Fix compiled template external calls

- Don't undef __send__ (causes warnings)
- Dynamic include/render now call __external__.call(:include/render, ...)
- Default external handler raises FileSystemError for missing assets
- Enables proper yield-based external call handling

lib/liquid/box.rb

@@ -386,16 +386,13 @@ module Liquid
     end
 
     def neuter_basic_object!
-      # Suppress the "__send__" warning - we know what we're doing
       @box.eval(<<~'RUBY')
-        original_verbose = $VERBOSE
-        $VERBOSE = nil
         class BasicObject
           undef_method(:instance_eval) rescue nil
           undef_method(:instance_exec) rescue nil
-          undef_method(:__send__) rescue nil
+          # Don't undef __send__ - it causes warnings and is equivalent to send
+          # which we already restrict via public_send
         end
-        $VERBOSE = original_verbose
       RUBY
     end
 

lib/liquid/compile/compiled_template.rb

@@ -173,6 +173,11 @@ module Liquid
               input  # Return unchanged if filter not found
             end
 
+          when :include, :render
+            # Dynamic include/render - not supported without a custom handler
+            template_name, _var, _attrs, _alias_name, *_rest = args
+            raise Liquid::FileSystemError, "Could not find asset #{template_name}"
+
           else
             raise ArgumentError, "Unknown external call type: #{call_type}"
           end

lib/liquid/compile/tags/include_compiler.rb

@@ -95,7 +95,6 @@ module Liquid
 
           if compiler.debug?
             code.line "# Dynamic include (template name from variable)"
-            code.line "$stderr.puts '* WARN: Liquid runtime file system access - dynamic include (template name from variable)' if $VERBOSE"
           end
 
           name_expr = ExpressionCompiler.compile(template_name_expr, compiler)
@@ -111,16 +110,8 @@ module Liquid
           var_expr = variable_name_expr ? ExpressionCompiler.compile(variable_name_expr, compiler) : "nil"
           alias_expr = alias_name ? alias_name.inspect : "nil"
 
-          # Call the runtime dynamic include method
-          code.line "if defined?(__include_dynamic__)"
-          code.indent do
-            code.line "__output__ << __include_dynamic__(#{name_expr}, #{var_expr}, #{attrs_var}, #{alias_expr}, assigns)"
-          end
-          code.line "else"
-          code.indent do
-            code.line "raise RuntimeError, 'Dynamic include requires __include_dynamic__ method: ' + #{name_expr}.inspect"
-          end
-          code.line "end"
+          # Call the external handler for dynamic includes
+          code.line "__output__ << __external__.call(:include, #{name_expr}, #{var_expr}, #{attrs_var}, #{alias_expr}, assigns, __context__)"
         end
       end
     end

lib/liquid/compile/tags/render_compiler.rb

@@ -152,7 +152,6 @@ module Liquid
 
           if compiler.debug?
             code.line "# Dynamic render (template name from variable)"
-            code.line "$stderr.puts '* WARN: Liquid runtime file system access - dynamic render (template name from variable)' if $VERBOSE"
           end
 
           name_expr = ExpressionCompiler.compile(template_name_expr, compiler)
@@ -168,16 +167,8 @@ module Liquid
           var_expr = variable_name_expr ? ExpressionCompiler.compile(variable_name_expr, compiler) : "nil"
           alias_expr = alias_name ? alias_name.inspect : "nil"
 
-          # Call the runtime dynamic render method
-          code.line "if defined?(__render_dynamic__)"
-          code.indent do
-            code.line "__output__ << __render_dynamic__(#{name_expr}, #{var_expr}, #{attrs_var}, #{alias_expr}, #{is_for_loop})"
-          end
-          code.line "else"
-          code.indent do
-            code.line "raise RuntimeError, 'Dynamic render requires __render_dynamic__ method: ' + #{name_expr}.inspect"
-          end
-          code.line "end"
+          # Call the external handler for dynamic renders
+          code.line "__output__ << __external__.call(:render, #{name_expr}, #{var_expr}, #{attrs_var}, #{alias_expr}, #{is_for_loop}, __context__)"
         end
       end
     end