qe-defect-intelligence

name	qe-defect-intelligence
description	Predicts defect-prone code using change frequency, complexity metrics, and historical bug patterns. Use when predicting defects before they escape, analyzing root causes of test failures, learning from past defect patterns, or implementing proactive quality management.
trust_tier	3
validation	{"schema_path":"schemas/output.json","validator_path":"scripts/validate-config.json","eval_path":"evals/qe-defect-intelligence.yaml"}

QE Defect Intelligence

Purpose

Guide the use of v3's defect intelligence capabilities including ML-based defect prediction, pattern recognition from historical data, and automated root cause analysis.

Activation

• When predicting defect-prone code
• When analyzing failure patterns
• When performing root cause analysis
• When learning from past defects
• When prioritizing testing based on risk

Quick Start

# Predict defects in changed code
aqe defect predict --changes HEAD~5..HEAD

# Analyze failure patterns
aqe defect patterns --period 90d --min-occurrences 3

# Root cause analysis
aqe defect rca --failure "test/auth.test.ts:45"

# Learn from resolved defects
aqe defect learn --source jira --status resolved

Agent Workflow

// Defect prediction
Task("Predict defect-prone code", `
  Analyze PR #456 changes and predict defect likelihood:
  - Historical defect correlation
  - Code complexity factors
  - Author experience with module
  - Test coverage gaps
  Flag high-risk changes requiring extra review.
`, "qe-defect-predictor")

// Root cause analysis
Task("Analyze test failure", `
  Investigate recurring failure in AuthService tests:
  - Collect failure history (last 30 days)
  - Identify common patterns
  - Trace to potential root causes
  - Suggest fixes using 5-whys analysis
`, "qe-root-cause-analyzer")

Prediction Models

1. Change-Based Prediction

await defectPredictor.predictFromChanges({
  changes: prChanges,
  factors: {
    codeChurn: { weight: 0.2 },
    complexity: { weight: 0.25 },
    authorExperience: { weight: 0.15 },
    fileHistory: { weight: 0.2 },
    testCoverage: { weight: 0.2 }
  },
  threshold: {
    high: 0.7,
    medium: 0.4,
    low: 0.2
  }
});

2. Pattern Learning

await patternLearner.learnPatterns({
  source: {
    defects: 'jira:project=MYAPP&type=bug',
    commits: 'git:last-6-months',
    tests: 'test-results:last-1000-runs'
  },
  patterns: [
    'code-smell-to-defect',
    'change-coupling',
    'test-gap-correlation',
    'complexity-defect-density'
  ],
  output: {
    rules: true,
    visualizations: true,
    recommendations: true
  }
});

3. Root Cause Analysis

await rootCauseAnalyzer.analyze({
  failure: testFailure,
  methods: [
    'five-whys',
    'fishbone-diagram',
    'fault-tree',
    'change-impact'
  ],
  context: {
    recentChanges: true,
    environmentDiff: true,
    dependencyChanges: true,
    similarFailures: true
  }
});

Defect Prediction Report

interface DefectPrediction {
  file: string;
  riskScore: number;  // 0-1
  riskLevel: 'critical' | 'high' | 'medium' | 'low';
  factors: {
    name: string;
    contribution: number;
    details: string;
  }[];
  historicalDefects: {
    count: number;
    recent: Defect[];
    patterns: string[];
  };
  recommendations: {
    action: string;
    priority: string;
    expectedRiskReduction: number;
  }[];
}

Pattern Categories

Pattern	Detection	Prevention
Null pointer	Static analysis	Null checks, Optional
Race condition	Concurrency analysis	Locks, atomic ops
Memory leak	Heap analysis	Resource cleanup
Off-by-one	Boundary analysis	Loop invariants
Injection	Taint analysis	Input validation

Root Cause Templates

root_cause_analysis:
  five_whys:
    max_depth: 5
    prompt_template: "Why did {effect} happen?"

  fishbone:
    categories:
      - people
      - process
      - tools
      - environment
      - materials
      - measurement

  fault_tree:
    top_event: "Test Failure"
    gate_types: [AND, OR, NOT]
    basic_events: true

Integration with Issue Tracking

await defectIntelligence.syncWithTracker({
  source: 'jira',
  project: 'MYAPP',
  sync: {
    defectData: 'bidirectional',
    predictions: 'create-tasks',
    patterns: 'update-labels'
  },
  automation: {
    flagHighRisk: true,
    suggestAssignee: true,
    linkRelated: true
  }
});

Coordination

Primary Agents: qe-defect-predictor, qe-pattern-learner, qe-root-cause-analyzer Coordinator: qe-defect-intelligence-coordinator Related Skills: qe-coverage-analysis, qe-quality-assessment