Code Style

Coding standards and conventions for Duckling.

Python (Backend)

General Guidelines

• Follow PEP 8 guidelines
• Use type hints
• Maximum line length: 100 characters
• Use docstrings for functions and classes

Function Documentation

def convert_document(file_path: str, settings: dict) -> ConversionResult:
    """
    Convert a document using Docling.

    Args:
        file_path: Path to the document file
        settings: Conversion settings dictionary

    Returns:
        ConversionResult object with converted content

    Raises:
        ValueError: If file format is not supported
        IOError: If file cannot be read
    """
    pass

Class Documentation

class ConverterService:
    """
    Service for document conversion operations.

    This service manages the conversion pipeline, job queue,
    and interaction with the Docling library.

    Attributes:
        _job_queue: Queue for pending conversion jobs
        _max_concurrent_jobs: Maximum parallel conversions
    """
    pass

Imports

Order imports as:

1. Standard library
2. Third-party packages
3. Local modules

import os
import json
from typing import Optional, Dict, List

from flask import Flask, request
from sqlalchemy import Column, String

from models.database import Conversion
from services.converter import ConverterService

Formatting

Use Black for automatic formatting:

pip install black
black backend/

TypeScript/React (Frontend)

General Guidelines

• Use functional components with hooks
• Use TypeScript for type safety
• Follow ESLint configuration
• Use meaningful component and variable names

Component Structure

interface ButtonProps {
  label: string;
  onClick: () => void;
  disabled?: boolean;
  variant?: 'primary' | 'secondary';
}

export function Button({
  label,
  onClick,
  disabled = false,
  variant = 'primary'
}: ButtonProps) {
  return (
    <button
      onClick={onClick}
      disabled={disabled}
      className={`btn btn-${variant}`}
    >
      {label}
    </button>
  );
}

Hooks

export function useConversion() {
  const [status, setStatus] = useState<ConversionStatus>('idle');
  const [result, setResult] = useState<ConversionResult | null>(null);

  const startConversion = useCallback(async (file: File) => {
    setStatus('uploading');
    // ...
  }, []);

  return { status, result, startConversion };
}

File Organization

components/
├── Button/
│   ├── Button.tsx
│   ├── Button.test.tsx
│   └── index.ts
├── DropZone/
│   ├── DropZone.tsx
│   ├── DropZone.test.tsx
│   └── index.ts

Imports

// React and hooks first
import { useState, useCallback, useEffect } from 'react';

// Third-party libraries
import { motion } from 'framer-motion';
import axios from 'axios';

// Local components
import { Button } from '@/components/Button';
import { useConversion } from '@/hooks/useConversion';

// Types
import type { ConversionResult } from '@/types';

Formatting

Use Prettier for automatic formatting:

npm run format

Commit Messages

Follow Conventional Commits:

type(scope): description

[optional body]

[optional footer]

Types

Examples

feat(upload): add drag-and-drop file upload

Implemented drag-and-drop functionality using react-dropzone.
Supports multiple file selection in batch mode.

Closes #123

fix(converter): handle large PDF files correctly

Fixed memory issue when processing PDFs > 50MB by streaming
the file instead of loading entirely into memory.

docs(readme): update installation instructions

Added Docker setup instructions and troubleshooting section.

CSS/Tailwind

Class Organization

Order Tailwind classes consistently:

1. Layout (flex, grid, position)
2. Spacing (margin, padding)
3. Sizing (width, height)
4. Typography (font, text)
5. Visual (background, border, shadow)
6. Interactive (hover, focus)

<div className="flex items-center gap-4 p-4 w-full text-sm bg-gray-800 rounded-lg hover:bg-gray-700">
  {/* content */}
</div>

Custom Classes

Use @apply sparingly, prefer composition:

/* Prefer this */
.btn-primary {
  @apply px-4 py-2 bg-teal-500 text-white rounded-lg hover:bg-teal-600;
}

/* Over inline classes everywhere */

API Design

Endpoint Naming

• Use nouns, not verbs
• Use plural forms
• Use kebab-case for multi-word resources

GET    /api/conversions
POST   /api/conversions
GET    /api/conversions/{id}
DELETE /api/conversions/{id}
GET    /api/conversions/{id}/status

Response Format

{
  "data": { ... },
  "meta": {
    "total": 100,
    "page": 1,
    "limit": 20
  }
}

Error Format

{
  "error": "ValidationError",
  "message": "File type not supported",
  "details": {
    "field": "file",
    "allowed": ["pdf", "docx", "png"]
  }
}