feat(server): revoke displaced client during activation claim

Author: pallyoung

packages/server/src/__tests__/activation-commands.test.ts

@@ -232,6 +232,44 @@ describe("activation commands", () => {
     });
   });
 
+  it("claiming from a second client revokes the previous websocket", async () => {
+    const request = createMockRequest();
+    const revokeAndCloseClient = vi.fn();
+    const ctx = createBaseContext({
+      broadcaster: {
+        broadcast: vi.fn(),
+        sendToClient: vi.fn(() => true),
+        sendBinaryToClient: vi.fn(() => true),
+        getRequestMetadata: vi.fn(() => request),
+        revokeAndCloseClient,
+      } as unknown as Broadcaster,
+    });
+
+    await dispatch(
+      {
+        kind: "command",
+        id: "00000000-0000-4000-8000-000000000003",
+        op: "activation.claim",
+        args: { clientInstanceId: "client-a" },
+      },
+      ctx,
+      "ws-a"
+    );
+
+    await dispatch(
+      {
+        kind: "command",
+        id: "00000000-0000-4000-8000-000000000004",
+        op: "activation.claim",
+        args: { clientInstanceId: "client-b" },
+      },
+      ctx,
+      "ws-b"
+    );
+
+    expect(revokeAndCloseClient).toHaveBeenCalledWith("ws-a", 2);
+  });
+
   it("does not block direct internal dispatches without websocket request metadata", async () => {
     const ctx = createBaseContext();
 

packages/server/src/commands/activation.ts

@@ -20,7 +20,12 @@ registerCommand(
       };
     }
 
-    return ctx.activationMgr.claim(args.clientInstanceId, clientId, request);
+    const claim = ctx.activationMgr.claim(args.clientInstanceId, clientId, request);
+    if (claim.displacedWsClientId) {
+      ctx.broadcaster.revokeAndCloseClient?.(claim.displacedWsClientId, claim.generation);
+    }
+
+    return claim;
   }
 );
 

packages/server/src/ws/hub.ts

@@ -62,6 +62,7 @@ export interface Broadcaster {
   sendToClient(clientId: ClientId, msg: ServerToClient): boolean;
   sendBinaryToClient(clientId: ClientId, data: Buffer): boolean;
   getRequestMetadata?(clientId: ClientId): FastifyRequest | undefined;
+  revokeAndCloseClient?(clientId: ClientId, generation: number): void;
 }
 
 export class WsHub implements Broadcaster {