canonicalize to NFC form on edit/import

anki/importing/noteimp.py

@@ -3,6 +3,9 @@
 # License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 import  cgi
+
+import unicodedata
+
 from anki.consts import NEW_CARDS_RANDOM, STARTING_FACTOR
 from anki.lang import _
 from anki.utils import fieldChecksum, guid64, timestampID, \
@@ -126,6 +129,8 @@ class NoteImporter(Importer):
                 n.fields[c] = n.fields[c].strip()
                 if not self.allowHTML:
                     n.fields[c] = n.fields[c].replace("\n", "<br>")
+                n.fields[c] = unicodedata.normalize("NFC", n.fields[c])
+            n.tags = [unicodedata.normalize("NFC", t) for t in n.tags]
             fld0 = n.fields[fld0idx]
             csum = fieldChecksum(fld0)
             # first field must exist

aqt/editor.py

@@ -10,6 +10,7 @@ import warnings
 import html
 import mimetypes
 import base64
+import unicodedata
 
 from anki.lang import _
 from aqt.qt import *
@@ -569,6 +570,7 @@ class Editor:
         if cmd.startswith("blur") or cmd.startswith("key"):
             (type, txt) = cmd.split(":", 1)
             txt = urllib.parse.unquote(txt)
+            txt = unicodedata.normalize("NFC", txt)
             txt = self.mungeHTML(txt)
             # misbehaving apps may include a null byte in the text
             txt = txt.replace("\x00", "")
@@ -763,8 +765,9 @@ class Editor:
     def saveTags(self):
         if not self.note:
             return
+        tagsTxt = unicodedata.normalize("NFC", self.tags.text())
         self.note.tags = self.mw.col.tags.canonify(
-            self.mw.col.tags.split(self.tags.text()))
+            self.mw.col.tags.split(tagsTxt))
         self.tags.setText(self.mw.col.tags.join(self.note.tags).strip())
         if not self.addMode:
             self.note.flush()