Fix Meta keys not reaching terminal in TTY Emacs

TTY Emacs delivers M-<key> as two events (ESC then <key>) via esc-map.
When the binding fires, last-command-event is just <key> with no meta
modifier — the ESC was consumed by the prefix lookup. GUI Emacs
delivers the composite single event with meta intact, which is why the
earlier fix only worked there.

Detect the esc-prefix path in ghostel--send-event via
this-command-keys-vector and re-inject meta. Also bind M-DEL so TTY
Alt-Backspace ([27 127]) routes through send-event instead of falling
through to global backward-kill-word.

Follow-up to 43220db. Fix #48.

Author: dakra

lisp/ghostel.el

@@ -1037,6 +1037,11 @@ is non-nil.")
       (let ((key-str (format "M-%c" c)))
         (unless (member key-str ghostel-keymap-exceptions)
           (define-key map (kbd key-str) #'ghostel--send-event))))
+    ;; M-DEL: TTY Emacs delivers Alt-Backspace as ESC + 0x7f, which
+    ;; resolves to ?\M-\d.  The `M-<backspace>' form above only covers
+    ;; the `[M-backspace]' symbol path; without this binding, TTY
+    ;; Alt-Backspace falls through to global `backward-kill-word'.
+    (define-key map (kbd "M-DEL") #'ghostel--send-event)
     ;; C-@ (NUL, same as C-SPC) — used by programs like Emacs-in-terminal
     (define-key map (kbd "C-@")
                 (lambda () (interactive) (ghostel--send-string "\x00")))
@@ -1282,12 +1287,21 @@ paste, yank, drop."
   "Send the current key event to the terminal via the key encoder.
 Extracts the base key name and modifiers from `last-command-event'
 and routes through the ghostty key encoder, which respects terminal
-modes (application cursor keys, Kitty keyboard protocol, etc.)."
+modes (application cursor keys, Kitty keyboard protocol, etc.).
+
+In TTY Emacs, `M-<key>' arrives as two events (ESC then <key>) via
+`esc-map'; `last-command-event' is just <key> and has no meta bit.
+Detect that case via `this-command-keys-vector' and re-inject meta."
   (interactive)
   (ghostel--snap-to-input)
   (let* ((event last-command-event)
+         (keys (this-command-keys-vector))
+         (via-esc (and (> (length keys) 1) (eq (aref keys 0) 27)))
          (base (event-basic-type event))
          (mods (event-modifiers event))
+         (mods (if (and via-esc (not (memq 'meta mods)))
+                   (cons 'meta mods)
+                 mods))
          (key-name (cond
                     ;; backtab is Emacs's name for S-TAB
                     ((eq base 'backtab) "tab")

test/ghostel-test.el

@@ -5955,7 +5955,36 @@ rather than the selected window's buffer."
             (should-not (eq binding #'ghostel--send-event))
           (should (eq binding #'ghostel--send-event))))))
   ;; M-y should be bound to ghostel-yank-pop, not send-event
-  (should (eq (lookup-key ghostel-mode-map (kbd "M-y")) #'ghostel-yank-pop)))
+  (should (eq (lookup-key ghostel-mode-map (kbd "M-y")) #'ghostel-yank-pop))
+  ;; M-DEL must be bound so TTY Alt-Backspace ([27 127]) routes through
+  ;; ghostel--send-event instead of global backward-kill-word.
+  (should (eq (lookup-key ghostel-mode-map (kbd "M-DEL")) #'ghostel--send-event)))
+
+(ert-deftest ghostel-test-send-event-tty-esc-prefix ()
+  "Re-inject meta when the key arrives via ESC prefix (TTY Emacs).
+In TTY Emacs, M-<key> is delivered as two events ([27 KEY]) via
+`esc-map'.  `last-command-event' is just KEY with no meta modifier,
+but `this-command-keys-vector' retains the ESC prefix."
+  (let (captured-key captured-mods)
+    (cl-letf (((symbol-function 'ghostel--send-encoded)
+               (lambda (key mods &optional _utf8)
+                 (setq captured-key key captured-mods mods))))
+      (cl-flet ((sim-tty (keys-vec event expected-key expected-mods)
+                  (setq captured-key nil captured-mods nil)
+                  (cl-letf (((symbol-function 'this-command-keys-vector)
+                             (lambda () keys-vec)))
+                    (let ((last-command-event event))
+                      (ghostel--send-event)))
+                  (should (equal expected-key captured-key))
+                  (should (equal expected-mods captured-mods))))
+        ;; M-b in TTY: ESC then b → re-inject meta
+        (sim-tty (vector 27 ?b)   ?b  "b" "meta")
+        (sim-tty (vector 27 ?f)   ?f  "f" "meta")
+        (sim-tty (vector 27 ?d)   ?d  "d" "meta")
+        ;; M-DEL in TTY: ESC then 127 → backspace + meta
+        (sim-tty (vector 27 127)  127 "backspace" "meta")
+        ;; Already-meta event (shouldn't double-add meta)
+        (sim-tty (vector 27 ?b)   (aref (kbd "M-b") 0) "b" "meta")))))
 
 ;; -----------------------------------------------------------------------
 ;; Test: ghostel-yank-pop DWIM
@@ -7004,6 +7033,7 @@ while :; do sleep 0.1; done'\n")
     ghostel-test-c-g-exits-copy-mode
     ghostel-test-inhibit-quit
     ghostel-test-meta-key-bindings
+    ghostel-test-send-event-tty-esc-prefix
     ghostel-test-yank-pop-after-yank
     ghostel-test-yank-pop-no-preceding-yank
     ghostel-test-copy-mode-recenter