feat(ai-vterm): add Claude launcher with vertical-split vterm

The new module picks a Claude-template project from a filtered completing-read list. It scans the same roots the `ai` shell launcher uses, then opens or reuses a vterm buffer named `claude [<repo>]` on the right. F9 launches it. The prior `cj/toggle-gptel` binding moves from F9 to C-F9 so both AI tools share the same physical key.

The display rule chains reuse-window -> use-some-window -> in-direction (right). The resulting window isn't dedicated. That matters because side-window dedication was breaking `buffer-move` (C-M-arrows) and `switch-to-buffer` replacement on the claude buffer. I also narrowed `vterm-toggle`'s display rule to skip `claude [` buffers. Otherwise it claimed them first with its bottom-split + dedicated treatment.

I added 23 tests across 5 files: the buffer-name transform, candidate walker, show-or-create dispatch, picker, and display rule. Design lives at docs/design/ai-vterm.org.

1 files changed, 74 insertions, 0 deletions

diff --git a/tests/test-ai-vterm--display-rule.el b/tests/test-ai-vterm--display-rule.el
new file mode 100644
index 000000000..af481eb3b
--- /dev/null
+++ b/tests/test-ai-vterm--display-rule.el
@@ -0,0 +1,74 @@
+;;; test-ai-vterm--display-rule.el --- Tests for the AI-vterm display-buffer rule -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; The module installs a `display-buffer-alist' entry routing buffers
+;; whose names match "\\`claude \\[" to a right-side window.  These
+;; tests verify the rule reaches the right side and ignores buffers
+;; that don't match the prefix.
+
+;;; Code:
+
+(require 'ert)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'ai-vterm)
+
+(defun test-ai-vterm--cleanup (name)
+  "Kill buffer NAME if it exists."
+  (when (get-buffer name)
+    (kill-buffer name)))
+
+(defmacro test-ai-vterm--with-clean-frame (&rest body)
+  "Run BODY in a context with one window and the AI-vterm rule loaded."
+  (declare (indent 0) (debug t))
+  `(save-window-excursion
+     (delete-other-windows)
+     (let ((display-buffer-alist (cj/--ai-vterm-display-rule-list)))
+       ,@body)))
+
+(ert-deftest test-ai-vterm--display-rule-routes-claude-buffer-to-right ()
+  "Normal: a buffer named \"claude [foo]\" lands in a window to the right.
+
+The rule uses `display-buffer-in-direction' with `(direction . right)',
+which splits the current window so the new window's left edge sits at
+a positive column.  The buffer winds up in that new window."
+  (let ((name "claude [display-rule-test]"))
+    (test-ai-vterm--cleanup name)
+    (unwind-protect
+        (test-ai-vterm--with-clean-frame
+          (let* ((buf (get-buffer-create name))
+                 (win (display-buffer buf)))
+            (should (windowp win))
+            (should (> (window-left-column win) 0))))
+      (test-ai-vterm--cleanup name))))
+
+(ert-deftest test-ai-vterm--display-rule-skips-non-matching-buffer ()
+  "Boundary: a buffer not named \"claude [...]\" does not match the rule.
+
+The rule's regex doesn't fire, so `display-buffer' falls back to the
+default action -- reuse the current window -- and no rightward split
+occurs."
+  (let ((name "scratch-buffer-no-match"))
+    (test-ai-vterm--cleanup name)
+    (unwind-protect
+        (test-ai-vterm--with-clean-frame
+          (let* ((buf (get-buffer-create name))
+                 (win (display-buffer buf)))
+            (should (windowp win))
+            (should (= (window-left-column win) 0))))
+      (test-ai-vterm--cleanup name))))
+
+(ert-deftest test-ai-vterm--display-rule-prefix-not-substring ()
+  "Boundary: \"foo claude [bar]\" does not match -- the rule anchors at start."
+  (let ((name "foo claude [substring-test]"))
+    (test-ai-vterm--cleanup name)
+    (unwind-protect
+        (test-ai-vterm--with-clean-frame
+          (let* ((buf (get-buffer-create name))
+                 (win (display-buffer buf)))
+            (should (windowp win))
+            (should (= (window-left-column win) 0))))
+      (test-ai-vterm--cleanup name))))
+
+(provide 'test-ai-vterm--display-rule)
+;;; test-ai-vterm--display-rule.el ends here