z3ed Command Abstraction Layer Guide

Created: October 11, 2025
Status: Implementation Complete

Overview

This guide documents the new command abstraction layer for z3ed CLI commands. The abstraction layer eliminates ~500+ lines of duplicated code across tool commands and provides a consistent, maintainable architecture for future command development.

Problem Statement

Before Abstraction

The original tool_commands.cc (1549 lines) had severe code duplication:

1. ROM Loading: Every command had 20-30 lines of identical ROM loading logic
2. Argument Parsing: Each command manually parsed --format, --rom, --type, etc.
3. Output Formatting: JSON vs text formatting was duplicated across every command
4. Label Initialization: Resource label loading was repeated in every handler
5. Error Handling: Inconsistent error messages and validation patterns

Code Duplication Example

// Repeated in EVERY command (30+ times):
Rom rom_storage;
Rom* rom = nullptr;
if (rom_context != nullptr && rom_context->is_loaded()) {
  rom = rom_context;
} else {
  auto rom_or = LoadRomFromFlag();
  if (!rom_or.ok()) {
    return rom_or.status();
  }
  rom_storage = std::move(rom_or.value());
  rom = &rom_storage;
}
 
// Initialize labels (repeated in every command that needs labels)
if (rom->resource_label()) {
  if (!rom->resource_label()->labels_loaded_) {
    core::YazeProject project;
    project.use_embedded_labels = true;
    auto labels_status = project.InitializeEmbeddedLabels();
    // ... more boilerplate ...
  }
}
 
// Manual argument parsing (repeated everywhere)
std::string format = "json";
for (size_t i = 0; i < arg_vec.size(); ++i) {
  const std::string& token = arg_vec[i];
  if (token == "--format") {
    if (i + 1 >= arg_vec.size()) {
      return absl::InvalidArgumentError("--format requires a value.");
    }
    format = arg_vec[++i];
  } else if (absl::StartsWith(token, "--format=")) {
    format = token.substr(9);
  }
}
 
// Manual output formatting (repeated everywhere)
if (format == "json") {
  std::cout << "{\n";
  std::cout << "  \"field\": \"value\",\n";
  std::cout << "}\n";
} else {
  std::cout << "Field: value\n";
}

Solution Architecture

Three-Layer Abstraction

1. CommandContext - ROM loading, context management
2. ArgumentParser - Unified argument parsing
3. OutputFormatter - Consistent output formatting
4. CommandHandler (Optional) - Base class for structured commands

File Structure

src/cli/service/resources/
├── command_context.h          # Context management
├── command_context.cc
├── command_handler.h          # Base handler class
├── command_handler.cc
└── (existing files...)
 
src/cli/handlers/agent/
├── tool_commands.cc           # Original (to be refactored)
├── tool_commands_refactored.cc # Example refactored commands
└── (other handlers...)

Core Components

1. CommandContext

Encapsulates ROM loading and common context:

// Create context
CommandContext::Config config;
config.external_rom_context = rom_context;  // Optional: use existing ROM
config.rom_path = "/path/to/rom.sfc";       // Optional: override ROM path
config.use_mock_rom = false;                // Optional: use mock for testing
config.format = "json";
 
CommandContext context(config);
 
// Get ROM (auto-loads if needed)
ASSIGN_OR_RETURN(Rom* rom, context.GetRom());
 
// Ensure labels loaded
RETURN_IF_ERROR(context.EnsureLabelsLoaded(rom));

Benefits:

• Single location for ROM loading logic
• Automatic error handling
• Mock ROM support for testing
• Label management abstraction

2. ArgumentParser

Unified argument parsing with type safety:

ArgumentParser parser(arg_vec);
 
// String arguments
auto type = parser.GetString("type");        // Returns std::optional<string>
auto format = parser.GetString("format").value_or("json");
 
// Integer arguments (supports hex with 0x prefix)
ASSIGN_OR_RETURN(int room_id, parser.GetInt("room"));
 
// Hex-only arguments
ASSIGN_OR_RETURN(int tile_id, parser.GetHex("tile"));
 
// Flags
if (parser.HasFlag("verbose")) {
  // ...
}
 
// Validation
RETURN_IF_ERROR(parser.RequireArgs({"type", "query"}));

Benefits:

• Consistent argument parsing across all commands
• Type-safe with proper error handling
• Supports both --arg=value and --arg value forms
• Built-in hex parsing for ROM addresses

3. OutputFormatter

Consistent JSON/text output:

ASSIGN_OR_RETURN(auto formatter, OutputFormatter::FromString("json"));
 
formatter.BeginObject("Room Information");
formatter.AddField("room_id", "0x12");
formatter.AddHexField("address", 0x1234, 4);  // Formats as "0x1234"
formatter.AddField("sprite_count", 5);
 
formatter.BeginArray("sprites");
formatter.AddArrayItem("Sprite 1");
formatter.AddArrayItem("Sprite 2");
formatter.EndArray();
 
formatter.EndObject();
formatter.Print();

Output (JSON):

{
  "room_id": "0x12",
  "address": "0x1234",
  "sprite_count": 5,
  "sprites": [
    "Sprite 1",
    "Sprite 2"
  ]
}

Output (Text):

=== Room Information ===
  room_id              : 0x12
  address              : 0x1234
  sprite_count         : 5
  sprites:
    - Sprite 1
    - Sprite 2

Benefits:

• No manual JSON escaping
• Consistent formatting rules
• Easy to switch between JSON and text
• Proper indentation handling

4. CommandHandler (Optional Base Class)

For more complex commands, use the base class pattern:

class MyCommandHandler : public CommandHandler {
 protected:
  std::string GetUsage() const override {
    return "agent my-command --required <value> [--format <json|text>]";
  }
  
  absl::Status ValidateArgs(const ArgumentParser& parser) override {
    return parser.RequireArgs({"required"});
  }
  
  absl::Status Execute(Rom* rom, const ArgumentParser& parser,
                      OutputFormatter& formatter) override {
    auto value = parser.GetString("required").value();
    
    // Business logic here
    formatter.AddField("result", value);
    
    return absl::OkStatus();
  }
  
  bool RequiresLabels() const override { return true; }
};
 
// Usage:
absl::Status HandleMyCommand(const std::vector<std::string>& args, Rom* rom) {
  MyCommandHandler handler;
  return handler.Run(args, rom);
}

Benefits:

• Enforces consistent structure
• Automatic context setup and teardown
• Built-in error handling
• Easy to test individual components

Migration Guide

Step-by-Step Refactoring

Before (80 lines):

absl::Status HandleResourceListCommand(
    const std::vector<std::string>& arg_vec, Rom* rom_context) {
  std::string type;
  std::string format = "table";
 
  // Manual argument parsing (20 lines)
  for (size_t i = 0; i < arg_vec.size(); ++i) {
    const std::string& token = arg_vec[i];
    if (token == "--type") {
      if (i + 1 >= arg_vec.size()) {
        return absl::InvalidArgumentError("--type requires a value.");
      }
      type = arg_vec[++i];
    } else if (absl::StartsWith(token, "--type=")) {
      type = token.substr(7);
    }
    // ... repeat for --format ...
  }
 
  if (type.empty()) {
    return absl::InvalidArgumentError("Usage: ...");
  }
 
  // ROM loading (30 lines)
  Rom rom_storage;
  Rom* rom = nullptr;
  if (rom_context != nullptr && rom_context->is_loaded()) {
    rom = rom_context;
  } else {
    auto rom_or = LoadRomFromFlag();
    if (!rom_or.ok()) {
      return rom_or.status();
    }
    rom_storage = std::move(rom_or.value());
    rom = &rom_storage;
  }
 
  // Label initialization (15 lines)
  if (rom->resource_label()) {
    if (!rom->resource_label()->labels_loaded_) {
      core::YazeProject project;
      project.use_embedded_labels = true;
      auto labels_status = project.InitializeEmbeddedLabels();
      if (labels_status.ok()) {
        rom->resource_label()->labels_ = project.resource_labels;
        rom->resource_label()->labels_loaded_ = true;
      }
    }
  }
 
  // Business logic
  ResourceContextBuilder context_builder(rom);
  auto labels_or = context_builder.GetLabels(type);
  if (!labels_or.ok()) {
    return labels_or.status();
  }
  auto labels = std::move(labels_or.value());
 
  // Manual output formatting (15 lines)
  if (format == "json") {
    std::cout << "{\n";
    for (const auto& [key, value] : labels) {
      std::cout << "  \"" << key << "\": \"" << value << "\",\n";
    }
    std::cout << "}\n";
  } else {
    for (const auto& [key, value] : labels) {
      std::cout << key << ": " << value << "\n";
    }
  }
 
  return absl::OkStatus();
}

After (30 lines):

absl::Status HandleResourceListCommand(
    const std::vector<std::string>& arg_vec, Rom* rom_context) {
  
  // Parse arguments
  ArgumentParser parser(arg_vec);
  auto type = parser.GetString("type");
  auto format_str = parser.GetString("format").value_or("table");
  
  if (!type.has_value()) {
    return absl::InvalidArgumentError(
        "Usage: agent resource-list --type <type> [--format <table|json>]");
  }
  
  // Create formatter
  ASSIGN_OR_RETURN(auto formatter, OutputFormatter::FromString(format_str));
  
  // Setup context
  CommandContext::Config config;
  config.external_rom_context = rom_context;
  CommandContext context(config);
  
  // Get ROM and labels
  ASSIGN_OR_RETURN(Rom* rom, context.GetRom());
  RETURN_IF_ERROR(context.EnsureLabelsLoaded(rom));
  
  // Execute business logic
  ResourceContextBuilder builder(rom);
  ASSIGN_OR_RETURN(auto labels, builder.GetLabels(*type));
  
  // Format output
  formatter.BeginObject("Labels");
  for (const auto& [key, value] : labels) {
    formatter.AddField(key, value);
  }
  formatter.EndObject();
  formatter.Print();
  
  return absl::OkStatus();
}

Savings: 50+ lines eliminated, clearer intent, easier to maintain

Commands to Refactor

Priority order for refactoring (based on duplication level):

1. ✅ High Priority (Heavy duplication):
   • HandleResourceListCommand - Example provided ✓
   • HandleResourceSearchCommand - Example provided ✓
   • HandleDungeonDescribeRoomCommand - 80 lines → ~35 lines
   • HandleOverworldDescribeMapCommand - 100 lines → ~40 lines
   • HandleOverworldListWarpsCommand - 120 lines → ~45 lines
2. Medium Priority (Moderate duplication):
   • HandleDungeonListSpritesCommand
   • HandleOverworldFindTileCommand
   • HandleOverworldListSpritesCommand
   • HandleOverworldGetEntranceCommand
   • HandleOverworldTileStatsCommand
3. Low Priority (Simple commands, less duplication):
   • HandleMessageListCommand (delegates to message handler)
   • HandleMessageReadCommand (delegates to message handler)
   • HandleMessageSearchCommand (delegates to message handler)

Estimated Impact

Metric	Before	After	Savings
Lines of code (tool_commands.cc)	1549	~800	48%
Duplicated ROM loading	~600 lines	0	600 lines
Duplicated arg parsing	~400 lines	0	400 lines
Duplicated formatting	~300 lines	0	300 lines
Total Duplication Removed			**~1300 lines**

Testing Strategy

Unit Testing

TEST(CommandContextTest, LoadsRomFromConfig) {
  CommandContext::Config config;
  config.rom_path = "test.sfc";
  CommandContext context(config);
  
  auto rom_or = context.GetRom();
  ASSERT_OK(rom_or);
  EXPECT_TRUE(rom_or.value()->is_loaded());
}
 
TEST(ArgumentParserTest, ParsesStringArguments) {
  std::vector<std::string> args = {"--type=dungeon", "--format", "json"};
  ArgumentParser parser(args);
  
  EXPECT_EQ(parser.GetString("type").value(), "dungeon");
  EXPECT_EQ(parser.GetString("format").value(), "json");
}
 
TEST(OutputFormatterTest, GeneratesValidJson) {
  auto formatter = OutputFormatter::FromString("json").value();
  formatter.BeginObject("Test");
  formatter.AddField("key", "value");
  formatter.EndObject();
  
  std::string output = formatter.GetOutput();
  EXPECT_THAT(output, HasSubstr("\"key\": \"value\""));
}

Integration Testing

TEST(ResourceListCommandTest, ListsDungeons) {
  std::vector<std::string> args = {"--type=dungeon", "--format=json"};
  Rom rom;
  rom.LoadFromFile("test.sfc");
  
  auto status = HandleResourceListCommand(args, &rom);
  EXPECT_OK(status);
}

Benefits Summary

For Developers

1. Less Code to Write: New commands take 30-40 lines instead of 80-120
2. Consistent Patterns: All commands follow the same structure
3. Better Error Handling: Standardized error messages and validation
4. Easier Testing: Each component can be tested independently
5. Self-Documenting: Clear separation of concerns

For Maintainability

1. Single Source of Truth: ROM loading logic in one place
2. Easy to Update: Change all commands by updating one class
3. Consistent Behavior: All commands handle errors the same way
4. Reduced Bugs: Less duplication = fewer places for bugs

For AI Integration

1. Predictable Structure: AI can generate commands using templates
2. Type Safety: ArgumentParser prevents common errors
3. Consistent Output: AI can reliably parse JSON responses
4. Easy to Extend: New tool types follow existing patterns

Next Steps

Immediate (Current PR)

1. ✅ Create abstraction layer (CommandContext, ArgumentParser, OutputFormatter)
2. ✅ Add CommandHandler base class
3. ✅ Provide refactored examples
4. ✅ Update build system
5. ✅ Document architecture

Phase 2 (Next PR)

1. Refactor high-priority commands (5 commands)
2. Add comprehensive unit tests
3. Update AI tool dispatcher to use new patterns
4. Create command generator templates for AI

Phase 3 (Future)

1. Refactor remaining commands
2. Remove old helper functions
3. Add performance benchmarks
4. Create VS Code snippets for command development

Migration Checklist

For each command being refactored:

• [ ] Replace manual argument parsing with ArgumentParser
• [ ] Replace ROM loading with CommandContext
• [ ] Replace label initialization with context.EnsureLabelsLoaded()
• [ ] Replace manual formatting with OutputFormatter
• [ ] Update error messages to use GetUsage()
• [ ] Add unit tests for the command
• [ ] Update documentation
• [ ] Test with both JSON and text output
• [ ] Test with missing/invalid arguments
• [ ] Test with mock ROM

References

• Implementation: src/cli/service/resources/command_context.{h,cc}
• Examples: src/cli/handlers/agent/tool_commands_refactored.cc
• Base class: src/cli/service/resources/command_handler.{h,cc}
• Build config: src/cli/agent.cmake

Questions & Answers

Q: Should I refactor all commands at once?
A: No. Refactor in phases to minimize risk. Start with 2-3 commands as proof of concept.

Q: What if my command needs custom argument handling?
A: ArgumentParser is flexible. You can still access raw args or add custom parsing logic.

Q: Can I use both old and new patterns temporarily?
A: Yes. The new abstraction layer works alongside existing code. Migrate gradually.

Q: Will this affect AI tool calling?
A: No breaking changes. The command interfaces remain the same. Internal implementation improves.

Q: How do I test commands with the new abstractions?
A: Use CommandContext with mock ROM, or pass external rom_context in tests.

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Last Updated: October 11, 2025
Author: AI Assistant
Review Status: Ready for Implementation