diff --git a/Gemfile b/Gemfile
index 48ecdf45..a831e984 100644
--- a/Gemfile
+++ b/Gemfile
@@ -117,3 +117,5 @@ gem "openssl", "~> 3.1"
 
 # mail 2.8.0 breaks sendmail usage: https://github.com/mikel/mail/issues/1538
 gem "mail", "~> 2.7.1"
+
+gem "prometheus-client", "~> 4.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index 94439de4..5e5b0320 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -285,6 +285,7 @@ GEM
     pg (1.4.5)
     pghero (3.1.0)
       activerecord (>= 6)
+    prometheus-client (4.0.0)
     public_suffix (4.0.7)
     puma (6.1.0)
       nio4r (~> 2.0)
@@ -527,6 +528,7 @@ DEPENDENCIES
   openssl (~> 3.1)
   pg
   pghero
+  prometheus-client (~> 4.0)
   puma
   pundit (~> 2.3)
   questiongenerator (~> 1.2)!
diff --git a/app/controllers/about_controller.rb b/app/controllers/about_controller.rb
index b957e445..0b20d1b2 100644
--- a/app/controllers/about_controller.rb
+++ b/app/controllers/about_controller.rb
@@ -4,26 +4,27 @@ class AboutController < ApplicationController
   def index; end
 
   def about
-    user_count = User
-                 .where.not(confirmed_at: nil)
-                 .where("answered_count > 0")
-                 .count
-
-    current_ban_count = UserBan
-                        .current
-                        .joins(:user)
-                        .where.not("users.confirmed_at": nil)
-                        .where("users.answered_count > 0")
-                        .count
-
-    @users = user_count - current_ban_count
-    @questions = Question.count
-    @answers = Answer.count
-    @comments = Comment.count
-    @smiles = Appendable::Reaction.count
+    @users = Rails.cache.fetch("about_count_users", expires_in: 1.hour) { user_count - current_ban_count }
+    @questions = Rails.cache.fetch("about_count_questions", expires_in: 1.hour) { Question.count(:id) }
+    @answers = Rails.cache.fetch("about_count_answers", expires_in: 1.hour) { Answer.count(:id) }
+    @comments = Rails.cache.fetch("about_count_comments", expires_in: 1.hour) { Comment.count(:id) }
   end
 
   def privacy_policy; end
 
   def terms; end
+
+  private
+
+  def user_count = User
+    .where.not(confirmed_at: nil)
+    .where("answered_count > 0")
+    .count
+
+  def current_ban_count = UserBan
+    .current
+    .joins(:user)
+    .where.not("users.confirmed_at": nil)
+    .where("users.answered_count > 0")
+    .count
 end
diff --git a/app/controllers/inbox_controller.rb b/app/controllers/inbox_controller.rb
index d849dafc..f6a1aff2 100644
--- a/app/controllers/inbox_controller.rb
+++ b/app/controllers/inbox_controller.rb
@@ -5,7 +5,7 @@ class InboxController < ApplicationController
 
   after_action :mark_inbox_entries_as_read, only: %i[show]
 
-  def show # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
+  def show # rubocop:disable Metrics/MethodLength
     find_author
     find_inbox_entries
 
@@ -37,6 +37,7 @@ class InboxController < ApplicationController
                                 user:                current_user)
 
     inbox = Inbox.create!(user: current_user, question_id: question.id, new: true)
+    increment_metric
 
     respond_to do |format|
       format.turbo_stream do
@@ -85,4 +86,14 @@ class InboxController < ApplicationController
     # using .dup to not modify @inbox -- useful in tests
     @inbox&.dup&.update_all(new: false) # rubocop:disable Rails/SkipsModelValidations
   end
+
+  def increment_metric
+    Retrospring::Metrics::QUESTIONS_ASKED.increment(
+      labels: {
+        anonymous: true,
+        followers: false,
+        generated: true,
+      }
+    )
+  end
 end
diff --git a/app/controllers/metrics_controller.rb b/app/controllers/metrics_controller.rb
new file mode 100644
index 00000000..257b8b7e
--- /dev/null
+++ b/app/controllers/metrics_controller.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require "prometheus/client/formats/text"
+
+class MetricsController < ActionController::API
+  include ActionController::MimeResponds
+
+  def show
+    fetch_sidekiq_metrics
+
+    render plain: metrics
+  end
+
+  private
+
+  SIDEKIQ_STATS_METHODS = %i[
+    processed
+    failed
+    scheduled_size
+    retry_size
+    dead_size
+    processes_size
+  ].freeze
+
+  def fetch_sidekiq_metrics
+    stats = Sidekiq::Stats.new
+    SIDEKIQ_STATS_METHODS.each do |key|
+      Retrospring::Metrics::SIDEKIQ[key].set stats.public_send(key)
+    end
+
+    stats.queues.each do |queue, value|
+      Retrospring::Metrics::SIDEKIQ[:queue_enqueued].set value, labels: { queue: }
+    end
+  end
+
+  def metrics
+    Prometheus::Client::Formats::Text.marshal(Retrospring::Metrics::PROMETHEUS)
+  end
+end
diff --git a/app/helpers/markdown_helper.rb b/app/helpers/markdown_helper.rb
index 6d80f255..ef634209 100644
--- a/app/helpers/markdown_helper.rb
+++ b/app/helpers/markdown_helper.rb
@@ -1,36 +1,42 @@
-module MarkdownHelper
+# frozen_string_literal: true
 
+module MarkdownHelper
   def markdown(content)
-    md = Redcarpet::Markdown.new(FlavoredMarkdown, MARKDOWN_OPTS)
-    Sanitize.fragment(md.render(content), EVIL_TAGS).html_safe
+    renderer = FlavoredMarkdown.new(**MARKDOWN_RENDERER_OPTS)
+    md = Redcarpet::Markdown.new(renderer, **MARKDOWN_OPTS)
+    # As the string has been sanitized we can mark it as HTML safe
+    Sanitize.fragment(md.render(content), EVIL_TAGS).strip.html_safe # rubocop:disable Rails/OutputSafety
   end
 
   def strip_markdown(content)
-    md = Redcarpet::Markdown.new(Redcarpet::Render::StripDown, MARKDOWN_OPTS)
+    renderer = Redcarpet::Render::StripDown.new
+    md = Redcarpet::Markdown.new(renderer, **MARKDOWN_OPTS)
     CGI.unescape_html(Sanitize.fragment(CGI.escape_html(md.render(content)), EVIL_TAGS)).strip
   end
 
   def twitter_markdown(content)
-    md = Redcarpet::Markdown.new(TwitteredMarkdown, MARKDOWN_OPTS)
+    renderer = TwitteredMarkdown.new
+    md = Redcarpet::Markdown.new(renderer, **MARKDOWN_OPTS)
     CGI.unescape_html(Sanitize.fragment(CGI.escape_html(md.render(content)), EVIL_TAGS)).strip
   end
 
   def question_markdown(content)
-    md = Redcarpet::Markdown.new(QuestionMarkdown.new, MARKDOWN_OPTS)
-    Sanitize.fragment(md.render(content), EVIL_TAGS).html_safe
+    renderer = QuestionMarkdown.new
+    md = Redcarpet::Markdown.new(renderer, **MARKDOWN_OPTS)
+    # As the string has been sanitized we can mark it as HTML safe
+    Sanitize.fragment(md.render(content), EVIL_TAGS).strip.html_safe # rubocop:disable Rails/OutputSafety
   end
 
   def raw_markdown(content)
-    md = Redcarpet::Markdown.new(Redcarpet::Render::HTML, RAW_MARKDOWN_OPTS)
+    renderer = Redcarpet::Render::HTML.new(**MARKDOWN_RENDERER_OPTS)
+    md = Redcarpet::Markdown.new(renderer, **MARKDOWN_OPTS)
     raw md.render content
   end
 
   def get_markdown(path, relative_to = Rails.root)
-    begin
-      File.read relative_to.join(path)
-    rescue Errno::ENOENT
-      "# Error reading #{relative_to.join(path)}"
-    end
+    File.read relative_to.join(path)
+  rescue Errno::ENOENT
+    "# Error reading #{relative_to.join(path)}"
   end
 
   def markdown_io(path, relative_to = Rails.root)
diff --git a/app/javascript/retrospring/features/inbox/index.ts b/app/javascript/retrospring/features/inbox/index.ts
index 02206e9a..6eff6cbe 100644
--- a/app/javascript/retrospring/features/inbox/index.ts
+++ b/app/javascript/retrospring/features/inbox/index.ts
@@ -1,6 +1,5 @@
 import registerEvents from 'utilities/registerEvents';
 import registerInboxEntryEvents from './entry';
-import { authorSearchHandler } from './author';
 import { deleteAllAuthorQuestionsHandler, deleteAllQuestionsHandler } from './delete';
 
 export default (): void => {
diff --git a/app/models/user.rb b/app/models/user.rb
index 6370ed01..725582ef 100644
--- a/app/models/user.rb
+++ b/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
 
diff --git a/app/services/flavored_markdown.rb b/app/services/flavored_markdown.rb
index a6ecde56..85aecdfb 100644
--- a/app/services/flavored_markdown.rb
+++ b/app/services/flavored_markdown.rb
@@ -15,10 +15,6 @@ class FlavoredMarkdown < Redcarpet::Render::HTML
   end
 
   def header(text, _header_level)
-    paragraph text
-  end
-
-  def paragraph(text)
     "<p>#{text}</p>"
   end
 
diff --git a/app/services/question_markdown.rb b/app/services/question_markdown.rb
index 6ae585ea..6a251641 100644
--- a/app/services/question_markdown.rb
+++ b/app/services/question_markdown.rb
@@ -6,9 +6,7 @@ class QuestionMarkdown < Redcarpet::Render::StripDown
   include Rails.application.routes.url_helpers
   include SharedMarkers
 
-  def paragraph(text)
-    "<p>#{text}</p>"
-  end
+  def paragraph(text) = "<p>#{text.gsub("\n", '<br>')}</p>"
 
   def link(link, _title, _content)
     process_link(link)
diff --git a/app/views/about/about.html.haml b/app/views/about/about.html.haml
index 5dd5ba2b..6dcc22a4 100644
--- a/app/views/about/about.html.haml
+++ b/app/views/about/about.html.haml
@@ -17,13 +17,13 @@
           %h2= t(".statistics.header")
           %p= t(".statistics.body", app_name: APP_CONFIG["site_name"])
           .entry
-            .entry__value= @questions
+            .entry__value{ title: number_to_human(@questions) }= number_to_human @questions, units: :short, format: "%n%u"
             %h4.entry__description= Question.model_name.human(count: @questions)
           .entry
-            .entry__value= @answers
+            .entry__value{ title: number_to_human(@answers) }= number_to_human @answers, units: :short, format: "%n%u"
             %h4.entry__description= Answer.model_name.human(count: @answers)
           .entry
-            .entry__value= @users
+            .entry__value{ title: number_to_human(@users) }= number_to_human @users, units: :short, format: "%n%u"
             %h4.entry__description= User.model_name.human(count: @users)
 
 = render "shared/links"
diff --git a/app/views/layouts/user/profile.html.haml b/app/views/layouts/user/profile.html.haml
index e0673ed2..1af75a29 100644
--- a/app/views/layouts/user/profile.html.haml
+++ b/app/views/layouts/user/profile.html.haml
@@ -3,10 +3,10 @@
     .profile__header-container
       %img.profile__header-image{ src: @user.profile_header.url(:web) }
   .row
-    .col-md-3.col-xs-12.col-sm-4
+    .col-lg-3.col-md-4.col-xs-12.col-sm-4
       = render 'user/profile', user: @user
       .d-none.d-sm-block= render 'shared/links'
-    .col-md-9.col-xs-12.col-sm-8
+    .col-lg-9.col-md-8.col-xs-12.col-sm-8
       = render 'questionbox', user: @user
       = render 'tabs/profile', user: @user
       = yield
diff --git a/config/initializers/prometheus.rb b/config/initializers/prometheus.rb
new file mode 100644
index 00000000..7d86c92f
--- /dev/null
+++ b/config/initializers/prometheus.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+return if Rails.env.test? # no need for the direct file store in testing
+
+require "prometheus/client/data_stores/direct_file_store"
+
+Rails.application.config.before_configuration do
+  dir = Rails.root.join("tmp/prometheus_metrics")
+  FileUtils.mkdir_p dir
+
+  Prometheus::Client.config.data_store = Prometheus::Client::DataStores::DirectFileStore.new(dir:)
+end
+
+Rails.application.config.after_initialize do
+  # ensure the version metric is populated
+  Retrospring::Metrics::VERSION_INFO
+end
diff --git a/config/initializers/redcarpet.rb b/config/initializers/redcarpet.rb
index aed5e5ff..484a8b18 100644
--- a/config/initializers/redcarpet.rb
+++ b/config/initializers/redcarpet.rb
@@ -1,32 +1,28 @@
-require 'redcarpet/render_strip'
+# frozen_string_literal: true
+
+require "redcarpet/render_strip"
 
 MARKDOWN_OPTS = {
-    filter_html: true,
-    escape_html: true,
-    no_images: true,
-    no_styles: true,
-    safe_links_only: true,
-    xhtml: false,
-    hard_wrap: true,
-    no_intra_emphasis: true,
-    tables: true,
-    fenced_code_blocks: true,
-    autolink: true,
-    disable_indented_code_blocks: true,
-    strikethrough: true,
-    superscript: false
-}
-
-RAW_MARKDOWN_OPTS = {
-  tables: true,
-  fenced_code_blocks: true,
-  autolink: true,
+  no_intra_emphasis:            true,
+  tables:                       true,
+  fenced_code_blocks:           true,
+  autolink:                     true,
   disable_indented_code_blocks: true,
-  strikethrough: true,
-  superscript: false
-}
+  strikethrough:                true,
+  superscript:                  false,
+}.freeze
+
+MARKDOWN_RENDERER_OPTS = {
+  filter_html:     true,
+  escape_html:     true,
+  no_images:       true,
+  no_styles:       true,
+  safe_links_only: true,
+  xhtml:           false,
+  hard_wrap:       true,
+}.freeze
 
 ALLOWED_HOSTS_IN_MARKDOWN = [
-  APP_CONFIG['hostname'],
-  *APP_CONFIG['allowed_hosts_in_markdown']
-]
\ No newline at end of file
+  APP_CONFIG["hostname"],
+  *APP_CONFIG["allowed_hosts_in_markdown"]
+].freeze
diff --git a/config/locales/units.en.yml b/config/locales/units.en.yml
new file mode 100644
index 00000000..2494fcb1
--- /dev/null
+++ b/config/locales/units.en.yml
@@ -0,0 +1,7 @@
+en:
+  short:
+    unit: ""
+    thousand: "K"
+    million: "M"
+    billion: "B"
+    trillion: "T"
diff --git a/config/locales/views.en.yml b/config/locales/views.en.yml
index 351e2c03..d16c9ce5 100644
--- a/config/locales/views.en.yml
+++ b/config/locales/views.en.yml
@@ -567,7 +567,6 @@ en:
     formatting:
       body_html: |
         <p>%{app_name} uses <b>Markdown</b> for formatting</p>
-        <p>A blank line starts a new paragraph</p>
         <p><code>*italic text*</code> for <i>italic text</i></p>
         <p><code>**bold text**</code> for <b>bold text</b></p>
         <p><code>[link](https://example.com)</code> for <a href="https://example.com">link</a></p>
diff --git a/config/routes.rb b/config/routes.rb
index 744a8d83..8f485cb7 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -49,6 +49,10 @@ Rails.application.routes.draw do
   get "/linkfilter", to: "link_filter#index", as: :linkfilter
   get "/manifest.json", to: "manifests#show", as: :webapp_manifest
 
+  constraints(Constraints::LocalNetwork) do
+    get "/metrics", to: "metrics#show"
+  end
+
   # Devise routes
   devise_for :users, path: "user", skip: %i[sessions registrations]
   as :user do
diff --git a/db/migrate/20230218142952_add_index_for_created_at_on_answers.rb b/db/migrate/20230218142952_add_index_for_created_at_on_answers.rb
new file mode 100644
index 00000000..536db607
--- /dev/null
+++ b/db/migrate/20230218142952_add_index_for_created_at_on_answers.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddIndexForCreatedAtOnAnswers < ActiveRecord::Migration[6.1]
+  def change
+    add_index :answers, :created_at, order: :desc
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index e85a2c7e..0e8fadfd 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2023_02_12_181044) do
+ActiveRecord::Schema.define(version: 2023_02_18_142952) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -49,6 +49,7 @@ ActiveRecord::Schema.define(version: 2023_02_12_181044) do
     t.datetime "updated_at"
     t.integer "smile_count", default: 0, null: false
     t.datetime "pinned_at"
+    t.index ["created_at"], name: "index_answers_on_created_at", order: :desc
     t.index ["question_id"], name: "index_answers_on_question_id"
     t.index ["user_id", "created_at"], name: "index_answers_on_user_id_and_created_at"
     t.index ["user_id", "pinned_at"], name: "index_answers_on_user_id_and_pinned_at"
diff --git a/lib/constraints/local_network.rb b/lib/constraints/local_network.rb
new file mode 100644
index 00000000..2db324a5
--- /dev/null
+++ b/lib/constraints/local_network.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module Constraints
+  module LocalNetwork
+    module_function
+
+    SUBNETS = %w[
+      10.0.0.0/8
+      127.0.0.0/8
+      172.16.0.0/12
+      192.168.0.0/16
+    ].map { IPAddr.new(_1) }.freeze
+
+    def matches?(request)
+      SUBNETS.find do |net|
+        net.include? request.remote_ip
+      rescue
+        false
+      end
+    end
+  end
+end
diff --git a/lib/retrospring/metrics.rb b/lib/retrospring/metrics.rb
new file mode 100644
index 00000000..7c52dcb6
--- /dev/null
+++ b/lib/retrospring/metrics.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+module Retrospring
+  module Metrics
+    PROMETHEUS = Prometheus::Client.registry
+
+    # 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|
+          PROMETHEUS.public_send(meth, name, *args, **kwargs)
+        rescue Prometheus::Client::Registry::AlreadyRegisteredError
+          raise unless Rails.env.development?
+
+          PROMETHEUS.unregister name
+          retry
+        end
+      end
+    end
+
+    VERSION_INFO = gauge(
+      :retrospring_version_info,
+      docstring:     "Information about the currently running version",
+      labels:        [:version],
+      preset_labels: {
+        version: Retrospring::Version.to_s,
+      }
+    ).tap { _1.set 1 }
+
+    QUESTIONS_ASKED = counter(
+      :retrospring_questions_asked_total,
+      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"
+    )
+
+    # metrics from Sidekiq::Stats.new
+    SIDEKIQ = {
+      processed:      gauge(
+        :sidekiq_processed,
+        docstring: "Number of jobs processed by Sidekiq"
+      ),
+      failed:         gauge(
+        :sidekiq_failed,
+        docstring: "Number of jobs that failed"
+      ),
+      scheduled_size: gauge(
+        :sidekiq_scheduled_jobs,
+        docstring: "Number of jobs that are enqueued"
+      ),
+      retry_size:     gauge(
+        :sidekiq_retried_jobs,
+        docstring: "Number of jobs that are being retried"
+      ),
+      dead_size:      gauge(
+        :sidekiq_dead_jobs,
+        docstring: "Number of jobs that are dead"
+      ),
+      processes_size: gauge(
+        :sidekiq_processes,
+        docstring: "Number of active Sidekiq processes"
+      ),
+      queue_enqueued: gauge(
+        :sidekiq_queues_enqueued,
+        docstring: "Number of enqueued jobs per queue",
+        labels:    %i[queue]
+      ),
+    }.freeze
+  end
+end
diff --git a/lib/retrospring/version.rb b/lib/retrospring/version.rb
index 57250b36..78573924 100644
--- a/lib/retrospring/version.rb
+++ b/lib/retrospring/version.rb
@@ -15,11 +15,11 @@ module Retrospring
 
     def year = 2023
 
-    def month = 1
+    def month = 2
 
-    def day = 31
+    def day = 19
 
-    def patch = 1
+    def patch = 2
 
     def suffix = ""
 
diff --git a/lib/use_case/question/create.rb b/lib/use_case/question/create.rb
index 5cc8f174..17987a1d 100644
--- a/lib/use_case/question/create.rb
+++ b/lib/use_case/question/create.rb
@@ -18,6 +18,7 @@ module UseCase
         return if filtered?(question)
 
         increment_asked_count
+        increment_metric
 
         inbox = ::Inbox.create!(user: target_user, question:, new: true)
         notify(inbox)
@@ -26,8 +27,8 @@ module UseCase
           status:   201,
           resource: question,
           extra:    {
-            inbox:
-          }
+            inbox:,
+          },
         }
       end
 
@@ -92,6 +93,16 @@ module UseCase
         source_user.save
       end
 
+      def increment_metric
+        Retrospring::Metrics::QUESTIONS_ASKED.increment(
+          labels: {
+            anonymous:,
+            followers: false,
+            generated: false,
+          }
+        )
+      end
+
       def filtered?(question)
         target_user.mute_rules.any? { |rule| rule.applies_to? question } ||
           (anonymous && AnonymousBlock.where(identifier: question.author_identifier, user_id: [target_user.id, nil]).any?) ||
diff --git a/lib/use_case/question/create_followers.rb b/lib/use_case/question/create_followers.rb
index 21c2e89d..04fe3844 100644
--- a/lib/use_case/question/create_followers.rb
+++ b/lib/use_case/question/create_followers.rb
@@ -9,20 +9,21 @@ module UseCase
 
       def call
         question = ::Question.create!(
-          content:             content,
+          content:,
           author_is_anonymous: false,
-          author_identifier:   author_identifier,
+          author_identifier:,
           user:                source_user,
           direct:              false
         )
 
         increment_asked_count
+        increment_metric
 
         QuestionWorker.perform_async(source_user_id, question.id)
 
         {
           status:   201,
-          resource: question
+          resource: question,
         }
       end
 
@@ -33,6 +34,16 @@ module UseCase
         source_user.save
       end
 
+      def increment_metric
+        Retrospring::Metrics::QUESTIONS_ASKED.increment(
+          labels: {
+            anonymous: false,
+            followers: true,
+            generated: false,
+          }
+        )
+      end
+
       def source_user
         @source_user ||= ::User.find(source_user_id)
       end
diff --git a/spec/controllers/metrics_controller_spec.rb b/spec/controllers/metrics_controller_spec.rb
new file mode 100644
index 00000000..89f4316e
--- /dev/null
+++ b/spec/controllers/metrics_controller_spec.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe MetricsController, type: :controller do
+  describe "#show" do
+    subject { get :show }
+
+    it "returns the metrics" do
+      expect(subject.body).to include "retrospring_version_info"
+    end
+  end
+end
diff --git a/spec/helpers/markdown_helper_spec.rb b/spec/helpers/markdown_helper_spec.rb
index 177b42c7..b4c22b76 100644
--- a/spec/helpers/markdown_helper_spec.rb
+++ b/spec/helpers/markdown_helper_spec.rb
@@ -31,6 +31,10 @@ describe MarkdownHelper, type: :helper do
     it "should escape HTML tags" do
       expect(markdown("I'm <h1>a test</h1>")).to eq("<p>I'm &lt;h1&gt;a test&lt;/h1&gt;</p>")
     end
+
+    it "should turn line breaks into <br> tags" do
+      expect(markdown("Some\ntext")).to eq("<p>Some<br>\ntext</p>")
+    end
   end
 
   describe "#strip_markdown" do
@@ -70,6 +74,10 @@ describe MarkdownHelper, type: :helper do
     it "should not process invalid links" do
       expect(question_markdown("https://example.com/example.質問")).to eq("<p>https://example.com/example.質問</p>")
     end
+
+    it "should turn line breaks into <br> tags" do
+      expect(markdown("Some\ntext")).to eq("<p>Some<br>\ntext</p>")
+    end
   end
 
   describe "#raw_markdown" do
diff --git a/spec/lib/constraints/local_network_spec.rb b/spec/lib/constraints/local_network_spec.rb
new file mode 100644
index 00000000..88326ccb
--- /dev/null
+++ b/spec/lib/constraints/local_network_spec.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe Constraints::LocalNetwork do
+  describe ".matches?" do
+    let(:request) { double("Rack::Request", remote_ip:) }
+
+    subject { described_class.matches?(request) }
+
+    context "with a private address from the 10.0.0.0/8 range" do
+      let(:remote_ip) { "10.0.2.100" }
+
+      it { is_expected.to be_truthy }
+    end
+
+    context "with a private address from the 127.0.0.0/8 range" do
+      let(:remote_ip) { "127.0.0.1" }
+
+      it { is_expected.to be_truthy }
+    end
+
+    context "with a private address from the 172.16.0.0/12 range" do
+      let(:remote_ip) { "172.31.33.7" }
+
+      it { is_expected.to be_truthy }
+    end
+
+    context "with a private address from the 192.168.0.0/16 range" do
+      let(:remote_ip) { "192.168.123.45" }
+
+      it { is_expected.to be_truthy }
+    end
+
+    context "with a non-private/loopback address" do
+      let(:remote_ip) { "193.186.6.83" }
+
+      it { is_expected.to be_falsey }
+    end
+
+    context "with some fantasy address" do
+      let(:remote_ip) { "fe80:3::1ff:fe23:4567:890a" }
+
+      it { is_expected.to be_falsey }
+    end
+
+    context "with an actual invalid address" do
+      let(:remote_ip) { "herbert" }
+
+      it { is_expected.to be_falsey }
+    end
+  end
+end
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index 43662e83..11da5afa 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -2,7 +2,7 @@
 
 # This file is copied to spec/ when you run 'rails generate rspec:install'
 ENV["RAILS_ENV"] ||= "test"
-require File.expand_path("../../config/environment", __FILE__)
+require File.expand_path("../config/environment", __dir__)
 # Prevent database truncation if the environment is production
 abort("The Rails environment is running in production mode!") if Rails.env.production?
 require "spec_helper"
@@ -26,6 +26,7 @@ require "rspec-sidekiq"
 # require only the support files necessary.
 #
 # Dir[Rails.root.join('spec/support/**/*.rb')].each { |f| require f }
+require "support/nokogiri_matchers"
 
 # Checks for pending migration and applies them before tests are run.
 # If you are not using ActiveRecord, you can remove this line.
@@ -33,7 +34,7 @@ ActiveRecord::Migration.maintain_test_schema!
 
 RSpec.configure do |config|
   # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
-  config.fixture_path = "#{::Rails.root}/spec/fixtures"
+  config.fixture_path = Rails.root.join("spec/fixtures")
 
   # If you're not using ActiveRecord, or you'd prefer not to run each of your
   # examples within a transaction, remove the following line or assign false
@@ -66,6 +67,7 @@ RSpec.configure do |config|
 
   config.include Devise::Test::ControllerHelpers, type: :controller
   config.include Devise::Test::ControllerHelpers, type: :helper
+  config.include Devise::Test::ControllerHelpers, type: :view
 end
 
 Shoulda::Matchers.configure do |config|
@@ -75,4 +77,4 @@ Shoulda::Matchers.configure do |config|
   end
 end
 
-Dir[Rails.root.join "spec", "shared_examples", "*.rb"].sort.each { |f| require f }
+Dir[Rails.root.join("spec/shared_examples/*.rb")].each { |f| require f }
diff --git a/spec/support/nokogiri_matchers.rb b/spec/support/nokogiri_matchers.rb
new file mode 100644
index 00000000..d1630f60
--- /dev/null
+++ b/spec/support/nokogiri_matchers.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module NokogiriMatchers
+  RSpec::Matchers.matcher :have_css do |css|
+    description { %(have at least one element matching the CSS selector #{css.inspect}) }
+
+    match do |rendered|
+      Nokogiri::HTML.parse(rendered).css(css).size.positive?
+    end
+  end
+
+  RSpec::Matchers.matcher :have_attribute do |expected_attribute|
+    description do
+      case expected_attribute
+      when Hash
+        raise ArgumentError.new("have_attribute only wants one key=>value pair") unless expected_attribute.size == 1
+
+        key = expected_attribute.keys.first
+        value = expected_attribute.values.first
+        %(have an attribute named #{key.inspect} with a value of #{value.inspect})
+      else
+        %(have an attribute named #{expected_attribute.inspect})
+      end
+    end
+
+    match do |element|
+      case expected_attribute
+      when Hash
+        raise ArgumentError.new("have_attribute only wants one key=>value pair") unless expected_attribute.size == 1
+
+        key = expected_attribute.keys.first
+        value = expected_attribute.values.first
+
+        element.attr(key.to_s).value == value
+      else
+        !element.attr(expected_attribute.to_s).nil?
+      end
+    end
+  end
+end
+
+RSpec.configure do |c|
+  c.include NokogiriMatchers, view: true
+end
diff --git a/spec/views/inbox/_actions.html.haml_spec.rb b/spec/views/inbox/_actions.html.haml_spec.rb
new file mode 100644
index 00000000..21caf679
--- /dev/null
+++ b/spec/views/inbox/_actions.html.haml_spec.rb
@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe "inbox/_actions.html.haml", type: :view do
+  let(:delete_id) { "ib-delete-all" }
+  let(:disabled) { false }
+
+  let(:user) { FactoryBot.create(:user) }
+
+  before do
+    sign_in user
+  end
+
+  subject(:rendered) do
+    render partial: "inbox/actions", locals: {
+      delete_id:,
+      disabled:,
+      inbox_count: 4020,
+    }
+  end
+
+  it "has a button for deleting all inbox entries" do
+    html = Nokogiri::HTML.parse(rendered)
+    button = html.css("button#ib-delete-all")
+    expect(button).not_to have_attribute(:disabled)
+  end
+
+  context "with disabled = true" do
+    let(:disabled) { true }
+
+    it "has a button for deleting all inbox entries" do
+      html = Nokogiri::HTML.parse(rendered)
+      button = html.css("button#ib-delete-all")
+      expect(button).to have_attribute(:disabled)
+    end
+  end
+
+  context "with delete_id = ib-delete-all-author" do
+    let(:delete_id) { "ib-delete-all-author" }
+
+    it "has a button for deleting all inbox entries" do
+      html = Nokogiri::HTML.parse(rendered)
+      button = html.css("button#ib-delete-all-author")
+
+      expect(button).to have_attribute("data-ib-count" => "4020")
+    end
+  end
+end
diff --git a/spec/views/inbox/_entry.html.haml_spec.rb b/spec/views/inbox/_entry.html.haml_spec.rb
new file mode 100644
index 00000000..72243982
--- /dev/null
+++ b/spec/views/inbox/_entry.html.haml_spec.rb
@@ -0,0 +1,121 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe "inbox/_entry.html.haml", type: :view do
+  let(:inbox_entry)         { Inbox.create(user: inbox_user, question:, new:) }
+  let(:inbox_user)          { user }
+  let(:user)                { FactoryBot.create(:user, sharing_enabled:, sharing_custom_url:) }
+  let(:sharing_enabled)     { true }
+  let(:sharing_custom_url)  { nil }
+  let(:question)            { FactoryBot.create(:question, content: "owo what's this?", author_is_anonymous:, user: question_user, answer_count:) }
+  let(:author_is_anonymous) { true }
+  let(:question_user)       { nil }
+  let(:answer_count)        { 0 }
+  let(:new)                 { false }
+
+  before do
+    sign_in user
+  end
+
+  subject(:rendered) do
+    render partial: "inbox/entry", locals: {
+      i: inbox_entry,
+    }
+  end
+
+  it "does not set the inbox-entry--new class on non-new inbox entries" do
+    html = Nokogiri::HTML.parse(rendered)
+    classes = html.css("#inbox_#{inbox_entry.id}").attr("class").value
+    expect(classes).not_to include "inbox-entry--new"
+  end
+
+  context "when the inbox entry is new" do
+    let(:new) { true }
+
+    it "sets the inbox-entry--new class" do
+      html = Nokogiri::HTML.parse(rendered)
+      classes = html.css("#inbox_#{inbox_entry.id}").attr("class").value
+      expect(classes).to include "inbox-entry--new"
+    end
+  end
+
+  context "when question author is not anonymous" do
+    let(:question_user)       { FactoryBot.create(:user) }
+    let(:author_is_anonymous) { false }
+
+    it "has an avatar" do
+      expect(rendered).to have_css(%(img.answerbox__question-user-avatar))
+    end
+
+    it "does not have an icon indicating the author is anonymous" do
+      expect(rendered).not_to have_css(%(i.fas.fa-user-secret))
+    end
+
+    context "when the question already has some answers" do
+      let(:answer_count) { 9001 }
+
+      it "has a link to the question view" do
+        html = Nokogiri::HTML.parse(rendered)
+        selector = %(a[href="/@#{question_user.screen_name}/q/#{question.id}"])
+        expect(rendered).to have_css(selector)
+        expect(html.css(selector).text.strip).to eq "9001 answers"
+      end
+    end
+  end
+
+  it "has an icon indicating the author is anonymous" do
+    expect(rendered).to have_css(%(i.fas.fa-user-secret))
+  end
+
+  it "contains the question text" do
+    expect(rendered).to match "owo what's this?"
+  end
+
+  it "has interactive elements" do
+    expect(rendered).to have_css(%(textarea[name="ib-answer"][data-id="#{inbox_entry.id}"]))
+    expect(rendered).to have_css(%(button[name="ib-answer"][data-ib-id="#{inbox_entry.id}"]))
+    expect(rendered).to have_css(%(button[name="ib-destroy"][data-ib-id="#{inbox_entry.id}"]))
+  end
+
+  it "has a hidden sharing bit" do
+    expect(rendered).to have_css(%(.inbox-entry__sharing.d-none))
+  end
+
+  it "has a link-button to share to tumblr" do
+    expect(rendered).to have_css(%(.inbox-entry__sharing a.btn[data-inbox-sharing-target="tumblr"]))
+  end
+
+  it "has a link-button to share to twitter" do
+    expect(rendered).to have_css(%(.inbox-entry__sharing a.btn[data-inbox-sharing-target="twitter"]))
+  end
+
+  it "does not have a link-button to share to a custom site" do
+    expect(rendered).not_to have_css(%(.inbox-entry__sharing a.btn[data-inbox-sharing-target="custom"]))
+  end
+
+  context "when the user has a custom share url set" do
+    let(:sharing_custom_url) { "https://pounced-on.me/share?text=" }
+
+    it "has a link-button to share to a custom site" do
+      html = Nokogiri::HTML.parse(rendered)
+      selector = %(.inbox-entry__sharing a.btn[data-inbox-sharing-target="custom"])
+      expect(rendered).to have_css(selector)
+      expect(html.css(selector).text.strip).to eq "pounced-on.me"
+    end
+  end
+
+  context "when the inbox entry does not belong to the current user" do
+    let(:inbox_user) { FactoryBot.create(:user) }
+
+    it "does not have any interactive elements" do
+      expect(rendered).not_to have_css(%(textarea[name="ib-answer"][data-id="#{inbox_entry.id}"]))
+      expect(rendered).not_to have_css(%(button[name="ib-answer"][data-ib-id="#{inbox_entry.id}"]))
+      expect(rendered).not_to have_css(%(button[name="ib-destroy"][data-ib-id="#{inbox_entry.id}"]))
+    end
+
+    it "does not have the sharing bit" do
+      expect(rendered).not_to have_css(%(.inbox-entry__sharing.d-none))
+    end
+  end
+end
diff --git a/spec/views/inbox/_push_settings.haml_spec.rb b/spec/views/inbox/_push_settings.haml_spec.rb
new file mode 100644
index 00000000..6fa036f1
--- /dev/null
+++ b/spec/views/inbox/_push_settings.haml_spec.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe "inbox/_push_settings.haml", type: :view do
+  subject(:rendered) { render }
+
+  it "has a button to enable push notifications" do
+    expect(rendered).to have_css(%(button[data-action="push-enable"]))
+  end
+
+  it "has a button to dismiss the view" do
+    expect(rendered).to have_css(%(button[data-action="push-dismiss"]))
+  end
+end
diff --git a/spec/views/inbox/show.html.haml_spec.rb b/spec/views/inbox/show.html.haml_spec.rb
new file mode 100644
index 00000000..fc157874
--- /dev/null
+++ b/spec/views/inbox/show.html.haml_spec.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe "inbox/show.html.haml", type: :view do
+  let(:user) { FactoryBot.create(:user) }
+
+  before do
+    sign_in user
+  end
+
+  subject(:rendered) { render }
+
+  context "with an empty inbox" do
+    before do
+      assign :inbox, []
+    end
+
+    it "displays an 'inbox is empty' message" do
+      html = Nokogiri::HTML.parse(rendered)
+      selector = "p.empty"
+      expect(rendered).to have_css(selector)
+      expect(html.css(selector).text.strip).to eq "Nothing to see here."
+    end
+  end
+
+  context "with some inbox entries" do
+    let(:inbox_entry1) { Inbox.create(user:, question: FactoryBot.create(:question)) }
+    let(:inbox_entry2) { Inbox.create(user:, question: FactoryBot.create(:question)) }
+
+    before do
+      assign :inbox, [inbox_entry2, inbox_entry1]
+    end
+
+    it "renders inbox entries" do
+      expect(rendered).to have_css("#inbox_#{inbox_entry1.id}")
+      expect(rendered).to have_css("#inbox_#{inbox_entry2.id}")
+    end
+
+    it "does not contain the empty inbox message" do
+      expect(rendered).not_to have_css("p.empty")
+    end
+
+    it "does not render the paginator" do
+      expect(rendered).not_to have_css("#paginator")
+    end
+
+    context "when more data is available" do
+      before do
+        assign :more_data_available, true
+        assign :inbox_last_id, 1337
+      end
+
+      it "renders the paginator" do
+        expect(rendered).to have_css("#paginator")
+      end
+
+      it "has the correct params on the button" do
+        expect(rendered).to have_css(%(input[type="hidden"][name="last_id"][value="1337"]))
+        expect(rendered).not_to have_css(%(input[type="hidden"][name="author"]))
+      end
+
+      context "when passed an author" do
+        before do
+          assign :author, "jyrki"
+        end
+
+        it "has the correct params on the button" do
+          expect(rendered).to have_css(%(input[type="hidden"][name="last_id"][value="1337"]))
+          expect(rendered).to have_css(%(input[type="hidden"][name="author"]))
+        end
+      end
+    end
+  end
+end
diff --git a/spec/views/inbox/show.turbo_stream.haml_spec.rb b/spec/views/inbox/show.turbo_stream.haml_spec.rb
new file mode 100644
index 00000000..f7a49245
--- /dev/null
+++ b/spec/views/inbox/show.turbo_stream.haml_spec.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe "inbox/show.turbo_stream.haml", type: :view do
+  let(:user) { FactoryBot.create(:user) }
+
+  before do
+    sign_in user
+  end
+
+  subject(:rendered) { render }
+
+  context "with some inbox entries" do
+    let(:inbox_entry1) { Inbox.create(user:, question: FactoryBot.create(:question)) }
+    let(:inbox_entry2) { Inbox.create(user:, question: FactoryBot.create(:question)) }
+
+    before do
+      assign :inbox, [inbox_entry2, inbox_entry1]
+    end
+
+    it "appends to entries" do
+      expect(rendered).to have_css(%(turbo-stream[action="append"][target="entries"]))
+    end
+
+    it "renders inbox entries" do
+      expect(rendered).to have_css("#inbox_#{inbox_entry1.id}")
+      expect(rendered).to have_css("#inbox_#{inbox_entry2.id}")
+    end
+
+    it "updates the paginator" do
+      expect(rendered).to have_css(%(turbo-stream[action="update"][target="paginator"]))
+    end
+
+    context "when more data is available" do
+      before do
+        assign :more_data_available, true
+        assign :inbox_last_id, 1337
+      end
+
+      it "has the correct params on the button" do
+        expect(rendered).to have_css(%(input[type="hidden"][name="last_id"][value="1337"]))
+        expect(rendered).not_to have_css(%(input[type="hidden"][name="author"]))
+      end
+
+      context "when passed an author" do
+        before do
+          assign :author, "jyrki"
+        end
+
+        it "has the correct params on the button" do
+          expect(rendered).to have_css(%(input[type="hidden"][name="last_id"][value="1337"]))
+          expect(rendered).to have_css(%(input[type="hidden"][name="author"]))
+        end
+      end
+    end
+  end
+end