Domain 3 Overview

Weight: 20% of total exam score.

Key insight: This is the most configuration-heavy domain. You either know where the files go and what the options do, or you do not. Reasoning alone will not save you here.

3.1 CLAUDE.md Hierarchy

The Three Levels

The Exam's Favourite Trap

A new team member is not receiving instructions.

Root cause: Instructions are in user-level config (~/.claude/CLAUDE.md) instead of project-level (.claude/CLAUDE.md).

New team members cloning the repo do NOT get user-level instructions.

Modular Organisation

@import syntax: Reference external files from CLAUDE.md:

<!-- .claude/CLAUDE.md -->
@import ../docs/api-conventions.md
@import ../docs/testing-standards.md

.claude/rules/ directory: Topic-specific rule files as an alternative to one massive file:

.claude/rules/
  testing.md
  api-conventions.md
  deployment.md

Debugging Tool

/memory command verifies which memory files are loaded. Use when behaviour is inconsistent across sessions.

Practice Scenario

Check Questions

3.2 Custom Slash Commands and Skills

Directory Structure

Skill Frontmatter Options

---
name: codebase-analysis
description: Analyse codebase structure and patterns
context: fork           # Runs in isolated sub-agent context
allowed-tools:          # Restricts available tools
  - Read
  - Grep
  - Glob
argument-hint: "path to analyse"  # Prompts for parameters
---

Key Distinction

Do not put task-specific procedures in CLAUDE.md. Do not put universal standards in skills.

Personal Customisation

Create personal variants in ~/.claude/skills/ with different names. Avoids affecting teammates.

Practice Scenario

3.3 Path-Specific Rules

Configuration

# .claude/rules/testing.md
---
paths: ["**/*.test.tsx", "**/*.spec.ts"]
---
All test files must:
- Use describe/it blocks
- Include at least one assertion per test
- Mock external services, never hit real endpoints in unit tests

Key Advantage Over Directory-Level CLAUDE.md

Token Efficiency

Path-scoped rules load ONLY when editing matching files. Reduces irrelevant context compared to always-loaded instructions.

Practice Scenario

3.4 Plan Mode vs Direct Execution

Decision Framework

Explore Subagent

• Isolates verbose discovery output from the main conversation
• Returns summaries to preserve main conversation context
• Use during multi-phase tasks to prevent context window exhaustion

Combination Pattern

Phase 1: Plan mode → investigate and design
Phase 2: Direct execution → implement the planned approach

This hybrid is common in practice and tested on the exam.

Practice Scenario

Classify each task:

3.5 Iterative Refinement

Technique Hierarchy

Batch vs Sequential Feedback

Practice Scenario

3.6 CI/CD Integration

The -p Flag

# WRONG: Hangs waiting for interactive input
claude "Analyse this PR"

# CORRECT: Non-interactive mode
claude -p "Analyse this PR"

This is Q10 in the sample set. Memorise it.

Structured CI Output

claude -p --output-format json --json-schema schema.json "Review this PR"

Produces machine-parseable findings. Automated systems can post as inline PR comments.

Session Context Isolation

The same Claude session that generated code is LESS effective at reviewing its own changes.

It retains reasoning context that makes it less likely to question its decisions. Use an independent review instance for code review.

Incremental Review Context

When re-running reviews after new commits:

• Include prior review findings in context
• Instruct Claude to report ONLY new or still-unaddressed issues
• Prevents duplicate comments that erode developer trust

CLAUDE.md for CI

Document testing standards, valuable test criteria, and available fixtures. CI-invoked Claude Code uses this to generate high-quality tests. Without it, test generation produces low-value boilerplate.

Practice Scenario

Domain 3 Practice Exam

Quick Reference Card

CLAUDE.md HIERARCHY:
  ~/.claude/CLAUDE.md     → personal, NOT shared
  .claude/CLAUDE.md       → project, shared via git
  subdirectory/CLAUDE.md  → directory-scoped

  New hire missing instructions? → Probably in user-level config

PATH-SPECIFIC RULES:
  .claude/rules/testing.md with paths: ["**/*.test.tsx"]
  Loads only when editing matching files
  Glob patterns match across entire codebase

COMMANDS & SKILLS:
  .claude/commands/   → project (shared)
  ~/.claude/commands/ → personal
  Skills: context: fork, allowed-tools, argument-hint
  Skills = on-demand | CLAUDE.md = always-loaded

PLAN MODE:
  Complex/multi-file/architectural → Plan mode
  Simple/clear/single-file → Direct execution
  Common: Plan first, then direct execution

ITERATIVE REFINEMENT:
  Input/output examples > prose descriptions
  Batch feedback when fixes interact
  Sequential when issues are independent

CI/CD:
  -p flag = non-interactive mode (MEMORISE THIS)
  --output-format json for structured output
  Independent review instance (not same session)
  Include prior findings to prevent duplicate comments