panes[col][0];
+            return;
+        }
+        _ = layout.focusDir(c.p, c.id, .down);
     }
 };
 
 pub const Up = struct {
     pub fn run(c: Ctx) void {
-        layout.focusDir(c.p, c.id, .up);
+        if (c.p.header_focus) {
+            if (c.p.header_column != null and c.p.topBarHeight() > 0) c.p.enterHeader(null);
+            return;
+        }
+        if (layout.focusDir(c.p, c.id, .up)) return;
+        if (c.p.columnBarHeight() > 0) {
+            if (layout.findPane(c.p, c.id)) |at| c.p.enterHeader(at.col);
+        } else if (c.p.topBarHeight() > 0) c.p.enterHeader(null);
     }
 };
 
 pub const Right = struct {
     pub fn run(c: Ctx) void {
-        layout.focusDir(c.p, c.id, .right);
+        if (c.p.header_focus) {
+            if (c.p.header_column) |column| if (column + 1 < c.p.ncol) c.p.enterHeader(column + 1);
+            return;
+        }
+        _ = layout.focusDir(c.p, c.id, .right);
     }
 };