docs: add second inspection listing

Add listing-002.md exploring Kernel patches, CLI script, and gemspec for Fagan inspection.

Author: tzanko-matev

listing-002.md

@@ -0,0 +1,185 @@
+# Listing 002
+
+This listing continues the inspection by detailing how runtime I/O is captured and how the gem is packaged. We review the output-hooking helpers in `gems/codetracer-ruby-recorder/lib/codetracer/kernel_patches.rb`, the CLI entry script `gems/codetracer-ruby-recorder/bin/codetracer-ruby-recorder`, and the gem specification `gems/codetracer-ruby-recorder/codetracer-ruby-recorder.gemspec`.
+
+**File declares MIT license and begins KernelPatches module tracking installed tracers.**
+```ruby
+# SPDX-License-Identifier: MIT
+
+module CodeTracer
+  module KernelPatches
+    @@tracers = []
+```
+
+**Add a tracer unless already present and store it in the class variable.**
+```ruby
+    def self.install(tracer)
+      return if @@tracers.include?(tracer)
+      @@tracers << tracer
+```
+
+**When the first tracer is installed, patch Kernel methods.**
+```ruby
+      if @@tracers.length == 1
+        Kernel.module_eval do
+```
+
+**Alias original I/O methods so they can be restored later.**
+```ruby
+          alias_method :codetracer_original_p, :p unless method_defined?(:codetracer_original_p)
+          alias_method :codetracer_original_puts, :puts unless method_defined?(:codetracer_original_puts)
+          alias_method :codetracer_original_print, :print unless method_defined?(:codetracer_original_print)
+```
+
+**Redefine `p` to compute a printable representation and log it.**
+```ruby
+          define_method(:p) do |*args|
+            loc = caller_locations(1, 1).first
+            content = if args.length == 1 && args.first.is_a?(Array)
+```
+
+**Handle array arguments or multiple values uniformly.**
+```ruby
+              args.first.map(&:inspect).join("\n")
+            else
+              args.map(&:inspect).join("\n")
+            end
+```
+
+**Record the event with all active tracers before delegating.**
+```ruby
+            @@tracers.each do |t|
+              t.record_event(loc.path, loc.lineno, content)
+            end
+            codetracer_original_p(*args)
+          end
+```
+
+**Redefine `puts` to capture line-oriented output.**
+```ruby
+          define_method(:puts) do |*args|
+            loc = caller_locations(1, 1).first
+            @@tracers.each do |t|
+              t.record_event(loc.path, loc.lineno, args.join("\n"))
+            end
+```
+
+**Forward `puts` after logging the captured lines.**
+```ruby
+            codetracer_original_puts(*args)
+          end
+```
+
+**Redefine `print` to intercept raw output without newlines.**
+```ruby
+          define_method(:print) do |*args|
+            loc = caller_locations(1, 1).first
+            @@tracers.each do |t|
+              t.record_event(loc.path, loc.lineno, args.join)
+            end
+```
+
+**Delegate `print` to the original implementation afterward.**
+```ruby
+            codetracer_original_print(*args)
+          end
+        end
+      end
+    end
+```
+
+**Remove a tracer and restore Kernel methods when none remain.**
+```ruby
+    def self.uninstall(tracer)
+      @@tracers.delete(tracer)
+
+      if @@tracers.empty? && Kernel.private_method_defined?(:codetracer_original_p)
+        Kernel.module_eval do
+          alias_method :p, :codetracer_original_p
+          alias_method :puts, :codetracer_original_puts
+          alias_method :print, :codetracer_original_print
+        end
+      end
+    end
+```
+
+**Provide helper to uninstall every active tracer.**
+```ruby
+    # Uninstall all active tracers and restore the original Kernel methods.
+    def self.reset
+      @@tracers.dup.each do |tracer|
+        uninstall(tracer)
+      end
+    end
+  end
+end
+```
+
+**Shebang, license, and comment establish the CLI script.**
+```ruby
+#!/usr/bin/env ruby
+# SPDX-License-Identifier: MIT
+# CLI wrapper for the native tracer
+```
+
+**Load the library path and require the main recorder.**
+```ruby
+lib_dir = File.expand_path('../lib', __dir__)
+$LOAD_PATH.unshift(lib_dir) unless $LOAD_PATH.include?(lib_dir)
+require 'codetracer_ruby_recorder'
+```
+
+**Invoke the argument parser and exit with its status.**
+```ruby
+exit CodeTracer::RubyRecorder.parse_argv_and_trace_ruby_file(ARGV)
+```
+
+**Begin gem specification and compute version from file.**
+```ruby
+Gem::Specification.new do |spec|
+  spec.name          = 'codetracer-ruby-recorder'
+  version_file = File.expand_path('../../version.txt', __dir__)
+  spec.version       = File.read(version_file).strip
+```
+
+**Define authorship metadata for the gem.**
+```ruby
+  spec.authors       = ['Metacraft Labs']
+  spec.email         = ['[email protected]']
+```
+
+**Provide summary, description, license, and homepage.**
+```ruby
+  spec.summary       = 'CodeTracer Ruby recorder with native extension'
+  spec.description   = 'Ruby tracer that records execution steps via a Rust native extension.'
+  spec.license       = 'MIT'
+  spec.homepage      = 'https://github.com/metacraft-labs/codetracer-ruby-recorder'
+```
+
+**Enumerate files to include in the gem package.**
+```ruby
+  spec.files         = Dir[
+    'lib/**/*',
+    'ext/native_tracer/**/{Cargo.toml,*.rs}',
+```
+
+**List native extension build scripts and compiled targets.**
+```ruby
+    'ext/native_tracer/extconf.rb',
+    'ext/native_tracer/target/release/*'
+  ]
+```
+
+**Configure load paths, extensions, and executable entrypoint.**
+```ruby
+  spec.require_paths = ['lib']
+  spec.extensions    = []
+  spec.bindir        = 'bin'
+  spec.executables   = ['codetracer-ruby-recorder']
+```
+
+**Add development dependency on rb_sys and close specification.**
+```ruby
+  spec.add_development_dependency 'rb_sys', '~> 0.9'
+end
+```