Show the first person in the realm an invite banner if they are alone.

Previously we unconditionally showed the "get the desktop app"
banner. Now, if the first user declines to invite people as part of
their onboarding workflow, show the invite banner instead.

(imported from commit f7892fef17c923154a700149b8f5be99e9c03fa0)

static/js/tutorial.js

@@ -265,7 +265,14 @@ function finale() {
         callback();
     });
     deferred_work = [];
-    var alert_contents = "<i class='icon-vector-desktop alert-icon'></i> Have you heard: the <a href='/apps' target='_blank'>Zulip desktop app</a> is awesome and you should get it!";
+
+    var alert_contents;
+
+    if (page_params.prompt_for_invites) {
+        alert_contents = "<i class='icon-vector-heart alert-icon'></i>It's lonely in here! <a href='#invite-user' data-toggle='modal'>Invite some coworkers</a>.";
+    } else {
+        alert_contents = "<i class='icon-vector-desktop alert-icon'></i> Have you heard: the <a href='/apps' target='_blank'>Zulip desktop app</a> is awesome and you should get it!";
+    }
     show_app_alert(alert_contents);
 }
 

zerver/views/__init__.py

@@ -135,6 +135,10 @@ def list_to_streams(streams_raw, user_profile, autocreate=False, invite_only=Fal
 
     return existing_streams, created_streams
 
+def realm_user_count(realm):
+    user_dicts = get_active_user_dicts_in_realm(realm)
+    return len([user_dict for user_dict in user_dicts if not user_dict["is_bot"]])
+
 def send_signup_message(sender, signups_stream, user_profile,
                         internal=False, realm=None):
     if internal:
@@ -143,11 +147,10 @@ def send_signup_message(sender, signups_stream, user_profile,
     else:
         internal_blurb = " "
 
+    user_count = realm_user_count(user_profile.realm)
     # Send notification to realm notifications stream if it exists
     # Don't send notification for the first user in a realm
-    user_dicts = get_active_user_dicts_in_realm(user_profile.realm)
+    if user_profile.realm.notifications_stream is not None and user_count > 1:
-    realm_user_count = len([user_dict for user_dict in user_dicts if not user_dict["is_bot"]])
-    if user_profile.realm.notifications_stream is not None and realm_user_count > 1:
         internal_send_message(sender, "stream",
                               user_profile.realm.notifications_stream.name,
                               "New users", "%s just signed up for Zulip. Say hello!" % \
@@ -160,7 +163,7 @@ def send_signup_message(sender, signups_stream, user_profile,
                 user_profile.full_name,
                 user_profile.email,
                 internal_blurb,
-                realm_user_count,
+                user_count,
                 )
             )
 
@@ -775,6 +778,11 @@ def home(request):
     needs_tutorial = settings.TUTORIAL_ENABLED and \
         user_profile.tutorial_status != UserProfile.TUTORIAL_FINISHED
 
+    # If you are the only person in the realm and you didn't invite
+    # anyone, we'll continue to encourage you to do so on the frontend.
+    prompt_for_invites = (realm_user_count(user_profile.realm) == 1) and \
+        not PreregistrationUser.objects.filter(referred_by=user_profile).count()
+
     if user_profile.pointer == -1 and user_has_messages:
         # Put the new user's pointer at the bottom
         #
@@ -822,6 +830,7 @@ def home(request):
         referrals             = register_ret['referrals'],
         realm_emoji           = register_ret['realm_emoji'],
         needs_tutorial        = needs_tutorial,
+        prompt_for_invites    = prompt_for_invites,
         desktop_notifications_enabled =
             user_profile.enable_desktop_notifications,
         sounds_enabled =