diff --git a/Gemfile b/Gemfile
index 1699e8a74..d4349c7cd 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,5 @@
 source "https://rubygems.org"
+git_source(:bc) { |repo| "https://github.com/basecamp/#{repo}" }
 ruby file: ".ruby-version"
 
 gem "rails", github: "rails/rails", branch: "main"
@@ -9,6 +10,7 @@ gem "propshaft"
 gem "stimulus-rails"
 gem "turbo-rails"
 gem "hotwire_combobox", github: "josefarias/hotwire_combobox", branch: :main
+gem "house_md", bc: "house", branch: :renderer
 
 # Deployment and drivers
 gem "bootsnap", require: false
diff --git a/Gemfile.lock b/Gemfile.lock
index 4b63b69ab..1c26d38e1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,3 +1,12 @@
+GIT
+  remote: https://github.com/basecamp/house
+  revision: a8b19e70bbb95a7a0d27e38985a99c2d697a6650
+  branch: renderer
+  specs:
+    house_md (1.0.0)
+      rails
+      zeitwerk
+
 GIT
   remote: https://github.com/josefarias/hotwire_combobox.git
   revision: 57ee6c9087320fab9383a07fa919fe75e0ea72ba
@@ -346,6 +355,7 @@ DEPENDENCIES
   capybara
   debug
   hotwire_combobox!
+  house_md!
   importmap-rails
   jbuilder
   propshaft
diff --git a/config/initializers/markdown.rb b/config/initializers/markdown.rb
index 57e7c4384..2d3a879a3 100644
--- a/config/initializers/markdown.rb
+++ b/config/initializers/markdown.rb
@@ -1,4 +1,4 @@
 ActiveSupport.on_load :action_text_markdown do
   require "markdown_renderer"
-  ActionText::Markdown.renderer = -> { MarkdownRenderer.new }
+  ActionText::Markdown.html_renderer = -> { MarkdownRenderer.new }
 end
diff --git a/lib/markdown_renderer.rb b/lib/markdown_renderer.rb
index 1205e6d6d..9117b28d0 100644
--- a/lib/markdown_renderer.rb
+++ b/lib/markdown_renderer.rb
@@ -1,40 +1,47 @@
-class MarkdownRenderer
-  require_relative "markdown_renderer/parsing"
-  require_relative "markdown_renderer/markup"
+require "rouge/plugins/redcarpet"
 
-  include Parsing, Markup
+class MarkdownRenderer < HouseMd::Renderer
+  class Generator < HouseMd::Generator::Html
+    include Rouge::Plugins::Redcarpet
 
-  def initialize
-    @id_counts = Hash.new(0)
-  end
+    def initialize
+      @id_counts = Hash.new 0
+    end
 
-  def render(content)
-    content
-      .then { |c| parse_paragraphs(c) }
-      .then { |c| parse_bold_italics(c) }
-      .then { |c| parse_bold(c) }
-      .then { |c| parse_italics(c) }
-      .then { |c| parse_strikethrough(c) }
-      .then { |c| parse_highlight(c) }
-      .then { |c| parse_headers(c) }
-      .then { |c| parse_tables(c) }
-      .then { |c| parse_ordered_lists(c) }
-      .then { |c| parse_unordered_lists(c) }
-      .then { |c| parse_block_quotes(c) }
-      .then { |c| parse_horizontal_rules(c) }
-      .then { |c| parse_images(c) }
-      .then { |c| parse_links(c) }
-      .then { |c| parse_code_blocks(c) }
-      .then { |c| parse_code_spans(c) }
-  end
-
-  private
-    attr_reader :id_counts
-
-    def unique_id(text)
-      text.parameterize.then do |base_id|
-        id_counts[base_id] += 1
-        id_counts[base_id] > 1 ? "#{base_id}-#{id_counts[base_id]}" : base_id
+    def header(text, header_level)
+      unique_id(text).then do |id|
+        <<~HTML.chomp
+          <h#{header_level} id="#{id}">
+            #{text} <a href="##{id}" class="heading__link" aria-hidden="true">#</a>
+          </h#{header_level}>
+        HTML
       end
     end
+
+    def image(url, alt_text)
+      <<~HTML.chomp
+        <a href="#{url}" data-action="lightbox#open:prevent" data-lightbox-target="image" data-lightbox-url-value="#{url}?disposition=attachment">
+          <img src="#{url}" alt="#{alt_text}">
+        </a>
+      HTML
+    end
+
+    def code_block(code, language)
+      block_code(code, language) # call Rouge Redcarpet plugin
+    end
+
+    private
+      attr_reader :id_counts
+
+      def unique_id(text)
+        text.parameterize.then do |base_id|
+          id_counts[base_id] += 1
+          id_counts[base_id] > 1 ? "#{base_id}-#{id_counts[base_id]}" : base_id
+        end
+      end
+  end
+
+  def initialize
+    @generator = Generator.new
+  end
 end
diff --git a/lib/markdown_renderer/markup.rb b/lib/markdown_renderer/markup.rb
deleted file mode 100644
index 2e2753c5e..000000000
--- a/lib/markdown_renderer/markup.rb
+++ /dev/null
@@ -1,117 +0,0 @@
-require "rouge/plugins/redcarpet"
-
-module MarkdownRenderer::Markup
-  include Rouge::Plugins::Redcarpet
-
-  TABLE_ROW_INDENT    = " " * 4
-  LIST_ITEM_INDENT    = " " * 2
-  BLOCK_QUOTE_INDENT  = " " * 2
-  TABLE_HEADER_INDENT = " " * 6
-
-  # FIXME: the attributes suggest this should be an app-level override instead
-  def header(text, header_level)
-    unique_id(text).then do |id|
-      <<~HTML.chomp
-        <h#{header_level} id="#{id}">
-          #{text} <a href="##{id}" class="heading__link" aria-hidden="true">#</a>
-        </h#{header_level}>
-      HTML
-    end
-  end
-
-  def bold(text)
-    "<strong>#{text}</strong>"
-  end
-
-  def italics(text)
-    "<em>#{text}</em>"
-  end
-
-  def strikethrough(text)
-    "<s>#{text}</s>"
-  end
-
-  def highlight(text)
-    "<mark>#{text}</mark>"
-  end
-
-  def table(headers, rows)
-    <<~HTML
-      <table>
-        <thead>
-          <tr>
-            #{headers.map { |header| "<th>#{header}</th>" }.join("\n" + TABLE_HEADER_INDENT)}
-          </tr>
-        </thead>
-        <tbody>
-          #{rows.map { |row| "<tr>#{row.map { |cell| "<td>#{cell}</td>" }.join}</tr>" }.join("\n" + TABLE_ROW_INDENT)}
-        </tbody>
-      </table>
-    HTML
-  end
-
-  def ordered_list(contents)
-    <<~HTML
-      <ol>
-        #{contents.split("\n").join("\n" + LIST_ITEM_INDENT)}
-      </ol>
-    HTML
-  end
-
-  def unordered_list(contents)
-    <<~HTML
-      <ul>
-        #{contents.split("\n").join("\n" + LIST_ITEM_INDENT)}
-      </ul>
-    HTML
-  end
-
-  def list_item(text)
-    "<li>#{text}</li>"
-  end
-
-  def block_quote(text)
-    <<~HTML
-      <blockquote>
-        #{text.gsub(/^>\s?/, '').split("\n").join("\n" + BLOCK_QUOTE_INDENT)}
-      </blockquote>
-    HTML
-  end
-
-  def horizontal_rule
-    "<hr>"
-  end
-
-  def link(text, href)
-    "<a href=\"#{href}\">#{text}</a>"
-  end
-
-  def code_block(code, language)
-    block_code(code, language) # call Rouge Redcarpet plugin
-  end
-
-  def code_span(text)
-    "<code>#{text}</code>"
-  end
-
-  # FIXME: the attributes suggest this should be an app-level override instead
-  def image(url, alt_text)
-    <<~HTML.chomp
-      <a href="#{url}" data-action="lightbox#open:prevent" data-lightbox-target="image" data-lightbox-url-value="#{url}?disposition=attachment">
-        <img src="#{url}" alt="#{alt_text}">
-      </a>
-    HTML
-  end
-
-  def paragraph(text)
-    "<p>#{text}</p>"
-  end
-
-  def soft_line_break
-    "\n#{line_break}\n"
-  end
-
-  def line_break
-    "<br>"
-  end
-end
diff --git a/lib/markdown_renderer/parsing.rb b/lib/markdown_renderer/parsing.rb
deleted file mode 100644
index 3069251cb..000000000
--- a/lib/markdown_renderer/parsing.rb
+++ /dev/null
@@ -1,136 +0,0 @@
-module MarkdownRenderer::Parsing
-  HR = /^---$/
-  INLINE_HTML_BLOCK_START = /^</
-  HEADING_START = /^#/
-  CODE_BLOCK_START = /^```/
-
-  NEWLINE_OR_EOF = /\n|$/
-  SOFT_LINE_BREAK = /(?<=[^\n])\n(?=[^\n])/
-
-  NUMBERED_LIST_START = /^\d+\.\s/
-  NUMBERED_LIST_ITEM = /#{NUMBERED_LIST_START}[^\n]*#{NEWLINE_OR_EOF}/
-
-  UNORDERED_LIST_START = /^-\s/
-  UNORDERED_LIST_ITEM = /#{UNORDERED_LIST_START}[^\n]*#{NEWLINE_OR_EOF}/
-
-  BLOCK_QUOTE_START = /^>\s?/
-  BLOCK_QUOTE_CONTENT = /#{BLOCK_QUOTE_START}[^\n]*#{NEWLINE_OR_EOF}/
-
-  TABLE_START = /^\|/
-  TABLE_HEADER_ROW = /^\|(.+)\|/
-  TABLE_SEPARATOR = /^\|[-|]+\|/
-  TABLE_DATA_ROW = /^\|.+\|/
-  TABLE = /#{TABLE_HEADER_ROW}\r?\n#{TABLE_SEPARATOR}\r?\n((?:#{TABLE_DATA_ROW}\r?\n)*)/
-
-  BLOCK_STARTERS = Regexp.union [
-    HR,
-    TABLE_START,
-    HEADING_START,
-    CODE_BLOCK_START,
-    BLOCK_QUOTE_START,
-    NUMBERED_LIST_START,
-    UNORDERED_LIST_START,
-    INLINE_HTML_BLOCK_START
-  ]
-
-  private
-    def parse_paragraphs(content)
-      content.split(/\n\n+/).map do |text|
-        if text.match?(BLOCK_STARTERS)
-          text
-        else
-          paragraph text.gsub(SOFT_LINE_BREAK, soft_line_break)
-        end
-      end.join("\n\n")
-    end
-
-    def parse_bold_italics(content)
-      transform = ->(match) { bold(italics(match)) }
-
-      content
-        .gsub(/(?<!\*)\*\*\*([^*]+)\*\*\*(?!\*)/) { transform.($1) }
-        .gsub(/(?<!_)___([^_]+)___(?!_)/) { transform.($1) }
-    end
-
-    def parse_bold(content)
-      transform = ->(match) { bold(match) }
-
-      content
-        .gsub(/(?<!\*)\*\*([^*]+)\*\*(?!\*)/) { transform.($1) }
-        .gsub(/(?<!_)__([^_]+)__(?!_)/) { transform.($1) }
-    end
-
-    def parse_italics(content)
-      transform = ->(match) { italics(match) }
-
-      content
-        .gsub(/(?<!\*)\*([^*]+)\*(?!\*)/) { transform.($1) }
-        .gsub(/(?<!_)_([^_]+)_(?!_)/) { transform.($1) }
-    end
-
-    def parse_strikethrough(content)
-      content.gsub(/~~(.*?)~~/) { strikethrough($1) }
-    end
-
-    def parse_highlight(content)
-      content.gsub(/==(.*?)==/) { highlight($1) }
-    end
-
-    def parse_headers(content)
-      content
-        .gsub(/^# (.*)$/) { header($1, 1) }
-        .gsub(/^## (.*)$/) { header($1, 2) }
-        .gsub(/^### (.*)$/) { header($1, 3) }
-        .gsub(/^#### (.*)$/) { header($1, 4) }
-        .gsub(/^##### (.*)$/) { header($1, 5) }
-        .gsub(/^###### (.*)$/) { header($1, 6) }
-    end
-
-    def parse_tables(content)
-      content.gsub(TABLE) do
-        headers = $1.split("|").map(&:strip).compact_blank
-        rows = $2.split("\n").map { |row| row.split("|").map(&:strip).compact_blank unless row.blank? }.compact
-        table(headers, rows) if rows.map(&:size).all?(headers.size)
-      end
-    end
-
-    def parse_ordered_lists(content)
-      content.gsub(/(?:#{NUMBERED_LIST_ITEM})+/) { |list| ordered_list(parse_ordered_list_items(list.strip)) }
-    end
-
-    def parse_ordered_list_items(content)
-      content.gsub(/#{NUMBERED_LIST_START}(.*)$/) { list_item($1) }
-    end
-
-    def parse_unordered_lists(content)
-      content.gsub(/(?:#{UNORDERED_LIST_ITEM})+/) { |list| unordered_list(parse_unordered_list_items(list.strip)) }
-    end
-
-    def parse_unordered_list_items(content)
-      content.gsub(/#{UNORDERED_LIST_START}(.*)$/) { list_item($1) }
-    end
-
-    def parse_block_quotes(content)
-      content.gsub(/(?:#{BLOCK_QUOTE_CONTENT})+/) { |text| block_quote(text.strip) }
-    end
-
-    def parse_horizontal_rules(content)
-      content.gsub(HR) { horizontal_rule }
-    end
-
-    def parse_images(content)
-      content.gsub(/!\[(.*?)\]\((.*?)\)/) { image($2, $1) }
-    end
-
-    def parse_links(content)
-      content.gsub(/\[(.*?)\]\((.*?)\)/) { link($1, $2) }
-    end
-
-    def parse_code_blocks(content)
-      content.gsub(/#{CODE_BLOCK_START}(\w*)\n(.*?)```$/m) { code_block($2, $1) }
-    end
-
-    def parse_code_spans(content)
-      content.gsub(/`([^`\n]+)`/) { code_span($1) }
-    end
-end
diff --git a/lib/rails_ext/action_text_markdown.rb b/lib/rails_ext/action_text_markdown.rb
index 41c21a893..f5d57ece1 100644
--- a/lib/rails_ext/action_text_markdown.rb
+++ b/lib/rails_ext/action_text_markdown.rb
@@ -1,28 +1,16 @@
-require "redcarpet/render_strip"
-
 module ActionText
   class Markdown < Record
-    DEFAULT_RENDERER_OPTIONS = {
-      filter_html: false
-    }
-
-    DEFAULT_MARKDOWN_EXTENSIONS = {
-      autolink: true,
-      highlight: true,
-      no_intra_emphasis: true,
-      fenced_code_blocks: true,
-      lax_spacing: true,
-      strikethrough: true,
-      tables: true
-    }
-
-    mattr_accessor :renderer, default: Redcarpet::Markdown.new(Redcarpet::Render::HTML.new(DEFAULT_RENDERER_OPTIONS), DEFAULT_MARKDOWN_EXTENSIONS)
-    mattr_accessor :plain_renderer, default: Redcarpet::Markdown.new(Redcarpet::Render::StripDown)
+    mattr_accessor :html_renderer
+    mattr_accessor :plain_renderer
 
     belongs_to :record, polymorphic: true, touch: true
 
     def to_html
-      (renderer.try(:call) || renderer).render(content).html_safe
+      to_unsafe_html.html_safe
+    end
+
+    def to_unsafe_html
+      (html_renderer.try(:call) || html_renderer).render(content)
     end
 
     def to_plain_text
diff --git a/test/lib/markdown_renderer_test.rb b/test/lib/markdown_renderer_test.rb
deleted file mode 100644
index c2bd93ca9..000000000
--- a/test/lib/markdown_renderer_test.rb
+++ /dev/null
@@ -1,230 +0,0 @@
-require "test_helper"
-
-class MarkdownRendererTest < ActiveSupport::TestCase
-  setup do
-    @renderer = MarkdownRenderer.new
-  end
-
-  test "renders a complete markdown document" do
-    assert_equal expected_html, @renderer.render(markdown_content)
-  end
-
-  private
-    def expected_html
-      <<~HTML
-        <h1 id="welcome-to-my-document">
-          Welcome to My Document <a href="#welcome-to-my-document" class="heading__link" aria-hidden="true">#</a>
-        </h1>
-
-        <p>This is an introduction paragraph with some text.</p>
-
-        <hr>
-
-        <p><strong><em>Hello, world!</em></strong> <strong>Hello, world!</strong> <em>Hello, world!</em> <s>Hello, world!</s> <mark>Hello, world!</mark></p>
-
-        <p><strong><em>Hello, world!</em></strong>
-        <br>
-        <strong>Hello, world!</strong>
-        <br>
-        <em>Hello, world!</em>
-        <br>
-        <s>Hello, world!</s>
-        <br>
-        <mark>Hello, world!</mark></p>
-
-        <h2 id="getting-started">
-          Getting Started <a href="#getting-started" class="heading__link" aria-hidden="true">#</a>
-        </h2>
-
-        <p>Here’s what you need to know:</p>
-
-        <ol>
-          <li>First important point</li>
-          <li>Second crucial thing</li>
-          <li>Don’t forget this</li>
-        </ol>
-
-        <h2 id="key-features">
-          Key Features <a href="#key-features" class="heading__link" aria-hidden="true">#</a>
-        </h2>
-
-        <p>Our product offers:</p>
-
-        <ul>
-          <li>Simple interface</li>
-          <li>Powerful features</li>
-          <li>Great documentation</li>
-        </ul>
-
-        <p><a href="https://basecamp.com">Get Basecamp</a></p>
-
-        <h3 id="important-note-2">
-          Important Note <a href="#important-note-2" class="heading__link" aria-hidden="true">#</a>
-        </h3>
-
-        <p>Here’s some
-        <br>
-        multiline text.
-        <br>
-        It has line breaks
-        <br>
-        in-between.</p>
-
-        <blockquote>
-          Please read this carefully
-          It contains vital information
-          That you shouldn’t miss
-        </blockquote>
-
-        <p><a href="https://placehold.co/600x400" data-action="lightbox#open:prevent" data-lightbox-target="image" data-lightbox-url-value="https://placehold.co/600x400?disposition=attachment">
-          <img src="https://placehold.co/600x400" alt="Placeholder image">
-        </a></p>
-
-        <h2 id="important-note">
-          Important Note <a href="#important-note" class="heading__link" aria-hidden="true">#</a>
-        </h2>
-
-        <p><a href="https://placehold.co/400x400" data-action="lightbox#open:prevent" data-lightbox-target="image" data-lightbox-url-value="https://placehold.co/400x400?disposition=attachment">
-          <img src="https://placehold.co/400x400" alt="Placeholder image">
-        </a></p>
-
-        <ol>
-          <li>Remember to save</li>
-          <li>Back up your work</li>
-        </ol>
-
-        <p><a href="https://basecamp.com">Get Basecamp</a></p>
-
-        <table>
-          <thead>
-            <tr>
-              <th>Table 1 Header 1</th>
-              <th>Table 1 Header 2</th>
-            </tr>
-          </thead>
-          <tbody>
-            <tr><td>Table 1 Data 1</td><td>Table 1 Data 2</td></tr>
-            <tr><td>Table 1 Data 3</td><td>Table 1 Data 4</td></tr>
-          </tbody>
-        </table>
-
-        <p>Some content between tables...</p>
-
-        <table>
-          <thead>
-            <tr>
-              <th>Table 2 Header 1</th>
-              <th>Table 2 Header 2</th>
-            </tr>
-          </thead>
-          <tbody>
-            <tr><td>Table 2 Data 1</td><td>Table 2 Data 2</td></tr>
-            <tr><td>Table 2 Data 3</td><td>Table 2 Data 4</td></tr>
-          </tbody>
-        </table>
-
-        <div class="highlight"><pre class="highlight ruby"><code><span class="k">class</span> <span class="nc">Post</span> <span class="o">&lt;</span> <span class="no">ApplicationRecord</span>
-          <span class="k">def</span> <span class="nf">title</span>
-            <span class="s2">"foo"</span>
-          <span class="k">end</span>
-        <span class="k">end</span>
-        </code></pre></div>
-
-        <p><code>puts "Hello, world!"</code></p>
-
-        <p>Thanks for reading!</p>
-
-        <details>
-          <summary>Summary</summary>
-          Details
-        </details>
-      HTML
-    end
-
-    def markdown_content
-      <<~MARKDOWN
-        # Welcome to My Document
-
-        This is an introduction paragraph with some text.
-
-        ---
-
-        ***Hello, world!*** **Hello, world!** *Hello, world!* ~~Hello, world!~~ ==Hello, world!==
-
-        ***Hello, world!***
-        **Hello, world!**
-        *Hello, world!*
-        ~~Hello, world!~~
-        ==Hello, world!==
-
-        ## Getting Started
-
-        Here’s what you need to know:
-
-        1. First important point
-        2. Second crucial thing
-        3. Don’t forget this
-
-        ## Key Features
-
-        Our product offers:
-
-        - Simple interface
-        - Powerful features
-        - Great documentation
-
-        [Get Basecamp](https://basecamp.com)
-
-        ### Important Note
-
-        Here’s some
-        multiline text.
-        It has line breaks
-        in-between.
-
-        > Please read this carefully
-        > It contains vital information
-        > That you shouldn’t miss
-
-        ![Placeholder image](https://placehold.co/600x400)
-
-        ## Important Note
-
-        ![Placeholder image](https://placehold.co/400x400)
-
-        1. Remember to save
-        2. Back up your work
-
-        [Get Basecamp](https://basecamp.com)
-
-        | Table 1 Header 1 | Table 1 Header 2 |
-        |-|-|
-        | Table 1 Data 1 | Table 1 Data 2 |
-        | Table 1 Data 3 | Table 1 Data 4 |
-
-        Some content between tables...
-
-        | Table 2 Header 1 | Table 2 Header 2 |
-        |------------------|------------------|
-        | Table 2 Data 1   | Table 2 Data 2   |
-        | Table 2 Data 3   | Table 2 Data 4   |
-
-        ```rb
-        class Post < ApplicationRecord
-          def title
-            "foo"
-          end
-        end
-        ```
-
-        `puts "Hello, world!"`
-
-        Thanks for reading!
-
-        <details>
-          <summary>Summary</summary>
-          Details
-        </details>
-      MARKDOWN
-    end
-end
diff --git a/test/models/bubble_test.rb b/test/models/bubble_test.rb
index fdfd65c82..d890ee19a 100644
--- a/test/models/bubble_test.rb
+++ b/test/models/bubble_test.rb
@@ -10,7 +10,7 @@ class BubbleTest < ActiveSupport::TestCase
       bubbles(:logo).capture Comment.new(body: "Agreed.")
     end
 
-    assert_equal "Agreed.\n", bubbles(:logo).messages.last.messageable.body.to_plain_text
+    assert_equal "Agreed.", bubbles(:logo).messages.last.messageable.body.to_plain_text
   end
 
   test "boosting" do