File the tag code into tagline.zig and draw tags beside bodies

With tags reduced to Texts, what is left of them is the computed prefix, the
default and saved tails, entering and leaving a tag and the headers: that goes
to tagline.zig, as acme keeps the tag half of a window in wind.c. Tag and
header drawing moves next to body drawing in body_layer.zig, and the tag hit
helpers go to tag_layer.zig with the Hit they read, where sameCell now also
tells the lines of a taller tag apart. The docs describe the tag as a Text.

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

1 files changed, 3 insertions, 2 deletions

diff --git a/src/exec.zig b/src/exec.zig
index a673e9e7..a0e3d47f 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -3,6 +3,7 @@
 //! chord hands over, the terminals commands run in, placing a document, and
 //! saving a pane.
 const pardes = @import("pardes.zig");
+const tagline = @import("tagline.zig");
 const std = @import("std");
 const layout = @import("layout.zig");
 const modal = @import("modal.zig");
@@ -352,7 +353,7 @@ pub fn replaceStillborn(p: *Pardes) void {
     const out = file.output orelse return;
     if (out.from != .cmd or out.from.cmd != .New) return;
     if (file.revision != 0 or file.content.len != 0) return;
-    if (old.tag.own) |own| if (!std.mem.eql(u8, own, Pardes.defaultTail(old))) return;
+    if (old.tag.own) |own| if (!std.mem.eql(u8, own, tagline.defaultTail(old))) return;
     const was_active = p.active == old_id;
     layout.compute(p); // the joiner may have no rect yet; absorb snaps to rows
     p.removePane(old_id, new_id) catch |err| return p.reportError(old_id, "close", err);
@@ -490,7 +491,7 @@ pub fn applySettingBuiltin(p: *Pardes, setting: config.Runtime.Setting, arg: ?[]
     const tagline_metrics_changed = setting.action == .tagline_size and
         p.settings.font.tagline_percent != previous_tagline_percent;
     if (p.settings.column_tags != previous_column_tags) {
-        if (p.header_column != null) p.exitHeader();
+        if (p.header_column != null) tagline.exitHeader(p);
     }
     if (transition_changed or tagline_metrics_changed or p.settings.column_tags != previous_column_tags) {
         p.abandonPanelAnimations();