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+# Code Operation Summary - Rivals for Catan Implementation
+
+## Executive Summary
+
+This document provides a comprehensive overview of how the Rivals for Catan card game implementation operates, including its functionalities, architectural relationships, and communication flows. The codebase is a well-structured, modular Java application that implements the Rivals for Catan card game with support for both local and network multiplayer gameplay.
+
+---
+
+## 1. Core Functionalities
+
+### 1.1 Game Management
+The system provides complete game flow management:
+- **Game Initialization**: Set up players, decks, and starting boards
+- **Turn Management**: Orchestrate turn sequences including pre-roll, event die, production, and action phases
+- **Victory Tracking**: Monitor victory points and determine when a player reaches 7+ VP to win
+- **Event System**: Handle event die outcomes (Brigand, Trade, Celebration, Event Cards)
+- **Card Effects**: Execute diverse card effects (resource generation, placement, trading, etc.)
+
+### 1.2 Card and Deck Management
+- **Card Loading**: Parse and load cards from `cards.json` configuration file
+- **Deck Organization**: Manage multiple deck types:
+  - 49 center cards (24 regions, 9 settlements, 7 cities, 9 roads)
+  - 36 basic action cards (distributed across 4 stacks)
+  - 9 event cards (with "Yule" positioned 4th from bottom)
+- **Card Distribution**: Deal opening hands, replenish cards, and handle deck exhaustion
+- **Production**: Generate resources based on dice rolls and region tiles
+
+### 1.3 Placement and Building
+- **Structure Placement**: Validate and place settlements, roads, cities, and buildings
+- **Placement Rules**: Enforce game rules:
+  - Settlements require adjacent roads and no adjacent settlements
+  - Roads must connect to existing structures
+  - Cities require existing settlements at that location
+  - Buildings require appropriate slots in settlements/cities
+- **Upgrade System**: Handle settlement-to-city upgrades
+
+### 1.4 Resource and Trade Management
+- **Resource Tracking**: Manage 5 resource types (Lumber, Ore, Wool, Grain, Gold)
+- **Trading**: Support bank trades (4:1 or 3:1 with discounts) and player-to-player trades
+- **Cost Validation**: Verify players can afford card plays and building placements
+- **Resource Production**: Generate resources based on dice rolls and production boosters
+
+### 1.5 Special Effects and Abilities
+The system implements numerous special card effects:
+
+**Action Cards:**
+- Goldsmith: Exchange gold for victory points
+- Merchant: Trade advantages and resource manipulation
+- Merchant Caravan: Enhanced trading capabilities
+- Road Building: Place roads at reduced cost
+- Relocation: Move structures on the board
+- Brigitta the Wise: Pre-roll phase effects
+- Scout: Card drawing mechanics
+- Harvest: Enhanced resource generation
+
+**Event Cards:**
+- Feud: Competitive effects between players
+- Fraternal Feuds: Player conflict mechanics
+- Invention: Free upgrades
+- Trade Ships Race: Trading competitions
+- Traveling Merchant: Merchant visits
+- Year of Plenty: Free resources
+- Yule: Special celebration effects
+
+**Building Effects:**
+- Abbey: Card draw bonuses
+- Marketplace: Trade discounts
+- Storehouse: Resource storage bonuses
+- Toll Bridge: Opponent resource penalties
+
+**Unit Effects:**
+- Common Heroes: Combat and defense
+- Trade Ships: Enhanced trading
+- Large Trade Ships: Superior trading capabilities
+
+### 1.6 Input/Output Systems
+- **Console Interface**: Text-based gameplay for local multiplayer
+- **Network Support**: Socket-based networking for online multiplayer
+- **Mock I/O**: Test doubles for automated testing
+- **Board Display**: ASCII-based board visualization showing regions, structures, and resources
+
+### 1.7 Testing Infrastructure
+Comprehensive test suite covering:
+- Card effect behaviors
+- Placement rules and validation
+- Production mechanics
+- Trade operations
+- Event handling
+- Victory conditions
+- Edge cases and error scenarios
+
+---
+
+## 2. Relationship Between Classes and Folders
+
+### 2.1 Package Structure and Responsibilities
+
+```
+HomeExam/
+├── src/
+│   ├── Main.java                    # Application entry point
+│   │
+│   ├── model/                       # Domain Models (12 classes)
+│   │   ├── Card.java                # Base card abstraction
+│   │   ├── BasicCard.java           # Action/building cards
+│   │   ├── CenterCard.java          # Region/settlement/city/road cards
+│   │   ├── EventCard.java           # Event deck cards
+│   │   ├── Deck.java                # Generic deck container
+│   │   ├── Player.java              # Player state and hand
+│   │   ├── Principality.java        # Player's board/grid
+│   │   ├── RegionTile.java          # Individual region tile
+│   │   ├── Resource.java            # Resource types enum
+│   │   ├── Structure.java           # Structure types enum
+│   │   ├── VictoryPointTracker.java # VP calculation
+│   │   └── Points.java              # Point types (VP, CP, SP, etc.)
+│   │
+│   ├── controller/                  # Game Logic (56 classes)
+│   │   ├── GameController.java      # Main coordinator
+│   │   ├── TurnManager.java         # Turn sequencing
+│   │   ├── DeckManager.java         # Deck operations
+│   │   ├── EventManager.java        # Event coordination
+│   │   ├── CardFactory.java         # Card creation from JSON
+│   │   ├── RuleValidator.java       # Rule enforcement
+│   │   ├── EffectCatalog.java       # Effect registry
+│   │   ├── EffectRegistry.java      # Effect registration helper
+│   │   ├── GameContext.java         # Shared game state
+│   │   ├── SetupService.java        # Game initialization
+│   │   ├── TurnState.java           # Turn state tracking
+│   │   ├── AdvantageManager.java    # Player advantages
+│   │   ├── ICardEffect.java         # Effect interface
+│   │   │
+│   │   ├── interfaces/              # Controller contracts
+│   │   ├── actions/                 # Action card effects (9 classes)
+│   │   ├── event/                   # Event card effects (7 classes)
+│   │   ├── eventDieEvents/          # Event die outcomes (4 classes)
+│   │   ├── phases/                  # Game phases (1 class)
+│   │   ├── placement/               # Placement handlers (8 classes)
+│   │   └── settlement/              # Settlement effects
+│   │       ├── buildings/           # Building effects (4 classes)
+│   │       └── units/               # Unit effects (3 classes)
+│   │
+│   ├── view/                        # Display Layer
+│   │   └── BoardPrinter.java        # ASCII board rendering
+│   │
+│   ├── io/                          # I/O Abstractions
+│   │   ├── ConsoleInput.java        # Console input
+│   │   ├── ConsoleOutput.java       # Console output
+│   │   ├── SocketInput.java         # Network input
+│   │   ├── SocketOutput.java        # Network output
+│   │   ├── MockIO.java              # Test I/O
+│   │   └── interfaces/              # I/O contracts
+│   │
+│   ├── network/                     # Networking Layer
+│   │   ├── Server.java              # Game server
+│   │   ├── ServerHandler.java       # Server logic
+│   │   ├── ClientConnection.java    # Client connection
+│   │   ├── OnlinePlayer.java        # Remote player
+│   │   ├── NetworkService.java      # Network utilities
+│   │   └── interfaces/              # Network contracts
+│   │
+│   ├── util/                        # Utilities
+│   │   ├── Dice.java                # Dice rolling
+│   │   ├── Logger.java              # Logging
+│   │   ├── Randomizer.java          # RNG abstraction
+│   │   ├── GameConfig.java          # Game configuration
+│   │   ├── CostParser.java          # Cost parsing
+│   │   └── policy/                  # Game policies
+│   │       ├── PlacementPolicy.java
+│   │       ├── ProductionPolicy.java
+│   │       ├── TradePolicy.java
+│   │       ├── VictoryPolicy.java
+│   │       └── impl/BasePolicies.java
+│   │
+│   └── tests/                       # Unit Tests (20+ test classes)
+│
+├── cards.json                       # Card definitions
+├── gson.jar                         # JSON library
+└── Documentation files (*.md)
+```
+
+### 2.2 Key Relationships
+
+#### Layered Architecture:
+1. **Presentation Layer** → Main.java, view/
+2. **Application Layer** → controller/ (GameController, TurnManager, etc.)
+3. **Business Logic Layer** → controller/ subdirectories (actions/, events/, placement/)
+4. **Domain Layer** → model/
+5. **Infrastructure Layer** → io/, network/, util/
+6. **Testing Layer** → tests/
+
+#### Dependency Flow:
+- **Main → Controller → Model**: One-way dependency from entry point through controllers to domain
+- **Controller → I/O**: Controllers use I/O abstractions via interfaces
+- **Effects → Model**: All effects modify Player/Principality state
+- **View → Model**: View reads model state for display
+- **Network → I/O**: Network implements I/O interfaces
+- **Util → Independent**: Utilities have no dependencies on other packages
+
+### 2.3 Design Patterns Used
+
+1. **Strategy Pattern**: ICardEffect interface with multiple implementations
+2. **Registry Pattern**: EffectCatalog maps effect names to implementations
+3. **Factory Pattern**: CardFactory creates cards from JSON
+4. **Dependency Injection**: Controllers receive dependencies via constructors
+5. **Abstract Factory**: PlacementRegistry for creating placement handlers
+6. **Template Method**: PlacementHandler defines placement workflow
+7. **Observer Pattern** (implicit): GameContext for shared state
+8. **Adapter Pattern**: Socket I/O adapters for network play
+
+---
+
+## 3. Communication Flow
+
+### 3.1 Application Startup Flow
+
+```
+1. Main.main()
+   ↓
+2. Initialize components:
+   - Randomizer (RNG)
+   - GameConfig (game rules)
+   - ConsoleInput/ConsoleOutput (I/O)
+   ↓
+3. Load cards from cards.json:
+   - CardFactory.loadBasic()
+   - Parse JSON and create card objects
+   - Fallback to placeholder decks on failure
+   ↓
+4. Create DeckManager:
+   - Organize cards into decks (basic, event, center)
+   - Shuffle decks
+   ↓
+5. Initialize game components:
+   - RuleValidator (rule enforcement)
+   - EventManager (event handling)
+   - TurnManager (turn coordination)
+   - GameController (main orchestrator)
+   ↓
+6. Create players:
+   - Player("Player 1")
+   - Player("Player 2")
+   ↓
+7. Deal opening hands:
+   - Each player chooses a stack (1-4)
+   - Draw 3 cards from chosen stack
+   ↓
+8. Setup starting boards:
+   - SetupService.seedIntroPrincipality()
+   - Place initial regions, settlements, roads
+   ↓
+9. Display boards:
+   - BoardPrinter.printPlayerBoard()
+   ↓
+10. Randomly determine starting player
+    ↓
+11. Enter game loop
+```
+
+### 3.2 Turn Execution Flow
+
+```
+TurnManager.playTurn(current, opponent)
+   ↓
+Phase 1: PRE-ROLL PHASE
+   - Check for pre-roll effects (e.g., Brigitta the Wise)
+   - Execute pre-roll card effects if any
+   ↓
+Phase 2: EVENT DIE ROLL
+   - Dice.roll(6) → Event die result (1-6)
+   - Parse event result:
+     • 1-3: Brigand (steal resource from opponent)
+     • 4: Trade (execute trade event)
+     • 5: Celebration (bonus resources)
+     • 6: Draw and execute event card
+   ↓
+Phase 3: PRODUCTION PHASE
+   - Roll production die: Dice.roll(6)
+   - For each region with matching dice number:
+     • Generate resources
+     • Apply production boosters (e.g., Storehouse)
+     • Store resources on region tiles
+   - Collect resources from all regions
+   ↓
+Phase 4: ACTION PHASE (repeating until player passes)
+   - Display menu:
+     1. Build structure (settlement/road/city/building)
+     2. Play action card
+     3. Trade with bank/opponent
+     4. End turn
+   ↓
+   Player chooses action:
+   
+   BUILD STRUCTURE:
+      - Select structure type
+      - Get placement handler from PlacementRegistry
+      - Validate placement rules
+      - Check resource cost
+      - Deduct resources
+      - Place structure on Principality
+      - Update victory points
+      - Return to action menu
+   
+   PLAY CARD:
+      - Select card from hand
+      - Get effect from EffectCatalog
+      - Validate preconditions (e.g., can afford)
+      - Execute ICardEffect.apply(GameContext)
+      - Remove card from hand
+      - Apply card effects (placement, resources, etc.)
+      - Return to action menu
+   
+   TRADE:
+      - Choose trade type (bank/opponent)
+      - Select resources to exchange
+      - Validate trade (4:1 or 3:1 ratio)
+      - Execute resource exchange
+      - Return to action menu
+   
+   END TURN:
+      - Exit action phase
+   ↓
+Phase 5: REPLENISH PHASE
+   - DeckManager.replenish()
+   - Player may draw cards to refill hand
+   ↓
+Phase 6: EXCHANGE PHASE
+   - Optional: Exchange resources with bank
+   ↓
+Phase 7: VICTORY CHECK
+   - RuleValidator.hasWon(player)
+   - Check if player has 7+ victory points
+   - If yes: End game, declare winner
+   - If no: Switch to opponent's turn
+```
+
+### 3.3 Card Effect Execution Flow
+
+```
+Player plays action card
+   ↓
+GameController receives play card request
+   ↓
+1. Retrieve card from player's hand
+   ↓
+2. Validate preconditions:
+   - RuleValidator.canAfford(player, card)
+   - Check card-specific prerequisites
+   ↓
+3. Deduct resource cost:
+   - player.spendResources(card.getCost())
+   ↓
+4. Create GameContext:
+   - Contains: player, opponent, game state, I/O
+   ↓
+5. Lookup effect in EffectCatalog:
+   - EffectCatalog.get(card.getName())
+   - Returns ICardEffect implementation
+   ↓
+6. Execute effect:
+   - ICardEffect.apply(GameContext)
+   ↓
+7. Effect-specific logic (examples):
+   
+   Goldsmith Effect:
+      - Prompt for number of gold to convert
+      - Validate player has enough gold
+      - Deduct gold resources
+      - Add victory points
+      - Update VictoryPointTracker
+   
+   Merchant Caravan Effect:
+      - Grant trading advantage
+      - Enable 3:1 trade ratio
+      - Player performs trades
+      - Remove advantage after use
+   
+   Road Building Effect:
+      - Get RoadPlacementHandler
+      - Prompt for road positions
+      - Validate placement rules
+      - Place roads at reduced cost
+      - Update Principality
+   
+   Abbey Effect:
+      - Check player has city
+      - Place Abbey in city slot
+      - Grant card draw bonus
+      - Trigger on specific events
+   
+   Scout Effect:
+      - Draw cards from basic deck
+      - Add to player hand
+      - No resource cost
+   ↓
+8. Update game state:
+   - Modify player resources
+   - Update board state
+   - Recalculate victory points
+   ↓
+9. Notify players:
+   - Display effect results
+   - Update board display
+   ↓
+10. Remove card from hand (if one-time use)
+    ↓
+11. Return to action phase
+```
+
+### 3.4 Placement Validation Flow
+
+```
+Player requests structure placement
+   ↓
+GameController.handlePlacement()
+   ↓
+1. PlacementRegistry.getHandler(cardType)
+   - Returns appropriate PlacementHandler:
+     • SettlementPlacementHandler
+     • RoadPlacementHandler
+     • CityPlacementHandler
+     • GenericBuildingPlacementHandler
+     • AbbeyPlacementHandler
+     • HeroPlacementHandler
+   ↓
+2. PlacementHandler.canHandle(card) → boolean
+   ↓
+3. PlacementHandler.place(card, context):
+   
+   For Settlement:
+      a. Prompt player for intersection coordinates
+      b. Validate rules:
+         - Is intersection empty?
+         - Is there an adjacent road owned by player?
+         - Are there no adjacent settlements?
+      c. If valid:
+         - Place settlement on Principality
+         - Add 1 victory point
+         - Return success
+      d. If invalid:
+         - Display error message
+         - Return failure
+   
+   For Road:
+      a. Prompt for edge coordinates
+      b. Validate rules:
+         - Is edge empty?
+         - Is road connected to player's structure?
+      c. If valid:
+         - Place road on Principality
+         - Return success
+      d. If invalid:
+         - Return failure
+   
+   For City:
+      a. Prompt for settlement to upgrade
+      b. Validate rules:
+         - Does settlement exist at location?
+         - Does player own the settlement?
+         - Can player afford upgrade cost?
+      c. If valid:
+         - Upgrade settlement to city
+         - Add 1 victory point
+         - Return success
+      d. If invalid:
+         - Return failure
+   
+   For Building (Abbey, Marketplace, etc.):
+      a. Find available building slot
+      b. Validate rules:
+         - Is slot available in settlement/city?
+         - No duplicate building type?
+         - Meets prerequisites (e.g., city for Abbey)?
+      c. If valid:
+         - Place building in slot
+         - Activate building effect
+         - Return success
+      d. If invalid:
+         - Return failure
+   ↓
+4. Update Principality state
+   ↓
+5. Recalculate victory points:
+   - VictoryPointTracker.calculate(player)
+   ↓
+6. Display updated board:
+   - BoardPrinter.printPlayerBoard()
+   ↓
+7. Return placement result
+```
+
+### 3.5 Network Multiplayer Flow (Future Feature)
+
+```
+HOSTING PLAYER:
+   Server.main()
+      ↓
+   1. Initialize server
+   2. Listen on port
+   3. Wait for client connection
+      ↓
+   4. Client connects
+   5. Create ClientConnection
+   6. Create OnlinePlayer with SocketI/O
+   7. Synchronize game state
+      ↓
+   8. Enter game loop (same as local)
+   
+CLIENT PLAYER:
+   NetworkService.connect()
+      ↓
+   1. Connect to server IP:port
+   2. Create SocketInput/SocketOutput
+   3. Receive initial game state
+      ↓
+   4. Enter game loop
+   
+DURING GAMEPLAY:
+   Local player action:
+      - Execute locally
+      - Broadcast state to remote
+      - Update both clients
+   
+   Remote player action:
+      - Receive action via socket
+      - Validate action
+      - Execute if valid
+      - Broadcast state update
+      - Update both clients
+```
+
+### 3.6 Data Flow Through System
+
+```
+cards.json (file)
+   ↓ [parsed by]
+CardFactory
+   ↓ [creates]
+Card objects (BasicCard, CenterCard, EventCard)
+   ↓ [organized by]
+DeckManager
+   ↓ [into]
+Deck<Card> instances
+   ↓ [distributed to]
+Player.hand (List<Card>)
+   ↓ [during turn]
+GameController receives player action
+   ↓ [validates via]
+RuleValidator
+   ↓ [executes via]
+EffectCatalog → ICardEffect
+   ↓ [modifies]
+Player (resources, hand)
+Principality (board state)
+VictoryPointTracker (points)
+   ↓ [displayed via]
+BoardPrinter → IOutputService → Console/Socket
+   ↓ [continues until]
+hasWon(player) == true
+```
+
+---
+
+## 4. Key Design Principles
+
+### 4.1 SOLID Principles Adherence
+
+1. **Single Responsibility**: Each class has one clear purpose
+   - GameController: orchestrates game flow
+   - DeckManager: manages decks
+   - EventManager: handles events
+   - Each effect class: implements one card behavior
+
+2. **Open/Closed**: Extensible without modification
+   - New cards: add ICardEffect implementation, register in EffectCatalog
+   - New placement types: add PlacementHandler, register in PlacementRegistry
+   - New I/O: implement IInputService/IOutputService
+   - New policies: implement policy interfaces
+
+3. **Liskov Substitution**: Subtypes are substitutable
+   - All Card subtypes work with Deck<Card>
+   - All I/O implementations work interchangeably
+   - All effect implementations work through ICardEffect
+
+4. **Interface Segregation**: Focused interfaces
+   - IInputService, IOutputService (separate concerns)
+   - ICardEffect (single method)
+   - Policy interfaces (specific to purpose)
+
+5. **Dependency Inversion**: Depend on abstractions
+   - Controllers depend on I/O interfaces, not implementations
+   - Effects depend on GameContext abstraction
+   - High-level modules independent of low-level details
+
+### 4.2 Modifiability and Extensibility
+
+**Easy to extend:**
+- Add new cards: Just implement ICardEffect and register
+- Add new eras: Implement new policy interfaces
+- Add new placement types: Implement PlacementHandler
+- Add new I/O methods: Implement IInputService/IOutputService
+- Add new game modes: Extend GameConfig
+
+**Hard to break:**
+- Core game logic isolated from I/O
+- Effects are independent and isolated
+- Placement validation centralized
+- Tests verify behavior
+
+### 4.3 Testability
+
+- **Mock I/O**: MockIO for automated testing without user input
+- **Dependency Injection**: All dependencies passed via constructors
+- **Small, focused classes**: Each class easily testable in isolation
+- **Randomizer abstraction**: Dice and Randomizer can be mocked for deterministic tests
+- **20+ test classes**: Comprehensive test coverage
+
+---
+
+## 5. Technology Stack
+
+- **Language**: Java
+- **Build Tool**: Manual compilation (javac) with Maven structure
+- **Libraries**: 
+  - Gson (JSON parsing)
+  - JUnit Jupiter 5.10.2 (testing)
+- **Architecture**: Layered, modular
+- **Paradigm**: Object-oriented with functional elements (Strategy pattern)
+
+---
+
+## 6. File Organization
+
+### 6.1 Configuration Files
+- `cards.json`: Card definitions with effects, costs, and properties
+- `pom.xml`: Maven/JUnit configuration
+- `.gitignore`: Git exclusions
+
+### 6.2 Documentation Files
+- `README.md`: Quick start and structure reference
+- `ARCHITECTURE.md`: Architecture details and design rationale
+- `FOLDER_STRUCTURE.md`: Detailed folder/class diagram
+- `FOLDER_CONNECTIONS.md`: Package dependencies and relationships
+- `GAME_FLOW.md`: Game flow and sequence diagrams
+- `DESIGN_REPORT.md`: SOLID principles and design analysis
+- `TEST_SUMMARY.md`: Test coverage summary
+- `ANSWERS_TO_QUESTIONS.md`: Q&A documentation
+- `Rivals_for_Catan_Rulebook.pdf`: Official game rules
+
+### 6.3 Build Artifacts
+- `target/`: Compiled classes (generated)
+- `gson.jar`: JSON library dependency
+
+---
+
+## 7. Execution Instructions
+
+### 7.1 Local Compilation and Execution
+
+```bash
+# Navigate to project directory
+cd /home/runner/work/HomeExam/HomeExam
+
+# Clean previous build
+rm -rf bin
+mkdir -p bin
+
+# Compile all Java files with gson dependency
+javac -d bin -cp "gson.jar" $(find src -name "*.java")
+
+# Run the game
+java -cp "bin:gson.jar" src.Main
+```
+
+### 7.2 Network Multiplayer (Future)
+
+```bash
+# Terminal A (Host)
+java -cp "bin:gson.jar" src.network.Server
+
+# Terminal B (Client)
+java -cp "bin:gson.jar" src.network.Server online
+```
+
+---
+
+## 8. Summary
+
+### 8.1 What the Code Does
+The codebase implements a complete, playable version of Rivals for Catan card game with:
+- Full game mechanics (production, trading, building, events)
+- 100+ different cards with unique effects
+- Comprehensive rule validation
+- Victory point tracking
+- Support for local and network multiplayer
+- Extensive test coverage
+
+### 8.2 How It's Organized
+- **Layered architecture**: Presentation → Application → Business → Domain → Infrastructure
+- **Modular packages**: Each package has clear responsibility
+- **56 controller classes**: Distributed across specialized subdirectories
+- **12 model classes**: Core domain entities
+- **20+ test classes**: Ensuring correctness
+
+### 8.3 How Components Communicate
+- **Main** initializes and orchestrates via **GameController**
+- **GameController** coordinates **TurnManager**, **DeckManager**, **EventManager**, **RuleValidator**
+- **TurnManager** executes turn phases and delegates to effect implementations
+- **Effects** modify **Model** objects (**Player**, **Principality**)
+- **View** reads **Model** and renders via **I/O** abstractions
+- **Network** layer enables remote play by implementing **I/O** interfaces
+
+### 8.4 Key Strengths
+1. **Well-documented**: Extensive markdown documentation
+2. **Testable**: Comprehensive test suite with mock I/O
+3. **Extensible**: Easy to add new cards, effects, and features
+4. **Maintainable**: Clear separation of concerns, SOLID principles
+5. **Flexible I/O**: Console, network, and test I/O interchangeable
+6. **Policy-based**: Game rules can be customized via policy interfaces
+
+---
+
+## Conclusion
+
+This is a well-architected implementation of Rivals for Catan that demonstrates professional software engineering practices. The code is organized into clear layers with well-defined responsibilities, uses design patterns appropriately, and is built to be extended without modification. The comprehensive documentation and test coverage make it maintainable and reliable for future enhancements.