2 files changed, 5 insertions, 0 deletions
diff --git a/changelog.d/16775.bugfix b/changelog.d/16775.bugfix
new file mode 100644
index 0000000000..99f04ca59d
--- /dev/null
+++ b/changelog.d/16775.bugfix
@@ -0,0 +1 @@
+Adds the recursion_depth parameter to the response of the /relations endpoint if MSC3981 recursion is being performed.
diff --git a/synapse/handlers/relations.py b/synapse/handlers/relations.py
index 444b795872..642f7acf97 100644
--- a/synapse/handlers/relations.py
+++ b/synapse/handlers/relations.py
@@ -180,6 +180,10 @@ class RelationsHandler:
                 config=serialize_options,
             ),
         }
+
+        if recurse:
+            return_value["recursion_depth"] = 3
+
         if include_original_event:
             # Do not bundle aggregations when retrieving the original event because
             # we want the content before relations are applied to it.