MSRP, Multishipping & MysqlMq Decoupling Report

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1. MSRP (Minimum Suggested Retail Price)

Module Family (32 files total)

Module	Files	Role
Msrp	27	Core MSRP logic — price rendering, helper, admin UI
MsrpConfigurableProduct	2	MSRP price calculator for configurable products
MsrpGroupedProduct	3	MSRP price calculator for grouped products

Who Depends on MSRP

Module	composer.json	PHP imports	Type
Catalog	hard require	1 file: Pricing/Render/FinalPriceBox.php imports MsrpPrice	Direct code coupling
Checkout	hard require	1 file: CustomerData/DefaultItem.php imports Msrp\Helper\Data	Direct code coupling
GroupedProduct	hard require	1 file: Model/Product/Type/Grouped.php imports Msrp\Helper\Data	Direct code coupling
ConfigurableProduct	suggest (already correct)	0	Clean
MsrpConfigurableProduct	hard require (expected)	1 file	Internal to MSRP family
MsrpGroupedProduct	hard require (expected)	1 file	Internal to MSRP family

Coupling Details

Catalog — Pricing/Render/FinalPriceBox.php:

use Magento\Msrp\Pricing\Price\MsrpPrice;
// Checks if MSRP applies, hides actual price if "show before order confirm" is set
if ($this->isMsrpPriceApplicable()) {
    $msrpPriceType = $this->getSaleableItem()->getPriceInfo()->getPrice(MsrpPrice::PRICE_CODE);
}

Checkout — CustomerData/DefaultItem.php:

protected $msrpHelper; // Magento\Msrp\Helper\Data
// Adds 'canApplyMsrp' flag to cart item data
'canApplyMsrp' => $this->msrpHelper->isShowBeforeOrderConfirm($product)
    && $this->msrpHelper->isMinimalPriceLessMsrp($product),

GroupedProduct — Model/Product/Type/Grouped.php:

protected $msrpData; // Magento\Msrp\Helper\Data
// getChildrenMsrp() — returns MSRP for grouped children

Decoupling Plan

Catalog FinalPriceBox: The MSRP check should be a plugin from the Msrp module, not hardcoded in Catalog's price renderer. Msrp module hooks into FinalPriceBox::toHtml() via afterToHtml() or aroundToHtml() to apply MSRP logic. Catalog renders the price normally; Msrp wraps/overrides the output when applicable.

Checkout DefaultItem: The canApplyMsrp flag should be added via plugin on DefaultItem::getItemData() from the Msrp module, not via constructor injection in Checkout.

GroupedProduct Grouped.php: The msrpData helper and getChildrenMsrp() method should move to MsrpGroupedProduct module as a plugin or be provided via extension attributes.

Composer changes:

Module	Change
Catalog/composer.json	Remove magento/module-msrp
Checkout/composer.json	Remove magento/module-msrp
GroupedProduct/composer.json	Move magento/module-msrp to suggest

Difficulty: Medium. The price rendering coupling in Catalog is the trickiest — MSRP fundamentally changes how prices are displayed. But the plugin approach is well-established in Magento.

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2. Multishipping

Module Size: 65 PHP files

A complete alternative checkout flow for splitting orders across multiple shipping addresses.

Who Depends on Multishipping

Module	composer.json	PHP/XML coupling	Type
GiftMessage	hard require	2 plugins in frontend/di.xml targeting Multishipping blocks/models	Code + XML
SalesRule	hard require	1 plugin file CouponUsagesIncrementMultishipping.php + DI registration	Code + XML

That's it. Only 2 external modules.

Coupling Details

GiftMessage — 2 plugins:

<!-- GiftMessage/etc/frontend/di.xml -->
<type name="Magento\Multishipping\Block\Checkout\Shipping">
    <plugin name="getItemsBoxTextAfter" type="Magento\GiftMessage\Block\Message\Multishipping\Plugin\ItemsBox"/>
</type>
<type name="Magento\Multishipping\Model\Checkout\Type\Multishipping">
    <plugin name="save_gift_messages" type="Magento\GiftMessage\Model\Type\Plugin\Multishipping"/>
</type>

GiftMessage hooks into Multishipping to add gift message functionality to multishipping checkout.

SalesRule — 1 plugin:

// SalesRule/Plugin/CouponUsagesIncrementMultishipping.php
use Magento\Multishipping\Model\Checkout\Type\Multishipping\PlaceOrderDefault;
// Tracks coupon usage when orders are placed via multishipping

Decoupling Plan

GiftMessage plugins: Move plugin registrations and the 2 plugin classes from GiftMessage into either: - A new GiftMessageMultishipping bridge module, OR - The Multishipping module itself (Multishipping contributes gift message support)

The second option is cleaner — Multishipping already depends on many modules, adding GiftMessage as a suggest is natural.

SalesRule plugin: Move CouponUsagesIncrementMultishipping.php + DI registration from SalesRule into the Multishipping module. Multishipping already depends on Quote/Sales, adding SalesRule as a suggest for coupon usage tracking is appropriate.

Composer changes:

Module	Change
GiftMessage/composer.json	Remove magento/module-multishipping
SalesRule/composer.json	Remove magento/module-multishipping

After this, Multishipping can be entirely disabled/removed: - Standard checkout works perfectly without it - GiftMessage works without multishipping (plugins just don't load) - SalesRule coupon tracking works for normal orders (multishipping-specific tracking just doesn't happen)

Difficulty: Low-Medium. Move 3 plugin files + 3 DI registrations. Straightforward.

Multishipping's Own Dependencies

Multishipping requires 10 core modules (Checkout, Customer, Directory, Payment, Quote, Sales, Store, Tax, Theme, Captcha). This is expected — it's a full checkout flow. These dependencies are all legitimate; Multishipping is a consumer, not a dependency.

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3. MysqlMq

Module Size: 18 PHP files

MySQL-based message queue transport — the fallback when RabbitMQ is not installed.

Who Depends on MysqlMq

Type	Count
composer.json require	0
PHP imports	0
XML references	0

Zero external coupling. Already documented in cron_and_message_queue.md.

MysqlMq's Own Dependencies

• magento/framework + magento/framework-message-queue + magento/module-store
• Has a crontab.xml (cleans old queue messages)

Verdict

MysqlMq is already fully decoupled. It's a pure SPI (Service Provider Interface) implementation — the MessageQueue framework discovers and uses it at runtime via DI configuration. Can be disabled/removed via module:disable or composer with zero impact. When removed, RabbitMQ (Amqp module) must be configured instead, or MessageQueue module itself must be disabled.

No work needed.

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Summary

Module	Inbound Coupling	Decoupling Effort	Can Be Removed?
Msrp	3 modules (Catalog, Checkout, GroupedProduct)	Medium — move price logic to plugins	Yes, after decoupling
MsrpConfigurableProduct	0 external	None	Yes — already optional
MsrpGroupedProduct	0 external (only MsrpGroupedProduct itself)	None	Yes — already optional
Multishipping	2 modules (GiftMessage, SalesRule)	Low-Medium — move 3 plugins	Yes, after decoupling
MysqlMq	0	None needed	Yes — already fully decoupled

Quick Wins

Action	Effort
Remove MysqlMq (if RabbitMQ is used)	Already possible
Remove MsrpConfigurableProduct / MsrpGroupedProduct	Already possible
Move GiftMessage + SalesRule multishipping plugins to Multishipping	Low

Medium Effort

Action	Effort
Decouple MSRP from Catalog FinalPriceBox	Medium — refactor to plugin-based MSRP rendering
Decouple MSRP from Checkout DefaultItem	Medium — move to plugin
Decouple MSRP from GroupedProduct	Low — move to MsrpGroupedProduct