Domain 3: Claude Code Configuration and Workflows (20%)

3.1 Configuring CLAUDE.md with Hierarchy, Scope, and Modular Organization

Key knowledge:

• CLAUDE.md hierarchy: user (~/.claude/CLAUDE.md), project (.claude/CLAUDE.md or root CLAUDE.md), and directory-level (CLAUDE.md in subdirectories)
• User-level settings apply only to one user and are not shared via VCS
• @path syntax for referencing external files (e.g., @./standards/coding-style.md) to modularize CLAUDE.md
• The .claude/rules/ directory for topic-focused rule files instead of a monolithic CLAUDE.md

Key skills:

• Diagnose hierarchy issues (a new team member misses instructions because they are user-level instead of project-level)
• Use @path (e.g., @./standards/testing.md) to selectively include standards in each package's CLAUDE.md
• Split large CLAUDE.md into multiple .claude/rules/ files (testing.md, api-conventions.md, deployment.md)

3.2 Creating and Configuring Custom Slash Commands and Skills

Key knowledge:

• Project commands in .claude/commands/ (shared via VCS) vs user commands in ~/.claude/commands/
• Skills in .claude/skills/ with SKILL.md frontmatter: context: fork, allowed-tools, argument-hint
• context: fork runs the skill in an isolated subagent context so it does not pollute the main session
• Personal skill variants can live in ~/.claude/skills/ under different names

Key skills:

• Store project slash commands in .claude/commands/ so the whole team gets them
• Use context: fork to isolate skills with verbose output
• Use allowed-tools to restrict what tools a skill can use
• Use argument-hint to prompt developers for required parameters

3.3 Using Path-specific Rules for Conditional Convention Loading

Key knowledge:

• .claude/rules/ files can include YAML frontmatter paths to activate rules based on glob patterns
• Path-scoped rules load only when editing matching files, saving context and tokens
• Glob-based path rules can be preferable to directory-level CLAUDE.md when conventions apply across many directories (e.g., tests)

Key skills:

• Create .claude/rules/ files with paths: ["terraform/**/*"] to load only when working on matching files
• Use glob patterns (**/*.test.tsx) to apply conventions by file type regardless of location
• Prefer path-specific rules over directory-level CLAUDE.md when conventions span the codebase

3.4 Deciding When to Use Planning Mode vs Direct Execution

Key knowledge:

• Planning mode: for complex tasks with large changes, multiple viable approaches, and architectural decisions
• Direct execution: for simple, well-understood changes (e.g., adding a single validation)
• Planning mode enables safe exploration of the codebase before making changes
• Explore subagent isolates verbose discovery output

Key skills:

• Use planning mode for tasks with architectural consequences (microservices, migrations touching 45+ files)
• Use direct execution for fixes with a clear stack trace and a single file
• Use Explore subagent to prevent context-window exhaustion in multi-phase tasks
• Combine approaches: plan for discovery, then execute for implementation

3.5 Iterative Refinement for Progressive Improvement

Key knowledge:

• Concrete input/output examples are the most effective way to communicate expectations
• Test-driven iteration: write tests first, then iterate based on failures
• The "interview" pattern: Claude asks questions to surface non-obvious design considerations
• When to provide all issues in one message (interdependent) vs sequentially (independent)

Key skills:

• Provide 2–3 concrete input/output examples to clarify transformation requirements
• Build test sets with expected behavior, edge cases, and performance requirements before implementation
• Use the interview pattern to surface design aspects (cache invalidation, failure modes)
• Provide concrete test cases with sample inputs and expected outputs for edge cases

3.6 Integrating Claude Code into CI/CD Pipelines

Key knowledge:

• The -p (or --print) flag for non-interactive mode in automated pipelines
• --output-format json and --json-schema for structured output in CI
• CLAUDE.md provides project context (testing standards, review criteria) for CI-triggered Claude Code
• Session context isolation: the same session that generated code is less effective at reviewing it than an independent instance

Key skills:

• Run Claude Code in CI with -p to avoid hanging on interactive input
• Use --output-format json + --json-schema for structured results (e.g., inline PR comments)
• Include prior review results when re-running after new commits (report only new/unfixed issues)
• Document testing standards and available fixtures in CLAUDE.md to improve test generation quality
• Include existing test files in context when generating new tests to avoid duplication and keep style consistent