feat(FN-4824): forward task assignment events across remote runtime

Fusion-Task-Id: FN-4824
Fusion-Task-Lineage: 65f53a33-0939-4b6f-b62b-4a255ad14d9e

packages/dashboard/src/__tests__/sse.test.ts

@@ -325,6 +325,36 @@ describe("createSSE client cleanup", () => {
     expect(getActiveSSEConnections()).toBe(baseline);
   });
 
+  it("emits task:assigned SSE event from agent assignments", () => {
+    let onAssigned: ((agent: unknown, taskId: string) => void) | undefined;
+    const store = createMockStore();
+    const agentStore = {
+      on: vi.fn((event: string, handler: (agent: unknown, taskId: string) => void) => {
+        if (event === "agent:assigned") onAssigned = handler;
+      }),
+      off: vi.fn(),
+    };
+    const socket = new MockSocket();
+    const req = new EventEmitter() as Request & { query: Record<string, string>; socket: MockSocket };
+    req.query = { clientId: "assigned-client" };
+    req.socket = socket;
+    const res = new MockResponse(socket);
+
+    createSSE(store, undefined, undefined, undefined, undefined, agentStore as never)(
+      req,
+      res as unknown as Response
+    );
+
+    onAssigned?.({ id: "agent-1" }, "FN-1");
+
+    expect(res.write).toHaveBeenCalledWith(
+      expect.stringContaining("event: task:assigned")
+    );
+    expect(res.write).toHaveBeenCalledWith(
+      expect.stringContaining('"taskId":"FN-1"')
+    );
+  });
+
   it("closes the connection when the outbound buffer exceeds the backpressure threshold", () => {
     // Capture the task:created listener so we can fire a send after the
     // socket buffer has been bloated past the threshold.

packages/dashboard/src/sse.ts

@@ -389,6 +389,17 @@ export function createSSE(
     const onUpdated = (task: unknown) => {
       send(`event: task:updated\ndata: ${JSON.stringify(stripTaskListHeavyFields(task))}\n\n`);
     };
+    const onTaskAssigned = (agent: unknown, taskId: string) => {
+      const payload = {
+        taskId,
+        agentId:
+          agent && typeof agent === "object" && "id" in agent
+            ? String((agent as { id: unknown }).id)
+            : "",
+        assignedAt: new Date().toISOString(),
+      };
+      send(`event: task:assigned\ndata: ${JSON.stringify(payload)}\n\n`);
+    };
     const onDeleted = (task: unknown) => {
       send(`event: task:deleted\ndata: ${JSON.stringify(stripTaskListHeavyFields(task))}\n\n`);
     };
@@ -713,6 +724,7 @@ export function createSSE(
         agentStore.off("agent:updated", onAgentUpdated);
         agentStore.off("agent:deleted", onAgentDeleted);
         agentStore.off("agent:stateChanged", onAgentStateChanged);
+        agentStore.off("agent:assigned", onTaskAssigned);
       }
       if (messageStore) {
         messageStore.off("message:sent", onMessageSent);
@@ -822,6 +834,7 @@ export function createSSE(
       agentStore.on("agent:updated", onAgentUpdated);
       agentStore.on("agent:deleted", onAgentDeleted);
       agentStore.on("agent:stateChanged", onAgentStateChanged);
+      agentStore.on("agent:assigned", onTaskAssigned);
     }
 
     if (messageStore) {