refactor(ai-config): switch gptel to local fork, drop tab-width advice

I switched the gptel use-package form to `:load-path "~/code/gptel"`
with `:ensure nil` so Emacs loads from the fork instead of the MELPA
release. The fork now carries the narrow `tab-width' copy in
`gptel-org--create-prompt' that karthink redirected the upstream PR
to, which replaces the local `:around' advice on
`gptel--with-buffer-copy-internal' I'd been carrying.

I also dropped the stale test file
`tests/test-ai-config-gptel-prompt-tab-width.el' and the matching
stub in `tests/testutil-ai-config.el'. Both existed only to test the
advice I removed.

1 files changed, 0 insertions, 106 deletions

diff --git a/tests/test-ai-config-gptel-prompt-tab-width.el b/tests/test-ai-config-gptel-prompt-tab-width.el
deleted file mode 100644
index 6f857cdc..00000000
--- a/tests/test-ai-config-gptel-prompt-tab-width.el
+++ /dev/null
@@ -1,106 +0,0 @@
-;;; test-ai-config-gptel-prompt-tab-width.el --- Tests for gptel prompt-buffer tab-width fix -*- lexical-binding: t; -*-
-
-;;; Commentary:
-;; Regression tests for the `org-element--list-struct: Tab width in Org
-;; files must be 8, not 4' error that fires when `gptel-magit' is
-;; invoked from a `COMMIT_EDITMSG' buffer where `git-commit-major-mode'
-;; is `org-mode'.
-;;
-;; Root cause: gptel's `gptel--with-buffer-copy-internal'
-;; (gptel-request.el:945) sets the prompt buffer's `major-mode' to the
-;; source buffer's mode as a *symbol*, without running mode hooks.  So
-;; an inherited `org-mode' prompt buffer keeps the global default
-;; `tab-width' (4 in this config) — `org-mode-hook' never runs to set
-;; 8.  When gptel later parses the prompt buffer with `org-element',
-;; Org's `tab-width=8' guard raises.
-;;
-;; Fix: an `:around' advice on `gptel--with-buffer-copy-internal' in
-;; ai-config.el sets `tab-width=8' inside the prompt buffer when its
-;; inherited `major-mode' is `org-mode'.
-;;
-;; These tests verify the advice fires for org-mode source buffers and
-;; stays out of the way for other modes.  Each test pins
-;; `default-value' of `tab-width' to 4 — matching Craig's real config
-;; — so the advice's effect is observable in batch tests (where the
-;; default would otherwise be Emacs's built-in 8).
-
-;;; Code:
-
-(require 'ert)
-
-(add-to-list 'load-path (expand-file-name "tests" user-emacs-directory))
-(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
-
-;; testutil-ai-config provides the gptel--with-buffer-copy-internal stub
-;; and the gptel stubs ai-config needs to load.
-(require 'testutil-ai-config)
-(require 'ai-config)
-
-(defmacro test-ai-config--with-default-tab-width (sentinel &rest body)
-  "Bind `default-value' of `tab-width' to SENTINEL during BODY.
-Restores the prior default on unwind.  New buffers created inside BODY
-inherit SENTINEL as their `tab-width'."
-  (declare (indent 1))
-  `(let ((saved (default-value 'tab-width)))
-     (unwind-protect
-         (progn (setq-default tab-width ,sentinel)
-                ,@body)
-       (setq-default tab-width saved))))
-
-;;; Normal Cases
-
-(ert-deftest test-ai-config-gptel-prompt-tab-width-org-mode-source-sets-8 ()
-  "Normal: source buffer in `org-mode' → prompt buffer has `tab-width=8'.
-Regression net for the `org-element--list-struct: Tab width must be 8'
-error when gptel-magit runs from COMMIT_EDITMSG with
-`git-commit-major-mode=org-mode'."
-  (test-ai-config--with-default-tab-width 4
-    (let ((recorded nil))
-      (with-temp-buffer
-        (setq major-mode 'org-mode)
-        (gptel--with-buffer-copy-internal
-         (current-buffer) nil nil
-         (lambda () (setq recorded tab-width))))
-      (should (= recorded 8)))))
-
-;;; Boundary Cases
-
-(ert-deftest test-ai-config-gptel-prompt-tab-width-text-mode-source-not-overridden ()
-  "Boundary: source buffer in `text-mode' → advice does NOT set `tab-width=8'.
-Only `org-mode' source triggers the override; other modes keep the
-inherited default."
-  (test-ai-config--with-default-tab-width 4
-    (let ((recorded nil))
-      (with-temp-buffer
-        (setq major-mode 'text-mode)
-        (gptel--with-buffer-copy-internal
-         (current-buffer) nil nil
-         (lambda () (setq recorded tab-width))))
-      (should (= recorded 4)))))
-
-(ert-deftest test-ai-config-gptel-prompt-tab-width-fundamental-mode-source-not-overridden ()
-  "Boundary: source buffer in `fundamental-mode' → no override.
-Confirms the advice's `(eq major-mode 'org-mode)' gate is strict."
-  (test-ai-config--with-default-tab-width 4
-    (let ((recorded nil))
-      (with-temp-buffer
-        (setq major-mode 'fundamental-mode)
-        (gptel--with-buffer-copy-internal
-         (current-buffer) nil nil
-         (lambda () (setq recorded tab-width))))
-      (should (= recorded 4)))))
-
-(ert-deftest test-ai-config-gptel-prompt-tab-width-advice-does-not-leak ()
-  "Boundary: advice's `setq-local' stays buffer-local to the prompt buffer.
-After body-thunk completes and the prompt buffer is killed, the source
-buffer's `tab-width' is unchanged."
-  (with-temp-buffer
-    (setq major-mode 'org-mode)
-    (setq-local tab-width 4)
-    (gptel--with-buffer-copy-internal
-     (current-buffer) nil nil
-     (lambda () nil))
-    (should (= tab-width 4))))
-
-(provide 'test-ai-config-gptel-prompt-tab-width)
-;;; test-ai-config-gptel-prompt-tab-width.el ends here