Add Synapse support for MSC4143

roles/custom/matrix-synapse/defaults/main.yml

@@ -1430,6 +1430,13 @@ matrix_synapse_experimental_features_msc4140_enabled: false
 # See `matrix_synapse_experimental_features_msc4140_enabled`.
 matrix_synapse_max_event_delay_duration: 24h
 
+# Controls whether to enable the MSC4143 experimental feature (RTC transports).
+#
+# This is used by MatrixRTC clients to discover the unstable RTC transports API.
+#
+# See https://github.com/matrix-org/matrix-spec-proposals/pull/4143
+matrix_synapse_experimental_features_msc4143_enabled: false
+
 # Controls whether to enable the MSC4222 experimental feature (adding `state_after` to sync v2).
 #
 # Allow clients to opt-in to a change of the sync v2 API that allows them to correctly track the state of the room.

roles/custom/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -3010,6 +3010,9 @@ experimental_features:
   {% if matrix_synapse_experimental_features_msc4140_enabled %}
   msc4140_enabled: true
   {% endif %}
+  {% if matrix_synapse_experimental_features_msc4143_enabled %}
+  msc4143_enabled: true
+  {% endif %}
   {% if matrix_synapse_experimental_features_msc4222_enabled %}
   msc4222_enabled: true
   {% endif %}