feat: add websocket upstream adapter

crates/crank-core/src/protocol.rs

@@ -8,6 +8,7 @@ pub enum Protocol {
     Rest,
     Graphql,
     Grpc,
+    Websocket,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
@@ -49,6 +50,7 @@ impl Protocol {
             Self::Rest => true,
             Self::Graphql => matches!(mode, ExecutionMode::Unary),
             Self::Grpc => true,
+            Self::Websocket => !matches!(mode, ExecutionMode::Unary),
         }
     }
 
@@ -57,6 +59,7 @@ impl Protocol {
             Self::Rest => true,
             Self::Graphql => matches!(behavior, TransportBehavior::RequestResponse),
             Self::Grpc => !matches!(behavior, TransportBehavior::DeferredResult),
+            Self::Websocket => !matches!(behavior, TransportBehavior::RequestResponse),
         }
     }
 }
@@ -79,4 +82,20 @@ mod tests {
         assert!(Protocol::Grpc.supports_execution_mode(ExecutionMode::Session));
         assert!(!Protocol::Grpc.supports_transport_behavior(TransportBehavior::DeferredResult));
     }
+
+    #[test]
+    fn websocket_requires_streaming_modes() {
+        assert!(!Protocol::Websocket.supports_execution_mode(ExecutionMode::Unary));
+        assert!(Protocol::Websocket.supports_execution_mode(ExecutionMode::Window));
+        assert!(Protocol::Websocket.supports_execution_mode(ExecutionMode::Session));
+        assert!(Protocol::Websocket.supports_execution_mode(ExecutionMode::AsyncJob));
+        assert!(
+            !Protocol::Websocket.supports_transport_behavior(TransportBehavior::RequestResponse)
+        );
+        assert!(Protocol::Websocket.supports_transport_behavior(TransportBehavior::ServerStream));
+        assert!(
+            Protocol::Websocket.supports_transport_behavior(TransportBehavior::StatefulSession)
+        );
+        assert!(Protocol::Websocket.supports_transport_behavior(TransportBehavior::DeferredResult));
+    }
 }