refactoring

name	refactoring
description	["Code Quality"]
Restructure code without changing behavior using extract method, extract class, rename, move, and inline patterns. Triggers	refactor, extract method, extract class, rename symbol, restructure code, clean up code, decompose function. Use when this capability is needed.
metadata	{"author":"duc01226"}

[IMPORTANT] Use TaskCreate to break ALL work into small tasks BEFORE starting — including tasks for each file read. This prevents context loss from long files. For simple tasks, AI MUST ATTENTION ask user whether to skip.

Understand Code First — HARD-GATE: Do NOT write, plan, or fix until you READ existing code.

1. Search 3+ similar patterns (grep/glob) — cite file:line evidence
2. Read existing files in target area — understand structure, base classes, conventions
3. Run python .claude/scripts/code_graph trace <file> --direction both --json when .code-graph/graph.db exists
4. Map dependencies via connections or callers_of — know what depends on your target
5. Write investigation to .ai/workspace/analysis/ for non-trivial tasks (3+ files)
6. Re-read analysis file before implementing — never work from memory alone
7. NEVER invent new patterns when existing ones work — match exactly or document deviation

BLOCKED until: - [ ] Read target files - [ ] Grep 3+ patterns - [ ] Graph trace (if graph.db exists) - [ ] Assumptions verified with evidence

Evidence-Based Reasoning — Speculation is FORBIDDEN. Every claim needs proof.

1. Cite file:line, grep results, or framework docs for EVERY claim
2. Declare confidence: >80% act freely, 60-80% verify first, <60% DO NOT recommend
3. Cross-service validation required for architectural changes
4. "I don't have enough evidence" is valid and expected output

BLOCKED until: - [ ] Evidence file path (file:line) - [ ] Grep search performed - [ ] 3+ similar patterns found - [ ] Confidence level stated

Forbidden without proof: "obviously", "I think", "should be", "probably", "this is because" If incomplete → output: "Insufficient evidence. Verified: [...]. Not verified: [...]."

Design Patterns Quality — Priority checks for every code change:

1. DRY via OOP: Same-suffix classes (*Entity, *Dto, *Service) MUST ATTENTION share base class. 3+ similar patterns → extract to shared abstraction.
2. Right Responsibility: Logic in LOWEST layer (Entity > Domain Service > Application Service > Controller). Never business logic in controllers.
3. SOLID: Single responsibility (one reason to change). Open-closed (extend, don't modify). Liskov (subtypes substitutable). Interface segregation (small interfaces). Dependency inversion (depend on abstractions).
4. After extraction/move/rename: Grep ENTIRE scope for dangling references. Zero tolerance.
5. YAGNI gate: NEVER recommend patterns unless 3+ occurrences exist. Don't extract for hypothetical future use.

Anti-patterns to flag: God Object, Copy-Paste inheritance, Circular Dependency, Leaky Abstraction.

• docs/project-reference/domain-entities-reference.md — Domain entity catalog, relationships, cross-service sync (read when task involves business entities/models) (content auto-injected by hook — check for [Injected: ...] header before reading)

Quick Summary

Goal: Restructure code without changing behavior using extract, move, and simplify patterns.

Workflow:

1. Analysis — Identify target, map dependencies with Grep, assess impact, verify test coverage
2. Plan — Document refactoring type, changes, and risks
3. Execute — Apply refactoring (extract method/class, move to entity/extension, simplify conditionals)
4. Verify — Run tests, confirm no behavior change, check compilation

Key Rules:

• Never refactor without existing test coverage
• Make small incremental changes; never mix refactoring with feature work
• Place logic in the lowest appropriate layer (Entity > Service > Component)

Investigation Mindset (NON-NEGOTIABLE)

Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).

• Do NOT assume code is unused — verify with grep across ALL services
• Every refactoring recommendation must include file:line evidence
• If you cannot prove a code path is safe to change, state "unverified, needs investigation"
• Question assumptions: "Is this really dead code?" → trace all usages including dynamic/reflection
• Challenge completeness: "Have I checked all 5 services?" → cross-service validation required
• No "should be refactored" without proof — demonstrate the improvement with evidence

⚠️ MANDATORY: Confidence & Evidence Gate

MANDATORY IMPORTANT MUST ATTENTION declare Confidence: X% with evidence list + file:line proof for EVERY claim. 95%+ recommend freely | 80-94% with caveats | 60-79% list unknowns | <60% STOP — gather more evidence. Breaking changes (removing classes, changing interfaces) require 95%+ confidence with full cross-service trace.

Code Refactoring

Expert code restructuring agent. Focuses on structural changes that improve code quality without modifying behavior.

Refactoring Catalog

Extract Patterns

Pattern	When to Use	Example
Extract Method	Long method, duplicated code	Move logic to private method
Extract Class	Class has multiple responsibilities	Create Helper, Service, or Strategy class
Extract Interface	Need abstraction for testing/DI	Create I{ClassName} interface
Extract Expression	Complex inline expression	Move to Entity static expression
Extract Validator	Repeated validation logic	Create validator extension method

Move Patterns

Pattern	When to Use	Example
Move Method	Method belongs to different class	Move from Handler to Helper/Entity
Move to Extension	Reusable repository logic	Create {Entity}RepositoryExtensions
Move to DTO	Mapping logic in handler	Use project DTO base .MapToEntity() (see docs/project-reference/backend-patterns-reference.md)
Move to Entity	Business logic in handler	Add instance method or static expression

Simplify Patterns

Pattern	When to Use	Example
Inline Variable	Temporary variable used once	Remove intermediate variable
Inline Method	Method body is obvious	Replace call with body
Replace Conditional	Complex if/switch	Use Strategy pattern or expression
Introduce Parameter Obj	Method has many parameters	Create Command/Query DTO

Workflow

Phase 1: Analysis

1. Identify Target: Locate code to refactor
2. Map Dependencies: Find all usages with Grep
3. Assess Impact: List affected files and tests
4. Verify Tests: Ensure test coverage exists
5. External Memory: Write analysis to .ai/workspace/analysis/{refactoring-name}.analysis.md. Re-read before planning.

Phase 2: Plan

Document refactoring plan:

## Refactoring Plan

**Target**: [file:line_number]
**Type**: [Extract Method | Move to Extension | etc.]
**Reason**: [Why this refactoring improves code]

### Changes

1. [ ] Create/modify [file]
2. [ ] Update usages in [files]
3. [ ] Run tests

### Risks

- [Potential issues]

Phase 3: Execute

// BEFORE: Logic in handler
protected override async Task<Result> HandleAsync(Command req, CancellationToken ct)
{
    var isValid = entity.Status == Status.Active &&
                  entity.User?.IsActive == true &&
                  !entity.IsDeleted;
    if (!isValid) throw new Exception();
}

// AFTER: Extracted to entity static expression
// In Entity.cs
public static Expression<Func<Entity, bool>> IsActiveExpr()
    => e => e.Status == Status.Active &&
            e.User != null && e.User.IsActive &&
            !e.IsDeleted;

// In Handler
var entity = await repository.FirstOrDefaultAsync(Entity.IsActiveExpr(), ct)
    .EnsureFound("Entity not active");

Phase 4: Verify

1. Run affected tests
2. Verify no behavior change
3. Check code compiles
4. Review for consistency

Project-Specific Refactorings

Handler to Helper

// BEFORE: Reused logic in multiple handlers
var employee = await repo.FirstOrDefaultAsync(Employee.UniqueExpr(userId, companyId), ct)
    ?? await CreateEmployeeAsync(userId, companyId, ct);

// AFTER: Extracted to Helper
// In EmployeeHelper.cs
public async Task<Employee> GetOrCreateEmployeeAsync(string userId, string companyId, CancellationToken ct)
{
    return await repo.FirstOrDefaultAsync(Employee.UniqueExpr(userId, companyId), ct)
        ?? await CreateEmployeeAsync(userId, companyId, ct);
}

Handler to Repository Extension

// BEFORE: Query logic in handler
var employees = await repo.GetAllAsync(
    e => e.CompanyId == companyId && e.Status == Status.Active && e.DepartmentIds.Contains(deptId), ct);

// AFTER: Extracted to extension
// In EmployeeRepositoryExtensions.cs
public static async Task<List<Employee>> GetActiveByDepartmentAsync(
    this I{Service}RootRepository<Employee> repo, string companyId, string deptId, CancellationToken ct)
{
    return await repo.GetAllAsync(
        Employee.OfCompanyExpr(companyId)
            .AndAlso(Employee.IsActiveExpr())
            .AndAlso(e => e.DepartmentIds.Contains(deptId)), ct);
}

Mapping to DTO

// BEFORE: Mapping in handler
var config = new AuthConfig
{
    ClientId = req.Dto.ClientId,
    Secret = encryptService.Encrypt(req.Dto.Secret)
};

// AFTER: DTO owns mapping
// In AuthConfigDto.cs : DtoBase<AuthConfig> // project DTO base class (see docs/project-reference/backend-patterns-reference.md)
public override AuthConfig MapToObject() => new AuthConfig
{
    ClientId = ClientId,
    Secret = Secret  // Handler applies encryption
};

// In Handler
var config = req.Dto.MapToObject()
    .With(c => c.Secret = encryptService.Encrypt(c.Secret));

Index Impact Check

[IMPORTANT] Database Performance Protocol (MANDATORY):

1. Paging Required — ALL list/collection queries MUST ATTENTION use pagination. NEVER load all records into memory. Verify: no unbounded GetAll(), ToList(), or Find() without Skip/Take or cursor-based paging.
2. Index Required — ALL query filter fields, foreign keys, and sort columns MUST ATTENTION have database indexes configured. Verify: entity expressions match index field order, database collections have index management methods, migrations include indexes for WHERE/JOIN/ORDER BY columns.

When extracting expressions or moving queries, verify index coverage:

• New expression fields have indexes in DbContext?
• Moved queries still use indexed fields?
• Refactored filters maintain index selectivity order?
• List queries use pagination (no unbounded GetAll/ToList)?

Safety Checklist

Before any refactoring:

• Searched all usages across ALL services (static + dynamic + reflection)?
• Test coverage exists?
• Documented in todo list?
• Changes are incremental?
• No behavior change verified?
• Confidence declared — Confidence: X% with evidence list?

If ANY checklist item incomplete → STOP. State "Insufficient evidence to proceed."

Code Responsibility Refactoring (Priority Check)

⚠️ MUST ATTENTION READ: CLAUDE.md "Code Responsibility Hierarchy" for the Entity/Model > Service > Component layering rule. When refactoring, verify logic is in the LOWEST appropriate layer.

Component HTML & SCSS Standards

⚠️ MUST ATTENTION READ: CLAUDE.md "Component HTML Template Standard (BEM Classes)" and docs/project-reference/scss-styling-guide.md for BEM class requirements and host/wrapper styling patterns. When refactoring components, ensure all HTML elements have proper BEM classes.

Anti-Patterns

• Big Bang Refactoring: Make small, incremental changes
• Refactoring Without Tests: Ensure coverage first
• Mixing Refactoring with Features: Do one or the other
• Breaking Public APIs: Maintain backward compatibility
• Logic in Wrong Layer: Leads to duplicated code - move to lowest appropriate layer

Graph-Assisted Investigation — MANDATORY when .code-graph/graph.db exists.

HARD-GATE: MUST ATTENTION run at least ONE graph command on key files before concluding any investigation.

Pattern: Grep finds files → trace --direction both reveals full system flow → Grep verifies details

Task	Minimum Graph Action
Investigation/Scout	trace --direction both on 2-3 entry files
Fix/Debug	callers_of on buggy function + tests_for
Feature/Enhancement	connections on files to be modified
Code Review	tests_for on changed functions
Blast Radius	trace --direction downstream

CLI: python .claude/scripts/code_graph {command} --json. Use --node-mode file first (10-30x less noise), then --node-mode function for detail.

Run python .claude/scripts/code_graph connections <file> --json on refactored files to find all consumers needing updates.

Graph Intelligence (RECOMMENDED if graph.db exists)

If .code-graph/graph.db exists, enhance analysis with structural queries:

• Impact of restructuring -- trace callers: python .claude/scripts/code_graph query callers_of <function> --json
• Impact of restructuring -- check importers: python .claude/scripts/code_graph query importers_of <module> --json
• Batch analysis: python .claude/scripts/code_graph batch-query file1 file2 --json

See <!-- SYNC:graph-assisted-investigation --> block above for graph query patterns.

Graph-Trace for Refactoring Impact

When graph DB is available, BEFORE refactoring, trace to verify all consumers:

• python .claude/scripts/code_graph trace <file-to-refactor> --direction downstream --json — all downstream consumers that depend on this code
• python .claude/scripts/code_graph trace <file-to-refactor> --direction both --json — full picture: callers + consumers
• Flag any consumer NOT covered in your refactoring plan — it may break silently

Related

• code-simplifier
• code-review

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Workflow Recommendation

MANDATORY IMPORTANT MUST ATTENTION — NO EXCEPTIONS: If you are NOT already in a workflow, you MUST ATTENTION use AskUserQuestion to ask the user. Do NOT judge task complexity or decide this is "simple enough to skip" — the user decides whether to use a workflow, not you:

1. Activate refactor workflow (Recommended) — scout → investigate → plan → code → review → sre-review → test → docs
2. Execute /refactoring directly — run this skill standalone

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AI Agent Integrity Gate (NON-NEGOTIABLE)

Completion ≠ Correctness. Before reporting ANY work done, prove it:

1. Grep every removed name. Extraction/rename/delete touched N files? Grep confirms 0 dangling refs across ALL file types.
2. Ask WHY before changing. Existing values are intentional until proven otherwise. No "fix" without traced rationale.
3. Verify ALL outputs. One build passing ≠ all builds passing. Check every affected stack.
4. Evaluate pattern fit. Copying nearby code? Verify preconditions match — same scope, lifetime, base class, constraints.
5. New artifact = wired artifact. Created something? Prove it's registered, imported, and reachable by all consumers.

Closing Reminders

• IMPORTANT MUST ATTENTION break work into small todo tasks using TaskCreate BEFORE starting
• IMPORTANT MUST ATTENTION search codebase for 3+ similar patterns before creating new code
• IMPORTANT MUST ATTENTION cite file:line evidence for every claim (confidence >80% to act)
• IMPORTANT MUST ATTENTION add a final review todo task to verify work quality MANDATORY IMPORTANT MUST ATTENTION READ the following files before starting:
• IMPORTANT MUST ATTENTION search 3+ existing patterns and read code BEFORE any modification. Run graph trace when graph.db exists.
• IMPORTANT MUST ATTENTION cite file:line evidence for every claim. Confidence >80% to act, <60% = do NOT recommend.
• IMPORTANT MUST ATTENTION check DRY via OOP, right responsibility layer, SOLID. Grep for dangling refs after moves.
• IMPORTANT MUST ATTENTION run at least ONE graph command on key files when graph.db exists. Pattern: grep → trace → verify.

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