Backend: migrate notification translations and email ICS attachments toggles to feature flags

Move ENABLE_NOTIFICATION_TRANSLATIONS and ENABLE_EMAIL_ICS_ATTACHMENTS from
env config onto per-user feature flags (notification_translations_enabled,
email_ics_attachments_enabled, both defaulting True). Both are evaluated for
the recipient user in the notification-email job via make_background_user_context,
since that context has the user in scope; the ICS decision is threaded into
render_email_notification as a keyword argument to keep the renderer pure.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: aapeliv

app/backend.dev.env

@@ -33,8 +33,6 @@ SMS_SENDER_ID=invalid
 NOTIFICATION_EMAIL_SENDER=Couchers.org
 NOTIFICATION_EMAIL_ADDRESS=notify@couchers.org.invalid
 NOTIFICATION_PREFIX='[DEV] '
-ENABLE_NOTIFICATION_TRANSLATIONS=1
-ENABLE_EMAIL_ICS_ATTACHMENTS=1
 
 REPORTS_EMAIL_RECIPIENT=reports@couchers.org.invalid
 CONTRIBUTOR_FORM_EMAIL_RECIPIENT=forms@couchers.org.invalid

app/backend/src/couchers/config.py

@@ -64,8 +64,6 @@
     ("NOTIFICATION_EMAIL_ADDRESS", str),
     # An optional prefix for email subject, e.g. [STAGING]
     ("NOTIFICATION_PREFIX", str, ""),
-    ("ENABLE_NOTIFICATION_TRANSLATIONS", bool),
-    ("ENABLE_EMAIL_ICS_ATTACHMENTS", bool),
     # Address to send emails about reported users
     ("REPORTS_EMAIL_RECIPIENT", str),
     # Address to send contributor forms when users sign up/fill the form

app/backend/src/couchers/notifications/background.py

@@ -41,11 +41,18 @@ def _send_email_notification(session: Session, user: User, notification: Notific
         logger.info(f"Tried emailing {user} based on notification {notification.topic_action} but user is deleted")
         return
 
+    context = make_background_user_context(user.id)
+
     loc_context = LocalizationContext.from_user(user)
-    if not config["ENABLE_NOTIFICATION_TRANSLATIONS"]:
+    if not context.get_boolean_value("notification_translations_enabled", default=True):
         loc_context = dataclasses.replace(loc_context, locale="en")
 
-    rendered = render_email_notification(user, notification, loc_context)
+    rendered = render_email_notification(
+        user,
+        notification,
+        loc_context,
+        include_ics_attachments=context.get_boolean_value("email_ics_attachments_enabled", default=True),
+    )
 
     queue_email(
         session,

app/backend/src/couchers/notifications/render_email.py

@@ -41,7 +41,7 @@ class RenderedEmailNotification:
 
 
 def render_email_notification(
-    user: User, notification: Notification, loc_context: LocalizationContext
+    user: User, notification: Notification, loc_context: LocalizationContext, *, include_ics_attachments: bool
 ) -> RenderedEmailNotification:
     footer = get_email_footer(user, notification, loc_context)
 
@@ -90,7 +90,7 @@ def render_email_notification(
         source_data = config["VERSION"] + f"/{custom_templated.template_name}"
 
     list_unsubscribe_header = get_list_unsubscribe_header(notification)
-    if config.get("ENABLE_EMAIL_ICS_ATTACHMENTS"):
+    if include_ics_attachments:
         attachment = get_ics_attachment(notification, loc_context)
     else:
         attachment = None

app/backend/src/tests/conftest.py

@@ -173,7 +173,6 @@ def testconfig():
     config["REPORTS_EMAIL_RECIPIENT"] = "reports@couchers.org.invalid"
     config["CONTRIBUTOR_FORM_EMAIL_RECIPIENT"] = "forms@couchers.org.invalid"
     config["MODS_EMAIL_RECIPIENT"] = "mods@couchers.org.invalid"
-    config["ENABLE_EMAIL_ICS_ATTACHMENTS"] = True
 
     config["STRIPE_API_KEY"] = ""
     config["STRIPE_WEBHOOK_SECRET"] = ""
@@ -246,8 +245,6 @@ def testconfig():
     config["SLACK_DONATIONS_CHANNEL"] = ""
     config["SLACK_MERCH_CHANNEL"] = ""
 
-    config["ENABLE_NOTIFICATION_TRANSLATIONS"] = False
-
     yield None
 
     config.clear()

app/backend/src/tests/test_calendar_events.py

@@ -175,6 +175,44 @@ def test_host_request_attachments(db, moderator: Moderator):
     assert ics_event.status == "CANCELLED"
 
 
+def test_host_request_attachments_disabled(db, feature_flags, moderator: Moderator):
+    feature_flags.set("email_ics_attachments_enabled", False)
+
+    host, host_token = generate_user(complete_profile=True)
+    surfer, surfer_token = generate_user(complete_profile=True)
+
+    from_date = today() + timedelta(days=2)
+    to_date = today() + timedelta(days=3)
+
+    with requests_session(surfer_token) as api:
+        hr_id = api.CreateHostRequest(
+            requests_pb2.CreateHostRequestReq(
+                host_user_id=host.id,
+                from_date=from_date.isoformat(),
+                to_date=to_date.isoformat(),
+                text=valid_request_text("can i stay plz"),
+            )
+        ).host_request_id
+
+    with mock_notification_email():
+        moderator.approve_host_request(hr_id)
+
+    # Host accepts: normally the surfer would get a calendar attachment, but the flag is off
+    with requests_session(host_token) as api:
+        with mock_notification_email() as mock:
+            api.RespondHostRequest(
+                requests_pb2.RespondHostRequestReq(
+                    host_request_id=hr_id,
+                    status=conversations_pb2.HOST_REQUEST_STATUS_ACCEPTED,
+                    text="Accepting host request",
+                )
+            )
+
+    e = email_fields(mock)
+    assert "accept" in e.subject and host.name in e.subject
+    assert not e.attachments
+
+
 def _get_email_ics_attachment_calendar_event(e) -> ics.Event:
     assert len(e.attachments or []) == 1
     ics_attachment = e.attachments[0]