fix(sse): update readyState to CLOSED on owner disposal

Co-authored-by: JavanPoirier <42590458+JavanPoirier@users.noreply.github.com>

Author: Copilot

packages/sse/src/sse.ts

@@ -341,6 +341,7 @@ export const createSSE = <T = string>(
   onCleanup(() => {
     clearReconnectTimer();
     teardown();
+    setReadyState(SSEReadyState.CLOSED);
   });
 
   return { source, data, error, readyState, close: disconnect, reconnect: manualReconnect };

packages/sse/test/index.test.ts

@@ -286,4 +286,23 @@ describe("createSSE", () => {
         dispose();
       }),
     ));
+
+  it("readyState is CLOSED after owner disposal", () =>
+    createRoot(dispose => {
+      const { readyState } = createSSE("https://example.com/events");
+      vi.advanceTimersByTime(20);
+      expect(readyState()).toBe(SSEReadyState.OPEN);
+      dispose();
+      expect(readyState()).toBe(SSEReadyState.CLOSED);
+    }));
+
+  it("readyState updates to CONNECTING when server drops connection", () =>
+    createRoot(dispose => {
+      const { readyState, source } = createSSE("https://example.com/events");
+      vi.advanceTimersByTime(20);
+      expect(readyState()).toBe(SSEReadyState.OPEN);
+      (source() as unknown as MockEventSource).simulateTransientError();
+      expect(readyState()).toBe(SSEReadyState.CONNECTING);
+      dispose();
+    }));
 });