Make a pane's tag a Text edited with the body's own keys

The tag was a fixed buffer with its own one-line editor, a cursor measured
across the path, and a hijack of the body's mode while it was typed into.
It is now the pane's second Text: its own characters after the computed
prefix (path, dirty marker, PDF page), which is never stored in it, so a
rename or a dirty marker never moves its cursor. Normal and insert mode are
the body's, undo included; `:` moves the keyboard between body and tag, the
tag remembers its cursor and starts on Save, and executing a word from it
hands the keyboard back. The mouse still sees the prefix: a sweep selects
across it and a click on the path drafts a new name.

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

1 files changed, 4 insertions, 3 deletions

diff --git a/src/exec.zig b/src/exec.zig
index a2dbac7c..82b3da4a 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -260,8 +260,9 @@ pub fn saveTo(p: *Pardes, id: usize, path: []const u8) void {
         f.output = null; // an ordinary file pane from here on
         f.watch_after_save = true;
         pane.clearCwd();
-        pane.tag_init = false; // re-derive the tag as a plain file
-        pane.tag_tail_len = 0;
+        // re-derive the tag as a plain file's
+        if (pane.tag.own) |own| p.gpa.free(own);
+        pane.tag.own = null;
         p.emit(.{ .save_file = .{ .pane = @intCast(id) } });
         return;
     }
@@ -351,7 +352,7 @@ 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_init and !std.mem.eql(u8, old.tagSlice(), Pardes.defaultTail(old))) return;
+    if (old.tag.own) |own| if (!std.mem.eql(u8, own, Pardes.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);