Send device list updates to application services (MSC3202) - part 1 (#11881)

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

synapse/appservice/api.py

@@ -1,4 +1,5 @@
 # Copyright 2015, 2016 OpenMarket Ltd
+# Copyright 2022 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -27,7 +28,7 @@ from synapse.appservice import (
 from synapse.events import EventBase
 from synapse.events.utils import SerializeEventConfig, serialize_event
 from synapse.http.client import SimpleHttpClient
-from synapse.types import JsonDict, ThirdPartyInstanceID
+from synapse.types import DeviceListUpdates, JsonDict, ThirdPartyInstanceID
 from synapse.util.caches.response_cache import ResponseCache
 
 if TYPE_CHECKING:
@@ -225,6 +226,7 @@ class ApplicationServiceApi(SimpleHttpClient):
         to_device_messages: List[JsonDict],
         one_time_key_counts: TransactionOneTimeKeyCounts,
         unused_fallback_keys: TransactionUnusedFallbackKeys,
+        device_list_summary: DeviceListUpdates,
         txn_id: Optional[int] = None,
     ) -> bool:
         """
@@ -268,6 +270,7 @@ class ApplicationServiceApi(SimpleHttpClient):
                 }
             )
 
+        # TODO: Update to stable prefixes once MSC3202 completes FCP merge
         if service.msc3202_transaction_extensions:
             if one_time_key_counts:
                 body[
@@ -277,6 +280,11 @@ class ApplicationServiceApi(SimpleHttpClient):
                 body[
                     "org.matrix.msc3202.device_unused_fallback_keys"
                 ] = unused_fallback_keys
+            if device_list_summary:
+                body["org.matrix.msc3202.device_lists"] = {
+                    "changed": list(device_list_summary.changed),
+                    "left": list(device_list_summary.left),
+                }
 
         try:
             await self.put_json(