fix(ci): provision Ruby for agent authorship labels

.github/scripts/classify-agent-authorship.rb

@@ -0,0 +1,83 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "json"
+require "optparse"
+
+options = {
+  github_output: nil,
+}
+
+OptionParser.new do |parser|
+  parser.on("--github-output PATH", "Append key=value outputs for GitHub Actions") do |path|
+    options[:github_output] = path
+  end
+end.parse!
+
+input = ARGF.read
+
+messages = input.each_line.map do |line|
+  next if line.strip.empty?
+
+  parsed = JSON.parse(line)
+  if parsed.is_a?(Hash)
+    parsed.dig("commit", "message") || parsed["message"]
+  end
+end.compact
+
+required_patterns = {
+  "co_author" => /^Co-Authored-By:\s*Maestro\s+<maestro@evalops\.dev>\s*$/i,
+  "version" => /^Maestro-Version:\s*\S.*$/i,
+  "prompt_id" => /^Maestro-Prompt-Id:\s*\S.*$/i,
+  "approvals_id" => /^Maestro-Approvals-Id:\s*\S.*$/i,
+}
+
+marker_pattern = /
+  ^Co-Authored-By:\s*Maestro\s+<maestro@evalops\.dev>\s*$ |
+  ^Maestro-(?:Version|Prompt-Id|Approvals-Id):
+/ix
+
+agent_commits = 0
+untrailered_commits = 0
+incomplete_commits = 0
+
+messages.each do |message|
+  has_marker = message.lines.any? { |line| line.match?(marker_pattern) }
+
+  unless has_marker
+    untrailered_commits += 1
+    next
+  end
+
+  agent_commits += 1
+  missing_required = required_patterns.values.any? do |pattern|
+    message.lines.none? { |line| line.match?(pattern) }
+  end
+  incomplete_commits += 1 if missing_required
+end
+
+label =
+  if agent_commits.positive? && untrailered_commits.positive?
+    "mixed-authorship"
+  elsif agent_commits.positive?
+    "agent-authored"
+  else
+    "agent-assisted"
+  end
+
+outputs = {
+  "label" => label,
+  "total_commits" => messages.length,
+  "agent_commits" => agent_commits,
+  "untrailered_commits" => untrailered_commits,
+  "human_commits" => untrailered_commits,
+  "incomplete_agent_commits" => incomplete_commits,
+}
+
+outputs.each { |key, value| puts "#{key}=#{value}" }
+
+if options[:github_output]
+  File.open(options[:github_output], "a") do |file|
+    outputs.each { |key, value| file.puts("#{key}=#{value}") }
+  end
+end