feat(cli): add configurable banner tagline mode

src/cli/tagline.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+import { DEFAULT_TAGLINE, pickTagline } from "./tagline.js";
+
+describe("pickTagline", () => {
+  it("returns empty string when mode is off", () => {
+    expect(pickTagline({ mode: "off" })).toBe("");
+  });
+
+  it("returns default tagline when mode is default", () => {
+    expect(pickTagline({ mode: "default" })).toBe(DEFAULT_TAGLINE);
+  });
+
+  it("keeps OPENCLAW_TAGLINE_INDEX behavior in random mode", () => {
+    const value = pickTagline({
+      mode: "random",
+      env: { OPENCLAW_TAGLINE_INDEX: "0" } as NodeJS.ProcessEnv,
+    });
+    expect(value.length).toBeGreaterThan(0);
+    expect(value).not.toBe(DEFAULT_TAGLINE);
+  });
+});