fix: harden pairing flow

src/slack/monitor.tool-result.test.ts

@@ -399,4 +399,43 @@ describe("monitorSlackProvider tool results", () => {
       "Pairing code: PAIRCODE",
     );
   });
+
+  it("does not resend pairing code when a request is already pending", async () => {
+    config = {
+      ...config,
+      slack: { dm: { enabled: true, policy: "pairing", allowFrom: [] } },
+    };
+    upsertPairingRequestMock
+      .mockResolvedValueOnce({ code: "PAIRCODE", created: true })
+      .mockResolvedValueOnce({ code: "PAIRCODE", created: false });
+
+    const controller = new AbortController();
+    const run = monitorSlackProvider({
+      botToken: "bot-token",
+      appToken: "app-token",
+      abortSignal: controller.signal,
+    });
+
+    await waitForEvent("message");
+    const handler = getSlackHandlers()?.get("message");
+    if (!handler) throw new Error("Slack message handler not registered");
+
+    const baseEvent = {
+      type: "message",
+      user: "U1",
+      text: "hello",
+      ts: "123",
+      channel: "C1",
+      channel_type: "im",
+    };
+
+    await handler({ event: baseEvent });
+    await handler({ event: { ...baseEvent, ts: "124", text: "hello again" } });
+
+    await flush();
+    controller.abort();
+    await run;
+
+    expect(sendMock).toHaveBeenCalledTimes(1);
+  });
 });