clanker-agent/packages/ai/test/google-thinking-signature.test.ts

import { describe, expect, it } from "vitest";
import {
  isThinkingPart,
  retainThoughtSignature,
} from "../src/providers/google-shared.js";

describe("Google thinking detection (thoughtSignature)", () => {
  it("treats part.thought === true as thinking", () => {
    expect(isThinkingPart({ thought: true, thoughtSignature: undefined })).toBe(
      true,
    );
    expect(
      isThinkingPart({ thought: true, thoughtSignature: "opaque-signature" }),
    ).toBe(true);
  });

  it("does not treat thoughtSignature alone as thinking", () => {
    // Per Google docs, thoughtSignature is for context replay and can appear on any part type.
    // Only thought === true indicates thinking content.
    // See: https://ai.google.dev/gemini-api/docs/thought-signatures
    expect(
      isThinkingPart({
        thought: undefined,
        thoughtSignature: "opaque-signature",
      }),
    ).toBe(false);
    expect(
      isThinkingPart({ thought: false, thoughtSignature: "opaque-signature" }),
    ).toBe(false);
  });

  it("does not treat empty/missing signatures as thinking if thought is not set", () => {
    expect(
      isThinkingPart({ thought: undefined, thoughtSignature: undefined }),
    ).toBe(false);
    expect(isThinkingPart({ thought: false, thoughtSignature: "" })).toBe(
      false,
    );
  });

  it("preserves the existing signature when subsequent deltas omit thoughtSignature", () => {
    const first = retainThoughtSignature(undefined, "sig-1");
    expect(first).toBe("sig-1");

    const second = retainThoughtSignature(first, undefined);
    expect(second).toBe("sig-1");

    const third = retainThoughtSignature(second, "");
    expect(third).toBe("sig-1");
  });

  it("updates the signature when a new non-empty signature arrives", () => {
    const updated = retainThoughtSignature("sig-1", "sig-2");
    expect(updated).toBe("sig-2");
  });
});