add some more metrics for answers and comments

app/models/user.rb

@@ -115,6 +115,8 @@ class User < ApplicationRecord # rubocop:disable Metrics/ClassLength
     raise Errors::AnsweringSelfBlockedOther if self.blocking?(question.user)
     # rubocop:enable Style/RedundantSelf
 
+    Retrospring::Metrics::QUESTIONS_ANSWERED.increment
+
     Answer.create!(content:, user: self, question:)
   end
 
@@ -128,6 +130,8 @@ class User < ApplicationRecord # rubocop:disable Metrics/ClassLength
     raise Errors::CommentingOtherBlockedSelf if answer.user.blocking?(self)
     # rubocop:enable Style/RedundantSelf
 
+    Retrospring::Metrics::COMMENTS_CREATED.increment
+
     Comment.create!(user: self, answer:, content:)
   end
 

lib/retrospring/metrics.rb

@@ -4,7 +4,7 @@ module Retrospring
   module Metrics
     PROMETHEUS = Prometheus::Client.registry
 
-    # avoid re-registering metrics to make autoreloader happy:
+    # avoid re-registering metrics to make autoreloader happy during dev:
     class << self
       %i[counter gauge histogram summary].each do |meth|
         define_method meth do |name, *args, **kwargs|
@@ -32,5 +32,15 @@ module Retrospring
       docstring: "How many questions got asked",
       labels:    %i[anonymous followers generated]
     )
+
+    QUESTIONS_ANSWERED = counter(
+      :retrospring_questions_answered_total,
+      docstring: "How many questions got answered"
+    )
+
+    COMMENTS_CREATED = counter(
+      :retrospring_comments_created_total,
+      docstring: "How many comments got created"
+    )
   end
 end