diff --git a/src/shared/constants/cliTools.js b/src/shared/constants/cliTools.js
index 97de7434..9f8b23bf 100644
--- a/src/shared/constants/cliTools.js
+++ b/src/shared/constants/cliTools.js
@@ -45,6 +45,11 @@ export const MITM_TOOLS = {
     configType: "mitm",
     mitmDomain: "q.us-east-1.amazonaws.com",
     defaultModels: [
+      // Kiro's agent/"vibe" mode sends modelId "auto" for the main turn and "simple-task"
+      // for background sub-tasks (verified via MITM request dump of generateAssistantResponse).
+      // Both need a mappable slot — otherwise getMappedModel returns null and the chat call
+      // is passed through to AWS instead of being routed to the chosen provider.
+      { id: "auto", name: "Auto (Kiro Agent)", alias: "auto" },
       { id: "claude-sonnet-4.5", name: "Claude Sonnet 4.5", alias: "claude-sonnet-4.5" },
       { id: "claude-sonnet-4", name: "Claude Sonnet 4", alias: "claude-sonnet-4" },
       { id: "claude-haiku-4.5", name: "Claude Haiku 4.5", alias: "claude-haiku-4.5" },
diff --git a/tests/unit/kiro-model-slots.test.js b/tests/unit/kiro-model-slots.test.js
new file mode 100644
index 00000000..3eb9c7b8
--- /dev/null
+++ b/tests/unit/kiro-model-slots.test.js
@@ -0,0 +1,30 @@
+import { describe, expect, it } from "vitest";
+import { MITM_TOOLS } from "../../src/shared/constants/cliTools.js";
+
+// Guards the fix in commit 356607c: Kiro's agent/"vibe" mode sends modelId
+// "auto" for the main turn and "simple-task" for background sub-tasks. Both
+// need a mappable defaultModels slot — otherwise getMappedModel (src/mitm/server.js)
+// returns null and the /generateAssistantResponse call is passed through to AWS
+// instead of being routed to the user's chosen provider (surfacing as Kiro's
+// "monthly usage limit" once the AWS quota is gone).
+describe("Kiro MITM model slots", () => {
+  const kiro = MITM_TOOLS.kiro;
+
+  it("exposes the kiro mitm tool", () => {
+    expect(kiro).toBeTruthy();
+    expect(kiro.configType).toBe("mitm");
+    expect(Array.isArray(kiro.defaultModels)).toBe(true);
+  });
+
+  it("offers a mappable slot for the agent default model id 'auto'", () => {
+    const auto = kiro.defaultModels.find((m) => m.id === "auto");
+    expect(auto).toBeTruthy();
+    expect(auto.alias).toBe("auto");
+  });
+
+  it("offers a mappable slot for the background sub-task model id 'simple-task'", () => {
+    const simpleTask = kiro.defaultModels.find((m) => m.id === "simple-task");
+    expect(simpleTask).toBeTruthy();
+    expect(simpleTask.alias).toBe("simple-task");
+  });
+});