diff --git a/posthog/test/ai/test_prompts.py b/posthog/test/ai/test_prompts.py
index 753405b5..c1d0a0fe 100644
--- a/posthog/test/ai/test_prompts.py
+++ b/posthog/test/ai/test_prompts.py
@@ -50,7 +50,7 @@ def create_mock_posthog(
 
 
 class TestPromptsGet(TestPrompts):
-    """Tests for the Prompts.get() method."""
+    """Compatibility tests for the deprecated plain-string return value."""
 
     @patch("posthog.ai.prompts._get_session")
     def test_successfully_fetch_a_prompt(self, mock_get_session):
@@ -61,7 +61,7 @@ def test_successfully_fetch_a_prompt(self, mock_get_session):
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog)
 
-        result = prompts.get("test-prompt")
+        result = prompts.get("test-prompt", with_metadata=False)
 
         self.assertEqual(result, self.mock_prompt_response["prompt"])
         mock_get.assert_called_once()
@@ -89,7 +89,7 @@ def test_successfully_fetch_a_specific_prompt_version(self, mock_get_session):
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog)
 
-        result = prompts.get("test-prompt", version=1)
+        result = prompts.get("test-prompt", version=1, with_metadata=False)
 
         self.assertEqual(result, versioned_prompt_response["prompt"])
         mock_get.assert_called_once()
@@ -111,7 +111,7 @@ def test_return_cached_prompt_when_fresh(self, mock_time, mock_get_session):
         prompts = Prompts(posthog)
 
         # First call - fetches from API
-        result1 = prompts.get("test-prompt", cache_ttl_seconds=300)
+        result1 = prompts.get("test-prompt", cache_ttl_seconds=300, with_metadata=False)
         self.assertEqual(result1, self.mock_prompt_response["prompt"])
         self.assertEqual(mock_get.call_count, 1)
 
@@ -119,7 +119,7 @@ def test_return_cached_prompt_when_fresh(self, mock_time, mock_get_session):
         mock_time.return_value = 1060.0
 
         # Second call - should use cache
-        result2 = prompts.get("test-prompt", cache_ttl_seconds=300)
+        result2 = prompts.get("test-prompt", cache_ttl_seconds=300, with_metadata=False)
         self.assertEqual(result2, self.mock_prompt_response["prompt"])
         self.assertEqual(mock_get.call_count, 1)  # No additional fetch
 
@@ -146,14 +146,20 @@ def test_cache_latest_and_versioned_prompts_separately(self, mock_get_session):
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog)
 
-        self.assertEqual(prompts.get("test-prompt"), latest_prompt_response["prompt"])
         self.assertEqual(
-            prompts.get("test-prompt", version=1),
+            prompts.get("test-prompt", with_metadata=False),
+            latest_prompt_response["prompt"],
+        )
+        self.assertEqual(
+            prompts.get("test-prompt", version=1, with_metadata=False),
             versioned_prompt_response["prompt"],
         )
-        self.assertEqual(prompts.get("test-prompt"), latest_prompt_response["prompt"])
         self.assertEqual(
-            prompts.get("test-prompt", version=1),
+            prompts.get("test-prompt", with_metadata=False),
+            latest_prompt_response["prompt"],
+        )
+        self.assertEqual(
+            prompts.get("test-prompt", version=1, with_metadata=False),
             versioned_prompt_response["prompt"],
         )
         self.assertEqual(mock_get.call_count, 2)
@@ -206,7 +212,9 @@ def test_version_and_label_together_raises(self):
         prompts = Prompts(self.create_mock_posthog())
 
         with self.assertRaises(ValueError):
-            prompts.get("test-prompt", version=1, label="production")
+            prompts.get(
+                "test-prompt", version=1, label="production", with_metadata=False
+            )
 
     @patch("posthog.ai.prompts._get_session")
     def test_cache_labeled_and_latest_prompts_separately(self, mock_get_session):
@@ -233,14 +241,20 @@ def test_cache_labeled_and_latest_prompts_separately(self, mock_get_session):
 
         # A labeled fetch after a latest fetch must not be served from the
         # latest cache entry — that would silently return the wrong version.
-        self.assertEqual(prompts.get("test-prompt"), latest_prompt_response["prompt"])
         self.assertEqual(
-            prompts.get("test-prompt", label="production"),
+            prompts.get("test-prompt", with_metadata=False),
+            latest_prompt_response["prompt"],
+        )
+        self.assertEqual(
+            prompts.get("test-prompt", label="production", with_metadata=False),
             labeled_prompt_response["prompt"],
         )
-        self.assertEqual(prompts.get("test-prompt"), latest_prompt_response["prompt"])
         self.assertEqual(
-            prompts.get("test-prompt", label="production"),
+            prompts.get("test-prompt", with_metadata=False),
+            latest_prompt_response["prompt"],
+        )
+        self.assertEqual(
+            prompts.get("test-prompt", label="production", with_metadata=False),
             labeled_prompt_response["prompt"],
         )
         self.assertEqual(mock_get.call_count, 2)
@@ -265,7 +279,7 @@ def test_refetch_when_cache_is_stale(self, mock_time, mock_get_session):
         prompts = Prompts(posthog)
 
         # First call - fetches from API
-        result1 = prompts.get("test-prompt", cache_ttl_seconds=60)
+        result1 = prompts.get("test-prompt", cache_ttl_seconds=60, with_metadata=False)
         self.assertEqual(result1, self.mock_prompt_response["prompt"])
         self.assertEqual(mock_get.call_count, 1)
 
@@ -273,7 +287,7 @@ def test_refetch_when_cache_is_stale(self, mock_time, mock_get_session):
         mock_time.return_value = 1061.0
 
         # Second call - should refetch
-        result2 = prompts.get("test-prompt", cache_ttl_seconds=60)
+        result2 = prompts.get("test-prompt", cache_ttl_seconds=60, with_metadata=False)
         self.assertEqual(result2, updated_prompt_response["prompt"])
         self.assertEqual(mock_get.call_count, 2)
 
@@ -295,14 +309,14 @@ def test_use_stale_cache_on_fetch_failure_with_warning(
         prompts = Prompts(posthog)
 
         # First call - populates cache
-        result1 = prompts.get("test-prompt", cache_ttl_seconds=60)
+        result1 = prompts.get("test-prompt", cache_ttl_seconds=60, with_metadata=False)
         self.assertEqual(result1, self.mock_prompt_response["prompt"])
 
         # Advance time past TTL
         mock_time.return_value = 1061.0
 
         # Second call - should use stale cache
-        result2 = prompts.get("test-prompt", cache_ttl_seconds=60)
+        result2 = prompts.get("test-prompt", cache_ttl_seconds=60, with_metadata=False)
         self.assertEqual(result2, self.mock_prompt_response["prompt"])
 
         # Check warning was logged
@@ -323,7 +337,7 @@ def test_use_fallback_when_no_cache_and_fetch_fails_with_warning(
         prompts = Prompts(posthog)
 
         fallback = "Default system prompt."
-        result = prompts.get("test-prompt", fallback=fallback)
+        result = prompts.get("test-prompt", fallback=fallback, with_metadata=False)
 
         self.assertEqual(result, fallback)
 
@@ -342,7 +356,7 @@ def test_throw_when_no_cache_no_fallback_and_fetch_fails(self, mock_get_session)
         prompts = Prompts(posthog)
 
         with self.assertRaises(Exception) as context:
-            prompts.get("test-prompt")
+            prompts.get("test-prompt", with_metadata=False)
 
         self.assertIn("Network error", str(context.exception))
 
@@ -368,7 +382,7 @@ def test_handle_404_response(
         prompts = Prompts(posthog)
 
         with self.assertRaises(Exception) as context:
-            prompts.get("nonexistent-prompt", **get_kwargs)
+            prompts.get("nonexistent-prompt", with_metadata=False, **get_kwargs)
 
         self.assertIn(expected_message, str(context.exception))
 
@@ -382,7 +396,7 @@ def test_handle_403_response(self, mock_get_session):
         prompts = Prompts(posthog)
 
         with self.assertRaises(Exception) as context:
-            prompts.get("restricted-prompt")
+            prompts.get("restricted-prompt", with_metadata=False)
 
         self.assertIn(
             'Access denied for prompt "restricted-prompt"', str(context.exception)
@@ -394,7 +408,7 @@ def test_throw_when_no_personal_api_key_configured(self):
         prompts = Prompts(posthog)
 
         with self.assertRaises(Exception) as context:
-            prompts.get("test-prompt")
+            prompts.get("test-prompt", with_metadata=False)
 
         self.assertIn(
             "personal_api_key is required to fetch prompts", str(context.exception)
@@ -406,7 +420,7 @@ def test_throw_when_no_project_api_key_configured(self):
         prompts = Prompts(posthog)
 
         with self.assertRaises(Exception) as context:
-            prompts.get("test-prompt")
+            prompts.get("test-prompt", with_metadata=False)
 
         self.assertIn(
             "project_api_key is required to fetch prompts", str(context.exception)
@@ -422,7 +436,7 @@ def test_throw_when_api_returns_invalid_response_format(self, mock_get_session):
         prompts = Prompts(posthog)
 
         with self.assertRaises(Exception) as context:
-            prompts.get("test-prompt")
+            prompts.get("test-prompt", with_metadata=False)
 
         self.assertIn("Invalid response format", str(context.exception))
 
@@ -435,7 +449,7 @@ def test_use_custom_host_from_posthog_options(self, mock_get_session):
         posthog = self.create_mock_posthog(host="https://eu.posthog.com")
         prompts = Prompts(posthog)
 
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
 
         call_args = mock_get.call_args
         self.assertTrue(
@@ -457,21 +471,21 @@ def test_use_default_cache_ttl_5_minutes(self, mock_time, mock_get_session):
         prompts = Prompts(posthog)
 
         # First call
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 1)
 
         # Advance time by 4 minutes (within default 5-minute TTL)
         mock_time.return_value = 1000.0 + (4 * 60)
 
         # Second call - should use cache
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 1)
 
         # Advance time past 5-minute TTL
         mock_time.return_value = 1000.0 + (6 * 60)
 
         # Third call - should refetch
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 2)
 
     @patch("posthog.ai.prompts._get_session")
@@ -488,14 +502,14 @@ def test_use_custom_default_cache_ttl_from_constructor(
         prompts = Prompts(posthog, default_cache_ttl_seconds=60)
 
         # First call
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 1)
 
         # Advance time past custom TTL
         mock_time.return_value = 1061.0
 
         # Second call - should refetch
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 2)
 
     @patch("posthog.ai.prompts._get_session")
@@ -507,7 +521,7 @@ def test_url_encode_prompt_names_with_special_characters(self, mock_get_session)
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog)
 
-        prompts.get("prompt with spaces/and/slashes")
+        prompts.get("prompt with spaces/and/slashes", with_metadata=False)
 
         call_args = mock_get.call_args
         self.assertEqual(
@@ -525,7 +539,7 @@ def test_work_with_direct_options_no_posthog_client(self, mock_get_session):
             personal_api_key="phx_direct_key", project_api_key="phc_direct_key"
         )
 
-        result = prompts.get("test-prompt")
+        result = prompts.get("test-prompt", with_metadata=False)
 
         self.assertEqual(result, self.mock_prompt_response["prompt"])
         call_args = mock_get.call_args
@@ -549,7 +563,7 @@ def test_use_custom_host_from_direct_options(self, mock_get_session):
             host="https://eu.posthog.com",
         )
 
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
 
         call_args = mock_get.call_args
         self.assertEqual(
@@ -574,14 +588,14 @@ def test_use_custom_default_cache_ttl_from_direct_options(
         )
 
         # First call
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 1)
 
         # Advance time past custom TTL
         mock_time.return_value = 1061.0
 
         # Second call - should refetch
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=False)
         self.assertEqual(mock_get.call_count, 2)
 
 
@@ -949,9 +963,11 @@ def test_capture_exception_called_on_fetch_failure_with_fallback(
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog, capture_errors=True)
 
-        result = prompts.get("test-prompt", fallback="fallback prompt", version=3)
+        result = prompts.get(
+            "test-prompt", fallback="fallback prompt", version=3, with_metadata=True
+        )
 
-        self.assertEqual(result, "fallback prompt")
+        self.assertEqual(result.prompt, "fallback prompt")
         posthog.capture_exception.assert_called_once()
         captured_exc = posthog.capture_exception.call_args[0][0]
         self.assertIn("Network error", str(captured_exc))
@@ -979,14 +995,14 @@ def test_capture_exception_called_on_fetch_failure_with_stale_cache(
         prompts = Prompts(posthog, capture_errors=True)
 
         # First call populates cache
-        prompts.get("test-prompt", cache_ttl_seconds=60)
+        prompts.get("test-prompt", cache_ttl_seconds=60, with_metadata=True)
 
         # Expire cache
         mock_time.return_value = 1061.0
 
         # Second call falls back to stale cache
-        result = prompts.get("test-prompt", cache_ttl_seconds=60)
-        self.assertEqual(result, self.mock_prompt_response["prompt"])
+        result = prompts.get("test-prompt", cache_ttl_seconds=60, with_metadata=True)
+        self.assertEqual(result.prompt, self.mock_prompt_response["prompt"])
         posthog.capture_exception.assert_called_once()
 
     @patch("posthog.ai.prompts._get_session")
@@ -999,7 +1015,7 @@ def test_capture_exception_called_when_error_is_raised(self, mock_get_session):
         prompts = Prompts(posthog, capture_errors=True)
 
         with self.assertRaises(Exception):
-            prompts.get("test-prompt")
+            prompts.get("test-prompt", with_metadata=True)
 
         posthog.capture_exception.assert_called_once()
 
@@ -1012,7 +1028,7 @@ def test_no_capture_exception_when_capture_errors_is_false(self, mock_get_sessio
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog)
 
-        prompts.get("test-prompt", fallback="fallback prompt")
+        prompts.get("test-prompt", fallback="fallback prompt", with_metadata=True)
 
         posthog.capture_exception.assert_not_called()
 
@@ -1028,9 +1044,11 @@ def test_no_capture_exception_without_client(self, mock_get_session):
             capture_errors=True,
         )
 
-        result = prompts.get("test-prompt", fallback="fallback prompt")
+        result = prompts.get(
+            "test-prompt", fallback="fallback prompt", with_metadata=True
+        )
 
-        self.assertEqual(result, "fallback prompt")
+        self.assertEqual(result.prompt, "fallback prompt")
 
     @patch("posthog.ai.prompts._get_session")
     def test_no_capture_exception_on_successful_fetch(self, mock_get_session):
@@ -1041,7 +1059,7 @@ def test_no_capture_exception_on_successful_fetch(self, mock_get_session):
         posthog = self.create_mock_posthog()
         prompts = Prompts(posthog, capture_errors=True)
 
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=True)
 
         posthog.capture_exception.assert_not_called()
 
@@ -1055,9 +1073,11 @@ def test_capture_exception_failure_does_not_affect_fallback(self, mock_get_sessi
         posthog.capture_exception.side_effect = Exception("capture failed")
         prompts = Prompts(posthog, capture_errors=True)
 
-        result = prompts.get("test-prompt", fallback="fallback prompt")
+        result = prompts.get(
+            "test-prompt", fallback="fallback prompt", with_metadata=True
+        )
 
-        self.assertEqual(result, "fallback prompt")
+        self.assertEqual(result.prompt, "fallback prompt")
 
 
 class TestPromptsClearCache(TestPrompts):
@@ -1080,8 +1100,8 @@ def _populate_versioned_cache(self, prompts, mock_get):
             MockResponse(json_data=versioned_prompt_response),
         ]
 
-        prompts.get("test-prompt")
-        prompts.get("test-prompt", version=1)
+        prompts.get("test-prompt", with_metadata=True)
+        prompts.get("test-prompt", version=1, with_metadata=True)
 
         return latest_prompt_response, versioned_prompt_response
 
@@ -1111,19 +1131,19 @@ def test_clear_a_specific_prompt_from_cache(self, mock_get_session):
         prompts = Prompts(posthog)
 
         # Populate cache with two prompts
-        prompts.get("test-prompt")
-        prompts.get("other-prompt")
+        prompts.get("test-prompt", with_metadata=True)
+        prompts.get("other-prompt", with_metadata=True)
         self.assertEqual(mock_get.call_count, 2)
 
         # Clear only test-prompt
         prompts.clear_cache("test-prompt")
 
         # test-prompt should be refetched
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=True)
         self.assertEqual(mock_get.call_count, 3)
 
         # other-prompt should still be cached
-        prompts.get("other-prompt")
+        prompts.get("other-prompt", with_metadata=True)
         self.assertEqual(mock_get.call_count, 3)
 
     @patch("posthog.ai.prompts._get_session")
@@ -1140,10 +1160,10 @@ def test_clear_a_specific_prompt_version_from_cache(self, mock_get_session):
         mock_get.side_effect = [MockResponse(json_data=versioned_prompt_response)]
         prompts.clear_cache("test-prompt", version=1)
 
-        prompts.get("test-prompt")
+        prompts.get("test-prompt", with_metadata=True)
         self.assertEqual(mock_get.call_count, 2)
 
-        prompts.get("test-prompt", version=1)
+        prompts.get("test-prompt", version=1, with_metadata=True)
         self.assertEqual(mock_get.call_count, 3)
 
     @patch("posthog.ai.prompts._get_session")
@@ -1165,8 +1185,8 @@ def test_clear_a_prompt_name_clears_all_cached_versions(self, mock_get_session):
         ]
         prompts.clear_cache("test-prompt")
 
-        prompts.get("test-prompt")
-        prompts.get("test-prompt", version=1)
+        prompts.get("test-prompt", with_metadata=True)
+        prompts.get("test-prompt", version=1, with_metadata=True)
         self.assertEqual(mock_get.call_count, 4)
 
     @patch("posthog.ai.prompts._get_session")
@@ -1186,16 +1206,16 @@ def test_clear_all_prompts_from_cache(self, mock_get_session):
         prompts = Prompts(posthog)
 
         # Populate cache with two prompts
-        prompts.get("test-prompt")
-        prompts.get("other-prompt")
+        prompts.get("test-prompt", with_metadata=True)
+        prompts.get("other-prompt", with_metadata=True)
         self.assertEqual(mock_get.call_count, 2)
 
         # Clear all cache
         prompts.clear_cache()
 
         # Both prompts should be refetched
-        prompts.get("test-prompt")
-        prompts.get("other-prompt")
+        prompts.get("test-prompt", with_metadata=True)
+        prompts.get("other-prompt", with_metadata=True)
         self.assertEqual(mock_get.call_count, 4)
 
 
diff --git a/posthog/test/test_client.py b/posthog/test/test_client.py
index 137fbeff..fd798f7b 100644
--- a/posthog/test/test_client.py
+++ b/posthog/test/test_client.py
@@ -9,6 +9,7 @@
 
 from opentelemetry.trace import NonRecordingSpan, SpanContext, TraceFlags, use_span
 from parameterized import parameterized
+import pytest
 
 from posthog.capture_compression import CaptureCompression
 from posthog.client import Client
@@ -21,6 +22,18 @@
 from posthog.contexts import tag
 
 
+# Legacy single-flag behavior remains covered here; warning emission itself is
+# asserted in test_evaluate_flags.py.
+pytestmark = [
+    pytest.mark.filterwarnings(
+        r"ignore:`(feature_enabled|get_feature_flag|get_feature_flag_payload)` is deprecated:DeprecationWarning"
+    ),
+    pytest.mark.filterwarnings(
+        r"ignore:`send_feature_flags` is deprecated:DeprecationWarning"
+    ),
+]
+
+
 class TestClient(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
@@ -70,12 +83,13 @@ def test_trims_api_key_whitespace(
             mock_error.assert_not_called()
 
     def test_trims_host_and_personal_api_key_whitespace(self):
-        client = Client(
-            FAKE_TEST_API_KEY,
-            host=" \nhttps://eu.posthog.com/\t ",
-            personal_api_key=" \n\t ",
-            send=False,
-        )
+        with self.assertWarnsRegex(DeprecationWarning, "personal_api_key"):
+            client = Client(
+                FAKE_TEST_API_KEY,
+                host=" \nhttps://eu.posthog.com/\t ",
+                personal_api_key=" \n\t ",
+                send=False,
+            )
 
         self.assertEqual(client.raw_host, "https://eu.posthog.com/")
         self.assertEqual(client.host, "https://eu.i.posthog.com")
@@ -201,7 +215,7 @@ def test_message_only_logs_do_not_duplicate_existing_posthog_prefix(self):
 
     @mock.patch("posthog.client.get")
     def test_disabled_client_does_not_load_feature_flags(self, patch_get):
-        client = Client("", personal_api_key="test", send=False)
+        client = Client("", secret_key="test", send=False)
 
         client.load_feature_flags()
 
@@ -677,7 +691,7 @@ def test_basic_capture_with_feature_flags(self, patch_flags):
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             msg_uuid = client.capture(
@@ -800,7 +814,7 @@ def test_basic_capture_with_locally_evaluated_feature_flags(self, patch_flags):
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             client.feature_flags = [multivariate_flag, basic_flag, false_flag]
@@ -838,7 +852,7 @@ def test_basic_capture_with_locally_evaluated_feature_flags(self, patch_flags):
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             client.feature_flags = []
@@ -865,7 +879,7 @@ def test_load_feature_flags_quota_limited(self, patch_get):
         }
         patch_get.side_effect = APIError(402, mock_response["detail"])
 
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         with self.assertLogs("posthog", level="WARNING") as logs:
             client._load_feature_flags()
 
@@ -879,7 +893,7 @@ def test_load_feature_flags_quota_limited(self, patch_get):
     def test_load_feature_flags_unauthorized(self, patch_get):
         patch_get.side_effect = APIError(401, "Unauthorized")
 
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         with self.assertLogs("posthog", level="ERROR") as logs:
             client._load_feature_flags()
 
@@ -970,7 +984,7 @@ def test_dont_override_capture_with_local_flags(self, patch_flags):
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             client.feature_flags = [multivariate_flag, basic_flag]
@@ -1020,7 +1034,7 @@ def test_basic_capture_with_feature_flags_returns_active_only(self, patch_flags)
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             msg_uuid = client.capture(
@@ -1079,7 +1093,7 @@ def test_feature_flags_request_max_retries_is_forwarded(
             client = Client(
                 FAKE_TEST_API_KEY,
                 feature_flags_request_max_retries=expected_max_retries,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
             )
 
             client.get_all_flags("distinct_id")
@@ -1105,7 +1119,7 @@ def test_basic_capture_with_feature_flags_and_disable_geoip_returns_correctly(
                 FAKE_TEST_API_KEY,
                 host="https://app.posthog.com",
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 disable_geoip=True,
                 feature_flags_request_timeout_seconds=12,
                 sync_mode=True,
@@ -1164,7 +1178,7 @@ def test_basic_capture_with_feature_flags_switched_off_doesnt_send_them(
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             msg_uuid = client.capture(
@@ -1242,7 +1256,7 @@ def test_capture_with_send_feature_flags_false_and_local_evaluation_doesnt_send_
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             client.feature_flags = [multivariate_flag, simple_flag]
@@ -1324,7 +1338,7 @@ def test_capture_with_send_feature_flags_true_and_local_evaluation_uses_local_fl
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
             client.feature_flags = [multivariate_flag, simple_flag]
@@ -1370,7 +1384,7 @@ def test_capture_with_send_feature_flags_options_only_evaluate_locally_true(
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
 
@@ -1425,7 +1439,7 @@ def test_capture_with_send_feature_flags_options_only_evaluate_locally_false(
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
 
@@ -1471,7 +1485,7 @@ def test_capture_with_send_feature_flags_options_default_behavior(
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
 
@@ -1509,7 +1523,7 @@ def test_capture_exception_with_send_feature_flags_options(self, patch_flags):
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
 
@@ -2416,7 +2430,7 @@ def raise_effect():
             raise Exception("http exception")
 
         patch_get.return_value.raiseError.side_effect = raise_effect
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [{"key": "example"}]
 
         self.assertFalse(client.feature_enabled("example", "distinct_id"))
@@ -2972,7 +2986,7 @@ def test_enable_local_evaluation_false_disables_poller(
 
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test-personal-key",
+            secret_key="test-personal-key",
             enable_local_evaluation=False,
         )
 
@@ -3008,7 +3022,7 @@ def test_enable_local_evaluation_true_starts_poller(self, patch_get, patch_polle
 
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test-personal-key",
+            secret_key="test-personal-key",
             enable_local_evaluation=True,
         )
 
@@ -3028,7 +3042,7 @@ def test_get_remote_config_payload_works_without_poller(self, patch_remote_confi
 
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test-personal-key",
+            secret_key="test-personal-key",
             enable_local_evaluation=False,
         )
 
@@ -3148,7 +3162,7 @@ def test_capture_with_send_feature_flags_flag_keys_filter(self, patch_flags):
             client = Client(
                 FAKE_TEST_API_KEY,
                 on_error=self.set_fail,
-                personal_api_key=FAKE_TEST_API_KEY,
+                secret_key=FAKE_TEST_API_KEY,
                 sync_mode=True,
             )
 
@@ -3185,7 +3199,7 @@ def test_get_feature_flag_result_with_empty_string_payload(self, patch_batch_pos
         """Test that get_feature_flag_result returns a FeatureFlagResult when payload is empty string"""
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test_personal_api_key",
+            secret_key="test_personal_api_key",
             sync_mode=True,
         )
 
@@ -3236,7 +3250,7 @@ def test_get_all_flags_and_payloads_with_empty_string(self, patch_batch_post):
         """Test that get_all_flags_and_payloads includes flags with empty string payloads"""
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test_personal_api_key",
+            secret_key="test_personal_api_key",
             sync_mode=True,
         )
 
diff --git a/posthog/test/test_client_fork.py b/posthog/test/test_client_fork.py
index eabae53b..294dcffb 100644
--- a/posthog/test/test_client_fork.py
+++ b/posthog/test/test_client_fork.py
@@ -59,7 +59,7 @@ def test_reinit_after_fork_keeps_memory_cache_instance(self):
     def test_reinit_after_fork_restarts_poller_when_enabled(self, mock_poller):
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key=FAKE_TEST_API_KEY,
+            secret_key=FAKE_TEST_API_KEY,
             send=False,
             enable_local_evaluation=True,
             poll_interval=123,
@@ -82,7 +82,7 @@ def test_reinit_after_fork_restarts_poller_when_enabled(self, mock_poller):
     def test_reinit_after_fork_clears_poller_when_local_evaluation_disabled(self):
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key=FAKE_TEST_API_KEY,
+            secret_key=FAKE_TEST_API_KEY,
             send=False,
             enable_local_evaluation=False,
         )
@@ -281,7 +281,7 @@ def child_probe():
     def test_register_at_fork_reinitializes_poller_and_sessions_in_child_process(self):
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key=FAKE_TEST_API_KEY,
+            secret_key=FAKE_TEST_API_KEY,
             send=False,
             enable_local_evaluation=True,
             poll_interval=100,
diff --git a/posthog/test/test_feature_flag_called_minimization.py b/posthog/test/test_feature_flag_called_minimization.py
index bf32d9d6..c32b4ea2 100644
--- a/posthog/test/test_feature_flag_called_minimization.py
+++ b/posthog/test/test_feature_flag_called_minimization.py
@@ -281,7 +281,7 @@ def _definitions_payload(self, has_experiment, gate):
     def test_gated_non_experiment_flag_sends_exactly_the_allowlist(
         self, patch_get, _patch_poller
     ):
-        client, captured = self._make_client(personal_api_key="personal-key")
+        client, captured = self._make_client(secret_key="personal-key")
         self._load_definitions(
             client,
             patch_get,
@@ -313,7 +313,7 @@ def test_gated_non_experiment_flag_sends_exactly_the_allowlist(
     @mock.patch("posthog.client.Poller")
     @mock.patch("posthog.client.get")
     def test_gated_experiment_flag_sends_full_event(self, patch_get, _patch_poller):
-        client, captured = self._make_client(personal_api_key="personal-key")
+        client, captured = self._make_client(secret_key="personal-key")
         self._load_definitions(
             client,
             patch_get,
@@ -331,7 +331,7 @@ def test_gated_experiment_flag_sends_full_event(self, patch_get, _patch_poller):
     @mock.patch("posthog.client.Poller")
     @mock.patch("posthog.client.get")
     def test_gate_absent_from_payload_sends_full_event(self, patch_get, _patch_poller):
-        client, captured = self._make_client(personal_api_key="personal-key")
+        client, captured = self._make_client(secret_key="personal-key")
         self._load_definitions(
             client,
             patch_get,
@@ -348,7 +348,7 @@ def test_gate_absent_from_payload_sends_full_event(self, patch_get, _patch_polle
     @mock.patch("posthog.client.Poller")
     @mock.patch("posthog.client.get")
     def test_gate_survives_not_modified_polls(self, patch_get, _patch_poller):
-        client, captured = self._make_client(personal_api_key="personal-key")
+        client, captured = self._make_client(secret_key="personal-key")
         self._load_definitions(
             client,
             patch_get,
diff --git a/posthog/test/test_feature_flags.py b/posthog/test/test_feature_flags.py
index 47eba37b..497069ef 100644
--- a/posthog/test/test_feature_flags.py
+++ b/posthog/test/test_feature_flags.py
@@ -7,6 +7,7 @@
 from dateutil.relativedelta import relativedelta
 from freezegun import freeze_time
 from parameterized import parameterized
+import pytest
 
 from posthog.client import Client
 import posthog.feature_flags
@@ -20,6 +21,18 @@
 from posthog.test.test_utils import FAKE_TEST_API_KEY
 
 
+# This module preserves the legacy single-flag API's compatibility behavior;
+# warning emission itself is asserted in test_evaluate_flags.py.
+pytestmark = [
+    pytest.mark.filterwarnings(
+        r"ignore:`(feature_enabled|get_feature_flag|get_feature_flag_payload)` is deprecated:DeprecationWarning"
+    ),
+    pytest.mark.filterwarnings(
+        r"ignore:send_feature_flag_events is deprecated in get_feature_flag_payload:DeprecationWarning"
+    ),
+]
+
+
 class TestLocalEvaluation(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
@@ -487,7 +500,7 @@ def test_flag_with_complex_definition(self, patch_get, patch_flags):
         patch_flags.return_value = {
             "featureFlags": {"complex-flag": "flags-fallback-value"}
         }
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -617,7 +630,7 @@ def test_feature_flags_fallback_to_flags(self, patch_get, patch_flags):
         patch_flags.return_value = {
             "featureFlags": {"beta-feature": "alakazam", "beta-feature2": "alakazam2"}
         }
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -685,7 +698,7 @@ def test_feature_flags_dont_fallback_to_flags_when_only_local_evaluation_is_true
         patch_flags.return_value = {
             "featureFlags": {"beta-feature": "alakazam", "beta-feature2": "alakazam2"}
         }
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -767,7 +780,7 @@ def test_feature_flag_never_returns_undefined_during_regular_evaluation(
         self, patch_get, patch_flags
     ):
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -802,7 +815,7 @@ def test_feature_flag_return_none_when_flags_errors_out(
         self, patch_get, patch_flags
     ):
         patch_flags.side_effect = APIError(400, "Flags error")
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = []
 
         # beta-feature2 falls back to /flags, which on error returns None
@@ -817,7 +830,7 @@ def test_experience_continuity_flag_not_evaluated_locally(self, patch_flags):
         patch_flags.return_value = {
             "featureFlags": {"beta-feature": "flags-fallback-value"}
         }
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -1345,7 +1358,7 @@ def test_compute_inactive_flags_locally(self, patch_flags, patch_capture):
     @mock.patch("posthog.client.flags")
     @mock.patch("posthog.client.get")
     def test_feature_flags_local_evaluation_None_values(self, patch_get, patch_flags):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 id: 1,
@@ -1420,7 +1433,7 @@ def test_feature_flags_local_evaluation_None_values(self, patch_get, patch_flags
     @mock.patch("posthog.client.flags")
     @mock.patch("posthog.client.get")
     def test_feature_flags_local_evaluation_for_cohorts(self, patch_get, patch_flags):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 2,
@@ -1508,7 +1521,7 @@ def test_feature_flags_local_evaluation_for_cohorts(self, patch_get, patch_flags
     def test_feature_flags_local_evaluation_for_negated_cohorts(
         self, patch_get, patch_flags
     ):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 2,
@@ -1611,7 +1624,7 @@ def test_feature_flags_with_flag_dependencies(
     ):
         # Mock remote flags call to return empty for this flag (fallback returns None)
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -1670,7 +1683,7 @@ def test_feature_flags_with_flag_dependencies(
     @mock.patch("posthog.client.get")
     def test_flag_dependencies_simple_chain(self, patch_get, patch_flags):
         """Test basic flag dependency: flag-b depends on flag-a"""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -1739,7 +1752,7 @@ def test_flag_dependencies_circular_dependency(self, patch_get, patch_flags):
         """Test circular dependency handling: flag-a depends on flag-b, flag-b depends on flag-a"""
         # Mock remote flags call to return empty for these flags (fallback returns None)
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -1801,7 +1814,7 @@ def test_flag_dependencies_missing_flag(self, patch_get, patch_flags):
         """Test handling of missing flag dependency"""
         # Mock remote flags call to return empty for this flag (fallback returns None)
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -1836,7 +1849,7 @@ def test_flag_dependencies_missing_flag(self, patch_get, patch_flags):
     @mock.patch("posthog.client.get")
     def test_flag_dependencies_complex_chain(self, patch_get, patch_flags):
         """Test complex dependency chain: flag-d -> flag-c -> [flag-a, flag-b]"""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -1932,7 +1945,7 @@ def test_flag_dependencies_complex_chain(self, patch_get, patch_flags):
     @mock.patch("posthog.client.get")
     def test_flag_dependencies_mixed_conditions(self, patch_get, patch_flags):
         """Test flag dependency mixed with other property conditions"""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2009,7 +2022,7 @@ def test_flag_dependencies_malformed_chain(self, patch_get, patch_flags):
         """Test handling of malformed dependency chains"""
         # Mock remote flags call to return empty for this flag (fallback returns None)
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2087,7 +2100,7 @@ def test_flag_dependencies_without_context_raises_inconclusive(self):
     @mock.patch("posthog.client.get")
     def test_flag_dependencies_evaluates_to_false(self, patch_get, patch_flags):
         """A `flag_evaluates_to: false` condition matches when the referenced flag is conclusively False, without falling back to /flags."""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2150,7 +2163,7 @@ def test_flag_dependencies_multi_level_evaluates_to_false(
         self, patch_get, patch_flags
     ):
         """Multi-level chain with a legitimately-False ancestor: A(false) -> B(true) -> D(true)."""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2217,7 +2230,7 @@ def test_flag_dependencies_inactive_base_evaluates_to_false(
         self, patch_get, patch_flags
     ):
         """An inactive base flag caches False, so `flag_evaluates_to: false` matches."""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2260,7 +2273,7 @@ def test_flag_dependencies_inconclusive_base_falls_back(
     ):
         """An inconclusive base (missing person properties) is distinct from False and falls back to /flags."""
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2319,7 +2332,7 @@ def test_flag_dependencies_null_value_no_match_locally(
     ):
         """A malformed `value: null` condition is a definitive local no-match (False), never falling back to /flags."""
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2365,7 +2378,7 @@ def test_flag_dependencies_missing_key_no_match_locally(
     ):
         """A dependency condition with an empty/missing `key` is a definitive local no-match (False)."""
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2409,7 +2422,7 @@ def test_flag_dependencies_wrong_operator_no_match_locally(
     ):
         """A dependency condition with the wrong operator is a definitive local no-match (False)."""
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2453,7 +2466,7 @@ def test_flag_dependencies_malformed_condition_warns_once(
     ):
         """A malformed dependency condition warns on first eval, then stays quiet (dedup)."""
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2511,7 +2524,7 @@ def test_flag_dependencies_malformed_condition_falls_through_to_other_group(
     ):
         """A malformed dependency condition no-matches its group, but a second matching group still resolves the flag locally."""
         patch_flags.return_value = {"featureFlags": {}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -2579,7 +2592,7 @@ def test_flag_dependencies_malformed_condition_falls_through_to_other_group(
     @mock.patch("posthog.client.get")
     def test_multi_level_multivariate_dependency_chain(self, patch_get, patch_flags):
         """Test multi-level multivariate dependency chain: dependent-flag -> intermediate-flag -> leaf-flag"""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             # Leaf flag: multivariate with "control" and "test" variants using person property overrides
             {
@@ -2846,7 +2859,7 @@ def test_production_style_multivariate_dependency_chain(
         self, patch_get, patch_flags
     ):
         """Test production-style multivariate dependency chain: multivariate-root-flag -> multivariate-intermediate-flag -> multivariate-leaf-flag"""
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             # Leaf flag: multivariate with fruit variants
             {
@@ -3109,7 +3122,7 @@ def test_load_feature_flags(self, patch_get, patch_poll):
             },
             etag='"abc123"',
         )
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         with freeze_time("2020-01-01T12:01:00.0000Z"):
             client.load_feature_flags()
         self.assertEqual(len(client.feature_flags), 2)
@@ -3136,7 +3149,7 @@ def test_load_feature_flags_sends_etag_on_subsequent_requests(
             },
             etag='"initial-etag"',
         )
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.load_feature_flags()
 
         # First call should have no etag
@@ -3171,7 +3184,7 @@ def test_load_feature_flags_304_not_modified(self, patch_get, patch_poll):
         )
         patch_get.side_effect = [initial_response, not_modified_response]
 
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.load_feature_flags()
 
         # Verify initial flags are loaded
@@ -3212,7 +3225,7 @@ def test_load_feature_flags_etag_updated_on_new_response(
             ),
         ]
 
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.load_feature_flags()
         self.assertEqual(client._flags_etag, '"etag-v1"')
 
@@ -3245,7 +3258,7 @@ def test_load_feature_flags_clears_etag_when_server_stops_sending(
             ),
         ]
 
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.load_feature_flags()
         self.assertEqual(client._flags_etag, '"etag-v1"')
 
@@ -3257,7 +3270,7 @@ def test_load_feature_flags_clears_etag_when_server_stops_sending(
     @mock.patch("posthog.client.get")
     def test_load_feature_flags_wrong_key(self, patch_get, _patch_poll):
         patch_get.side_effect = APIError(401, "Unauthorized")
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         with self.assertLogs("posthog", level="ERROR") as logs:
             client.load_feature_flags()
@@ -3367,7 +3380,7 @@ def test_feature_enabled_simple_with_project_api_key(self, patch_get):
     @mock.patch("posthog.client.flags")
     def test_feature_enabled_request_multi_variate(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"beta-feature": "variant-1"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -3412,7 +3425,7 @@ def test_feature_enabled_simple_without_rollout_percentage(self, patch_get):
     @mock.patch("posthog.client.flags")
     def test_get_feature_flag(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"beta-feature": "variant-1"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -3457,7 +3470,7 @@ def test_feature_enabled_doesnt_exist(self, patch_flags, patch_poll):
     @mock.patch("posthog.client.Poller")
     @mock.patch("posthog.client.flags")
     def test_personal_api_key_doesnt_exist(self, patch_flags, patch_poll):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = []
 
         patch_flags.return_value = {"featureFlags": {"feature-flag": True}}
@@ -3471,7 +3484,7 @@ def raise_effect():
             raise Exception("http exception")
 
         patch_get.return_value.raiseError.side_effect = raise_effect
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = []
 
         self.assertFalse(client.feature_enabled("doesnt-exist", "distinct_id"))
@@ -3479,7 +3492,7 @@ def raise_effect():
     @mock.patch("posthog.client.flags")
     def test_get_feature_flag_with_variant_overrides(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"beta-feature": "variant-1"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -3542,7 +3555,7 @@ def test_get_feature_flag_with_variant_overrides(self, patch_flags):
     @mock.patch("posthog.client.flags")
     def test_flag_with_clashing_variant_overrides(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"beta-feature": "variant-1"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -3623,7 +3636,7 @@ def test_flag_with_clashing_variant_overrides(self, patch_flags):
     @mock.patch("posthog.client.flags")
     def test_flag_with_invalid_variant_overrides(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"beta-feature": "variant-1"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -3686,7 +3699,7 @@ def test_flag_with_invalid_variant_overrides(self, patch_flags):
     @mock.patch("posthog.client.flags")
     def test_conditions_evaluated_in_order(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"order-test": "server-variant"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key="test")
+        client = Client(FAKE_TEST_API_KEY, secret_key="test")
         client.feature_flags = [
             {
                 "id": 1,
@@ -3907,7 +3920,7 @@ def test_fallback_to_api_when_flag_has_static_cohort_in_multi_condition(
         This prevents returning wrong variants when later conditions could match
         locally but the user is actually in the static cohort.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # Mock the local flags response - cohort 999 is NOT in cohorts map (static cohort)
         client.feature_flags = [
@@ -3969,7 +3982,7 @@ def test_device_id_bucketing_uses_device_id_for_hash(self, patch_flags):
         When a flag has bucketing_identifier: "device_id", the device_id should be
         used for hashing instead of distinct_id.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # This flag uses device_id for bucketing
         client.feature_flags = [
@@ -4048,7 +4061,7 @@ def test_device_id_bucketing_same_device_different_users_same_result(
         When a flag uses device_id bucketing, different distinct_ids with the same
         device_id should get the same result.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4091,7 +4104,7 @@ def test_device_id_bucketing_fallback_when_device_id_missing(self, patch_flags):
         it should fallback to server evaluation.
         """
         patch_flags.return_value = {"featureFlags": {"device-bucketed-flag": True}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4125,7 +4138,7 @@ def test_device_id_bucketing_returns_none_when_only_evaluate_locally_and_no_devi
         When only_evaluate_locally=True and device_id is required but missing,
         should return None instead of falling back to API.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4159,7 +4172,7 @@ def test_default_bucketing_identifier_uses_distinct_id(self, patch_flags):
         When bucketing_identifier is not set or is 'distinct_id', should use
         distinct_id for hashing (default behavior).
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # Flag without bucketing_identifier (defaults to distinct_id)
         client.feature_flags = [
@@ -4192,7 +4205,7 @@ def test_device_id_bucketing_with_multivariate_flag(self, patch_flags):
         Multivariate flag variant selection should use device_id when
         bucketing_identifier is set to device_id.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4239,7 +4252,7 @@ def test_device_id_bucketing_from_context(self, patch_flags):
         """
         from posthog.contexts import new_context, set_context_device_id
 
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4273,7 +4286,7 @@ def test_group_flags_ignore_bucketing_identifier(self, patch_flags):
         Group flags should continue to use the group identifier for hashing,
         regardless of the bucketing_identifier setting.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4312,7 +4325,7 @@ def test_group_flag_dependency_receives_device_id(self, patch_flags):
         device_id-bucketed flags can be evaluated locally.
         """
         patch_flags.return_value = {"featureFlags": {"group-parent-flag": "from-api"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4373,7 +4386,7 @@ def test_group_flag_dependency_ignores_device_id_bucketing_identifier(
         the dependent group flag has bucketing_identifier set to device_id.
         """
         patch_flags.return_value = {"featureFlags": {"parent-group-flag": "from-api"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4489,7 +4502,7 @@ def test_group_flag_dependency_ignores_device_id_bucketing_identifier(
     )
     @mock.patch("posthog.client.flags")
     def test_mixed_targeting(self, _name, call_kwargs, expected, patch_flags):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [self.MIXED_FLAG]
         client.group_type_mapping = {"0": "company"}
 
@@ -4499,7 +4512,7 @@ def test_mixed_targeting(self, _name, call_kwargs, expected, patch_flags):
 
     @mock.patch("posthog.client.flags")
     def test_mixed_targeting_only_group_conditions_no_groups_passed(self, patch_flags):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -4529,7 +4542,7 @@ def test_mixed_targeting_only_group_conditions_no_groups_passed(self, patch_flag
 
     @mock.patch("posthog.client.flags")
     def test_mixed_targeting_rollout_uses_correct_bucketing(self, patch_flags):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -4569,7 +4582,7 @@ def test_get_all_flags_with_device_id_bucketing(self, patch_flags):
         """
         get_all_flags_and_payloads should properly handle flags with device_id bucketing.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -4609,7 +4622,7 @@ def test_get_all_flags_fallback_when_device_id_missing_for_some_flags(
         patch_flags.return_value = {
             "featureFlags": {"normal-flag": True, "device-flag": "from-api"}
         }
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -5573,7 +5586,7 @@ class TestCaptureCalls(unittest.TestCase):
     @mock.patch("posthog.client.flags")
     def test_capture_is_called(self, patch_flags, patch_capture):
         patch_flags.return_value = {"featureFlags": {"flags-flag": "flags-value"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -5800,7 +5813,7 @@ def test_capture_is_called_with_flag_details_and_payload(
     @mock.patch("posthog.client.flags")
     def test_capture_is_called_but_does_not_add_all_flags(self, patch_flags):
         patch_flags.return_value = {"featureFlags": {"flags-flag": "flags-value"}}
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -5858,9 +5871,7 @@ def test_get_feature_flag_payload_does_not_send_feature_flag_called_events(
             "featureFlags": {"person-flag": True},
             "featureFlagPayloads": {"person-flag": 300},
         }
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         client.feature_flags = [
             {
@@ -5896,7 +5907,7 @@ def test_fallback_to_api_in_get_feature_flag_payload_when_flag_has_static_cohort
         Test that get_feature_flag_payload falls back to API when evaluating
         a flag with static cohorts, similar to get_feature_flag behavior.
         """
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # Mock the local flags response - cohort 999 is NOT in cohorts map (static cohort)
         client.feature_flags = [
@@ -5947,7 +5958,7 @@ def test_fallback_to_api_in_get_feature_flag_payload_when_flag_has_static_cohort
     def test_disable_geoip_get_flag_capture_call(self, patch_flags, patch_capture):
         patch_flags.return_value = {"featureFlags": {"flags-flag": "flags-value"}}
         client = Client(
-            FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY, disable_geoip=True
+            FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY, disable_geoip=True
         )
         client.feature_flags = [
             {
@@ -5989,7 +6000,7 @@ def test_disable_geoip_get_flag_capture_call(self, patch_flags, patch_capture):
     @mock.patch.object(Client, "capture")
     @mock.patch("posthog.client.flags")
     def test_capture_fires_per_group_context(self, patch_flags, patch_capture):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -6038,7 +6049,7 @@ def test_capture_fires_per_group_context(self, patch_flags, patch_capture):
     def test_capture_dedupes_repeated_calls_under_same_group_context(
         self, _name, first_groups, second_groups, patch_flags, patch_capture
     ):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -6066,7 +6077,7 @@ def test_capture_dedupes_repeated_calls_under_same_group_context(
     def test_capture_multiple_users_doesnt_out_of_memory(
         self, patch_flags, patch_capture
     ):
-        client = Client(FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY)
+        client = Client(FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         # Set on the instance to avoid relying on module-constant patching behavior
         # across Python/runtime implementations.
         client.distinct_ids_feature_flags_reported.max_size = 100
@@ -6087,29 +6098,30 @@ def test_capture_multiple_users_doesnt_out_of_memory(
             }
         ]
 
-        for i in range(1000):
-            distinct_id = f"some-distinct-id{i}"
-            client.get_feature_flag(
-                "complex-flag",
-                distinct_id,
-                person_properties={"region": "USA", "name": "Aloha"},
-            )
-            patch_capture.assert_called_with(
-                "$feature_flag_called",
-                distinct_id=distinct_id,
-                properties={
-                    "$feature_flag": "complex-flag",
-                    "$feature_flag_response": True,
-                    "locally_evaluated": True,
-                    "$feature/complex-flag": True,
-                },
-                groups={},
-                disable_geoip=None,
-            )
+        with pytest.warns(DeprecationWarning, match="get_feature_flag.*deprecated"):
+            for i in range(1000):
+                distinct_id = f"some-distinct-id{i}"
+                client.get_feature_flag(
+                    "complex-flag",
+                    distinct_id,
+                    person_properties={"region": "USA", "name": "Aloha"},
+                )
+                patch_capture.assert_called_with(
+                    "$feature_flag_called",
+                    distinct_id=distinct_id,
+                    properties={
+                        "$feature_flag": "complex-flag",
+                        "$feature_flag_response": True,
+                        "locally_evaluated": True,
+                        "$feature/complex-flag": True,
+                    },
+                    groups={},
+                    disable_geoip=None,
+                )
 
-            self.assertEqual(
-                len(client.distinct_ids_feature_flags_reported), i % 100 + 1
-            )
+                self.assertEqual(
+                    len(client.distinct_ids_feature_flags_reported), i % 100 + 1
+                )
 
 
 class TestConsistency(unittest.TestCase):
@@ -7152,15 +7164,18 @@ def test_simple_flag_consistency(self, patch_get):
             True,
         ]
 
-        for i in range(1000):
-            distinctID = f"distinct_id_{i}"
+        with pytest.warns(DeprecationWarning, match="feature_enabled.*deprecated"):
+            for i in range(1000):
+                distinctID = f"distinct_id_{i}"
 
-            feature_flag_match = self.client.feature_enabled("simple-flag", distinctID)
+                feature_flag_match = self.client.feature_enabled(
+                    "simple-flag", distinctID
+                )
 
-            if results[i]:
-                self.assertTrue(feature_flag_match)
-            else:
-                self.assertFalse(feature_flag_match)
+                if results[i]:
+                    self.assertTrue(feature_flag_match)
+                else:
+                    self.assertFalse(feature_flag_match)
 
     @mock.patch("posthog.client.get")
     def test_multivariate_flag_consistency(self, patch_get):
@@ -8208,16 +8223,17 @@ def test_multivariate_flag_consistency(self, patch_get):
             "first-variant",
         ]
 
-        for i in range(1000):
-            distinctID = f"distinct_id_{i}"
-            feature_flag_match = self.client.get_feature_flag(
-                "multivariate-flag", distinctID
-            )
+        with pytest.warns(DeprecationWarning, match="get_feature_flag.*deprecated"):
+            for i in range(1000):
+                distinctID = f"distinct_id_{i}"
+                feature_flag_match = self.client.get_feature_flag(
+                    "multivariate-flag", distinctID
+                )
 
-            if results[i]:
-                self.assertEqual(feature_flag_match, results[i])
-            else:
-                self.assertFalse(feature_flag_match)
+                if results[i]:
+                    self.assertEqual(feature_flag_match, results[i])
+                else:
+                    self.assertFalse(feature_flag_match)
 
     @mock.patch("posthog.client.flags")
     def test_feature_flag_case_sensitive(self, mock_flags):
@@ -8225,9 +8241,7 @@ def test_feature_flag_case_sensitive(self, mock_flags):
             "featureFlags": {}
         }  # Ensure /flags returns empty flags
 
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -8251,9 +8265,7 @@ def test_feature_flag_payload_case_sensitive(self, mock_flags):
             "featureFlagPayloads": {"Beta-Feature": {"some": "value"}},
         }
 
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -8282,9 +8294,7 @@ def test_feature_flag_case_sensitive_consistency(self, mock_flags):
             "featureFlagPayloads": {"Beta-Feature": {"some": "value"}},
         }
 
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
         client.feature_flags = [
             {
                 "id": 1,
@@ -8321,9 +8331,7 @@ def test_get_all_flags_with_flag_keys_to_evaluate(self, mock_flags):
             }
         }
 
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # Call get_all_flags with flag_keys_to_evaluate
         result = client.get_all_flags(
@@ -8355,9 +8363,7 @@ def test_get_all_flags_and_payloads_with_flag_keys_to_evaluate(self, mock_flags)
             },
         }
 
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # Call get_all_flags_and_payloads with flag_keys_to_evaluate
         result = client.get_all_flags_and_payloads(
@@ -8384,9 +8390,7 @@ def test_get_all_flags_and_payloads_with_flag_keys_to_evaluate(self, mock_flags)
 
     def test_get_all_flags_locally_with_flag_keys_to_evaluate(self):
         """Test that local evaluation with flag_keys_to_evaluate only evaluates specified flags"""
-        client = Client(
-            project_api_key=FAKE_TEST_API_KEY, personal_api_key=FAKE_TEST_API_KEY
-        )
+        client = Client(project_api_key=FAKE_TEST_API_KEY, secret_key=FAKE_TEST_API_KEY)
 
         # Set up multiple flags
         client.feature_flags = [
diff --git a/posthog/test/test_flag_definition_cache.py b/posthog/test/test_flag_definition_cache.py
index 8cee6618..149ee332 100644
--- a/posthog/test/test_flag_definition_cache.py
+++ b/posthog/test/test_flag_definition_cache.py
@@ -123,7 +123,7 @@ def _create_client_with_cache(self) -> Client:
         """Create a client with the mock cache provider."""
         return Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test-personal-key",
+            secret_key="test-personal-key",
             flag_definition_cache_provider=self.cache_provider,
             sync_mode=True,
             enable_local_evaluation=False,  # Disable poller for tests
@@ -636,7 +636,7 @@ def test_works_without_cache_provider(self, mock_get):
         # Create client without cache provider
         client = Client(
             FAKE_TEST_API_KEY,
-            personal_api_key="test-personal-key",
+            secret_key="test-personal-key",
             sync_mode=True,
             enable_local_evaluation=False,
         )