fix(timeline): resync after sse reconnect

apps/web/src/hooks/useTimelineSSE.test.ts

@@ -1,5 +1,6 @@
 import { SSE_EVENT_TYPES } from "@capakraken/shared";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { getTimelineSseResyncKeys } from "./timelineSsePolicy.js";
 
 const invalidateQueries = vi.fn();
 const effectCleanups: Array<() => void> = [];
@@ -83,11 +84,23 @@ describe("useTimelineSSE", () => {
 
     expect(MockEventSource.instances).toHaveLength(1);
 
+    MockEventSource.instances[0]?.emitOpen();
+
     MockEventSource.instances[0]?.emitMessage(JSON.stringify({ type: SSE_EVENT_TYPES.PING }));
 
     expect(invalidateQueries).not.toHaveBeenCalled();
   });
 
+  it("does not resync on the initial successful SSE connection", () => {
+    useTimelineSSE();
+
+    expect(MockEventSource.instances).toHaveLength(1);
+
+    MockEventSource.instances[0]?.emitOpen();
+
+    expect(invalidateQueries).not.toHaveBeenCalled();
+  });
+
   it("resets reconnect backoff after ping and reconnects only once per pending timer", () => {
     useTimelineSSE();
 
@@ -117,6 +130,31 @@ describe("useTimelineSSE", () => {
     expect(invalidateQueries).not.toHaveBeenCalled();
   });
 
+  it("resyncs timeline queries exactly once after a successful reconnect", () => {
+    useTimelineSSE();
+
+    const firstConnection = MockEventSource.instances[0];
+    expect(firstConnection).toBeDefined();
+
+    firstConnection?.emitOpen();
+    firstConnection?.emitError();
+
+    vi.advanceTimersByTime(2_000);
+
+    expect(MockEventSource.instances).toHaveLength(2);
+
+    const secondConnection = MockEventSource.instances[1];
+    expect(secondConnection).toBeDefined();
+
+    secondConnection?.emitOpen();
+    secondConnection?.emitOpen();
+
+    expect(invalidateQueries).toHaveBeenCalledTimes(getTimelineSseResyncKeys().length);
+    expect(invalidateQueries.mock.calls).toEqual(
+      getTimelineSseResyncKeys().map((queryKey) => [{ queryKey }]),
+    );
+  });
+
   it("clears a pending reconnect when the hook is disposed", () => {
     useTimelineSSE();