diff --git a/tests/cookies.test.ts b/tests/cookies.test.ts
index 7f7e646..85a7b47 100644
--- a/tests/cookies.test.ts
+++ b/tests/cookies.test.ts
@@ -136,4 +136,44 @@ describe('cookies', () => {
       );
     });
   });
+
+  describe('extractCookiesFromChrome', () => {
+    it('returns cookies when sqlite yields hex values', async () => {
+      const fs = await import('node:fs');
+      const { execSync } = await import('node:child_process');
+      // Pretend Chrome cookie DB exists
+      (fs.existsSync as unknown as vi.Mock).mockImplementation((path: string) => path.includes('Cookies'));
+      (fs.copyFileSync as unknown as vi.Mock).mockImplementation(() => {});
+      // sqlite output with hex strings ("test_auth", "test_ct0")
+      (execSync as unknown as vi.Mock).mockImplementation((cmd: string) => {
+        if (cmd.includes('sqlite3')) {
+          return 'auth_token|746573745f61757468\nct0|746573745f637430';
+        }
+        return '';
+      });
+
+      const { extractCookiesFromChrome } = await import('../src/lib/cookies.js');
+      const result = await extractCookiesFromChrome('Default');
+
+      expect(result.cookies.authToken).toBe('test_auth');
+      expect(result.cookies.ct0).toBe('test_ct0');
+      expect(result.cookies.source).toContain('Chrome');
+      expect(result.warnings).toHaveLength(0);
+    });
+
+    it('warns when Chrome DB exists but contains no cookies', async () => {
+      const fs = await import('node:fs');
+      const { execSync } = await import('node:child_process');
+      (fs.existsSync as unknown as vi.Mock).mockImplementation((path: string) => path.includes('Cookies'));
+      (fs.copyFileSync as unknown as vi.Mock).mockImplementation(() => {});
+      (execSync as unknown as vi.Mock).mockReturnValue('');
+
+      const { extractCookiesFromChrome } = await import('../src/lib/cookies.js');
+      const result = await extractCookiesFromChrome('Default');
+
+      expect(result.cookies.authToken).toBeNull();
+      expect(result.cookies.ct0).toBeNull();
+      expect(result.warnings.some((w) => w.includes('No Twitter cookies found in Chrome'))).toBe(true);
+    });
+  });
 });
diff --git a/tests/twitter-client.test.ts b/tests/twitter-client.test.ts
index 13f878d..d7dad16 100644
--- a/tests/twitter-client.test.ts
+++ b/tests/twitter-client.test.ts
@@ -374,4 +374,116 @@ describe('TwitterClient', () => {
       expect(mockFetch).toHaveBeenCalledTimes(5);
     });
   });
+
+  describe('conversation helpers', () => {
+    let mockFetch: ReturnType<typeof vi.fn>;
+
+    beforeEach(() => {
+      mockFetch = vi.fn();
+      global.fetch = mockFetch as unknown as typeof fetch;
+    });
+
+    const makeConversationPayload = () => ({
+      data: {
+        threaded_conversation_with_injections_v2: {
+          instructions: [
+            {
+              entries: [
+                {
+                  content: {
+                    itemContent: {
+                      tweet_results: {
+                        result: {
+                          rest_id: '1',
+                          legacy: {
+                            full_text: 'root',
+                            created_at: '2024-01-01T00:00:00Z',
+                            reply_count: 0,
+                            retweet_count: 0,
+                            favorite_count: 0,
+                            conversation_id_str: '1',
+                          },
+                          core: { user_results: { result: { legacy: { screen_name: 'root', name: 'Root' } } } },
+                        },
+                      },
+                    },
+                  },
+                },
+                {
+                  content: {
+                    itemContent: {
+                      tweet_results: {
+                        result: {
+                          rest_id: '2',
+                          legacy: {
+                            full_text: 'child reply',
+                            created_at: '2024-01-02T00:00:00Z',
+                            reply_count: 0,
+                            retweet_count: 0,
+                            favorite_count: 0,
+                            conversation_id_str: '1',
+                            in_reply_to_status_id_str: '1',
+                          },
+                          core: { user_results: { result: { legacy: { screen_name: 'child', name: 'Child' } } } },
+                        },
+                      },
+                    },
+                  },
+                },
+              ],
+            },
+          ],
+        },
+      },
+    });
+
+    it('getReplies returns only replies to tweet', async () => {
+      mockFetch.mockResolvedValue({
+        ok: true,
+        status: 200,
+        json: async () => makeConversationPayload(),
+      });
+
+      const client = new TwitterClient({ cookies: validCookies });
+      const result = await client.getReplies('1');
+
+      expect(result.success).toBe(true);
+      expect(result.tweets?.length).toBe(1);
+      expect(result.tweets?.[0].id).toBe('2');
+    });
+
+    it('getThread returns sorted thread by createdAt', async () => {
+      const payload = makeConversationPayload();
+      // swap dates to verify sorting
+      payload.data.threaded_conversation_with_injections_v2.instructions[0]?.entries?.[0]?.content?.itemContent?.tweet_results?.result?.legacy &&
+        ((payload.data.threaded_conversation_with_injections_v2.instructions[0]!.entries![0]!.content!.itemContent!
+          .tweet_results!.result!.legacy!.created_at = '2024-01-03T00:00:00Z'));
+
+      mockFetch.mockResolvedValue({
+        ok: true,
+        status: 200,
+        json: async () => payload,
+      });
+
+      const client = new TwitterClient({ cookies: validCookies });
+      const result = await client.getThread('2');
+
+      expect(result.success).toBe(true);
+      expect(result.tweets?.map((t) => t.id)).toEqual(['2', '1']); // sorted by createdAt asc
+    });
+
+    it('propagates fetchTweetDetail errors', async () => {
+      mockFetch.mockResolvedValue({
+        ok: false,
+        status: 500,
+        text: async () => 'oops',
+      });
+
+      const client = new TwitterClient({ cookies: validCookies });
+      const result = await client.getThread('1');
+
+      expect(result.success).toBe(false);
+      expect(result.error).toContain('HTTP 500');
+    });
+  });
 });