feat(mail): map standard IMAP folders per profile

tests/test_mail_profile_helpers.py

@@ -290,6 +290,51 @@ class MailProfileTransportHelperTests(unittest.TestCase):
         self.assertEqual(audit.call_args.kwargs["details"]["protocol"], "imap")
         self.assertNotIn("imap-secret", repr(audit.call_args.kwargs))
 
+    def test_apply_transport_update_persists_standard_folder_mappings(self):
+        profile = SimpleNamespace(
+            id="profile-folders",
+            tenant_id="tenant-1",
+            scope_type="tenant",
+            scope_id="tenant-1",
+            smtp_config={"host": "smtp.example.org"},
+            smtp_username=None,
+            smtp_password_encrypted=None,
+            smtp_transport_revision="smtp-before",
+            imap_config={"host": "imap.example.org", "sent_folder": "Legacy Sent"},
+            imap_username=None,
+            imap_password_encrypted=None,
+            imap_transport_revision="imap-before",
+        )
+        session = SimpleNamespace(flush=lambda: None)
+
+        with patch("govoplan_mail.backend.mail_profiles.clear_mailbox_index"):
+            _apply_profile_transport_update(
+                session,  # type: ignore[arg-type]
+                profile,
+                user_id="user-1",
+                api_key_id=None,
+                smtp=None,
+                imap=ImapConfig(
+                    host="imap.example.org",
+                    folder_mappings={
+                        "inbox": "INBOX",
+                        "sent": "Sent Items",
+                        "drafts": "Drafts",
+                    },
+                ),
+                clear_imap=False,
+            )
+
+        self.assertEqual(profile.imap_config["sent_folder"], "Sent Items")
+        self.assertEqual(
+            profile.imap_config["folder_mappings"],
+            {
+                "inbox": "INBOX",
+                "sent": "Sent Items",
+                "drafts": "Drafts",
+            },
+        )
+
     def test_imap_password_replacement_clears_cache_without_rotating_identity_revision(self):
         profile = SimpleNamespace(
             id="profile-1",