Refactoring Planning

Purpose

Create a structured, prioritized plan for refactoring that balances risk, effort, and value.

Planning Principles

•Start with the biggest pain point - Address what hurts most first
•Prefer small, safe changes - Many small wins over big rewrites
•Maintain working software - Never break the build for long
•Get quick feedback - Validate often, adjust plan as needed

Planning Process

dot

digraph planning {
    rankdir=TB;
    node [shape=box];

    assess [label="Assessment\nReport" shape=ellipse];
    prioritize [label="1. Prioritize\nIssues"];
    group [label="2. Group\nRelated Changes"];
    sequence [label="3. Sequence\nDependencies"];
    estimate [label="4. Estimate\nEffort"];
    risk [label="5. Identify\nRisks"];
    plan [label="Refactoring\nPlan" shape=ellipse];

    assess -> prioritize;
    prioritize -> group;
    group -> sequence;
    sequence -> estimate;
    estimate -> risk;
    risk -> plan;
}

Step 1: Prioritize Issues

Use this matrix to prioritize:

code

                    HIGH IMPACT
                         │
    ┌────────────────────┼────────────────────┐
    │                    │                    │
    │   QUICK WINS       │    MAJOR           │
    │   Do First         │    PROJECTS        │
    │                    │    Plan Carefully  │
    │                    │                    │
LOW ├────────────────────┼────────────────────┤ HIGH
EFFORT                   │                    │ EFFORT
    │                    │                    │
    │   FILL-IN          │    DON'T DO        │
    │   If Time Allows   │    (Usually)       │
    │                    │                    │
    │                    │                    │
    └────────────────────┼────────────────────┘
                         │
                    LOW IMPACT

Priority Categories

Priority	Criteria	Action
P0	Blocks development	Fix immediately
P1	High impact, low effort	This sprint
P2	High impact, high effort	Plan and schedule
P3	Low impact, low effort	Opportunistic
P4	Low impact, high effort	Probably never

Step 2: Group Related Changes

Identify changes that should be done together:

markdown

## Group: User Authentication Refactoring

### Changes:
1. Extract AuthService from UserController
2. Move password validation to AuthService
3. Add dependency injection for AuthService

### Reason:
These changes affect the same area and have dependencies.
Doing them together minimizes integration risk.

Step 3: Sequence Dependencies

Create a dependency graph:

markdown

## Refactoring Sequence

1. **Extract Constants** (no dependencies)
   - Move magic numbers to config

2. **Add Interface** (depends on: none)
   - Create IUserRepository interface

3. **Extract Repository** (depends on: 2)
   - Move database calls to UserRepository

4. **Inject Dependencies** (depends on: 2, 3)
   - Use dependency injection for repository

Step 4: Break Into Atomic Tasks

Each task should be:

•Completable in one sitting
•Independently testable
•Independently deployable
•Describable in one sentence

Task Template

markdown

### Task: Extract validatePassword method

**File:** src/controllers/user_controller.py
**Lines:** 145-178

**Current State:**
Password validation logic mixed with login flow

**Target State:**
Separate `validate_password(password: str) -> bool` method

**Steps:**
1. Write characterization test for current behavior
2. Extract method using IDE refactoring
3. Run tests
4. Commit

**Risks:** Low - mechanical extraction
**Effort:** 15 minutes

Step 5: Create TodoWrite Tasks

Convert plan to TodoWrite format:

markdown

## Refactoring Plan: User Authentication

- [ ] Phase 1: Test Harness
  - [ ] Write characterization tests for login flow
  - [ ] Write characterization tests for registration flow
  - [ ] Verify all tests pass

- [ ] Phase 2: Extract Methods
  - [ ] Extract validatePassword from login
  - [ ] Extract hashPassword from registration
  - [ ] Extract validateEmail from registration

- [ ] Phase 3: Extract Service
  - [ ] Create AuthService class
  - [ ] Move extracted methods to AuthService
  - [ ] Update controllers to use AuthService

- [ ] Phase 4: Verification
  - [ ] All tests pass
  - [ ] No new smells
  - [ ] Complexity reduced

Risk Assessment

For each major change, document:

Risk	Likelihood	Impact	Mitigation
Break login flow	Medium	High	Characterization tests
Performance regression	Low	Medium	Benchmark before/after
Merge conflicts	High	Low	Rebase frequently

Plan Template

markdown

# Refactoring Plan: [Area Name]

## Objective
[What we're trying to achieve]

## Scope
- **In scope:** [What's included]
- **Out of scope:** [What's NOT included]

## Success Criteria
- [ ] [Measurable goal 1]
- [ ] [Measurable goal 2]

## Prerequisites
- [ ] Assessment complete
- [ ] Team notified
- [ ] Branch created

## Phase 1: [Name]
### Tasks
- [ ] Task 1
- [ ] Task 2

### Exit Criteria
- [ ] Tests pass
- [ ] Code review approved

## Phase 2: [Name]
...

## Risks and Mitigations
| Risk | Mitigation |
|------|------------|
| ... | ... |

## Rollback Plan
If critical issues arise:
1. git revert to last known good state
2. Notify team
3. Post-mortem analysis

## Timeline
- Phase 1: [X tasks]
- Phase 2: [Y tasks]
- Total: [Z tasks]

Checklist

markdown

- [ ] All issues prioritized
- [ ] Related changes grouped
- [ ] Dependencies sequenced
- [ ] Tasks are atomic
- [ ] Risks identified
- [ ] Mitigations planned
- [ ] Rollback plan defined
- [ ] User approved plan

Signal

When plan is approved, emit:

code

PLAN_APPROVED