fix(org-latex): setq-local instead of insert for tabularx — no buffer modification

Root cause of Emacs 31 recursion: insert in org-export-before-processing-hook
triggers hooks that inhibit-modification-hooks does not suppress on Emacs 31
(window management, org-fold text properties, etc.). The old Mac (older Emacs)
was not affected.

Fix: setq-local org-latex-default-table-environment in the hook.
No buffer content modification → no hook chains → no recursion possible.
org-latex.el natively handles tabularx by adding \linewidth width argument.
tabularx added to org-latex-packages-alist.

config.el

@@ -325,49 +325,18 @@ Bound to cmd+v in org-mode and markdown-mode."
 ;;; ORG MODE — LATEX EXPORT
 ;;; ============================================================
 
-;; Count data columns in an Org table line
+;; LaTeX table export: use tabularx automatically — no buffer modification.
-(defun my/org-count-table-columns (line)
+;; Setting a buffer-local variable in the hook is safe (no insert = no recursion).
-  "Count the number of data columns in Org table LINE."
+;; org-latex.el natively handles tabularx/tabulary by adding \linewidth width arg.
-  (length (cl-remove-if
+(defun my/org-set-tabularx (backend)
-           (lambda (s) (string-match-p "^-*$" (string-trim s)))
+  "Set tabularx as default LaTeX table environment for this export."
-           (cdr (butlast (split-string line "|"))))))
-
-;; Generate tabularx column spec: first column left-aligned, rest Y (auto-width)
-(defun my/org-table-attr-latex-spec (ncols)
-  "Return tabularx column spec for NCOLS columns: first l, rest Y."
-  (concat "l" (make-string (max 0 (1- ncols)) ?Y)))
-
-;; Automatically insert #+ATTR_LATEX tabularx before tables on LaTeX export.
-;; inhibit-modification-hooks prevents org-element-cache from recursing
-;; during the insert (which caused max-lisp-eval-depth on Emacs 31).
-(defun my/org-auto-tabularx (backend)
-  "Insert #+ATTR_LATEX tabularx before each table when exporting to LaTeX."
   (when (org-export-derived-backend-p backend 'latex)
-    (let ((inhibit-modification-hooks t))
+    (setq-local org-latex-default-table-environment "tabularx")))
-      (save-excursion
-        (goto-char (point-min))
-        (while (not (eobp))
-          (cond
-           ((looking-at "^|")
-            (let ((prev-line (save-excursion
-                               (forward-line -1)
-                               (buffer-substring-no-properties
-                                (line-beginning-position) (line-end-position)))))
-              (when (not (string-match-p "^|" prev-line))
-                (when (not (string-match-p "^#\\+ATTR_LATEX" prev-line))
-                  (let* ((table-line (buffer-substring-no-properties
-                                      (line-beginning-position) (line-end-position)))
-                         (ncols (my/org-count-table-columns table-line))
-                         (spec  (my/org-table-attr-latex-spec ncols))
-                         (attr  (format "#+ATTR_LATEX: :environment tabularx :width \\textwidth :align %s\n"
-                                        spec)))
-                    (when (> ncols 0)
-                      (insert attr)))))
-            (forward-line))
-           (t
-            (forward-line)))))))))
 
-(add-hook 'org-export-before-processing-hook #'my/org-auto-tabularx)
+(add-hook 'org-export-before-processing-hook #'my/org-set-tabularx)
+
+(with-eval-after-load 'ox-latex
+  (add-to-list 'org-latex-packages-alist '("" "tabularx")))
 
 ;; Optional: enable booktabs style (horizontal rules in tables)
 ;; (setq org-latex-tables-booktabs t)