ruby 3.4.8 (2025-12-17 revision 995b59f666) +PRISM [x86_64-linux]
Pattern 1: Contamination before .new
  Control (no Dir call):     [1, 2]
  Bug (after Dir[**{}]):     [1, 2]
  Control (Dir[**{sort:}]):  [1, 2]

Pattern 2: Contamination inside initialize (super)
  Result: [1, 2]
  Control (non-empty extra): [1, 2]

# Triggers on ALL dispatch paths (interpreter, JIT, indy)
# because Dir.[] is keywords=true — neither the wrapper nor finishBinding ever clears callInfo for it.

class Victim
  def initialize(a, k:)
    @a = a
    @k = k
  end

  def result
    [@a, @k]
  end
end

# -- Pattern 1: Contamination before .new ----------------------------------

def control_constructor
  v = Victim.new(1, k: 2)
  puts "  Control (no Dir call):     #{v.result.inspect}"
end

def bug_constructor(options)
  Dir["nonexistent_pattern", **options]
  v = Victim.new(1, k: 2)
  puts "  Bug (after Dir[**{}]):     #{v.result.inspect}"
end

def control_nonempty(options)
  Dir["nonexistent_pattern", **options]
  v = Victim.new(1, k: 2)
  puts "  Control (Dir[**{sort:}]):  #{v.result.inspect}"
end

# -- Pattern 2: Contamination inside initialize via super -------------------

class Base
  def initialize(a, k:)
    @a = a
    @k = k
  end

  def result
    [@a, @k]
  end
end

class Child < Base
  def initialize(a, k:, **extra)
    Dir["nonexistent_pattern", **extra]
    super(a, k: k)
  end
end

# -- Run tests --------------------------------------------------------------

puts "Pattern 1: Contamination before .new"

control_constructor

begin
  bug_constructor({})
rescue ArgumentError => e
  puts "  BUG TRIGGERED: #{e.message}"
  puts "    #{e.backtrace.first(3).join("\n    ")}"
end

control_nonempty({sort: false})

puts
puts "Pattern 2: Contamination inside initialize (super)"

begin
  puts "  Result: #{Child.new(1, k: 2).result.inspect}"
rescue ArgumentError => e
  puts "  BUG TRIGGERED: #{e.message}"
  puts "    #{e.backtrace.first(3).join("\n    ")}"
end

puts "  Control (non-empty extra): #{Child.new(1, k: 2, sort: false).result.inspect}"