📈(backend) capture an event when a user logs in

We want to capture an event every time a user logs in.

src/backend/core/authentication/backends.py

@@ -12,6 +12,7 @@ from lasuite.oidc_login.backends import (
 )
 
 from core.models import DuplicateEmailError
+from core.utils.analytics import PosthogEventName, posthog_capture
 
 logger = logging.getLogger(__name__)
 
@@ -77,3 +78,6 @@ class OIDCAuthenticationBackend(LaSuiteOIDCAuthenticationBackend):
             create_or_update_contact.delay(
                 email=user.email, attributes={"DOCS_SOURCE": ["SIGNIN"]}
             )
+
+        if user:
+            posthog_capture(PosthogEventName.USER_LOGIN, user)

src/backend/core/tests/authentication/test_backends.py

@@ -17,6 +17,7 @@ from core.authentication.backends import (
     create_or_update_contact,
 )
 from core.factories import UserFactory
+from core.utils.analytics import PosthogEventName
 
 pytestmark = pytest.mark.django_db
 
@@ -502,13 +503,22 @@ def test_authentication_post_get_or_create_user_new_user_to_marketing_email(sett
     settings.SIGNUP_NEW_USER_TO_MARKETING_EMAIL = True
 
     klass = OIDCAuthenticationBackend()
-    with mock.patch.object(
-        create_or_update_contact, "delay"
-    ) as mock_create_or_update_contact:
+    with (
+        mock.patch.object(
+            create_or_update_contact, "delay"
+        ) as mock_create_or_update_contact,
+        mock.patch(
+            "core.authentication.backends.posthog_capture"
+        ) as mock_posthog_capture,
+    ):
         klass.post_get_or_create_user(user, {}, True)
         mock_create_or_update_contact.assert_called_once_with(
             email=user.email, attributes={"DOCS_SOURCE": ["SIGNIN"]}
         )
+        mock_posthog_capture.assert_called_once_with(
+            PosthogEventName.USER_LOGIN,
+            user,
+        )
 
 
 def test_authentication_post_get_or_create_user_new_user_to_marketing_email_disabled(
@@ -523,11 +533,20 @@ def test_authentication_post_get_or_create_user_new_user_to_marketing_email_disa
     settings.SIGNUP_NEW_USER_TO_MARKETING_EMAIL = False
 
     klass = OIDCAuthenticationBackend()
-    with mock.patch.object(
-        create_or_update_contact, "delay"
-    ) as mock_create_or_update_contact:
+    with (
+        mock.patch.object(
+            create_or_update_contact, "delay"
+        ) as mock_create_or_update_contact,
+        mock.patch(
+            "core.authentication.backends.posthog_capture"
+        ) as mock_posthog_capture,
+    ):
         klass.post_get_or_create_user(user, {}, True)
         mock_create_or_update_contact.assert_not_called()
+        mock_posthog_capture.assert_called_once_with(
+            PosthogEventName.USER_LOGIN,
+            user,
+        )
 
 
 def test_authentication_post_get_or_create_user_existing_user_to_marketing_email(
@@ -542,11 +561,20 @@ def test_authentication_post_get_or_create_user_existing_user_to_marketing_email
     settings.SIGNUP_NEW_USER_TO_MARKETING_EMAIL = True
 
     klass = OIDCAuthenticationBackend()
-    with mock.patch.object(
-        create_or_update_contact, "delay"
-    ) as mock_create_or_update_contact:
+    with (
+        mock.patch.object(
+            create_or_update_contact, "delay"
+        ) as mock_create_or_update_contact,
+        mock.patch(
+            "core.authentication.backends.posthog_capture"
+        ) as mock_posthog_capture,
+    ):
         klass.post_get_or_create_user(user, {}, False)
         mock_create_or_update_contact.assert_not_called()
+        mock_posthog_capture.assert_called_once_with(
+            PosthogEventName.USER_LOGIN,
+            user,
+        )
 
 
 def test_authentication_post_get_or_create_user_existing_user_to_marketing_email_disabled(
@@ -561,8 +589,17 @@ def test_authentication_post_get_or_create_user_existing_user_to_marketing_email
     settings.SIGNUP_NEW_USER_TO_MARKETING_EMAIL = False
 
     klass = OIDCAuthenticationBackend()
-    with mock.patch.object(
-        create_or_update_contact, "delay"
-    ) as mock_create_or_update_contact:
+    with (
+        mock.patch.object(
+            create_or_update_contact, "delay"
+        ) as mock_create_or_update_contact,
+        mock.patch(
+            "core.authentication.backends.posthog_capture"
+        ) as mock_posthog_capture,
+    ):
         klass.post_get_or_create_user(user, {}, False)
         mock_create_or_update_contact.assert_not_called()
+        mock_posthog_capture.assert_called_once_with(
+            PosthogEventName.USER_LOGIN,
+            user,
+        )

src/backend/core/utils/analytics.py

@@ -16,6 +16,7 @@ class PosthogEventName(StrEnum):
 
     DOC_CREATED = "doc_created"
     DOC_DELETED = "doc_deleted"
+    USER_LOGIN = "user_login"
 
 
 def posthog_capture(