diff --git a/server/ws/outputHub.test.ts b/server/ws/outputHub.test.ts
new file mode 100644
index 0000000..92b9576
--- /dev/null
+++ b/server/ws/outputHub.test.ts
@@ -0,0 +1,31 @@
+// server/ws/outputHub.test.ts
+import { describe, it, expect, vi } from "vitest";
+import { OutputHub } from "./outputHub.js";
+
+describe("OutputHub", () => {
+  it("rejoue le buffer aux nouveaux abonnés", () => {
+    const hub = new OutputHub();
+    hub.publish("m1", "ligne1");
+    hub.publish("m1", "ligne2");
+    const received: string[] = [];
+    hub.subscribe("m1", (c) => received.push(c));
+    expect(received).toEqual(["ligne1", "ligne2"]);
+  });
+
+  it("diffuse les nouveaux chunks aux abonnés", () => {
+    const hub = new OutputHub();
+    const fn = vi.fn();
+    hub.subscribe("m1", fn);
+    hub.publish("m1", "x");
+    expect(fn).toHaveBeenCalledWith("x");
+  });
+
+  it("vide le buffer avec clear()", () => {
+    const hub = new OutputHub();
+    hub.publish("m1", "old");
+    hub.clear("m1");
+    const received: string[] = [];
+    hub.subscribe("m1", (c) => received.push(c));
+    expect(received).toEqual([]);
+  });
+});
diff --git a/server/ws/outputHub.ts b/server/ws/outputHub.ts
new file mode 100644
index 0000000..5e84320
--- /dev/null
+++ b/server/ws/outputHub.ts
@@ -0,0 +1,31 @@
+// server/ws/outputHub.ts
+type Listener = (chunk: string) => void;
+const MAX_BUFFER = 5000; // lignes/chunks gardés pour le rejeu
+
+export class OutputHub {
+  private buffers = new Map<string, string[]>();
+  private listeners = new Map<string, Set<Listener>>();
+
+  publish(machineId: string, chunk: string): void {
+    const buf = this.buffers.get(machineId) ?? [];
+    buf.push(chunk);
+    if (buf.length > MAX_BUFFER) buf.shift();
+    this.buffers.set(machineId, buf);
+    this.listeners.get(machineId)?.forEach((l) => l(chunk));
+  }
+
+  /** S'abonne et reçoit immédiatement le buffer existant (rejeu). */
+  subscribe(machineId: string, listener: Listener): () => void {
+    (this.buffers.get(machineId) ?? []).forEach((c) => listener(c));
+    const set = this.listeners.get(machineId) ?? new Set();
+    set.add(listener);
+    this.listeners.set(machineId, set);
+    return () => set.delete(listener);
+  }
+
+  clear(machineId: string): void {
+    this.buffers.delete(machineId);
+  }
+}
+
+export const outputHub = new OutputHub();