Transfer contact verification state during device pairing

When authorizing a new device, include the TOFU registry
(known_identity_keys) and manual verifications (verified_contacts) in
the encrypted pairing payload, so a contact verified on the existing
device stays verified on the newly paired one. Previously these stores
are device-local and started empty on the new device, dropping verified
status. Fields are optional and ignored by older clients; symmetric with
the iOS client.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

chat_core.py

@@ -1568,6 +1568,23 @@ class ChatClient:
                 self._cache_key = derive_self_encryption_key(ed_priv)
                 self._local_key = derive_local_storage_key(ed_priv)
                 self._load_verification_stores()
+
+                # Import verification state transferred from the authorizing
+                # device (optional — absent when paired from an older client)
+                vc_raw = keys_data.get("verified_contacts")
+                if vc_raw:
+                    try:
+                        self._verified_contacts = json.loads(vc_raw)
+                        _save_verified_contacts(email, self._verified_contacts, self._local_key)
+                    except (json.JSONDecodeError, TypeError):
+                        pass
+                kik_raw = keys_data.get("known_identity_keys")
+                if kik_raw:
+                    try:
+                        self._known_identity_keys = json.loads(kik_raw)
+                        _save_known_identity_keys(email, self._known_identity_keys, self._local_key)
+                    except (json.JSONDecodeError, TypeError):
+                        pass
                 self._pairing_temp_private_key = None
                 self._pairing_fingerprint = ""
                 self._pairing_code = ""
@@ -1618,6 +1635,14 @@ class ChatClient:
             "identity_private": serialize_ed25519_private_raw(self.identity_private).hex(),
         }
 
+        # Carry the TOFU registry + manual verifications so a contact verified on
+        # this device stays verified on the new one (these stores are local and
+        # would otherwise start empty). Receivers ignore unknown fields.
+        if self._verified_contacts:
+            keys_data["verified_contacts"] = json.dumps(self._verified_contacts)
+        if self._known_identity_keys:
+            keys_data["known_identity_keys"] = json.dumps(self._known_identity_keys)
+
         # Send keys to the new device first. Re-encrypting history can take a
         # while on large accounts; doing it before pairing_send can make a valid
         # code expire during authorization.