feat: dynamic OG image generation from achievements YAML

Replace static og-image.jpg with dynamically generated PNG that
auto-updates wins count and earnings from achievements.yml.
Uses MiniMagick + JetBrains Mono font. Cached until YAML changes.

- Add OgImageGenerator service
- Add /og-image endpoint with HTTP caching
- Bundle JetBrains Mono fonts for Docker
- Add imagemagick + fontconfig to Dockerfile

Author: rz1989s

Dockerfile

@@ -16,7 +16,7 @@ WORKDIR /rails
 
 # Install base packages
 RUN apt-get update -qq && \
-    apt-get install --no-install-recommends -y curl libjemalloc2 libvips postgresql-client && \
+    apt-get install --no-install-recommends -y curl libjemalloc2 libvips imagemagick fontconfig postgresql-client && \
     ln -s /usr/lib/$(uname -m)-linux-gnu/libjemalloc.so.2 /usr/local/lib/libjemalloc.so && \
     rm -rf /var/lib/apt/lists /var/cache/apt/archives
 

app/assets/fonts/JetBrainsMono-Bold.ttf

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class OgImagesController < ApplicationController
+  def show
+    path = OgImageGenerator.cached_path
+    expires_in 1.hour, public: true
+    send_file path, type: "image/png", disposition: "inline"
+  end
+end

app/assets/fonts/JetBrainsMono-Regular.ttf

@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+require "mini_magick"
+
+# Generates dynamic Open Graph images with live achievement stats.
+# Cached in tmp/cache/og/ — regenerates when achievements.yml changes.
+class OgImageGenerator
+  WIDTH = 1200
+  HEIGHT = 630
+  BG_COLOR = "#2D2320"
+
+  def self.cached_path
+    new.cached_path
+  end
+
+  def cached_path
+    generate! unless valid_cache?
+    cache_file
+  end
+
+  private
+
+  def cache_file
+    Rails.root.join("tmp", "cache", "og", "og-image.png")
+  end
+
+  def valid_cache?
+    cache_file.exist? && cache_file.mtime > achievements_mtime
+  end
+
+  def achievements_mtime
+    Rails.root.join("config", "achievements.yml").mtime
+  end
+
+  def generate!
+    FileUtils.mkdir_p(cache_file.dirname)
+
+    # Build canvas with text layers
+    MiniMagick::Tool::Convert.new do |c|
+      c.size "#{WIDTH}x#{HEIGHT}"
+      c.xc BG_COLOR
+
+      # Accent line (orange)
+      c.fill "#E58C2E"
+      c.draw "rectangle 80,225 130,229"
+
+      # "RECTOR" label
+      c.fill "white"
+      c.font font_path(:bold)
+      c.pointsize 22
+      c.gravity "NorthWest"
+      c.annotate "+120+68", "RECTOR"
+
+      # "Building for Eternity" heading
+      c.pointsize 48
+      c.annotate "+80+260", "Building for Eternity"
+
+      # Dynamic stats line
+      c.fill "#B0A090"
+      c.font font_path(:regular)
+      c.pointsize 22
+      c.annotate "+80+345", stats_text
+
+      # URL bottom-right
+      c.pointsize 16
+      c.gravity "SouthEast"
+      c.annotate "+50+40", "rectorspace.com"
+
+      c << cache_file.to_s
+    end
+
+    # Composite profile picture
+    composite_profile!
+  end
+
+  def composite_profile!
+    profile = MiniMagick::Image.open(profile_path.to_s)
+    profile.resize "60x60"
+
+    canvas = MiniMagick::Image.open(cache_file.to_s)
+    result = canvas.composite(profile) do |comp|
+      comp.compose "Over"
+      comp.geometry "+50+55"
+    end
+    result.write(cache_file.to_s)
+  end
+
+  def stats_text
+    count = Achievement.win_count
+    earnings = ActiveSupport::NumberHelper.number_to_delimited(Achievement.total_earnings)
+    "Full-stack builder. Hackathon hunter. #{count} wins, ~$#{earnings} earned."
+  end
+
+  def profile_path
+    Rails.root.join("app", "assets", "images", "rector_profile_image.png")
+  end
+
+  def font_path(weight)
+    name = weight == :bold ? "JetBrainsMono-Bold" : "JetBrainsMono-Regular"
+    bundled = Rails.root.join("app", "assets", "fonts", "#{name}.ttf")
+    return bundled.to_s if bundled.exist?
+
+    # Fallback to system font
+    weight == :bold ? "DejaVu-Sans-Mono-Bold" : "DejaVu-Sans-Mono"
+  end
+end

app/controllers/og_images_controller.rb

@@ -18,7 +18,7 @@
     <meta property="og:url" content="https://rectorspace.com<%= request.path %>">
     <meta property="og:title" content="<%= content_for(:title) ? "#{content_for(:title)} • RECTOR" : "RECTOR • Building for Eternity" %>">
     <meta property="og:description" content="<%= content_for(:meta_description) || "Full-stack builder. Hackathon hunter. #{achievements_summary}. Building for eternity." %>">
-    <meta property="og:image" content="<%= content_for(:og_image) || "https://rectorspace.com#{asset_path('og-image.jpg')}" %>">
+    <meta property="og:image" content="<%= content_for(:og_image) || "https://rectorspace.com/og-image" %>">
     <meta property="og:site_name" content="RECTOR">
 
     <%# Twitter Card meta tags %>
@@ -27,7 +27,7 @@
     <meta name="twitter:creator" content="@RZ1989sol">
     <meta name="twitter:title" content="<%= content_for(:title) ? "#{content_for(:title)} • RECTOR" : "RECTOR • Building for Eternity" %>">
     <meta name="twitter:description" content="<%= content_for(:meta_description) || "Full-stack builder. Hackathon hunter. #{achievements_summary}. Building for eternity." %>">
-    <meta name="twitter:image" content="<%= content_for(:og_image) || "https://rectorspace.com#{asset_path('og-image.jpg')}" %>">
+    <meta name="twitter:image" content="<%= content_for(:og_image) || "https://rectorspace.com/og-image" %>">
 
     <%= yield :head %>
 

app/services/og_image_generator.rb

@@ -13,6 +13,9 @@
   get "apply/arbital/retro",  to: "apply#arbital_retro",  as: :apply_arbital_retro
   get "apply/arbital/modern", to: "apply#arbital_modern", as: :apply_arbital_modern
 
+  # Dynamic OG image (auto-updates from achievements.yml)
+  get "og-image", to: "og_images#show", as: :og_image
+
   # Health check
   get "up" => "rails/health#show", as: :rails_health_check