diff --git a/lib/interfaces/proxy.rb b/lib/interfaces/proxy.rb
index daabde8..ac2ff80 100644
--- a/lib/interfaces/proxy.rb
+++ b/lib/interfaces/proxy.rb
@@ -10,7 +10,7 @@ class Proxy
 
     attr_reader :name
 
-    def_delegators :@source, :file_path, :lines, :lines=, :start_line, :end_line, :scope
+    def_delegators :@source, :file_path, :lines, :lines=, :start_line, :end_line, :start_index, :scope
     def_delegators :@source, :wrap, :export
 
     def initialize(name:, source:)
diff --git a/lib/models/source.rb b/lib/models/source.rb
index a4b6c8d..60b58c3 100644
--- a/lib/models/source.rb
+++ b/lib/models/source.rb
@@ -38,8 +38,6 @@ def export
       lines[start_index..end_index].join
     end
 
-    private
-
     def start_index
       start_line - 1
     end
diff --git a/lib/proxies/method_proxy.rb b/lib/proxies/method_proxy.rb
index 2a1338c..74e9d7a 100644
--- a/lib/proxies/method_proxy.rb
+++ b/lib/proxies/method_proxy.rb
@@ -29,6 +29,15 @@ def tagged_params(tag)
       @tagged_params[tag] || []
     end
 
+    def rewrite_signature
+      old_line = lines[start_index]
+      scope_prefix = old_line.match?(/def self\./) ? 'def self.' : 'def '
+      all_params = @params.map { |p| p.expression ? p.export(typed: false) : p.name.to_s }
+      return_suffix = @return_proxy ? " #{@return_proxy.export}" : ''
+      indent = old_line[/^\s*/]
+      lines[start_index] = "#{indent}#{scope_prefix}#{@name}(#{all_params.join(', ')})#{return_suffix}\n"
+    end
+
     def expressions?
       @params.any?(&:expression) || @return_proxy
     end
diff --git a/lib/proxies/param_proxy.rb b/lib/proxies/param_proxy.rb
index e0e1bac..22c6240 100644
--- a/lib/proxies/param_proxy.rb
+++ b/lib/proxies/param_proxy.rb
@@ -18,7 +18,42 @@ def initialize(name:, source:, type:, position: nil, value: :LOWKEY_UNDEFINED, e
     end
 
     def required?
-      @value == :LOWKEY_UNDEFINED
+      @value == :LOWKEY_UNDEFINED || @value == ':LOWKEY_UNDEFINED'
+    end
+
+    def export(typed: true)
+      return @source.export if typed
+      return untyped_keyword_param if %i[key_req key_opt].include?(@type)
+
+      untyped_positional_param
+    end
+
+    private
+
+    def untyped_keyword_param
+      default = resolved_default
+      default.nil? ? "#{@name}:" : "#{@name}: #{default}"
+    end
+
+    def untyped_positional_param
+      default = resolved_default
+      default.nil? ? @name.to_s : "#{@name} = #{default}"
+    end
+
+    def resolved_default
+      if @expression
+        return nil if @expression.default_value == :LOW_TYPE_UNDEFINED
+        return nil if @expression.default_value.nil? && required?
+
+        value = @expression.default_value
+        return value.value.inspect if value.is_a?(ValueExpression)
+
+        return value.inspect
+      end
+
+      return nil if @value == :LOWKEY_UNDEFINED || @value == ':LOWKEY_UNDEFINED'
+
+      @value
     end
   end
 end
diff --git a/spec/units/method_proxy_rewrite_spec.rb b/spec/units/method_proxy_rewrite_spec.rb
new file mode 100644
index 0000000..f7975b8
--- /dev/null
+++ b/spec/units/method_proxy_rewrite_spec.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require 'prism'
+require_relative '../../lib/lowkey'
+
+RSpec.describe Lowkey::MethodProxy do
+  subject(:file_proxy) { Lowkey.load('spec/fixtures/mock_node.rbx') }
+
+  let(:method_proxy) { file_proxy['Lowkey::MockNode'][:render] }
+
+  describe '#rewrite_signature' do
+    it 'replaces the signature line in the shared lines array' do
+      original_line = method_proxy.lines[method_proxy.start_index].dup
+      method_proxy.rewrite_signature
+      rewritten = method_proxy.lines[method_proxy.start_index]
+      expect(rewritten).not_to eq(original_line)
+    end
+
+    it 'removes type annotations from the signature' do
+      method_proxy.rewrite_signature
+      rewritten = method_proxy.lines[method_proxy.start_index]
+      expect(rewritten).not_to match(/String|Integer|Symbol/)
+    end
+
+    it 'preserves the method name' do
+      method_proxy.rewrite_signature
+      rewritten = method_proxy.lines[method_proxy.start_index]
+      expect(rewritten).to include('def render')
+    end
+
+    it 'is reflected in file_proxy.export since lines are shared' do
+      method_proxy.rewrite_signature
+      expect(file_proxy.export).to include(method_proxy.lines[method_proxy.start_index].strip)
+    end
+  end
+end
diff --git a/spec/units/param_proxy_spec.rb b/spec/units/param_proxy_spec.rb
new file mode 100644
index 0000000..f98d278
--- /dev/null
+++ b/spec/units/param_proxy_spec.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require 'prism'
+require_relative '../../lib/lowkey'
+
+RSpec.describe Lowkey::ParamProxy do
+  subject(:file_proxy) { Lowkey.load('spec/fixtures/mock_node.rbx') }
+
+  let(:method_proxy) { file_proxy['Lowkey::MockNode'][:render] }
+
+  describe '#export' do
+    context 'typed: true (default)' do
+      it 'returns the raw source for a positional param' do
+        param = method_proxy[:one]
+        expect(param.export).to eq(param.export(typed: true))
+      end
+
+      it 'returns the raw source for a keyword param' do
+        param = method_proxy[:three]
+        expect(param.export).to eq(param.export(typed: true))
+      end
+    end
+
+    context 'typed: false with no expression set' do
+      it 'returns plain name for a required positional param' do
+        param = method_proxy[:one]
+        expect(param.export(typed: false)).to eq('one')
+      end
+
+      it 'returns plain name for a required keyword param' do
+        param = method_proxy[:three]
+        expect(param.export(typed: false)).to eq('three:')
+      end
+
+      it 'returns name with default for an optional positional param' do
+        param = method_proxy[:two]
+        expect(param.export(typed: false)).to eq("two = 'mock value'")
+      end
+
+      it 'returns name with default for an optional keyword param' do
+        param = method_proxy[:four]
+        expect(param.export(typed: false)).to eq("four: 'mock value'")
+      end
+    end
+  end
+end