1 files changed, 69 insertions, 0 deletions
diff --git a/packages/message-queue/src/service.test.ts b/packages/message-queue/src/service.test.ts
index aa59dd3..086414e 100644
--- a/packages/message-queue/src/service.test.ts
+++ b/packages/message-queue/src/service.test.ts
@@ -99,3 +99,72 @@ describe("message-queue service", () => {
     expect(combine(drained)).toBe("alpha\n\nbeta");
   });
 });
+
+describe("message-queue service cancel", () => {
+  it("cancel removes the message and pushes a surface update (queue shrank)", () => {
+    const deps = makeDeps();
+    const svc = createMessageQueueService(deps);
+    svc.enqueue("c1", "a"); // q-1
+    svc.enqueue("c1", "b"); // q-2
+    svc.enqueue("c1", "c"); // q-3
+    expect(deps.calls.value).toBe(3); // three enqueues notified
+
+    const snapshot = svc.cancel("c1", "q-2");
+    expect(deps.calls.value).toBe(4); // cancel pushed a surface update
+    expect(snapshot.map((m) => m.id)).toEqual(["q-1", "q-3"]);
+
+    // live state reflects the removal
+    expect(svc.getQueue("c1").map((m) => m.id)).toEqual(["q-1", "q-3"]);
+  });
+
+  it("cancel of the only message empties the queue + pushes a surface update", () => {
+    const deps = makeDeps();
+    const svc = createMessageQueueService(deps);
+    svc.enqueue("c1", "only"); // q-1
+    expect(deps.calls.value).toBe(1);
+
+    const snapshot = svc.cancel("c1", "q-1");
+    expect(deps.calls.value).toBe(2); // surface update (queue → empty)
+    expect(snapshot).toEqual([]);
+    expect(svc.getQueue("c1")).toEqual([]);
+  });
+
+  it("cancel of a missing id does NOT push a surface update (no change)", () => {
+    const deps = makeDeps();
+    const svc = createMessageQueueService(deps);
+    svc.enqueue("c1", "a"); // q-1
+    expect(deps.calls.value).toBe(1);
+
+    // unknown message id — no-op, no notify
+    const snapshot = svc.cancel("c1", "nope");
+    expect(deps.calls.value).toBe(1); // unchanged — no change
+    expect(snapshot.map((m) => m.id)).toEqual(["q-1"]);
+
+    // unknown conversation — also a no-op, no notify
+    expect(svc.cancel("nope", "q-1")).toEqual([]);
+    expect(deps.calls.value).toBe(1); // still unchanged
+  });
+
+  it("cancel after a drain (queue empty) is a no-op with no surface update", () => {
+    const deps = makeDeps();
+    const svc = createMessageQueueService(deps);
+    svc.enqueue("c1", "a"); // q-1
+    svc.drain("c1");
+    expect(deps.calls.value).toBe(2); // enqueue + drain
+
+    expect(svc.cancel("c1", "q-1")).toEqual([]);
+    expect(deps.calls.value).toBe(2); // no notify — queue was already empty
+  });
+
+  it("cancel is scoped per conversation", () => {
+    const deps = makeDeps();
+    const svc = createMessageQueueService(deps);
+    svc.enqueue("c1", "a"); // q-1
+    svc.enqueue("c2", "b"); // q-2
+
+    const snapshot = svc.cancel("c1", "q-1");
+    expect(snapshot).toEqual([]);
+    expect(svc.getQueue("c1")).toEqual([]);
+    expect(svc.getQueue("c2").map((m) => m.id)).toEqual(["q-2"]);
+  });
+});