Temporarily move sync into package

packages/excalidraw/sync/protocol.ts

@@ -0,0 +1,40 @@
+export type RELAY_PAYLOAD = { buffer: ArrayBuffer };
+export type PULL_PAYLOAD = { lastAcknowledgedVersion: number };
+export type PUSH_PAYLOAD = {
+  type: "durable" | "ephemeral";
+  changes: Array<CLIENT_CHANGE>;
+};
+
+export type CLIENT_CHANGE = {
+  id: string;
+  appStateChange: any;
+  elementsChange: any;
+};
+
+export type CLIENT_MESSAGE =
+  | { type: "relay"; payload: RELAY_PAYLOAD }
+  | { type: "pull"; payload: PULL_PAYLOAD }
+  | { type: "push"; payload: PUSH_PAYLOAD };
+
+export type SERVER_CHANGE = { id: string; version: number; payload: string };
+export type SERVER_MESSAGE =
+  | {
+      type: "relayed";
+      payload: { changes: Array<CLIENT_CHANGE> } | RELAY_PAYLOAD;
+    }
+  | { type: "acknowledged"; payload: { changes: Array<SERVER_CHANGE> } }
+  | { type: "rejected"; payload: { ids: Array<string>; message: string } };
+
+export interface ChangesRepository {
+  saveAll(changes: Array<CLIENT_CHANGE>): Array<SERVER_CHANGE>;
+  getSinceVersion(version: number): Array<SERVER_CHANGE>;
+  getLastVersion(): number;
+}
+
+// TODO: should come from the shared types package
+export type ExcalidrawElement = {
+  id: string;
+  type: any;
+  version: number;
+  [key: string]: any;
+};