fix: avoid circular dependency in test-helpers InMemoryEventStore

Author: felixweinberger

test/helpers/src/helpers/inMemoryEventStore.ts

@@ -1,4 +1,17 @@
-import type { EventStore, JSONRPCMessage } from '@modelcontextprotocol/server';
+import type { JSONRPCMessage } from '@modelcontextprotocol/core';
+
+/**
+ * Interface for storing and replaying events for resumability.
+ * This is a copy of the EventStore interface from @modelcontextprotocol/server
+ * to avoid circular dependencies in test-helpers.
+ */
+interface EventStore {
+    storeEvent(streamId: string, message: JSONRPCMessage): Promise<string>;
+    replayEventsAfter(
+        lastEventId: string,
+        { send }: { send: (eventId: string, message: JSONRPCMessage) => Promise<void> }
+    ): Promise<string>;
+}
 
 /**
  * Simple in-memory implementation of the EventStore interface for resumability.