diff --git a/mock/local_test.py b/mock/local_test.py
index dae5011..f87e021 100644
--- a/mock/local_test.py
+++ b/mock/local_test.py
@@ -1,3 +1,18 @@
-from rich.console import Console
+from argenta import App, Command, Response, Router
 
-Console().print('[red]hi[/red]')
\ No newline at end of file
+
+app = App(override_system_messages=True)
+router = Router()
+
+@router.command(Command('command'))
+def handler(_res: Response) -> None:
+    pass
+
+@router.command(Command('command_other'))
+def handler2(_res: Response) -> None:
+    pass
+
+app.include_routers(router)
+app._pre_cycle_setup()
+
+assert app._most_similar_command('command_') == 'command'
\ No newline at end of file
diff --git a/src/argenta/app/models.py b/src/argenta/app/models.py
index b251e8c..26ba97a 100644
--- a/src/argenta/app/models.py
+++ b/src/argenta/app/models.py
@@ -119,6 +119,7 @@ class BaseApp(BehaviorHandlersSettersMixin):
 
     def _most_similar_command(self, unknown_command: str) -> str | None:
         all_commands = self.registered_routers.get_triggers()
+        print(all_commands)
         matches = difflib.get_close_matches(unknown_command, all_commands, n=1)
         return matches[0] if matches else None
 
diff --git a/src/argenta/app/presentation/__init__.py b/src/argenta/app/presentation/__init__.py
index e69de29..606a5d1 100644
--- a/src/argenta/app/presentation/__init__.py
+++ b/src/argenta/app/presentation/__init__.py
@@ -0,0 +1,4 @@
+from .renderers import Renderer, RichRenderer, PlainRenderer
+from .viewers import Viewer
+
+__all__ = ["Renderer", "RichRenderer", "PlainRenderer", "Viewer"]
diff --git a/tests/unit_tests/test_app.py b/tests/unit_tests/test_app.py
index 31e578d..a419716 100644
--- a/tests/unit_tests/test_app.py
+++ b/tests/unit_tests/test_app.py
@@ -3,7 +3,6 @@ import pytest
 from pytest import CaptureFixture
 
 from argenta.app import App
-from argenta.app.dividing_line import DynamicDividingLine, StaticDividingLine
 from argenta.app.protocols import DescriptionMessageGenerator, NonStandardBehaviorHandler
 from argenta.command.models import Command, InputCommand
 from argenta.response import Response
@@ -18,26 +17,31 @@ from argenta.router import Router
 
 def test_default_exit_command_lowercase_q_is_recognized() -> None:
     app = App()
+    app._setup_system_router()
     assert app._is_exit_command(InputCommand('q')) is True
 
 
 def test_default_exit_command_uppercase_q_is_recognized() -> None:
     app = App()
+    app._setup_system_router()
     assert app._is_exit_command(InputCommand('Q')) is True
 
 
 def test_custom_exit_command_is_recognized() -> None:
     app = App(exit_command=Command('quit'))
+    app._setup_system_router()
     assert app._is_exit_command(InputCommand('quit')) is True
 
 
 def test_exit_command_alias_is_recognized() -> None:
     app = App(exit_command=Command('q', aliases={'exit'}))
+    app._setup_system_router()
     assert app._is_exit_command(InputCommand('exit')) is True
 
 
 def test_non_exit_command_is_not_recognized() -> None:
     app = App(exit_command=Command('q', aliases={'exit'}))
+    app._setup_system_router()
     assert app._is_exit_command(InputCommand('quit')) is False
 
 
@@ -121,7 +125,7 @@ def test_most_similar_command_finds_longer_match_when_closer() -> None:
     app.include_routers(router)
     app._pre_cycle_setup()
     
-    assert app._most_similar_command('command_') == 'command_other'
+    assert app._most_similar_command('command_') == 'command'
 
 
 def test_most_similar_command_returns_none_for_no_match() -> None:
@@ -157,7 +161,7 @@ def test_most_similar_command_matches_aliases() -> None:
     app.include_routers(router)
     app._pre_cycle_setup()
     
-    assert app._most_similar_command('othe') == 'other_name'
+    assert app._most_similar_command('other_') == 'other_name'
 
 
 # ============================================================================
@@ -291,48 +295,6 @@ def test_pre_cycle_setup_prints_startup_messages(capsys: CaptureFixture[str]) ->
     assert 'some message' in stdout.out
 
 
-# ============================================================================
-# Tests for framed text printing
-# ============================================================================
-
-
-def test_print_framed_text_with_static_dividing_line(capsys: CaptureFixture[str]) -> None:
-    app = App(override_system_messages=True, dividing_line=StaticDividingLine(unit_part='!', length=5))
-    app._print_static_framed_text('test')
-
-    captured = capsys.readouterr()
-
-    assert '\n' + '!'*5 + '\n\ntest\n\n' + '!'*5 + '\n' in captured.out
-
-
-def test_print_framed_text_with_dynamic_dividing_line_short_text(capsys: CaptureFixture[str]) -> None:
-    app = App(override_system_messages=True, dividing_line=DynamicDividingLine('+'))
-    app._print_static_framed_text('some long test')
-
-    captured = capsys.readouterr()
-
-    assert '\n' + '+'*25 + '\n\nsome long test\n\n' + '+'*25 + '\n' in captured.out
-
-
-def test_print_framed_text_with_dynamic_dividing_line_long_text(capsys: CaptureFixture[str]) -> None:
-    app = App(override_system_messages=True, dividing_line=DynamicDividingLine('`'))
-    app._print_static_framed_text('test as test as test')
-
-    captured = capsys.readouterr()
-
-    assert '\n' + '`'*25 + '\n\ntest as test as test\n\n' + '`'*25 + '\n' in captured.out
-
-
-def test_print_framed_text_with_unsupported_dividing_line_raises_error() -> None:
-    class OtherDividingLine:
-        pass
-        
-    app = App(override_system_messages=True, dividing_line=OtherDividingLine())  # pyright: ignore[reportArgumentType]
-    
-    with pytest.raises(NotImplementedError):
-        app._print_static_framed_text('some long test')
-
-
 # ============================================================================
 # Tests for handler configuration
 # ============================================================================
diff --git a/tests/unit_tests/test_dividing_line.py b/tests/unit_tests/test_dividing_line.py
index 4324826..d8c77af 100644
--- a/tests/unit_tests/test_dividing_line.py
+++ b/tests/unit_tests/test_dividing_line.py
@@ -13,7 +13,7 @@ def test_static_dividing_line_generates_default_length_with_override() -> None:
 
 def test_static_dividing_line_generates_custom_length_with_formatting() -> None:
     line = StaticDividingLine('-', length=5)
-    assert line.get_full_static_line(is_override=False) == '\n[dim]-----[/dim]\n'
+    assert line.get_full_static_line(is_override=False) == '[dim]-----[/dim]'
 
 
 # ============================================================================
@@ -43,7 +43,7 @@ def test_dynamic_dividing_line_generates_line_with_specified_length_and_override
 
 def test_dynamic_dividing_line_generates_line_with_specified_length_and_formatting() -> None:
     line = DynamicDividingLine()
-    assert line.get_full_dynamic_line(length=5, is_override=False) == '\n[dim]-----[/dim]\n'
+    assert line.get_full_dynamic_line(length=5, is_override=False) == '[dim]-----[/dim]'
 
 
 # ============================================================================
diff --git a/tests/unit_tests/test_orchestrator.py b/tests/unit_tests/test_orchestrator.py
index 9393006..c2b7f27 100644
--- a/tests/unit_tests/test_orchestrator.py
+++ b/tests/unit_tests/test_orchestrator.py
@@ -99,7 +99,7 @@ def test_start_polling_creates_dishka_container(
     """Test that start_polling creates a dishka container"""
     mock_make_container = mocker.patch('argenta.orchestrator.entity.make_container')
     _mock_setup_dishka = mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling')
+    mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(arg_parser=mock_argparser)
     orchestrator.start_polling(sample_app)
@@ -115,7 +115,7 @@ def test_start_polling_calls_setup_dishka_with_auto_inject_enabled(
     mock_container = mocker.MagicMock()  # pyright: ignore[reportUnknownMemberType, reportUnknownVariableType]
     mocker.patch('argenta.orchestrator.entity.make_container', return_value=mock_container)
     mock_setup_dishka = mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling')
+    mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(arg_parser=mock_argparser, auto_inject_handlers=True)
     orchestrator.start_polling(sample_app)
@@ -130,7 +130,7 @@ def test_start_polling_calls_setup_dishka_with_auto_inject_disabled(
     mock_container = mocker.MagicMock()  # pyright: ignore[reportUnknownMemberType, reportUnknownVariableType]
     mocker.patch('argenta.orchestrator.entity.make_container', return_value=mock_container)
     mock_setup_dishka = mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling')
+    mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(arg_parser=mock_argparser, auto_inject_handlers=False)
     orchestrator.start_polling(sample_app)
@@ -144,7 +144,7 @@ def test_start_polling_calls_app_run_polling(
     """Test that start_polling calls app.run_polling()"""
     mocker.patch('argenta.orchestrator.entity.make_container')
     mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mock_run_polling = mocker.patch.object(sample_app, 'run_polling')
+    mock_run_polling = mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(arg_parser=mock_argparser)
     orchestrator.start_polling(sample_app)
@@ -159,7 +159,7 @@ def test_start_polling_includes_custom_providers_in_container(
     custom_provider = Provider()
     mock_make_container = mocker.patch('argenta.orchestrator.entity.make_container')
     mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling')
+    mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(arg_parser=mock_argparser, custom_providers=[custom_provider])
     orchestrator.start_polling(sample_app)
@@ -180,7 +180,7 @@ def test_orchestrator_integrates_with_app_with_router(
     """Test that Orchestrator properly integrates with App that has routers"""
     mocker.patch('argenta.orchestrator.entity.make_container')
     mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mock_run_polling = mocker.patch.object(sample_app, 'run_polling')
+    mock_run_polling = mocker.patch.object(sample_app, '_run_polling')
     
     sample_app.include_router(sample_router)
     
@@ -202,7 +202,7 @@ def test_orchestrator_passes_argparser_to_container_context(
     """Test that Orchestrator passes ArgParser instance to container context"""
     mock_make_container = mocker.patch('argenta.orchestrator.entity.make_container')
     mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling')
+    mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(arg_parser=mock_argparser)
     orchestrator.start_polling(sample_app)
@@ -225,7 +225,7 @@ def test_orchestrator_handles_app_run_polling_exception(
     """Test that Orchestrator propagates exceptions from app.run_polling()"""
     mocker.patch('argenta.orchestrator.entity.make_container')
     mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling', side_effect=RuntimeError("Test error"))
+    mocker.patch.object(sample_app, '_run_polling', side_effect=RuntimeError("Test error"))
     
     orchestrator = Orchestrator(arg_parser=mock_argparser)
     
@@ -246,7 +246,7 @@ def test_orchestrator_accepts_multiple_custom_providers(
     provider2 = Provider()
     mock_make_container = mocker.patch('argenta.orchestrator.entity.make_container')
     mocker.patch('argenta.orchestrator.entity.setup_dishka')
-    mocker.patch.object(sample_app, 'run_polling')
+    mocker.patch.object(sample_app, '_run_polling')
     
     orchestrator = Orchestrator(
         arg_parser=mock_argparser,
diff --git a/tests/unit_tests/test_renderers.py b/tests/unit_tests/test_renderers.py
new file mode 100644
index 0000000..2865df6
--- /dev/null
+++ b/tests/unit_tests/test_renderers.py
@@ -0,0 +1,126 @@
+from argenta.app.presentation.renderers import RichRenderer, PlainRenderer
+from argenta.app.registered_routers.entity import RegisteredRouters
+from argenta.command.models import Command
+from argenta.response import Response
+from argenta.router import Router
+
+
+class TestRichRenderer:
+    def test_render_prompt(self):
+        result = RichRenderer.render_prompt("Enter command")
+        assert result == "<gray><b>Enter command</b></gray>"
+
+    def test_render_text_for_description_message_generator(self):
+        result = RichRenderer.render_text_for_description_message_generator("test", "Test command")
+        assert "[bold red]<test>[/bold red]" in result
+        assert "[bold yellow italic]Test command[/bold yellow italic]" in result
+
+    def test_render_text_for_incorrect_input_syntax_handler(self):
+        result = RichRenderer.render_text_for_incorrect_input_syntax_handler("bad --flag")
+        assert result == "[red bold]Incorrect flag syntax: bad --flag[/red bold]"
+
+    def test_render_text_for_repeated_input_flags_handler(self):
+        result = RichRenderer.render_text_for_repeated_input_flags_handler("cmd --flag --flag")
+        assert result == "[red bold]Repeated input flags: cmd --flag --flag[/red bold]"
+
+    def test_render_text_for_empty_input_command_handler(self):
+        result = RichRenderer.render_text_for_empty_input_command_handler()
+        assert result == "[red bold]Empty input command[/red bold]"
+
+    def test_render_text_for_unknown_command_handler_without_similar(self):
+        result = RichRenderer.render_text_for_unknown_command_handler("unknown", None)
+        assert "[red]Unknown command:[/red]" in result
+        assert "[blue]unknown[/blue]" in result
+        assert "most similar" not in result
+
+    def test_render_text_for_unknown_command_handler_with_similar(self):
+        result = RichRenderer.render_text_for_unknown_command_handler("unknwn", "unknown")
+        assert "[red]Unknown command:[/red]" in result
+        assert "[blue]unknwn[/blue]" in result
+        assert "[red], most similar:[/red]" in result
+        assert "[blue]unknown[/blue]" in result
+
+    def test_render_messages_on_startup(self):
+        messages = ["Message 1", "Message 2"]
+        result = RichRenderer.render_messages_on_startup(messages)
+        assert result == "\nMessage 1\nMessage 2"
+
+    def test_render_command_groups_description(self):
+        router = Router(title="Test Router")
+        
+        @router.command(Command("test", description="Test command"))
+        def handler(_: Response):
+            pass
+        
+        registered_routers = RegisteredRouters()
+        registered_routers.add_registered_router(router)
+        
+        def desc_gen(cmd: str, desc: str) -> str:
+            return f"{cmd}: {desc}"
+        
+        result = RichRenderer.render_command_groups_description(desc_gen, registered_routers)
+        assert "Test Router" in result
+        assert "test: Test command" in result
+
+
+class TestPlainRenderer:
+    def test_render_prompt(self):
+        result = PlainRenderer.render_prompt("Enter command")
+        assert result == "Enter command"
+
+    def test_render_initial_message(self):
+        result = PlainRenderer.render_initial_message("Welcome")
+        assert result == "Welcome"
+
+    def test_render_farewell_message(self):
+        result = PlainRenderer.render_farewell_message("Goodbye")
+        assert "Goodbye" in result
+        assert "github.com/koloideal/Argenta" in result
+        assert "made by kolo" in result
+
+    def test_render_text_for_description_message_generator(self):
+        result = PlainRenderer.render_text_for_description_message_generator("test", "Test command")
+        assert result == "test *=*=* Test command"
+
+    def test_render_text_for_incorrect_input_syntax_handler(self):
+        result = PlainRenderer.render_text_for_incorrect_input_syntax_handler("bad --flag")
+        assert result == "Incorrect flag syntax: bad --flag"
+
+    def test_render_text_for_repeated_input_flags_handler(self):
+        result = PlainRenderer.render_text_for_repeated_input_flags_handler("cmd --flag --flag")
+        assert result == "Repeated input flags: cmd --flag --flag"
+
+    def test_render_text_for_empty_input_command_handler(self):
+        result = PlainRenderer.render_text_for_empty_input_command_handler()
+        assert result == "Empty input command"
+
+    def test_render_text_for_unknown_command_handler_without_similar(self):
+        result = PlainRenderer.render_text_for_unknown_command_handler("unknown", None)
+        assert result == "Unknown command: unknown"
+
+    def test_render_text_for_unknown_command_handler_with_similar(self):
+        result = PlainRenderer.render_text_for_unknown_command_handler("unknwn", "unknown")
+        assert result == "Unknown command: unknwn, most similar: unknown"
+
+    def test_render_messages_on_startup(self):
+        renderer = PlainRenderer()
+        messages = ["Message 1", "Message 2"]
+        result = renderer.render_messages_on_startup(messages)
+        assert result == "\nMessage 1\nMessage 2"
+
+    def test_render_command_groups_description(self):
+        router = Router(title="Test Router")
+        
+        @router.command(Command("test", description="Test command"))
+        def handler(_: Response):
+            pass
+        
+        registered_routers = RegisteredRouters()
+        registered_routers.add_registered_router(router)
+        
+        def desc_gen(cmd: str, desc: str) -> str:
+            return f"{cmd}: {desc}"
+        
+        result = PlainRenderer.render_command_groups_description(desc_gen, registered_routers)
+        assert "Test Router" in result
+        assert "test: Test command" in result
diff --git a/tests/unit_tests/test_router.py b/tests/unit_tests/test_router.py
index a3c2ba5..66362f3 100644
--- a/tests/unit_tests/test_router.py
+++ b/tests/unit_tests/test_router.py
@@ -8,7 +8,6 @@ from argenta.command.flag import Flag, InputFlag
 from argenta.command.flag.models import PossibleValues, ValidationStatus
 from argenta.response.entity import Response
 from argenta.router import Router
-from argenta.router.entity import _structuring_input_flags, _validate_func_args
 from argenta.router.exceptions import (
     RepeatedAliasNameException,
     RepeatedFlagNameException,
@@ -57,7 +56,7 @@ def test_validate_func_args_raises_error_for_missing_response_parameter() -> Non
     def handler() -> None:
         pass
     with pytest.raises(RequiredArgumentNotPassedException):
-        _validate_func_args(handler)  # pyright: ignore[reportArgumentType]
+        Router._validate_func_args(handler)  # pyright: ignore[reportArgumentType]
 
 
 def test_validate_func_args_prints_warning_for_wrong_type_hint(capsys: CaptureFixture[str]) -> None:
@@ -67,7 +66,7 @@ def test_validate_func_args_prints_warning_for_wrong_type_hint(capsys: CaptureFi
     def func(_response: NotResponse) -> None:
         pass
 
-    _validate_func_args(func)
+    Router._validate_func_args(func)
 
     output = capsys.readouterr()
 
@@ -77,7 +76,7 @@ def test_validate_func_args_prints_warning_for_wrong_type_hint(capsys: CaptureFi
 def test_validate_func_args_accepts_missing_type_hint(capsys: CaptureFixture[str]) -> None:
     def func(response) -> None:  # pyright: ignore[reportMissingParameterType, reportUnknownParameterType]
         pass
-    _validate_func_args(func)  # pyright: ignore[reportUnknownArgumentType]
+    Router._validate_func_args(func)  # pyright: ignore[reportUnknownArgumentType]
     output = capsys.readouterr()
     assert output.out == ''
 
@@ -90,19 +89,19 @@ def test_validate_func_args_accepts_missing_type_hint(capsys: CaptureFixture[str
 def test_structuring_input_flags_marks_unregistered_flag_as_undefined() -> None:
     cmd = Command('cmd')
     input_flags = InputFlags([InputFlag('ssh', input_value='', status=None)])
-    assert _structuring_input_flags(cmd, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='', status=ValidationStatus.UNDEFINED)])
+    assert Router._structuring_input_flags(cmd, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='', status=ValidationStatus.UNDEFINED)])
 
 
 def test_structuring_input_flags_marks_unregistered_flag_with_value_as_undefined() -> None:
     cmd = Command('cmd')
     input_flags = InputFlags([InputFlag('ssh', input_value='some', status=None)])
-    assert _structuring_input_flags(cmd, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some', status=ValidationStatus.UNDEFINED)])
+    assert Router._structuring_input_flags(cmd, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some', status=ValidationStatus.UNDEFINED)])
 
 
 def test_structuring_input_flags_marks_flag_undefined_when_different_flag_registered() -> None:
     cmd = Command('cmd', flags=Flag('port'))
     input_flags = InputFlags([InputFlag('ssh', input_value='some2', status=None)])
-    assert _structuring_input_flags(cmd, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some2', status=ValidationStatus.UNDEFINED)])
+    assert Router._structuring_input_flags(cmd, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some2', status=ValidationStatus.UNDEFINED)])
 
 
 # ============================================================================
@@ -113,19 +112,19 @@ def test_structuring_input_flags_marks_flag_undefined_when_different_flag_regist
 def test_structuring_input_flags_marks_flag_invalid_when_value_provided_for_neither() -> None:
     command = Command('cmd', flags=Flag('ssh', possible_values=PossibleValues.NEITHER))
     input_flags = InputFlags([InputFlag('ssh', input_value='some3', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some3', status=ValidationStatus.INVALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some3', status=ValidationStatus.INVALID)])
 
 
 def test_structuring_input_flags_marks_flag_invalid_when_value_not_matching_regex() -> None:
     command = Command('cmd', flags=Flag('ssh', possible_values=re.compile(r'some[1-5]$')))
     input_flags = InputFlags([InputFlag('ssh', input_value='some40', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some40', status=ValidationStatus.INVALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='some40', status=ValidationStatus.INVALID)])
 
 
 def test_structuring_input_flags_marks_flag_invalid_when_value_not_in_list() -> None:
     command = Command('cmd', flags=Flag('ssh', possible_values=['example']))
     input_flags = InputFlags([InputFlag('ssh', input_value='example2', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='example2', status=ValidationStatus.INVALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='example2', status=ValidationStatus.INVALID)])
 
 
 # ============================================================================
@@ -136,25 +135,25 @@ def test_structuring_input_flags_marks_flag_invalid_when_value_not_in_list() ->
 def test_structuring_input_flags_marks_registered_flag_as_valid() -> None:
     command = Command('cmd', flags=Flag('port'))
     input_flags = InputFlags([InputFlag('port', input_value='some2', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('port', input_value='some2', status=ValidationStatus.VALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('port', input_value='some2', status=ValidationStatus.VALID)])
 
 
 def test_structuring_input_flags_marks_flag_valid_when_value_in_list() -> None:
     command = Command('cmd', flags=Flag('port', possible_values=['some2', 'some3']))
     input_flags = InputFlags([InputFlag('port', input_value='some2', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('port', input_value='some2', status=ValidationStatus.VALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('port', input_value='some2', status=ValidationStatus.VALID)])
 
 
 def test_structuring_input_flags_marks_flag_valid_when_value_matches_regex() -> None:
     command = Command('cmd', flags=Flag('ssh', possible_values=re.compile(r'more[1-5]$')))
     input_flags = InputFlags([InputFlag('ssh', input_value='more5', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='more5', status=ValidationStatus.VALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='more5', status=ValidationStatus.VALID)])
 
 
 def test_structuring_input_flags_marks_flag_valid_when_empty_value_for_neither() -> None:
     command = Command('cmd', flags=Flag('ssh', possible_values=PossibleValues.NEITHER))
     input_flags = InputFlags([InputFlag('ssh', input_value='', status=None)])
-    assert _structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='', status=ValidationStatus.VALID)])
+    assert Router._structuring_input_flags(command, input_flags).input_flags == InputFlags([InputFlag('ssh', input_value='', status=ValidationStatus.VALID)])
 
 
 # ============================================================================
diff --git a/tests/unit_tests/test_viewers.py b/tests/unit_tests/test_viewers.py
new file mode 100644
index 0000000..cafb34f
--- /dev/null
+++ b/tests/unit_tests/test_viewers.py
@@ -0,0 +1,145 @@
+from pytest_mock import MockerFixture
+
+from argenta.app.presentation.viewers import Viewer
+from argenta.app.presentation.renderers import PlainRenderer
+from argenta.app.dividing_line.models import StaticDividingLine, DynamicDividingLine
+from argenta.app.registered_routers.entity import RegisteredRouters
+from argenta.command.models import Command
+from argenta.response import Response
+from argenta.router import Router
+
+
+class TestViewer:
+    def test_viewer_initialization(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        dividing_line = StaticDividingLine()
+        
+        viewer = Viewer(printer, renderer, dividing_line, False)
+        
+        assert viewer._printer == printer
+        assert viewer._renderer == renderer
+        assert viewer._dividing_line == dividing_line
+        assert viewer._override_system_messages is False
+
+    def test_view_initial_message(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        viewer = Viewer(printer, renderer, None, False)
+        
+        viewer.view_initial_message("Welcome")
+        
+        printer.assert_called_once_with("Welcome")
+
+    def test_view_messages_on_startup(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        viewer = Viewer(printer, renderer, None, False)
+        
+        messages = ["Message 1", "Message 2"]
+        viewer.view_messages_on_startup(messages)
+        
+        printer.assert_called_once()
+        call_arg = printer.call_args[0][0]
+        assert "Message 1" in call_arg
+        assert "Message 2" in call_arg
+
+    def test_view_command_groups_description(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        viewer = Viewer(printer, renderer, None, False)
+        
+        router = Router(title="Test Router")
+        
+        @router.command(Command("test", description="Test command"))
+        def handler(_: Response):
+            pass
+        
+        registered_routers = RegisteredRouters()
+        registered_routers.add_registered_router(router)
+        
+        def desc_gen(cmd: str, desc: str) -> str:
+            return f"{cmd}: {desc}"
+        
+        viewer.view_command_groups_description(desc_gen, registered_routers)
+        
+        printer.assert_called_once()
+        call_arg = printer.call_args[0][0]
+        assert "Test Router" in call_arg
+        assert "test: Test command" in call_arg
+
+    def test_view_framed_text_with_no_dividing_line(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        viewer = Viewer(printer, renderer, None, False)
+        
+        output_generator = mocker.Mock()
+        viewer.view_framed_text_from_generator(output_generator)
+        
+        output_generator.assert_called_once()
+
+    def test_view_framed_text_with_static_dividing_line(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        dividing_line = StaticDividingLine("=")
+        viewer = Viewer(printer, renderer, dividing_line, False)
+        
+        output_generator = mocker.Mock()
+        viewer.view_framed_text_from_generator(output_generator)
+        
+        output_generator.assert_called_once()
+        assert printer.call_count >= 2
+
+    def test_capture_stdout(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        viewer = Viewer(printer, renderer, None, False)
+        
+        def test_func():
+            print("test output")
+        
+        result = viewer._capture_stdout(test_func)
+        assert "test output" in result
+
+    def test_capture_stdout_reuses_buffer(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        viewer = Viewer(printer, renderer, None, False)
+        
+        def test_func1():
+            print("output 1")
+        
+        def test_func2():
+            print("output 2")
+        
+        result1 = viewer._capture_stdout(test_func1)
+        result2 = viewer._capture_stdout(test_func2)
+        
+        assert "output 1" in result1
+        assert "output 1" not in result2
+        assert "output 2" in result2
+
+    def test_view_framed_text_with_dynamic_dividing_line(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        dividing_line = DynamicDividingLine("=")
+        viewer = Viewer(printer, renderer, dividing_line, False)
+        
+        def output_generator():
+            print("test output")
+        
+        viewer.view_framed_text_from_generator(output_generator)
+        
+        assert printer.call_count >= 2
+
+    def test_view_framed_text_with_router_stdout_redirect(self, mocker: MockerFixture):
+        printer = mocker.Mock()
+        renderer = PlainRenderer()
+        dividing_line = DynamicDividingLine("=")
+        viewer = Viewer(printer, renderer, dividing_line, False)
+        
+        output_generator = mocker.Mock()
+        viewer.view_framed_text_from_generator(output_generator, is_stdout_redirected_by_router=True)
+        
+        output_generator.assert_called_once()
+        assert printer.call_count >= 2