diff --git a/src/shellmate/ai/engine.py b/src/shellmate/ai/engine.py
index 0da91ab..b528a29 100644
--- a/src/shellmate/ai/engine.py
+++ b/src/shellmate/ai/engine.py
@@ -1,8 +1,7 @@
 """Stockfish AI engine wrapper with move explanations."""
 
-import asyncio
 from dataclasses import dataclass
-from typing import Optional
+
 import chess
 from stockfish import Stockfish
 
diff --git a/src/shellmate/core/game.py b/src/shellmate/core/game.py
index 18b2850..9233015 100644
--- a/src/shellmate/core/game.py
+++ b/src/shellmate/core/game.py
@@ -3,7 +3,7 @@
 from dataclasses import dataclass, field
 from datetime import datetime
 from enum import Enum
-from typing import Optional
+
 import chess
 import chess.pgn
 
@@ -25,8 +25,8 @@ class Move:
     fen_after: str
     timestamp: datetime = field(default_factory=datetime.utcnow)
     think_time_ms: int = 0
-    evaluation: Optional[float] = None
-    explanation: Optional[str] = None
+    evaluation: float | None = None
+    explanation: str | None = None
 
 
 @dataclass
@@ -51,7 +51,7 @@ class ChessGame:
         """Return the ID of the player whose turn it is."""
         return self.white_player_id if self.board.turn == chess.WHITE else self.black_player_id
 
-    def make_move(self, uci: str) -> Optional[Move]:
+    def make_move(self, uci: str) -> Move | None:
         """Make a move and return Move object if valid."""
         try:
             chess_move = chess.Move.from_uci(uci)
@@ -86,7 +86,10 @@ class ChessGame:
     def _check_game_end(self) -> None:
         """Check if the game has ended and set result."""
         if self.board.is_checkmate():
-            self.result = GameResult.BLACK_WINS if self.board.turn == chess.WHITE else GameResult.WHITE_WINS
+            if self.board.turn == chess.WHITE:
+                self.result = GameResult.BLACK_WINS
+            else:
+                self.result = GameResult.WHITE_WINS
         elif self.board.is_stalemate() or self.board.is_insufficient_material():
             self.result = GameResult.DRAW
         elif self.board.can_claim_draw():
diff --git a/src/shellmate/core/player.py b/src/shellmate/core/player.py
index 06d937f..a0e6bf6 100644
--- a/src/shellmate/core/player.py
+++ b/src/shellmate/core/player.py
@@ -3,7 +3,6 @@
 from dataclasses import dataclass, field
 from datetime import datetime
 from enum import Enum
-from typing import Optional
 
 
 class PlayerType(Enum):
@@ -25,7 +24,7 @@ class Player:
     losses: int = 0
     draws: int = 0
     created_at: datetime = field(default_factory=datetime.utcnow)
-    last_seen: Optional[datetime] = None
+    last_seen: datetime | None = None
 
     @property
     def winrate(self) -> float:
diff --git a/src/shellmate/ssh/server.py b/src/shellmate/ssh/server.py
index e47db85..afd7f09 100644
--- a/src/shellmate/ssh/server.py
+++ b/src/shellmate/ssh/server.py
@@ -3,11 +3,8 @@
 import asyncio
 import logging
 import os
-import sys
-from typing import Optional
-import asyncssh
 
-from shellmate.tui.app import ShellMateApp
+import asyncssh
 
 logger = logging.getLogger(__name__)
 
@@ -16,13 +13,13 @@ class ShellMateSSHServer(asyncssh.SSHServer):
     """SSH server that launches ShellMate TUI for each connection."""
 
     def __init__(self):
-        self._username: Optional[str] = None
+        self._username: str | None = None
 
     def connection_made(self, conn: asyncssh.SSHServerConnection) -> None:
         peername = conn.get_extra_info('peername')
         logger.info(f"SSH connection from {peername}")
 
-    def connection_lost(self, exc: Optional[Exception]) -> None:
+    def connection_lost(self, exc: Exception | None) -> None:
         if exc:
             logger.error(f"SSH connection error: {exc}")
         else:
@@ -130,15 +127,13 @@ async def handle_client(process: asyncssh.SSHServerProcess) -> None:
 
 async def run_simple_menu(process, session: TerminalSession, username: str, mode: str) -> None:
     """Beautiful Rich-based menu that scales to terminal size."""
+
+    from rich.align import Align
+    from rich.box import ROUNDED
     from rich.console import Console
     from rich.panel import Panel
-    from rich.text import Text
-    from rich.align import Align
-    from rich.box import HEAVY, ROUNDED, DOUBLE
     from rich.table import Table
-    from rich.layout import Layout
-    from rich.style import Style
-    import io
+    from rich.text import Text
 
     class ProcessWriter:
         def __init__(self, sess):
@@ -154,7 +149,10 @@ async def run_simple_menu(process, session: TerminalSession, username: str, mode
         session._update_size()
 
         writer = ProcessWriter(session)
-        console = Console(file=writer, width=session.width, height=session.height, force_terminal=True, color_system="truecolor")
+        console = Console(
+            file=writer, width=session.width, height=session.height,
+            force_terminal=True, color_system="truecolor"
+        )
 
         session.clear()
 
@@ -186,10 +184,10 @@ async def run_simple_menu(process, session: TerminalSession, username: str, mode
         menu_table.add_column(justify="center")
         menu_table.add_row(Text(f"Welcome, {username}!", style="cyan"))
         menu_table.add_row("")
-        menu_table.add_row("[bright_white on blue] 1 [/bright_white on blue]  Play vs AI       [dim]♔ vs ♚[/dim]")
-        menu_table.add_row("[bright_white on magenta] 2 [/bright_white on magenta]  Play vs Human   [dim]♔ vs ♔[/dim]")
-        menu_table.add_row("[bright_white on green] 3 [/bright_white on green]  Learn & Practice [dim]📖[/dim]")
-        menu_table.add_row("[bright_white on red] q [/bright_white on red]  Quit             [dim]👋[/dim]")
+        menu_table.add_row("[bright_white on blue] 1 [/]  Play vs AI       [dim]♔ vs ♚[/]")
+        menu_table.add_row("[bright_white on magenta] 2 [/]  Play vs Human   [dim]♔ vs ♔[/]")
+        menu_table.add_row("[bright_white on green] 3 [/]  Learn & Practice [dim]📖[/]")
+        menu_table.add_row("[bright_white on red] q [/]  Quit             [dim]👋[/]")
         menu_table.add_row("")
         menu_table.add_row(Text("Press a key to select...", style="dim italic"))
 
@@ -205,7 +203,8 @@ async def run_simple_menu(process, session: TerminalSession, username: str, mode
 
         # Footer
         console.print()
-        console.print(Align.center(Text(f"Terminal: {session.width}×{session.height}", style="dim")))
+        term_info = f"Terminal: {session.width}×{session.height}"
+        console.print(Align.center(Text(term_info, style="dim")))
 
     render_menu()
 
@@ -248,11 +247,10 @@ async def run_simple_menu(process, session: TerminalSession, username: str, mode
 async def run_chess_game(process, session: TerminalSession, username: str, opponent: str) -> None:
     """Run a beautiful chess game session with Stockfish AI."""
     import chess
+    from rich.align import Align
+    from rich.box import ROUNDED
     from rich.console import Console
     from rich.panel import Panel
-    from rich.align import Align
-    from rich.text import Text
-    from rich.box import ROUNDED
 
     class ProcessWriter:
         def __init__(self, sess):
@@ -276,7 +274,7 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
         logger.warning(f"Stockfish not available: {e}")
 
     # Unicode pieces
-    PIECES = {
+    piece_chars = {
         'K': '♔', 'Q': '♕', 'R': '♖', 'B': '♗', 'N': '♘', 'P': '♙',
         'k': '♚', 'q': '♛', 'r': '♜', 'b': '♝', 'n': '♞', 'p': '♟',
     }
@@ -331,7 +329,7 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
                 bg, bg_end = get_cell_style(square, piece, is_light)
 
                 if piece:
-                    char = PIECES.get(piece.symbol(), '?')
+                    char = piece_chars.get(piece.symbol(), '?')
                     if piece.color == chess.WHITE:
                         piece_row += f"{bg}  \033[1;97m{char}\033[0m{bg}  {bg_end}"
                     else:
@@ -378,9 +376,9 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
         # Instructions based on state
         if selected_square is not None:
             sq_name = chess.square_name(selected_square).upper()
-            lines.append(f"    \033[36mSelected: {sq_name}\033[0m  →  Type destination (or ESC to cancel)")
+            lines.append(f"    \033[36mSelected: {sq_name}\033[0m  →  Type dest (ESC cancel)")
         else:
-            lines.append("    Type \033[36msquare\033[0m (e.g. E2) to select  │  \033[31mQ\033[0m = quit")
+            lines.append("    Type \033[36msquare\033[0m (e.g. E2)  │  \033[31mQ\033[0m quit")
 
         lines.append("")
 
@@ -398,9 +396,9 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
 
         # Input prompt
         if selected_square is not None:
-            session.write(pad + f"    \033[32m→ \033[0m")
+            session.write(pad + "    \033[32m→ \033[0m")
         else:
-            session.write(pad + f"    \033[36m> \033[0m")
+            session.write(pad + "    \033[36m> \033[0m")
         session.show_cursor()
 
     def parse_square(text):
@@ -497,9 +495,14 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
                                 # Check for promotion
                                 piece = board.piece_at(selected_square)
                                 if piece and piece.piece_type == chess.PAWN:
-                                    if (piece.color == chess.WHITE and chess.square_rank(sq) == 7) or \
-                                       (piece.color == chess.BLACK and chess.square_rank(sq) == 0):
-                                        move = chess.Move(selected_square, sq, promotion=chess.QUEEN)
+                                    is_white_promo = (piece.color == chess.WHITE and
+                                                      chess.square_rank(sq) == 7)
+                                    is_black_promo = (piece.color == chess.BLACK and
+                                                      chess.square_rank(sq) == 0)
+                                    if is_white_promo or is_black_promo:
+                                        move = chess.Move(
+                                            selected_square, sq, promotion=chess.QUEEN
+                                        )
 
                                 board.push(move)
                                 move_history.append(move.uci())
@@ -516,7 +519,7 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
                                             stockfish_engine.set_fen_position(board.fen())
                                             best_move = stockfish_engine.get_best_move()
                                             ai_move = chess.Move.from_uci(best_move)
-                                        except:
+                                        except Exception:
                                             import random
                                             ai_move = random.choice(list(board.legal_moves))
                                     else:
@@ -560,7 +563,10 @@ async def run_chess_game(process, session: TerminalSession, username: str, oppon
     if board.is_game_over():
         session.clear()
         writer = ProcessWriter(session)
-        console = Console(file=writer, width=session.width, height=session.height, force_terminal=True)
+        console = Console(
+            file=writer, width=session.width, height=session.height,
+            force_terminal=True
+        )
 
         console.print()
         if board.is_checkmate():
diff --git a/src/shellmate/tui/app.py b/src/shellmate/tui/app.py
index 7b266d4..cac752b 100644
--- a/src/shellmate/tui/app.py
+++ b/src/shellmate/tui/app.py
@@ -1,19 +1,18 @@
 """Main TUI application."""
 
-from typing import Any
-from textual.app import App, ComposeResult
-from textual.containers import Container, Horizontal, Vertical
-from textual.widgets import Footer, Header, Static
-from textual.binding import Binding
-from textual.screen import Screen
 import chess
+from textual.app import App, ComposeResult
+from textual.binding import Binding
+from textual.containers import Container, Horizontal, Vertical
+from textual.screen import Screen
+from textual.widgets import Footer, Header
 
 from shellmate.tui.widgets import (
     ChessBoardWidget,
-    MoveInput,
-    MoveListWidget,
     GameStatusWidget,
     MainMenu,
+    MoveInput,
+    MoveListWidget,
 )
 from shellmate.tui.widgets.move_input import parse_move
 
diff --git a/src/shellmate/tui/widgets/__init__.py b/src/shellmate/tui/widgets/__init__.py
index 149a017..3ea1416 100644
--- a/src/shellmate/tui/widgets/__init__.py
+++ b/src/shellmate/tui/widgets/__init__.py
@@ -1,10 +1,10 @@
 """TUI widgets for ShellMate."""
 
 from .board import ChessBoardWidget
+from .menu import MainMenu
 from .move_input import MoveInput
 from .move_list import MoveListWidget
 from .status import GameStatusWidget
-from .menu import MainMenu
 
 __all__ = [
     "ChessBoardWidget",
diff --git a/src/shellmate/tui/widgets/board.py b/src/shellmate/tui/widgets/board.py
index ad38569..d11d1f3 100644
--- a/src/shellmate/tui/widgets/board.py
+++ b/src/shellmate/tui/widgets/board.py
@@ -1,13 +1,12 @@
 """Chess board widget with Unicode pieces - Hyper-polished version."""
 
-from textual.widget import Widget
-from textual.reactive import reactive
-from textual.geometry import Size
-from rich.text import Text
-from rich.style import Style
-from rich.console import RenderableType
 import chess
-
+from rich.console import RenderableType
+from rich.style import Style
+from rich.text import Text
+from textual.geometry import Size
+from textual.reactive import reactive
+from textual.widget import Widget
 
 # Unicode chess pieces - using filled variants for better visibility
 PIECES_FILLED = {
@@ -120,7 +119,6 @@ class ChessBoardWidget(Widget):
     def _render_compact(self) -> RenderableType:
         """Compact board for small terminals."""
         text = Text()
-        cw = 3  # Fixed cell width for compact
 
         files = "abcdefgh" if not self.flipped else "hgfedcba"
 
diff --git a/src/shellmate/tui/widgets/menu.py b/src/shellmate/tui/widgets/menu.py
index 3d8cfbc..29a1ac1 100644
--- a/src/shellmate/tui/widgets/menu.py
+++ b/src/shellmate/tui/widgets/menu.py
@@ -1,11 +1,9 @@
 """Main menu widget."""
 
+from textual.containers import Vertical
+from textual.message import Message
 from textual.widget import Widget
 from textual.widgets import Button, Static
-from textual.containers import Vertical, Center
-from textual.message import Message
-from rich.text import Text
-from rich.console import RenderableType
 
 
 class MainMenu(Widget):
diff --git a/src/shellmate/tui/widgets/move_input.py b/src/shellmate/tui/widgets/move_input.py
index cf7ac5e..5eb9b08 100644
--- a/src/shellmate/tui/widgets/move_input.py
+++ b/src/shellmate/tui/widgets/move_input.py
@@ -1,8 +1,8 @@
 """Move input widget."""
 
-from textual.widgets import Input
-from textual.message import Message
 import chess
+from textual.message import Message
+from textual.widgets import Input
 
 
 class MoveInput(Input):
diff --git a/src/shellmate/tui/widgets/move_list.py b/src/shellmate/tui/widgets/move_list.py
index ac328e4..b93b018 100644
--- a/src/shellmate/tui/widgets/move_list.py
+++ b/src/shellmate/tui/widgets/move_list.py
@@ -1,10 +1,9 @@
 """Move list/history widget."""
 
-from textual.widget import Widget
-from textual.reactive import reactive
-from rich.text import Text
 from rich.console import RenderableType
-import chess
+from rich.text import Text
+from textual.reactive import reactive
+from textual.widget import Widget
 
 
 class MoveListWidget(Widget):
diff --git a/src/shellmate/tui/widgets/status.py b/src/shellmate/tui/widgets/status.py
index 812e3d2..db3b581 100644
--- a/src/shellmate/tui/widgets/status.py
+++ b/src/shellmate/tui/widgets/status.py
@@ -1,11 +1,9 @@
 """Game status widget."""
 
-from textual.widget import Widget
-from textual.reactive import reactive
-from rich.text import Text
-from rich.panel import Panel
-from rich.console import RenderableType
 import chess
+from rich.console import RenderableType
+from rich.text import Text
+from textual.widget import Widget
 
 
 class GameStatusWidget(Widget):
@@ -43,7 +41,7 @@ class GameStatusWidget(Widget):
 
         if self._is_checkmate:
             winner = self._black_name if self._turn == chess.WHITE else self._white_name
-            text.append(f"♚ CHECKMATE!\n", style="bold red")
+            text.append("♚ CHECKMATE!\n", style="bold red")
             text.append(f"{winner} wins!", style="bold yellow")
         elif self._is_stalemate:
             text.append("½ STALEMATE\n", style="bold yellow")
@@ -70,9 +68,13 @@ class GameStatusWidget(Widget):
             text.append(f"⚫ {black_time_str}", style=black_style)
 
         # Evaluation (if available)
-        if self._evaluation is not None and not (self._is_checkmate or self._is_stalemate or self._is_draw):
+        game_ended = self._is_checkmate or self._is_stalemate or self._is_draw
+        if self._evaluation is not None and not game_ended:
             text.append("\n\n")
-            eval_str = f"+{self._evaluation:.1f}" if self._evaluation > 0 else f"{self._evaluation:.1f}"
+            if self._evaluation > 0:
+                eval_str = f"+{self._evaluation:.1f}"
+            else:
+                eval_str = f"{self._evaluation:.1f}"
             bar = self._eval_bar(self._evaluation)
             text.append(f"Eval: {eval_str}\n", style="dim")
             text.append(bar)
diff --git a/tests/test_ssh_server.py b/tests/test_ssh_server.py
index afec699..2a94bd0 100644
--- a/tests/test_ssh_server.py
+++ b/tests/test_ssh_server.py
@@ -1,9 +1,9 @@
 """Tests for SSH server functionality."""
 
-import asyncio
-import pytest
 from unittest.mock import AsyncMock, MagicMock, patch
 
+import pytest
+
 
 class TestShellMateSSHServer:
     """Test SSH server authentication."""
@@ -113,9 +113,10 @@ class TestChessBoard:
 
     def test_board_initialization(self):
         """Board should initialize with standard position."""
-        from shellmate.tui.widgets.board import ChessBoardWidget
         import chess
 
+        from shellmate.tui.widgets.board import ChessBoardWidget
+
         widget = ChessBoardWidget()
 
         assert widget.board.fen() == chess.STARTING_FEN
@@ -136,9 +137,10 @@ class TestChessBoard:
 
     def test_square_selection(self):
         """Selecting a square should show legal moves."""
-        from shellmate.tui.widgets.board import ChessBoardWidget
         import chess
 
+        from shellmate.tui.widgets.board import ChessBoardWidget
+
         widget = ChessBoardWidget()
 
         # Select e2 pawn
@@ -152,9 +154,10 @@ class TestChessBoard:
 
     def test_square_deselection(self):
         """Deselecting should clear legal moves."""
-        from shellmate.tui.widgets.board import ChessBoardWidget
         import chess
 
+        from shellmate.tui.widgets.board import ChessBoardWidget
+
         widget = ChessBoardWidget()
         widget.select_square(chess.E2)
         widget.select_square(None)
@@ -251,9 +254,10 @@ class TestIntegration:
     @pytest.mark.asyncio
     async def test_server_starts(self):
         """Server should start without errors."""
-        from shellmate.ssh.server import start_server
-        import tempfile
         import os
+        import tempfile
+
+        from shellmate.ssh.server import start_server
 
         # Create a temporary host key
         with tempfile.TemporaryDirectory() as tmpdir:
diff --git a/tests/test_ui_render.py b/tests/test_ui_render.py
index f6bc02b..777e241 100644
--- a/tests/test_ui_render.py
+++ b/tests/test_ui_render.py
@@ -1,20 +1,22 @@
 """Tests for UI rendering - catches Rich markup errors before deployment."""
 
-import pytest
 from io import StringIO
+
+from rich.align import Align
+from rich.box import ROUNDED
 from rich.console import Console
 from rich.panel import Panel
 from rich.table import Table
 from rich.text import Text
-from rich.align import Align
-from rich.box import ROUNDED
 
 
 def test_menu_render_no_markup_errors():
     """Test that the main menu renders without Rich markup errors."""
     # Simulate the menu rendering code
     output = StringIO()
-    console = Console(file=output, width=80, height=24, force_terminal=True, color_system="truecolor")
+    console = Console(
+        file=output, width=80, height=24, force_terminal=True, color_system="truecolor"
+    )
 
     username = "testuser"
     width = 80
@@ -35,10 +37,18 @@ def test_menu_render_no_markup_errors():
     menu_table.add_column(justify="center")
     menu_table.add_row(Text(f"Welcome, {username}!", style="cyan"))
     menu_table.add_row("")
-    menu_table.add_row("[bright_white on blue] 1 [/bright_white on blue]  Play vs AI       [dim]♔ vs ♚[/dim]")
-    menu_table.add_row("[bright_white on magenta] 2 [/bright_white on magenta]  Play vs Human   [dim]♔ vs ♔[/dim]")
-    menu_table.add_row("[bright_white on green] 3 [/bright_white on green]  Learn & Practice [dim]📖[/dim]")
-    menu_table.add_row("[bright_white on red] q [/bright_white on red]  Quit             [dim]👋[/dim]")
+    menu_table.add_row(
+        "[bright_white on blue] 1 [/]  Play vs AI       [dim]♔ vs ♚[/dim]"
+    )
+    menu_table.add_row(
+        "[bright_white on magenta] 2 [/]  Play vs Human   [dim]♔ vs ♔[/dim]"
+    )
+    menu_table.add_row(
+        "[bright_white on green] 3 [/]  Learn & Practice [dim]📖[/dim]"
+    )
+    menu_table.add_row(
+        "[bright_white on red] q [/]  Quit             [dim]👋[/dim]"
+    )
     menu_table.add_row("")
     menu_table.add_row(Text("Press a key to select...", style="dim italic"))
 
@@ -93,7 +103,7 @@ def test_chess_board_render():
     """Test that chess board renders without errors."""
     output = StringIO()
 
-    PIECES = {
+    piece_map = {
         'K': '♔', 'Q': '♕', 'R': '♖', 'B': '♗', 'N': '♘', 'P': '♙',
         'k': '♚', 'q': '♛', 'r': '♜', 'b': '♝', 'n': '♞', 'p': '♟',
     }
@@ -106,8 +116,8 @@ def test_chess_board_render():
     # Render rank 8 with pieces
     pieces_row = ['r', 'n', 'b', 'q', 'k', 'b', 'n', 'r']
     row = "  8 |"
-    for file, piece_char in enumerate(pieces_row):
-        char = PIECES.get(piece_char, '?')
+    for piece_char in pieces_row:
+        char = piece_map.get(piece_char, '?')
         row += f" {char} |"
     row += " 8"
     lines.append(row)