feat: add session slug generator

src/agents/session-slug.test.ts

@@ -0,0 +1,26 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { createSessionSlug } from "./session-slug.js";
+
+describe("session slug", () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("generates a two-word slug by default", () => {
+    vi.spyOn(Math, "random").mockReturnValue(0);
+    const slug = createSessionSlug();
+    expect(slug).toBe("amber-atlas");
+  });
+
+  it("adds a numeric suffix when the base slug is taken", () => {
+    vi.spyOn(Math, "random").mockReturnValue(0);
+    const slug = createSessionSlug((id) => id === "amber-atlas");
+    expect(slug).toBe("amber-atlas-2");
+  });
+
+  it("falls back to three words when collisions persist", () => {
+    vi.spyOn(Math, "random").mockReturnValue(0);
+    const slug = createSessionSlug((id) => id === "amber-atlas" || id === "amber-atlas-2");
+    expect(slug).toBe("amber-atlas-atlas");
+  });
+});