Extract Requirements

Extract Requirements Workflow

Purpose

Systematic process for extracting business requirements from undocumented or poorly documented codebases.

When to Use

• ✅ Legacy system with no documentation
• ✅ Planning migration (need requirements baseline)
• ✅ M&A due diligence (understand acquired system)
• ✅ Compliance audit (document what system does)
• ✅ Knowledge transfer (developers leaving)

Prerequisites

Codebase Indexed

codecompass batch:index <path>

Infrastructure Running

codecompass health

Extraction Workflow

Phase 1: Automated Extraction

Step 1.1: Run Requirements Extractor

codecompass requirements:extract --project-id <id> --output requirements.md

What this extracts:

1. Validation Rules → Business constraints
2. Controller Actions → Use cases
3. Database Constraints → Data integrity rules
4. RBAC/Authorization → Access requirements
5. Business Logic → Domain rules

Step 1.2: Review Output Check generated requirements.md:

• Completeness (coverage of major features)
• Accuracy (rules match actual behavior)
• Gaps (missing business logic)

Phase 2: Validation Rule Analysis

From Models/Entities:

// Yii2 Model example
public function rules() {
  return [
    [['email', 'password'], 'required'],
    ['email', 'email'],
    ['password', 'string', 'min' => 8],
    ['age', 'integer', 'min' => 18],
  ];
}

Extracted Requirements:

### User Registration Requirements
- REQ-001: Email address is mandatory
- REQ-002: Email must be valid format
- REQ-003: Password is mandatory
- REQ-004: Password minimum length: 8 characters
- REQ-005: User must be at least 18 years old

Phase 3: Use Case Extraction

From Controllers:

// Controller actions → Use cases
public function actionCreate() {
  // Use Case: Create New Order
}

public function actionApprove($id) {
  // Use Case: Approve Order (with authorization check)
}

public function actionCancel($id) {
  // Use Case: Cancel Order (business rules apply)
}

Extracted Use Cases:

## Order Management Use Cases

### UC-001: Create New Order
**Actor**: Customer
**Preconditions**: User authenticated
**Steps**:
1. User selects products
2. System validates inventory
3. User provides shipping address
4. System calculates total
5. Order created in pending status

### UC-002: Approve Order
**Actor**: Manager
**Preconditions**:
- Order in pending status
- User has 'manager' role
**Steps**:
1. Manager reviews order details
2. System validates business rules
3. Order status changed to approved
4. Notification sent to customer

Phase 4: Business Rule Discovery

Semantic Search for Rules:

codecompass search:semantic "business validation rules for order approval"
codecompass search:semantic "conditions for discount calculation"
codecompass search:semantic "authorization checks for admin actions"

Common Patterns to Find:

1. Conditional Logic → Business rules
2. Status Transitions → Workflow states
3. Calculations → Business formulas
4. Validations → Constraints
5. Authorization Checks → Access rules

Phase 5: Data Model Requirements

From Database Schema:

CREATE TABLE orders (
  id INT PRIMARY KEY,
  status ENUM('pending', 'approved', 'shipped', 'cancelled'),
  total DECIMAL(10,2) NOT NULL CHECK (total >= 0),
  customer_id INT NOT NULL FOREIGN KEY REFERENCES customers(id),
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Extracted Requirements:

### Data Requirements
- REQ-010: Order must have unique identifier
- REQ-011: Order status: pending, approved, shipped, or cancelled
- REQ-012: Order total must be non-negative
- REQ-013: Order must be associated with a customer
- REQ-014: Order creation timestamp must be recorded

Phase 6: Workflow Mapping

Identify State Machines:

Order Status Flow:
pending → approved → shipped → delivered
         ↓
         cancelled

Extract Transitions:

### Order Workflow
**States**: pending, approved, shipped, cancelled, delivered

**Transitions**:
- pending → approved (requires: manager approval)
- approved → shipped (requires: items in stock)
- shipped → delivered (requires: delivery confirmation)
- pending|approved → cancelled (requires: cancellation reason)

**Business Rules**:
- Cannot cancel after shipped
- Cannot approve if out of stock
- Refund required if cancelled after payment

Extraction Techniques

Technique 1: Code Reading Patterns

Look for:

• if statements → Business conditions
• switch/case → State transitions
• Loops → Bulk operations
• Exceptions → Error handling requirements
• Comments → Intent (when present)

Technique 2: Test Analysis

Tests reveal:

• Expected behavior (what should happen)
• Edge cases (what shouldn't happen)
• Valid input ranges
• Error scenarios

codecompass search:semantic "test cases for order validation"

Technique 3: Configuration Analysis

Config files contain:

• Feature flags → Optional requirements
• Limits/thresholds → Business constraints
• Integration settings → External dependencies

Technique 4: Semantic Clustering

Find related code:

# Find all code related to "discount calculation"
codecompass search:semantic "discount calculation logic"

# Find all code related to "inventory management"
codecompass search:semantic "inventory stock management"

Group results by business capability

Output Formats

Format 1: Requirements Document (Markdown)

# Business Requirements - [System Name]

## Functional Requirements

### FR-001: User Authentication
**Priority**: High
**Description**: System must authenticate users via email and password
**Acceptance Criteria**:
- Email validation follows RFC 5322
- Password minimum 8 characters
- Account locked after 5 failed attempts
**Source**: UserController::actionLogin(), User::validatePassword()

### FR-002: Order Approval Workflow
...

Format 2: Capability Map (Structured)

{
  "capabilities": {
    "user_management": {
      "features": ["register", "login", "reset_password"],
      "rules": ["email_unique", "password_complexity"],
      "roles": ["user", "admin"]
    },
    "order_processing": {
      "features": ["create", "approve", "cancel", "ship"],
      "rules": ["approval_required", "inventory_check"],
      "workflow": "pending→approved→shipped→delivered"
    }
  }
}

Format 3: Use Case Catalog

| UC ID | Use Case Name | Actor | Complexity |
|-------|---------------|-------|------------|
| UC-001 | Create Order | Customer | Medium |
| UC-002 | Approve Order | Manager | Low |
| UC-003 | Cancel Order | Customer/Manager | High |

Validation Steps

Step 1: Cross-Check with Tests

Compare extracted requirements with test cases:

• Tests validate requirements
• Missing tests → Undocumented behavior
• Failing tests → Requirements changed

Step 2: Semantic Verification

# For each requirement, verify in code
codecompass search:semantic "password must be at least 8 characters"

Should find validator implementation

Step 3: Interview Stakeholders (if available)

• Validate extracted requirements
• Fill gaps in documentation
• Clarify ambiguous logic

Step 4: Traceability Matrix

Map requirements to code:

| Requirement | Source Files | Tests |
|-------------|--------------|-------|
| REQ-001 | User.php:45, UserController.php:102 | UserTest.php:23 |
| REQ-002 | Order.php:78 | OrderTest.php:56 |

Common Patterns

Pattern 1: Implicit Requirements

Code:

if ($order->total < 1000) {
  // No approval needed
}

Requirement:

REQ: Orders under $1000 do not require manager approval

Pattern 2: Embedded Business Logic

Code:

$discount = ($customer->vip) ? 0.20 : 0.10;

Requirement:

REQ: VIP customers receive 20% discount, regular customers 10%

Pattern 3: Temporal Constraints

Code:

if (strtotime($order->created_at) > strtotime('-30 days')) {
  // Can cancel
}

Requirement:

REQ: Orders can only be cancelled within 30 days of creation

Best Practices

✅ Do

• Extract from multiple sources (code, tests, configs)
• Use semantic search for concept discovery
• Validate with tests
• Document sources for traceability
• Prioritize by business impact
• Include non-functional requirements (performance, security)

❌ Don't

• Rely solely on comments (often outdated)
• Assume standard behavior without verification
• Skip edge cases
• Ignore error handling logic
• Document technical implementation instead of business requirements

Related Skills

• 0-discover-capabilities.md - Find relevant modules
• semantic-search.md - Search for business logic
• analyze-yii2-project.md - Framework-specific extraction

Related Modules

From .ai/capabilities.json:

• requirements - RequirementsExtractionService
• business-analyzer - CapabilityCatalogService
• search - Semantic code search
• analyzers - Code analysis for extraction

Remember: Requirements are what the system must do, not how it does it. Focus on business value, not technical implementation.