diff --git a/client/scripts/net/http_transport.gd b/client/scripts/net/http_transport.gd
index 2b53f65..dbd768c 100644
--- a/client/scripts/net/http_transport.gd
+++ b/client/scripts/net/http_transport.gd
@@ -31,5 +31,10 @@ func post_json(path: String, body: Dictionary) -> DmResponse:
 	var raw: PackedByteArray = signal_args[3]
 	if result != HTTPRequest.RESULT_SUCCESS:
 		return DmResponse.failed("transport result %d" % result)
-	var parsed = JSON.parse_string(raw.get_string_from_utf8())  # null if not JSON
+	# Parse via JSON.new() rather than JSON.parse_string(): the latter pushes an
+	# engine-level error on a non-JSON body (e.g. a gateway's HTML 502), which the
+	# project's gutconfig promotes to a false test failure. A non-JSON body stays
+	# null here — the service treats a non-dict body as a failure and degrades.
+	var json := JSON.new()
+	var parsed = null if json.parse(raw.get_string_from_utf8()) != OK else json.data
 	return DmResponse.ok(response_code, parsed)