<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
**Table of Contents**

- [Week 3 Prevention Systems - Implementation Guide](#week-3-prevention-systems---implementation-guide)
  - [Overview](#overview)
  - [System 1: Compile-Time Guarantees (PhantomData State Machines)](#system-1-compile-time-guarantees-phantomdata-state-machines)
    - [When to Use](#when-to-use)
    - [Implementation Steps](#implementation-steps)
      - [Step 1: Identify States and Transitions](#step-1-identify-states-and-transitions)
      - [Step 2: Define Type-Level States](#step-2-define-type-level-states)
      - [Step 3: Create State Machine Struct](#step-3-create-state-machine-struct)
      - [Step 4: Implement State-Specific Methods](#step-4-implement-state-specific-methods)
      - [Step 5: Write Compile-Time Tests](#step-5-write-compile-time-tests)
    - [Common Patterns](#common-patterns)
      - [Pattern 1: Builder with Validation](#pattern-1-builder-with-validation)
      - [Pattern 2: Connection Lifecycle](#pattern-2-connection-lifecycle)
    - [Benefits](#benefits)
    - [Limitations](#limitations)
  - [System 2: Architectural Integration Contracts (Trait-Based APIs)](#system-2-architectural-integration-contracts-trait-based-apis)
    - [When to Use](#when-to-use-1)
    - [Implementation Steps](#implementation-steps-1)
      - [Step 1: Define Contract Trait](#step-1-define-contract-trait)
      - [Step 2: Create Contract Verification Test](#step-2-create-contract-verification-test)
      - [Step 3: Implement Contract](#step-3-implement-contract)
      - [Step 4: Test Implementation Against Contract](#step-4-test-implementation-against-contract)
    - [Version Compatibility Pattern](#version-compatibility-pattern)
    - [Benefits](#benefits-1)
  - [System 3: Error Propagation Strategy](#system-3-error-propagation-strategy)
    - [When to Use](#when-to-use-2)
    - [Implementation Steps](#implementation-steps-2)
      - [Step 1: Define Error Hierarchy with `thiserror`](#step-1-define-error-hierarchy-with-thiserror)
      - [Step 2: Create Result Type Alias](#step-2-create-result-type-alias)
      - [Step 3: Implement Error Context Extension](#step-3-implement-error-context-extension)
      - [Step 4: Implement Error Builder](#step-4-implement-error-builder)
    - [Error Reporting Pattern](#error-reporting-pattern)
    - [Benefits](#benefits-2)
  - [System 4: DfLSS Design Review Process](#system-4-dflss-design-review-process)
    - [When to Use](#when-to-use-3)
    - [Implementation Steps](#implementation-steps-3)
      - [Step 1: Download Checklist Template](#step-1-download-checklist-template)
      - [Step 2: Complete FMEA (Failure Mode Analysis)](#step-2-complete-fmea-failure-mode-analysis)
      - [Step 3: Resolve Contradictions (TRIZ)](#step-3-resolve-contradictions-triz)
      - [Step 4: Design Type-Level Guarantees](#step-4-design-type-level-guarantees)
      - [Step 5: Score and Approve](#step-5-score-and-approve)
    - [Benefits](#benefits-3)
  - [System 5: Kaizen Continuous Improvement](#system-5-kaizen-continuous-improvement)
    - [When to Use](#when-to-use-4)
    - [Implementation Steps](#implementation-steps-4)
      - [Step 1: Set Up Monthly Cadence](#step-1-set-up-monthly-cadence)
      - [Step 2: Create Metrics Dashboard](#step-2-create-metrics-dashboard)
      - [Step 3: 5 Whys Template](#step-3-5-whys-template)
      - [Step 4: Quarterly Review](#step-4-quarterly-review)
    - [Benefits](#benefits-4)
  - [Integration: Putting It All Together](#integration-putting-it-all-together)
    - [Workflow: From Idea to Production](#workflow-from-idea-to-production)
  - [Training Resources](#training-resources)
    - [For New Team Members](#for-new-team-members)
    - [For Experienced Developers](#for-experienced-developers)
  - [Troubleshooting](#troubleshooting)
    - [Problem: Design review takes too long](#problem-design-review-takes-too-long)
    - [Problem: Kaizen improvements not effective](#problem-kaizen-improvements-not-effective)
    - [Problem: Team resistance to new process](#problem-team-resistance-to-new-process)
    - [Problem: Metrics hard to collect](#problem-metrics-hard-to-collect)
  - [Next Steps](#next-steps)

<!-- END doctoc generated TOC please keep comment here to allow auto update -->

# Week 3 Prevention Systems - Implementation Guide

**Version**: 1.0.0
**Audience**: Developers implementing DfLSS prevention systems
**Prerequisites**: Rust intermediate knowledge, familiarity with type systems

---

## Overview

This guide provides step-by-step instructions for implementing the 5 prevention systems:

1. **Compile-Time Guarantees** (PhantomData state machines)
2. **Architectural Integration Contracts** (Trait-based APIs)
3. **Error Propagation Strategy** (Comprehensive error taxonomy)
4. **DfLSS Design Review Process** (Checklist-driven)
5. **Kaizen Continuous Improvement** (Monthly/quarterly cycles)

---

## System 1: Compile-Time Guarantees (PhantomData State Machines)

### When to Use

Use PhantomData state machines when:
- You have a sequence of operations that must occur in order
- Invalid sequences would cause errors or undefined behavior
- You want the compiler to prevent misuse (not runtime checks)

### Implementation Steps

#### Step 1: Identify States and Transitions

**Example**: Template Registry

States:
- `Uninitialized` - Registry created but not loaded
- `Initialized` - Templates loaded from disk
- `Validated` - Templates syntax-checked

Transitions:
- `Uninitialized` → `Initialized` (via `initialize()`)
- `Initialized` → `Validated` (via `validate()`)

**Invalid Sequences** (prevent via types):
- Cannot `search()` on `Uninitialized` registry
- Cannot `render()` on `Initialized` registry (must validate first)

#### Step 2: Define Type-Level States

```rust
// Type-level states (zero-sized types)
pub struct Uninitialized;
pub struct Initialized;
pub struct Validated;
```

**Key Insight**: These types have no data, exist only at compile time.

#### Step 3: Create State Machine Struct

```rust
use std::marker::PhantomData;

pub struct Registry<State = Uninitialized> {
    // Actual data
    templates: Vec<Template>,

    // Type-level state marker (zero-cost)
    _state: PhantomData<State>,
}
```

**Key Insight**: `PhantomData<State>` is zero-sized, no runtime cost.

#### Step 4: Implement State-Specific Methods

```rust
// Methods only available in Uninitialized state
impl Registry<Uninitialized> {
    pub fn new() -> Self {
        Registry {
            templates: Vec::new(),
            _state: PhantomData,
        }
    }

    // State transition: Uninitialized → Initialized
    pub fn initialize(self, path: &Path) -> Result<Registry<Initialized>, Error> {
        let templates = load_templates(path)?;
        Ok(Registry {
            templates,
            _state: PhantomData,
        })
    }
}

// Methods only available in Initialized state
impl Registry<Initialized> {
    // State transition: Initialized → Validated
    pub fn validate(self) -> Result<Registry<Validated>, Error> {
        for template in &self.templates {
            check_syntax(template)?;
        }
        Ok(Registry {
            templates: self.templates,
            _state: PhantomData,
        })
    }
}

// Methods only available in Validated state
impl Registry<Validated> {
    pub fn search(&self, query: &str) -> Result<Vec<&Template>, Error> {
        // Implementation
    }

    pub fn render(&self, template: &Template) -> Result<String, Error> {
        // Implementation
    }
}
```

**Key Insight**: Each `impl` block is specific to one state.

#### Step 5: Write Compile-Time Tests

```rust
#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn valid_transitions_compile() {
        // ✅ This compiles correctly
        let registry = Registry::new()
            .initialize(Path::new("templates")).unwrap()
            .validate().unwrap();
        registry.search("pattern").unwrap();
    }

    // Document invalid usage (will not compile)
    // Uncomment to verify compiler errors:

    // #[test]
    // fn invalid_search_on_uninitialized() {
    //     let registry = Registry::new();
    //     registry.search("pattern").unwrap();  // ERROR: no method `search`
    // }

    // #[test]
    // fn invalid_render_on_initialized() {
    //     let registry = Registry::new()
    //         .initialize(Path::new("templates")).unwrap();
    //     registry.render(&template).unwrap();  // ERROR: no method `render`
    // }
}
```

### Common Patterns

#### Pattern 1: Builder with Validation

```rust
pub struct ConfigBuilder<State = Unvalidated> {
    settings: HashMap<String, String>,
    _state: PhantomData<State>,
}

impl ConfigBuilder<Unvalidated> {
    pub fn new() -> Self { /* ... */ }
    pub fn set(mut self, key: &str, value: &str) -> Self { /* ... */ }
    pub fn validate(self) -> Result<ConfigBuilder<Validated>, Error> { /* ... */ }
}

impl ConfigBuilder<Validated> {
    pub fn build(self) -> Config { /* ... */ }
}
```

#### Pattern 2: Connection Lifecycle

```rust
pub struct Connection<State = Disconnected> {
    handle: Option<Handle>,
    _state: PhantomData<State>,
}

impl Connection<Disconnected> {
    pub fn connect(self, url: &str) -> Result<Connection<Connected>, Error> { /* ... */ }
}

impl Connection<Connected> {
    pub fn query(&self, sql: &str) -> Result<Rows, Error> { /* ... */ }
    pub fn disconnect(self) -> Connection<Disconnected> { /* ... */ }
}
```

### Benefits

- **Compiler Enforcement**: Invalid usage won't compile
- **Zero Runtime Cost**: PhantomData is zero-sized
- **Self-Documenting**: Type signature shows state requirements
- **Refactoring Safety**: Breaking changes cause compile errors

### Limitations

- Cannot dynamically choose state at runtime
- Adds complexity to API (more types)
- Learning curve for users unfamiliar with pattern

---

## System 2: Architectural Integration Contracts (Trait-Based APIs)

### When to Use

Use trait-based contracts when:
- Multiple implementations of same interface exist
- You want to prevent integration failures
- Version compatibility is critical
- Testing requires mocking/stubbing

### Implementation Steps

#### Step 1: Define Contract Trait

```rust
/// Contract for template providers
pub trait TemplateProvider: Send + Sync {
    /// Discover templates at path
    fn discover(&self, path: &Path) -> Result<Vec<Template>, ProviderError>;

    /// Validate template syntax
    fn validate(&self, template: &Template) -> Result<(), ProviderError>;

    /// Render template with context
    fn render(&self, template: &Template, context: Context) -> Result<String, ProviderError>;

    /// Get provider version (for compatibility)
    fn version(&self) -> Version {
        Version::new(1, 0, 0)
    }
}
```

**Key Insight**: Trait defines required interface, default methods provide backward compatibility.

#### Step 2: Create Contract Verification Test

```rust
#[cfg(test)]
pub fn verify_template_provider_contract<P: TemplateProvider>(
    provider: P,
) -> Result<(), String> {
    // Contract requirement 1: discover must return valid templates
    let templates = provider.discover(Path::new("test/templates"))
        .map_err(|e| format!("discover failed: {}", e))?;

    if templates.is_empty() {
        return Err("Contract violation: discover returned empty list".to_string());
    }

    // Contract requirement 2: all discovered templates must validate
    for template in &templates {
        provider.validate(template)
            .map_err(|e| format!("validate failed for {}: {}", template.name, e))?;
    }

    // Contract requirement 3: render must succeed for valid template
    if let Some(template) = templates.first() {
        let context = Context::default();
        provider.render(template, context)
            .map_err(|e| format!("render failed: {}", e))?;
    }

    Ok(())
}
```

**Key Insight**: One test suite verifies all implementations.

#### Step 3: Implement Contract

```rust
pub struct FilesystemTemplateProvider {
    root: PathBuf,
}

impl TemplateProvider for FilesystemTemplateProvider {
    fn discover(&self, path: &Path) -> Result<Vec<Template>, ProviderError> {
        // Implementation
    }

    fn validate(&self, template: &Template) -> Result<(), ProviderError> {
        // Implementation
    }

    fn render(&self, template: &Template, context: Context) -> Result<String, ProviderError> {
        // Implementation
    }
}
```

#### Step 4: Test Implementation Against Contract

```rust
#[test]
fn filesystem_provider_satisfies_contract() {
    let provider = FilesystemTemplateProvider::new(PathBuf::from("templates"));
    verify_template_provider_contract(provider).unwrap();
}
```

### Version Compatibility Pattern

```rust
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
pub struct Version {
    pub major: u32,
    pub minor: u32,
    pub patch: u32,
}

impl Version {
    /// Check if this version is compatible with required version
    /// Compatible if: major versions match and this >= required
    pub fn is_compatible_with(&self, required: &Version) -> bool {
        self.major == required.major && self >= required
    }
}

// Usage in contract
pub trait TemplateProvider {
    fn version(&self) -> Version {
        Version::new(1, 0, 0)
    }
}

// Usage in CLI
pub fn check_provider_compatibility<P: TemplateProvider>(provider: &P) -> Result<(), Error> {
    let required = Version::new(1, 0, 0);
    let actual = provider.version();

    if !actual.is_compatible_with(&required) {
        return Err(Error::VersionIncompatible {
            required: required.to_string(),
            actual: actual.to_string(),
        });
    }

    Ok(())
}
```

### Benefits

- **Compile-Time Contract Enforcement**: Implementations must satisfy trait
- **Version Safety**: Explicit version checking prevents incompatibility
- **Testable**: Generic contract tests ensure all implementations behave correctly
- **Swappable**: Easy to change implementations

---

## System 3: Error Propagation Strategy

### When to Use

Always use comprehensive error types for:
- Public APIs (library crates)
- CLI applications (need user-friendly messages)
- Integration points (need diagnostic information)

### Implementation Steps

#### Step 1: Define Error Hierarchy with `thiserror`

```rust
use thiserror::Error;

#[derive(Error, Debug)]
pub enum GgenError {
    #[error("Template not found: {path}\nContext: {context}\nSuggestion: {suggestion}")]
    TemplateNotFound {
        path: String,
        context: String,
        suggestion: String,
    },

    #[error("Invalid syntax in {file}:{line}:{column}\n{snippet}\n{reason}")]
    InvalidSyntax {
        file: String,
        line: usize,
        column: usize,
        reason: String,
        snippet: String,
    },

    #[error("IO error: {operation} on {path}\n{source}\nSuggestion: {suggestion}")]
    Io {
        operation: String,
        path: String,
        #[source]
        source: std::io::Error,
        suggestion: String,
    },
}
```

**Key Insight**: Rich context in every error variant.

#### Step 2: Create Result Type Alias

```rust
pub type Result<T> = std::result::Result<T, GgenError>;
```

**Key Insight**: Makes APIs cleaner (`Result<T>` instead of `Result<T, GgenError>`).

#### Step 3: Implement Error Context Extension

```rust
pub trait ErrorContext<T> {
    fn context(self, msg: impl Into<String>) -> Result<T>;
}

impl<T, E: Into<GgenError>> ErrorContext<T> for std::result::Result<T, E> {
    fn context(self, msg: impl Into<String>) -> Result<T> {
        self.map_err(|e| {
            let error: GgenError = e.into();
            // Add context to error (implementation specific)
            error
        })
    }
}

// Usage
fn load_file(path: &Path) -> Result<String> {
    std::fs::read_to_string(path)
        .context(format!("Failed to load file: {}", path.display()))?
}
```

#### Step 4: Implement Error Builder

```rust
pub struct ErrorBuilder {
    error_type: ErrorType,
    context: Option<String>,
    suggestion: Option<String>,
}

impl ErrorBuilder {
    pub fn template_not_found(path: impl Into<String>) -> Self {
        Self {
            error_type: ErrorType::TemplateNotFound { path: path.into() },
            context: None,
            suggestion: None,
        }
    }

    pub fn context(mut self, context: impl Into<String>) -> Self {
        self.context = Some(context.into());
        self
    }

    pub fn suggestion(mut self, suggestion: impl Into<String>) -> Self {
        self.suggestion = Some(suggestion.into());
        self
    }

    pub fn build(self) -> GgenError {
        // Construct error from builder
    }
}

// Usage
let error = ErrorBuilder::template_not_found("config.toml")
    .context("Loading application configuration")
    .suggestion("Run 'ggen init' to create default config")
    .build();
```

### Error Reporting Pattern

```rust
pub fn report_error(error: &GgenError) {
    // Print main error
    eprintln!("ERROR: {}", error);

    // Print source chain
    let mut current: Option<&dyn std::error::Error> = Some(error);
    let mut level = 0;

    while let Some(err) = current {
        if level > 0 {
            eprintln!("  Caused by ({}): {}", level, err);
        }
        current = err.source();
        level += 1;
    }

    // Print debugging hint
    eprintln!("\nFor more information, run with RUST_LOG=debug");
}
```

### Benefits

- **No Silent Failures**: `Result<T, E>` forces error handling
- **Rich Diagnostics**: Every error has context and suggestions
- **User-Friendly**: Errors guide users to solutions
- **Debuggable**: Error chains show full causality

---

## System 4: DfLSS Design Review Process

### When to Use

Use design review checklist for:
- New features (before implementation)
- Major refactoring (before starting)
- API changes (before committing)
- Performance-critical code (before optimizing)

### Implementation Steps

#### Step 1: Download Checklist Template

Location: `/docs/week3-prevention/DESIGN_REVIEW_CHECKLIST.md`

#### Step 2: Complete FMEA (Failure Mode Analysis)

**For each feature, identify failure modes**:

| Failure Mode | Severity (1-10) | Probability (1-10) | Detection (1-10) | RPN | Mitigation |
|--------------|-----------------|-------------------|------------------|-----|------------|
| Invalid input | 8 | 6 | 3 | 144 | Add input validation with types |
| Null pointer | 10 | 2 | 2 | 40 | Use Option<T> instead of raw pointers |
| Race condition | 9 | 4 | 7 | 252 | Use Mutex/RwLock or actor pattern |

**RPN** (Risk Priority Number) = Severity × Probability × Detection

**Critical**: RPN > 100 requires mitigation before approval.

#### Step 3: Resolve Contradictions (TRIZ)

**Example**: Performance vs. Safety

Contradiction: Fast code often uses unsafe, but we want safety.

TRIZ Solutions:
- **Separation in Space**: Use unsafe in isolated module, safe API elsewhere
- **Separation in Time**: Use safe slow path normally, unsafe fast path when verified
- **Use Intermediary**: Zero-cost abstractions (generics, const generics)

#### Step 4: Design Type-Level Guarantees

**Question**: What can we prevent at compile time?

Example:
- Invalid state sequences → PhantomData state machine
- Null pointers → Option<T>
- Uninitialized data → MaybeUninit → Initialized transition
- Concurrent access → Send/Sync traits

#### Step 5: Score and Approve

Minimum score: 7.0/10 weighted average.

If score < 7.0, return to design phase with feedback.

### Benefits

- **Early Detection**: Find defects at design (10x cheaper than testing)
- **Systematic**: Checklist ensures nothing missed
- **Measurable**: Score provides objective assessment
- **Learning**: Process improves over time

---

## System 5: Kaizen Continuous Improvement

### When to Use

Always use Kaizen cycle:
- Monthly retrospectives (identify problems, analyze, fix, verify)
- Quarterly strategic reviews (trends, patterns, process updates)

### Implementation Steps

#### Step 1: Set Up Monthly Cadence

**Week 1**: Retrospective meeting (1 hour)
- Collect Andon signal data (compiler errors, test failures, SLO violations)
- Team discussion: What blocked us? What slowed us down?
- Prioritize top 3 problems (Pareto 80/20)

**Week 2**: Root cause analysis (5 Whys)
- For each top problem, ask "Why?" 5 times
- Validate root cause with data
- Design countermeasures (immediate, prevention, systemic)

**Week 3**: Implement countermeasures
- Code changes
- Process updates
- Documentation
- Training

**Week 4**: Verify improvements
- Collect metrics
- Compare to baseline
- Celebrate wins
- Standardize successful improvements

#### Step 2: Create Metrics Dashboard

```rust
#[derive(Debug, Clone, Serialize)]
pub struct KaizenMetrics {
    // Defect Metrics
    pub defect_density: f64,  // defects per 1000 LOC
    pub defects_in_design: usize,
    pub defects_in_testing: usize,
    pub defects_in_production: usize,

    // Cycle Time Metrics (hours)
    pub design_to_code: f64,
    pub code_to_test: f64,
    pub test_to_deploy: f64,
    pub total_cycle_time: f64,

    // Rework Metrics
    pub rework_percentage: f64,
    pub compiler_error_fixes: usize,
    pub test_failure_fixes: usize,

    // Quality Metrics
    pub test_pass_rate: f64,
    pub slo_compliance_rate: f64,

    // Team Metrics
    pub team_satisfaction: f64,  // 1-10
    pub kaizen_improvements: usize,
}
```

#### Step 3: 5 Whys Template

```
PROBLEM: [Specific, measurable problem]

1. Why? → [First cause]
2. Why? → [Second cause]
3. Why? → [Third cause]
4. Why? → [Fourth cause]
5. Why? → [ROOT CAUSE]

VALIDATION: [Data supporting root cause]

COUNTERMEASURES:
- Immediate: [Stop the symptom now]
- Prevention: [Stop this problem recurring]
- Systemic: [Stop entire class of problems]
```

#### Step 4: Quarterly Review

**Agenda** (half-day):
1. **Metrics Trend Analysis** (1 hour): 3-month charts
2. **Pattern Identification** (1 hour): What recurs?
3. **Process Update** (1 hour): Update DfLSS checklist
4. **Team Training** (1 hour): Teach new techniques
5. **Goals Setting** (30 min): Next quarter objectives

### Benefits

- **Data-Driven**: Metrics guide decisions
- **Systematic**: Regular cadence ensures continuous focus
- **Team-Driven**: Everyone participates
- **Measurable**: Clear metrics show impact

---

## Integration: Putting It All Together

### Workflow: From Idea to Production

```
1. IDEA
   ↓
2. DESIGN REVIEW (DfLSS Checklist)
   ├─ FMEA: Identify failure modes
   ├─ TRIZ: Resolve contradictions
   ├─ Types: PhantomData state machines
   ├─ Contracts: Trait-based APIs
   └─ Errors: Comprehensive taxonomy
   ↓
3. APPROVED? (Score ≥ 7.0/10)
   ├─ YES → IMPLEMENT
   └─ NO → RETURN TO DESIGN
   ↓
4. IMPLEMENT
   ├─ Follow approved design
   ├─ Use prevention systems
   └─ Write tests (Chicago TDD)
   ↓
5. TEST (Andon Signals)
   ├─ cargo make check (no errors)
   ├─ cargo make test (all pass)
   ├─ cargo make lint (no warnings)
   └─ cargo make slo-check (meet SLOs)
   ↓
6. ANDON SIGNALS CLEARED?
   ├─ YES → DEPLOY
   └─ NO → STOP THE LINE, FIX
   ↓
7. DEPLOY
   ↓
8. KAIZEN CYCLE
   ├─ Week 1: Retrospective
   ├─ Week 2: Root cause analysis
   ├─ Week 3: Countermeasures
   └─ Week 4: Verify improvements
   ↓
9. QUARTERLY REVIEW
   └─ Update prevention systems with learnings
```

---

## Training Resources

### For New Team Members

1. **Read**: Prevention Strategy guide (`/docs/week3-prevention/PREVENTION_STRATEGY.md`)
2. **Study**: Code examples in `/crates/ggen-core/src/prevention/`
3. **Practice**: Complete design review for small feature
4. **Pair**: Participate in monthly Kaizen retrospective
5. **Review**: Attend quarterly strategic review

### For Experienced Developers

1. **Lead**: Facilitate Kaizen retrospectives
2. **Mentor**: Guide new developers through design reviews
3. **Improve**: Propose updates to DfLSS checklist
4. **Share**: Present learnings at quarterly review

---

## Troubleshooting

### Problem: Design review takes too long

**Solution**: Focus on critical sections (FMEA, types, contracts). Skip low-priority sections for small changes.

### Problem: Kaizen improvements not effective

**Solution**: Verify root cause analysis is thorough (complete all 5 Whys). Measure impact rigorously.

### Problem: Team resistance to new process

**Solution**: Start small (1-2 prevention systems), demonstrate value, gradually expand.

### Problem: Metrics hard to collect

**Solution**: Automate data collection (CI metrics, git hooks, automated dashboards).

---

## Next Steps

1. **Implement first PhantomData state machine** for your critical workflow
2. **Define first trait-based contract** for integration point
3. **Schedule first Kaizen retrospective** (Week 1 of next month)
4. **Complete design review** for next feature using checklist
5. **Set up metrics dashboard** for tracking improvements

---

**Remember**: Prevention is 10x cheaper than detection. Invest in design phase to save 100x in production.
