[ ] Choose the right model: task-oriented vs chunk-oriented
[ ] steptypes.json exists at the cartridge ROOT (not under cartridge/)
[ ] Step script exports required functions for its step type
[ ] All resources closed (iterators, file readers/writers) in afterStep
[ ] Timeouts are explicit and realistic for the dataset
[ ] Transactions scoped intentionally (avoid giant single transactions)

my_cartridge/
├── cartridge/
│   ├── scripts/
│   │   └── steps/
│   │       ├── myTaskStep.js
│   │       └── myChunkStep.js
│   └── my_cartridge.properties
└── steptypes.json  ← Must be here, NOT inside cartridge/

'use strict';

var Status = require('dw/system/Status');
var Logger = require('dw/system/Logger');

exports.execute = function (parameters, stepExecution) {
    var log = Logger.getLogger('job', 'MyTaskStep');

    try {
        var inputFile = parameters.InputFile;
        
        if (!parameters.Enabled) {
            log.info('Step disabled, skipping');
            return new Status(Status.OK, 'SKIP', 'Step disabled');
        }

        // Your business logic here
        log.info('Processing file: ' + inputFile);

        return new Status(Status.OK);

    } catch (e) {
        log.error('Step failed: ' + e.message);
        return new Status(Status.ERROR, 'ERROR', e.message);
    }
};

// Success
return new Status(Status.OK);
return new Status(Status.OK, 'CUSTOM_CODE', 'Custom message');

// Error
return new Status(Status.ERROR);
return new Status(Status.ERROR, null, 'Error message');

'use strict';

var ProductMgr = require('dw/catalog/ProductMgr');
var Transaction = require('dw/system/Transaction');
var Logger = require('dw/system/Logger');

var log = Logger.getLogger('job', 'MyChunkStep');
var products;

exports.beforeStep = function (parameters, stepExecution) {
    log.info('Starting chunk processing');
    products = ProductMgr.queryAllSiteProducts();
};

exports.getTotalCount = function (parameters, stepExecution) {
    return products.count; // Use built-in count!
};

exports.read = function (parameters, stepExecution) {
    if (products.hasNext()) {
        return products.next();
    }
    // Return nothing = end of data
};

exports.process = function (product, parameters, stepExecution) {
    if (!product.online) {
        return;  // Filtered out
    }
    return {
        id: product.ID,
        name: product.name,
        price: product.priceModel.price.value
    };
};

exports.write = function (items, parameters, stepExecution) {
    for (var i = 0; i < items.size(); i++) {
        var item = items.get(i);
        // Write item...
    }
};

exports.afterStep = function (success, parameters, stepExecution) {
    if (products) {
        products.close(); // Critical: close iterators!
    }
    log.info(success ? 'Completed successfully' : 'Failed');
};

{
    "step-types": {
        "script-module-step": [
            {
                "@type-id": "custom.MyTaskStep",
                "@supports-site-context": true,
                "@supports-organization-context": false,
                "description": "My custom task step",
                "module": "my_cartridge/cartridge/scripts/steps/myTaskStep.js",
                "function": "execute",
                "timeout-in-seconds": 900,
                "parameters": {
                    "parameter": [
                        {
                            "@name": "InputFile",
                            "@type": "string",
                            "@required": true,
                            "description": "Path to input file"
                        }
                    ]
                },
                "status-codes": {
                    "status": [
                        { "@code": "OK", "description": "Step completed" },
                        { "@code": "ERROR", "description": "Step failed" }
                    ]
                }
            }
        ]
    }
}

{
    "step-types": {
        "chunk-script-module-step": [
            {
                "@type-id": "custom.MyChunkStep",
                "@supports-site-context": true,
                "@supports-organization-context": false,
                "description": "Bulk data processing step",
                "module": "my_cartridge/cartridge/scripts/steps/myChunkStep.js",
                "before-step-function": "beforeStep",
                "read-function": "read",
                "process-function": "process",
                "write-function": "write",
                "after-step-function": "afterStep",
                "total-count-function": "getTotalCount",
                "chunk-size": 100,
                "transactional": false,
                "timeout-in-seconds": 1800
            }
        ]
    }
}

// ✅ CORRECT - Uses built-in count
exports.getTotalCount = function() {
    return products.getCount(); // Instant, no DB hit
}

// ❌ WRONG - Creates duplicate query!
exports.getTotalCount = function() {
    var counter = ProductMgr.queryAllSiteProducts(); // Unnecessary!
    var count = 0;
    while (counter.hasNext()) { counter.next(); count++; }
    counter.close();
    return count;
}