Persist buffer modes in history.

source/buffer.lisp

@@ -206,6 +206,19 @@ buffer, with a meaningful result."
 To access all modes, including disabled ones, use `slot-value'."
   (sera:filter #'enabled-p (slot-value buffer 'modes)))
 
+(defmethod (setf modes) (value (buffer modable-buffer))
+  "Only return enabled modes.
+To access all modes, including disabled ones, use `slot-value'."
+  (setf (slot-value buffer 'modes) value)
+  (files:with-file-content (history (history-file buffer)
+                            :default (make-history-tree))
+    (let ((buffer-history-entry (or (htree:data (gethash (id buffer) (htree:owners history)))
+                                    (make-instance 'buffer-history-entry))))
+      (setf (modes buffer-history-entry)
+            (mapcar 'name (modes buffer)))
+      (setf (htree:data (gethash (id buffer) (htree:owners history)))
+            buffer-history-entry))))
+
 (define-class input-buffer (buffer)
   ((keyscheme
     keyscheme:cua
@@ -787,7 +800,9 @@ Return the created buffer."
                          :creator-id (when (and parent-buffer
                                                 (not (nosave-buffer-p buffer))
                                                 (not (nosave-buffer-p parent-buffer)))
-                                       (id parent-buffer))))))
+                                       (id parent-buffer))
+                         :data (make-instance 'buffer-history-entry
+                                              :modes (mapcar 'name (modes buffer)))))))
   buffer)
 
 (define-command update-document-model (&key (buffer (current-buffer)))

source/history.lisp

@@ -45,6 +45,14 @@ It's a list of a form (Y &OPTIONAL X)."))
 Entry for the global history.
 The total number of visit for a given URL is (+ explicit-visits implicit-visits)."))
 
+(define-class buffer-history-entry ()   ; TODO: Export?
+  ((modes
+    '()
+    :type (list-of symbol)
+    :documentation "List of modes that were last active for buffer."))
+  (:accessor-name-transformer (class*:make-name-transformer name))
+  (:documentation "Buffer state to restore when restoring history."))
+
 (export-always 'equals)
 (defmethod equals ((e1 history-entry) (e2 history-entry))
   (quri:uri= (url e1) (url e2)))
@@ -344,7 +352,8 @@ Return non-NIL of history was restored, NIL otherwise."
                                                   :url (url (htree:data current-node))
                                                   :load-url-p nil)))
                      (setf (gethash owner-id old-id->new-id) (id new-buffer))
-                     (setf (gethash (id new-buffer) new-owners) owner))))))
+                     (setf (gethash (id new-buffer) new-owners) owner)
+                     (enable-modes (modes (htree:data owner)) new-buffer))))))
             (alex:hash-table-alist (htree:owners history)))
       (maphash (lambda (_ owner)
                  (declare (ignore _))