fix(ai-vterm): make F9 toggle the agent from inside an agent buffer

vterm binds `<f1>`..`<f12>` to `vterm--self-insert`, so a plain `<f9>` typed while point is in an agent buffer goes to the terminal program instead of the global toggle. That's invisible most of the time — you press F9 from another window — but it bites when the agent buffer is the only window in the frame, because there's nowhere else to press it from.

I re-bound the F9 family in `vterm-mode-map` (via `with-eval-after-load 'vterm`) so that `<f9>`, `C-<f9>`, and `M-<f9>` reach `cj/ai-vterm`, `cj/ai-vterm-pick-project`, and `cj/ai-vterm-pick-buffer` from there too. The C-/M- variants aren't actually in vterm's intercept set, but binding them keeps things uniform. New `tests/test-ai-vterm--f9-in-vterm.el`: 4 ERT tests over the `vterm-mode-map` and global bindings. F12's `cj/vterm-toggle` has the same shape of bug and isn't touched here.

2 files changed, 54 insertions, 0 deletions

diff --git a/modules/ai-vterm.el b/modules/ai-vterm.el
index b0872b6b..ac246ee8 100644
--- a/modules/ai-vterm.el
+++ b/modules/ai-vterm.el
@@ -51,6 +51,7 @@
 (declare-function vterm "vterm" (&optional buffer-name))
 (declare-function vterm-send-string "vterm" (string &optional paste-p))
 (declare-function vterm-send-return "vterm" ())
+(defvar vterm-mode-map)
 
 (defgroup ai-vterm nil
   "In-Emacs AI-agent launcher with vertical-split vterm."
@@ -696,6 +697,17 @@ AI-vterm buffers without touching the project list."
 (keymap-global-set "C-<f9>" #'cj/ai-vterm-pick-project)
 (keymap-global-set "M-<f9>" #'cj/ai-vterm-pick-buffer)
 
+;; vterm binds <f1>..<f12> to `vterm--self-insert', so a plain <f9> typed
+;; while point is inside an agent buffer gets sent to the terminal program
+;; instead of toggling the agent -- which bites hard when the agent buffer is
+;; the only window in the frame.  Re-bind the F9 family in `vterm-mode-map' so
+;; the toggle reaches Emacs from there too.  (C-<f9> / M-<f9> aren't in vterm's
+;; intercept set, but bind them here as well so the behaviour is uniform.)
+(with-eval-after-load 'vterm
+  (keymap-set vterm-mode-map "<f9>"   #'cj/ai-vterm)
+  (keymap-set vterm-mode-map "C-<f9>" #'cj/ai-vterm-pick-project)
+  (keymap-set vterm-mode-map "M-<f9>" #'cj/ai-vterm-pick-buffer))
+
 ;; ---------- emacsclient: keep opened files off the agent vterm ----------
 ;;
 ;; `server-start' (in system-defaults.el) leaves `server-window' nil, so
diff --git a/tests/test-ai-vterm--f9-in-vterm.el b/tests/test-ai-vterm--f9-in-vterm.el
new file mode 100644
index 00000000..1355bd6a
--- /dev/null
+++ b/tests/test-ai-vterm--f9-in-vterm.el
@@ -0,0 +1,42 @@
+;;; test-ai-vterm--f9-in-vterm.el --- F9 reaches Emacs from inside an agent buffer -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; vterm binds <f1>..<f12> to `vterm--self-insert', so a plain <f9> typed
+;; while point is in an agent buffer is sent to the terminal program instead
+;; of toggling the agent -- which is exactly the case when the agent buffer
+;; fills the frame.  `ai-vterm.el' re-binds the F9 family in `vterm-mode-map'.
+;; These tests load real vterm so `vterm-mode-map' exists, then confirm the
+;; bindings landed (and the global ones are still there).
+
+;;; Code:
+
+(require 'ert)
+(require 'package)
+
+(setq package-user-dir (expand-file-name "elpa" user-emacs-directory))
+(package-initialize)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'vterm)
+(require 'ai-vterm)
+
+(ert-deftest test-ai-vterm-f9-bound-in-vterm-mode-map ()
+  "Normal: <f9> in `vterm-mode-map' runs the agent toggle, not `vterm--self-insert'."
+  (should (eq (keymap-lookup vterm-mode-map "<f9>") #'cj/ai-vterm)))
+
+(ert-deftest test-ai-vterm-f9-family-bound-in-vterm-mode-map ()
+  "Normal: the C-/M- F9 variants are bound in `vterm-mode-map' too."
+  (should (eq (keymap-lookup vterm-mode-map "C-<f9>") #'cj/ai-vterm-pick-project))
+  (should (eq (keymap-lookup vterm-mode-map "M-<f9>") #'cj/ai-vterm-pick-buffer)))
+
+(ert-deftest test-ai-vterm-f9-not-self-insert-in-vterm ()
+  "Boundary: vterm's default <f9> -> `vterm--self-insert' was overridden."
+  (should-not (eq (keymap-lookup vterm-mode-map "<f9>") 'vterm--self-insert)))
+
+(ert-deftest test-ai-vterm-f9-still-bound-globally ()
+  "Normal: the global F9 family bindings are intact."
+  (should (eq (lookup-key (current-global-map) (kbd "<f9>")) #'cj/ai-vterm))
+  (should (eq (lookup-key (current-global-map) (kbd "C-<f9>")) #'cj/ai-vterm-pick-project))
+  (should (eq (lookup-key (current-global-map) (kbd "M-<f9>")) #'cj/ai-vterm-pick-buffer)))
+
+(provide 'test-ai-vterm--f9-in-vterm)
+;;; test-ai-vterm--f9-in-vterm.el ends here