chore: add rbs gem and fix watcher/spec for type inference

- Add rbs gem dependency for E2E test RBS validation
- Fix watcher to handle single file paths (not just directories)
- Fix ir_spec to use keyword argument format (name: String)

Author: yhk1038

Gemfile

@@ -6,6 +6,7 @@ gemspec
 
 group :development, :test do
   gem "rake", "~> 13.0"
+  gem "rbs", "~> 3.0"
   gem "rspec", "~> 3.0"
   gem "rspec_junit_formatter", "~> 0.6.0"
   gem "rubocop", require: false

Gemfile.lock

@@ -18,6 +18,7 @@ GEM
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
+    logger (1.7.0)
     parallel (1.27.0)
     parser (3.3.10.0)
       ast (~> 2.4.1)
@@ -29,6 +30,8 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
+    rbs (3.10.0)
+      logger
     regexp_parser (2.11.3)
     rspec (3.13.2)
       rspec-core (~> 3.13.0)
@@ -77,6 +80,7 @@ PLATFORMS
 
 DEPENDENCIES
   rake (~> 13.0)
+  rbs (~> 3.0)
   rspec (~> 3.0)
   rspec_junit_formatter (~> 0.6.0)
   rubocop

lib/t_ruby/watcher.rb

@@ -248,17 +248,21 @@ def find_source_files_by_extension(ext)
       files = []
 
       # Always search in source_include directories only
-      source_dirs = if @paths == [File.expand_path(".")]
-                      @config.source_include.map { |dir| File.expand_path(dir) }
-                    else
-                      @paths.map { |path| File.expand_path(path) }
-                    end
-
-      source_dirs.each do |dir|
-        next unless Dir.exist?(dir)
-
-        Dir.glob(File.join(dir, "**", "*#{ext}")).each do |file|
-          files << file unless @config.excluded?(file)
+      source_paths = if @paths == [File.expand_path(".")]
+                       @config.source_include.map { |dir| File.expand_path(dir) }
+                     else
+                       @paths.map { |path| File.expand_path(path) }
+                     end
+
+      source_paths.each do |path|
+        if File.file?(path)
+          # Handle single file path
+          files << path if path.end_with?(ext) && !@config.excluded?(path)
+        elsif Dir.exist?(path)
+          # Handle directory path
+          Dir.glob(File.join(path, "**", "*#{ext}")).each do |file|
+            files << file unless @config.excluded?(file)
+          end
         end
       end
 

spec/t_ruby/ir_spec.rb

@@ -360,7 +360,7 @@ def greet(name: String): String
 
       output = generator.generate(program)
 
-      expect(output).to include("def greet: (String name) -> String")
+      expect(output).to include("def greet: (name: String) -> String")
     end
   end