Developer Code Organization

Code Organization

Use this reference for gh-aw code organization patterns, file structure guidelines, WASM build-variant stubs, and string sanitization/normalization conventions.

Table of Contents

• File Organization Principles
• Excellent Patterns to Follow
• File Size Guidelines
• Decision Trees
• Case Study: Refactoring Large Files
• Anti-Patterns to Avoid
• Helper File Conventions
• String Sanitization vs Normalization
• WASM Build-Variant Pattern

File Organization Principles

The codebase follows clear patterns for organizing code by functionality rather than type. This section provides guidance on maintaining code quality and structure.

Prefer Many Small Files Over Large Ones

Organize code into focused files of 100-500 lines rather than creating large monolithic files.

Example:

create_issue.go (160 lines)
create_pull_request.go (238 lines)
create_discussion.go (118 lines)

Group by Functionality, Not by Type

Recommended approach:

create_issue.go            # Issue creation logic
create_issue_test.go       # Issue creation tests
add_comment.go             # Comment addition logic
add_comment_test.go        # Comment tests

Avoid:

models.go                  # All structs
logic.go                   # All business logic
tests.go                   # All tests

Excellent Patterns to Follow

Create Functions Pattern

One file per GitHub entity creation operation:

• create_issue.go - GitHub issue creation logic
• create_pull_request.go - Pull request creation logic
• create_discussion.go - Discussion creation logic
• create_code_scanning_alert.go - Code scanning alert creation

Benefits:

• Clear separation of concerns
• Easy to locate specific functionality
• Prevents files from becoming too large
• Facilitates parallel development

Engine Separation Pattern

Each AI engine has its own file with shared helpers in engine_helpers.go:

• copilot_engine.go - GitHub Copilot engine
• claude_engine.go - Claude engine
• codex_engine.go - Codex engine
• custom_engine.go - Custom engine support
• engine_helpers.go - Shared engine utilities

Test Organization Pattern

Tests live alongside implementation files:

• Feature tests: feature.go + feature_test.go
• Integration tests: feature_integration_test.go
• Specific scenario tests: feature_scenario_test.go

File Size Guidelines

Decision Tree: Creating New Files

graph TD
    A[Need to add code] --> B{New safe output type?}
    B -->|Yes| C[Create create_entity.go]
    B -->|No| D{New AI engine?}
    D -->|Yes| E[Create engine_name_engine.go]
    D -->|No| F{Current file > 800 lines?}
    F -->|Yes| G[Consider splitting by boundaries]
    F -->|No| H{Functionality independent?}
    H -->|Yes| I[Create new file]
    H -->|No| J[Add to existing file]

Decision Tree: Splitting Files

graph TD
    A[Evaluating file split] --> B{File > 1000 lines?}
    B -->|Yes| C[SHOULD split]
    B -->|No| D{File > 800 lines?}
    D -->|Yes| E[CONSIDER splitting]
    D -->|No| F{Multiple responsibilities?}
    F -->|Yes| E
    F -->|No| G{Frequent merge conflicts?}
    G -->|Yes| E
    G -->|No| H[Keep as is]

Case Study: Refactoring Large Files

The refactoring of pkg/parser/frontmatter.go demonstrates applying file organization principles to a large monolithic file.

Initial State

• Original file: 1,907 lines (monolithic structure)
• Problem: Difficult to navigate, understand, and maintain
• Goal: Split into focused, maintainable modules

Refactoring Approach

graph TD
    A[frontmatter.go<br/>1,907 LOC] --> B[ansi_strip.go<br/>108 LOC]
    A --> C[frontmatter_content.go<br/>284 LOC]
    A --> D[remote_fetch.go<br/>258 LOC]
    A --> E[workflow_update.go<br/>129 LOC]
    A --> F[frontmatter.go<br/>1,166 LOC]

    B --> G[ANSI escape<br/>sequence utilities]
    C --> H[Frontmatter<br/>parsing & extraction]
    D --> I[GitHub remote<br/>content fetching]
    E --> J[Workflow file<br/>updates]
    F --> K[Core frontmatter<br/>processing]

    style B fill:#90EE90
    style C fill:#90EE90
    style D fill:#90EE90
    style E fill:#90EE90
    style F fill:#FFE4B5

Results

Modules Extracted

1. ansi_strip.go (108 LOC)

   • ANSI escape sequence stripping utilities
   • Standalone, no dependencies
   • Functions: StripANSI(), isFinalCSIChar(), isCSIParameterChar()

2. frontmatter_content.go (284 LOC)

   • Basic frontmatter parsing and extraction
   • Pure functions without side effects
   • Functions: ExtractFrontmatterFromContent(), ExtractFrontmatterString(), ExtractMarkdownContent(), etc.

3. remote_fetch.go (258 LOC)

   • GitHub remote content fetching
   • GitHub API interactions and caching
   • Functions: downloadIncludeFromWorkflowSpec(), resolveRefToSHA(), downloadFileFromGitHub()

4. workflow_update.go (129 LOC)

   • High-level workflow file updates
   • Frontmatter manipulation and cron expression handling
   • Functions: UpdateWorkflowFrontmatter(), EnsureToolsSection(), QuoteCronExpressions()

Key Principles Applied

• Single Responsibility: Each module handles one aspect of frontmatter processing
• Clear Boundaries: Well-defined interfaces between modules
• Progressive Refactoring: Extract standalone utilities first, then higher-level modules
• No Breaking Changes: Maintain public API compatibility throughout
• Test-Driven Safety: Run tests after each extraction

Remaining Work

Three complex modules remain in the original file (requiring future work):

• tool_sections.go (~420 LOC): Tool configuration extraction and merging
• include_expander.go (~430 LOC): Recursive include resolution with cycle detection
• frontmatter_imports.go (~360 LOC): BFS import traversal and processing

These remain due to high interdependency, stateful logic, and complex recursive algorithms.

Anti-Patterns to Avoid

God Files

Single file doing everything - split by responsibility instead. The frontmatter.go refactoring demonstrates how a 1,907-line "god file" can be systematically broken down.

Vague Naming

Avoid non-descriptive file names like utils.go, helpers.go, misc.go, common.go.

Use specific names like ansi_strip.go, remote_fetch.go, or workflow_update.go that clearly indicate their purpose.

Mixed Concerns

Keep files focused on one domain. Don't mix unrelated functionality in one file.

Test Pollution

Split tests by scenario rather than having one massive test file.

Premature Abstraction

Wait until you have 2-3 use cases before extracting common patterns.

Helper File Conventions

Helper files contain shared utility functions used across multiple modules. Follow these guidelines when creating or modifying helper files.

When to Create Helper Files

Create a helper file when you have:

1. Shared utilities used by 3+ files in the same domain
2. Clear domain focus (e.g., configuration parsing, MCP rendering, CLI wrapping)
3. Stable functionality that won't change frequently

Examples of Good Helper Files:

• github_cli.go - GitHub CLI wrapping functions (ExecGH, ExecGHWithOutput)
• config_helpers.go - Safe output configuration parsing (parseLabelsFromConfig, parseTitlePrefixFromConfig)
• map_helpers.go - Generic map/type utilities (parseIntValue, filterMapKeys)
• mcp_renderer.go - MCP configuration rendering (RenderGitHubMCPDockerConfig, RenderJSONMCPConfig)

Naming Conventions

Helper file names should be specific and descriptive, not generic:

Good Names:

• github_cli.go - Indicates GitHub CLI helpers
• mcp_renderer.go - Indicates MCP rendering helpers
• config_helpers.go - Indicates configuration parsing helpers

Avoid:

• helpers.go - Too generic
• utils.go - Too vague
• misc.go - Indicates poor organization
• common.go - Doesn't specify domain

What Belongs in Helper Files

Include:

• Small (< 50 lines) utility functions used by multiple files
• Domain-specific parsing/validation functions
• Wrapper functions that simplify common operations
• Type conversion utilities

Exclude:

• Complex business logic (belongs in domain-specific files)
• Functions used by only 1-2 callers (co-locate with callers)
• Large functions (> 100 lines) - consider dedicated files
• Multiple unrelated domains in one file

Helper File Organization

Current Helper Files in pkg/workflow:

When NOT to Create Helper Files

Avoid creating helper files when:

1. Single caller - Co-locate with the caller instead
2. Tight coupling - Function is tightly coupled to one module
3. Frequent changes - Helper files should be stable
4. Mixed concerns - Multiple unrelated utilities (split into focused files)

Example of co-location preference:

// Instead of: helpers.go containing formatStepName() used only by compiler.go
// Do: Put formatStepName() directly in compiler.go

Refactoring Guidelines

When refactoring helper files:

1. Group by domain - MCP rendering → mcp_renderer.go, not engine_helpers.go
2. Keep functions small - Large helpers (> 100 lines) may need dedicated files
3. Document usage - Add comments explaining when to use each helper
4. Check call sites - Ensure 3+ callers before keeping in helper file