Disable automatically for remote files

README.md

@@ -89,6 +89,9 @@ the configured formatter for the current buffer. Running with a prefix
 argument will cause the command to prompt you for which formatter to
 run.
 
+Apheleia does not currently support TRAMP, and is therefore
+automatically disabled for remote files.
+
 The following user options are also available:
 
 * `apheleia-post-format-hook`: Normal hook run after Apheleia formats

apheleia.el

@@ -513,6 +513,11 @@ even if a formatter is configured."
 (defvar apheleia--buffer-hash nil
   "Return value of `buffer-hash' when formatter started running.")
 
+(defun apheleia--disallowed-p ()
+  "Return an error message if Apheleia cannot be run, else nil."
+  (when (and buffer-file-name (file-remote-p buffer-file-name))
+    "Apheleia does not support remote files"))
+
 ;;;###autoload
 (defun apheleia-format-buffer (command &optional callback)
   "Run code formatter asynchronously on current buffer, preserving point.
@@ -550,10 +555,16 @@ aborted.
 If the formatter actually finishes running and the buffer is
 successfully updated (even if the formatter has not made any
 changes), CALLBACK, if provided, is invoked with no arguments."
-  (interactive (list (apheleia--get-formatter-command
+  (interactive (progn
+                 (when-let ((err (apheleia--disallowed-p)))
+                   (user-error err))
+                 (list (apheleia--get-formatter-command
                         (if current-prefix-arg
                             'prompt
-                        'interactive))))
+                          'interactive)))))
+  ;; Fail silently if disallowed, since we don't want to throw an
+  ;; error on `post-command-hook'.
+  (unless (apheleia--disallowed-p)
     (setq-local apheleia--buffer-hash (apheleia--buffer-hash))
     (apheleia--run-formatter
      command
@@ -567,7 +578,7 @@ changes), CALLBACK, if provided, is invoked with no arguments."
               (apheleia--apply-rcs-patch
                (current-buffer) patch-buffer)
               (when callback
-              (funcall callback)))))))))
+                (funcall callback))))))))))
 
 (defcustom apheleia-post-format-hook nil
   "Normal hook run after Apheleia formats a buffer."