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, 15 insertions, 9 deletions

diff --git a/test/snapshots/cmdword.snap b/test/snapshots/cmdword.snap
index eb0e0ea6..361e37ba 100644
--- a/test/snapshots/cmdword.snap
+++ b/test/snapshots/cmdword.snap
@@ -57,25 +57,31 @@ wait 10000 zzmark.txt
 stable 700 15000
 snap nested
 # the same syntax typed into a TAG — the other place the expansion has to know
-# about backticks (tagChordText). The look above left the shell focused, so `:`
-# opens ITS tag; `i` then End walks to the end of the tail, and the chord runs
-# the word under the cursor exactly as the body's does.
+# about backticks. The look above left the shell focused, so `:` opens ITS
+# tag; `A` appends at the end of it, Esc and `h` put the normal-mode cursor on
+# the last character typed, and the execute key runs the word under it
+# exactly as the body's does.
 key :
-key i
-key end
+key A
 key space
 text Exec
-key left
+key esc
+settle 100
+key h
 key tab
 stable 700 8000
 # ...except that word is `Exec` ITSELF, with nothing to execute. This is the
 # case that must not hang a re-entrant dispatcher: it runs out of argument
-# immediately and does nothing at all.
+# immediately and does nothing at all. Executing gave the keyboard back to the
+# body, and `:` finds the tag's cursor where it was left.
 snap execword
-key end
+key :
+key A
 key space
 text @`echo ZZ''T`
-key left
+key esc
+settle 100
+key h
 key tab
 wait 10000 ZZT
 stable 700 15000