git:20251230.9a88ee8 to git:20251231.cb53cf6

---

name: implementation-approach

---

# Implementation Strategy Selection Framework (Meta-cognitive Approach)

An implementation strategy selection framework based on meta-cognitive thinking. Derives optimal implementation approaches through a systematic decision process from understanding existing implementations to constraint compatibility.

## Meta-cognitive Strategy Selection Process

### Step 1: Comprehensive Current State Analysis

**Core Question**: "What does the existing implementation look like?"

#### Analysis Framework

```yaml

Architecture Analysis:

- Current responsibility separation and improvement potential

- Data flow identification and evaluation

- Dependency visualization and impact scope

- Technical debt quantification

Implementation Quality Assessment:

- Code quality and maintainability

- Test coverage and reliability

- Performance characteristics

- Security considerations

Historical Context Understanding:

- Why did it become the current form?

- Validity check of past decisions

- Changes in technical constraints

- Evolution of business requirements

```

#### Meta-cognitive Question List

- What is the true responsibility of this implementation?

- Which parts are business essence and which derive from technical constraints?

- What dependencies or implicit preconditions are unclear from the code?

- What benefits and constraints does the current design bring?

### Step 2: Strategy Exploration and Creation

**Core Question**: "When determining before → after, what implementation patterns or strategies should be referenced?"

#### Strategy Discovery Process

```yaml

Research and Exploration:

- Implementation examples and patterns from similar tech stacks (research online)

- Approach collection from projects handling similar challenges

- Open source implementation references

- Technical literature and blog research

Creative Thinking:

- Sequential/parallel application of multiple strategies

- Design based on project time/human/technical constraints

- Phase division and milestone setting

- Pre-design of necessary extension points

```

#### Reference Strategy Patterns (Creative Combinations Encouraged)

**Legacy Handling Strategies**:

- Strangler Pattern: Gradual migration through phased replacement

- Facade Pattern: Complexity hiding through unified interface

- Adapter Pattern: Bridge with existing systems

**New Development Strategies**:

- Feature-driven Development: Vertical implementation prioritizing user value

- Foundation-driven Development: Foundation-first construction prioritizing stability

- Risk-driven Development: Prioritize addressing maximum risk elements

**Integration/Migration Strategies**:

- Proxy Pattern: Transparent feature extension

- Decorator Pattern: Phased enhancement of existing features

- Bridge Pattern: Flexibility through abstraction

**Important**: The optimal solution is discovered through creative thinking according to each project's context.

### Step 3: Risk Assessment and Control

**Core Question**: "What risks arise when applying this to existing implementation, and what's the best way to control them?"

#### Risk Analysis Matrix

```yaml

Technical Risks:

- Impact on existing systems

- Data consistency assurance

- Performance degradation possibility

- Integration complexity

Operational Risks:

- Service availability impact

- Deployment downtime

- Monitoring/operation process changes

- Failure rollback procedures

Project Risks:

- Schedule delay possibility

- Technology learning costs

- Quality requirement achievement

- Cross-team coordination complexity

```

#### Risk Control Strategies

```yaml

Preventive Measures:

- Phased migration to new system without service disruption

- Verification through parallel operation of old and new systems

- Addition of integration and regression tests for new features

- Pre-implementation setup of performance and error monitoring

Incident Response:

- Clarify rollback procedures and conditions to old system

- Prepare log analysis and metrics dashboards

- Define communication system and role assignments for failures

- Document partial service continuation procedures

```

### Step 4: Constraint Compatibility Verification

**Core Question**: "What are this project's constraints?"

#### Constraint Checklist

```yaml

Technical Constraints:

- Compatibility with existing libraries/frameworks

- Server resource, network, database capacity limits

- Mandatory requirements like data protection, access control, audit logging

- Numerical targets like response time <5 seconds, 99.9% uptime

Temporal Constraints:

- Project deadlines and priorities

- Dependencies with other projects

- Milestone/release plans

- Learning/acquisition period considerations

Resource Constraints:

- Team size, new technology learning time, existing skill sets

- Developer work hours, server resources, operational system allocation

- Project budget ceiling, running cost ceiling

- External vendor support deadlines, SLAs, contract terms

Business Constraints:

- Market launch timing requirements

- Customer impact minimization requirements

- Regulatory/industry standard compliance

```

### Step 5: Implementation Approach Decision

Select optimal solution from basic implementation approaches (creative combinations encouraged):

#### Vertical Slice (Feature-driven)

**Characteristics**: Vertical implementation across all layers by feature unit

**Application Conditions**: Low inter-feature dependencies, output in user-usable form, changes needed across all architecture layers

**Verification Method**: End-user value delivery at each feature completion

#### Horizontal Slice (Foundation-driven)

**Characteristics**: Phased construction by architecture layer

**Application Conditions**: Foundation system stability important, multiple features depend on common foundation, layer-by-layer verification effective

**Verification Method**: Integrated operation verification when all foundation layers complete

#### Hybrid (Creative Combination)

**Characteristics**: Flexible combination according to project characteristics

**Application Conditions**: Unclear requirements, need to change approach per phase, transition from prototyping to full implementation

**Verification Method**: Verify at appropriate L1/L2/L3 levels according to each phase's goals

### Step 6: Decision Rationale Documentation

**Design Doc Documentation**: Clearly specify implementation strategy selection reasons and rationale.

## Verification Level Definitions

Priority for completion verification of each task:

- **L1: Functional Operation Verification** - Operates as end-user feature (e.g., search executable)

- **L2: Test Operation Verification** - New tests added and passing (e.g., type definition tests)

- **L3: Build Success Verification** - No compile errors (e.g., interface definitions)

**Priority**: L1 > L2 > L3 in order of verifiability importance

## Integration Point Definitions

Define integration points according to selected strategy:

- **Strangler-based**: When switching between old and new systems for each feature

- **Feature-driven**: When users can actually use the feature

- **Foundation-driven**: When all architecture layers are ready and E2E tests pass

- **Hybrid**: When individual goals defined for each phase are achieved

## Anti-patterns

- **Pattern Fixation**: Selecting only from listed strategies without considering unique combinations

- **Insufficient Analysis**: Skipping Step 1 analysis framework before strategy selection

- **Risk Neglect**: Starting implementation without Step 3 risk analysis matrix

- **Constraint Ignorance**: Deciding strategy without checking Step 4 constraint checklist

- **Rationale Omission**: Selecting strategy without using Step 6 documentation template

## Guidelines for Meta-cognitive Execution

1. **Leverage Known Patterns**: Use as starting point, explore creative combinations

2. **Active Web Research**: Research implementation examples from similar tech stacks

3. **Apply 5 Whys**: Pursue root causes to grasp essence

4. **Multi-perspective Evaluation**: Comprehensively evaluate from each Step 1-4 perspective

5. **Creative Thinking**: Consider sequential application of multiple strategies and designs leveraging project-specific constraints

6. **Clarify Decision Rationale**: Make strategy selection rationale explicit in design documents