document-types

majiayu000's avatarfrom majiayu000

Understand and work with mortgage document types and classification. Use when asking about document types, adding new document support, debugging classification, or understanding what DocType constants mean.

⭐0stars🔀0forks📁View on GitHub🕐Updated Jan 5, 2026
[Document Processing]

When & Why to Use This Skill

This Claude skill provides a comprehensive framework for managing and classifying mortgage-related documents within an underwriting system. It enables automated identification of income, asset, credit, and collateral documents using sophisticated filename pattern matching and structured data constants, significantly improving the efficiency of financial document workflows.

Use Cases

  • Automated Classification: Efficiently categorize incoming mortgage files (e.g., W-2s, pay stubs, bank statements) into predefined document types based on filename patterns.
  • System Extension: Provide step-by-step guidance for developers to add support for new document types, including updating constants, pattern maps, and agent logic.
  • Debugging Classification Logic: Troubleshoot and resolve issues where documents are incorrectly identified or fail to match existing inference patterns.
  • Data Structure Reference: Access detailed technical specifications for document models, including MIME types, metadata fields, and storage paths for mortgage applications.
namedocument-types
descriptionUnderstand and work with mortgage document types and classification. Use when asking about document types, adding new document support, debugging classification, or understanding what DocType constants mean.

Mortgage Document Types

Purpose

Work with document classification in the mortgage underwriting system.

Document Type Constants

Located in internal/model/document.go:

Income Documents

Constant Description Filename Patterns
DocTypeW2 W-2 wage statements *w2*, *w-2*
DocType1099 1099 contractor income *1099*
DocTypePaystub Pay stubs/earnings *paystub*, *pay_stub*, *pay-stub*, *earnings*
DocTypeTaxReturn Tax returns (1040) *tax*, *1040*
DocTypeProfitLoss P&L statements *profit*, *p&l*, *pnl*
DocTypeEmploymentLetter Employment verification *employment*, *verification*

Asset Documents

Constant Description Filename Patterns
DocTypeBankStatement Bank statements *bank*
DocTypeAssetStatement General assets *asset*
DocTypeRetirementStmt 401k/IRA statements *retirement*, *401k*, *ira*
DocTypeGiftLetter Gift fund letters *gift*

Credit Documents

Constant Description Filename Patterns
DocTypeCreditReport Credit bureau reports *credit*
DocTypeDebtPayoff Debt payoff letters *payoff*, *debt*

Collateral Documents

Constant Description Filename Patterns
DocTypeAppraisal Property appraisals *appraisal*
DocTypePurchaseContract Purchase agreements *purchase*, *contract*
DocTypeTitleReport Title reports *title*
DocTypePropertyInsurance Hazard insurance *insurance*, *hazard*, *homeowner*

Type Inference Logic

Located in internal/document/store.go:

// Files are classified by checking if filename contains pattern
lower := strings.ToLower(filepath.Base(path))
for pattern, docType := range patterns {
    if strings.Contains(lower, pattern) {
        return docType
    }
}

Adding a New Document Type

Step 1: Add constant to internal/model/document.go

const (
    // ... existing types ...
    DocTypeNewType DocumentType = "new_type"
)

Step 2: Add pattern to internal/document/store.go

patterns := map[string]model.DocumentType{
    // ... existing patterns ...
    "new_pattern": model.DocTypeNewType,
}

Step 3: Add to agent's document lists

In the relevant agent (e.g., internal/agent/income/income.go):

func (a *Agent) RequiredDocuments() []model.DocumentType {
    return []model.DocumentType{
        model.DocTypeW2,
        model.DocTypeNewType,  // Add here
    }
}

Step 4: Update prompts

Update the agent's prompt to describe how to handle the new document type.

Document Structure

type Document struct {
    ID            string            // Hash-based unique ID
    ApplicationID string            // Loan application ID
    Type          DocumentType      // One of the DocType* constants
    FileName      string            // Original filename
    MimeType      string            // application/pdf, image/png, etc.
    FilePath      string            // Local filesystem path
    GeminiURI     string            // Cached Gemini File API URI
    UploadedAt    time.Time
    BorrowerID    string
    Year          int               // Tax year for tax docs
    Period        string            // Pay period for paystubs
    Metadata      map[string]string // Additional metadata
}

Supported MIME Types

From internal/document/store.go:MimeTypeFromExtension:

  • .pdf -> application/pdf
  • .png -> image/png
  • .jpg, .jpeg -> image/jpeg
  • .gif -> image/gif
  • .webp -> image/webp

Related Files

  • internal/model/document.go - Type definitions
  • internal/document/store.go - Loading and type inference
  • cmd/underwriter/main.go - CLI type inference