feat(server): stream replayable harness events

apps/server/tests/shutdown.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it, vi } from "vitest";
+import { buildApp } from "../src/app.js";
+
+describe("shutdown lifecycle", () => {
+  it("closes SSE before disposing all sessions", async () => {
+    const order: string[] = [];
+    const app = buildApp({
+      sessionRegistry: {
+        create: vi.fn(), get: vi.fn(), delete: vi.fn(),
+        disposeAll: () => { order.push("sessions"); return Promise.resolve(); },
+      },
+      skillCatalog: { list: () => [] },
+      modelStore: {} as never,
+      attachmentStore: {} as never,
+      approvalBroker: {} as never,
+      sseRegistry: {
+        add: vi.fn(), closeForSession: vi.fn(),
+        closeAll: () => { order.push("sse"); },
+      },
+    });
+
+    await app.close();
+
+    expect(order).toEqual(["sse", "sessions"]);
+  });
+});

apps/server/tests/sse.test.ts

@@ -0,0 +1,84 @@
+import { EventEmitter } from "node:events";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { InMemoryEventStore } from "@agent-studio/harness";
+import * as sseModule from "../src/sse/sse-connection.js";
+
+class FakeResponse extends EventEmitter {
+  chunks: string[] = [];
+  ended = false;
+  shouldBackpressure = false;
+
+  write(chunk: string): boolean {
+    this.chunks.push(chunk);
+    return !this.shouldBackpressure;
+  }
+
+  end(): void {
+    this.ended = true;
+    this.emit("close");
+  }
+}
+
+afterEach(() => vi.useRealTimers());
+
+describe("SseConnection", () => {
+  it("replays after Last-Event-ID and gives it precedence over sequence", () => {
+    const store = new InMemoryEventStore();
+    const first = store.append("ses_1", { type: "session.started", payload: { cwd: "." } });
+    const second = store.append("ses_1", { type: "run.started", runId: "run_1", payload: { modelId: "demo" } });
+    const third = store.append("ses_1", { type: "assistant.delta", runId: "run_1", payload: { messageId: "msg_1", delta: "hi" } });
+    const Response = Reflect.get(sseModule, "SseConnection") as unknown as new (options: Record<string, unknown>) => { start(): void; close(): void };
+    expect(Response, "SseConnection must be exported").toBeDefined();
+    const response = new FakeResponse();
+    const connection = new Response({ sessionId: "ses_1", eventStore: store, response, cursor: { eventId: second.eventId, sequence: first.sequence } });
+
+    connection.start();
+
+    const output = response.chunks.join("");
+    expect(output).toContain(`id: ${third.eventId}`);
+    expect(output).not.toContain(`id: ${first.eventId}`);
+    connection.close();
+  });
+
+  it("emits reset for a retained-history gap and streams live events", () => {
+    const store = new InMemoryEventStore(1);
+    store.append("ses_1", { type: "session.started", payload: { cwd: "." } });
+    store.append("ses_1", { type: "run.started", runId: "run_1", payload: { modelId: "demo" } });
+    const response = new FakeResponse();
+    const Response = Reflect.get(sseModule, "SseConnection") as unknown as new (options: Record<string, unknown>) => { start(): void; close(): void };
+    const connection = new Response({ sessionId: "ses_1", eventStore: store, response, cursor: { sequence: 0 } });
+    connection.start();
+    store.append("ses_1", { type: "assistant.delta", runId: "run_1", payload: { messageId: "msg_1", delta: "live" } });
+
+    const output = response.chunks.join("");
+    expect(output).toContain("event: stream.reset");
+    expect(output).toContain('"delta":"live"');
+    connection.close();
+  });
+
+  it("clears its subscriber and heartbeat when closed", () => {
+    vi.useFakeTimers();
+    const store = new InMemoryEventStore() as InMemoryEventStore & { listenerCount(sessionId: string): number };
+    const response = new FakeResponse();
+    const Response = Reflect.get(sseModule, "SseConnection") as unknown as new (options: Record<string, unknown>) => { start(): void; close(): void };
+    const connection = new Response({ sessionId: "ses_1", eventStore: store, response, heartbeatMs: 15_000 });
+    connection.start();
+    expect(store.listenerCount("ses_1")).toBe(1);
+
+    connection.close();
+
+    expect(store.listenerCount("ses_1")).toBe(0);
+    expect(vi.getTimerCount()).toBe(0);
+  });
+
+  it("closes a persistently backpressured client at the configured bound", () => {
+    const store = new InMemoryEventStore();
+    const response = new FakeResponse();
+    response.shouldBackpressure = true;
+    const Response = Reflect.get(sseModule, "SseConnection") as unknown as new (options: Record<string, unknown>) => { start(): void };
+    const connection = new Response({ sessionId: "ses_1", eventStore: store, response, maxQueuedBytes: 20 });
+    connection.start();
+    store.append("ses_1", { type: "assistant.delta", runId: "run_1", payload: { messageId: "msg_1", delta: "a long live chunk" } });
+    expect(response.ended).toBe(true);
+  });
+});