[Resolved] WCML setting wcml_client_currency cookies on guest pages — no currency used

Hi Bobby,

Thank you for your explanation regarding the `wcml_client_currency` and `wcml_client_currency_language` cookies.

Our use case is a bit different from a normal ecommerce store:

* The site uses WooCommerce only as a catalogue structure.
* There are no visible prices.
* There is no cart.
* There is no checkout.
* There is no currency switcher.
* Multicurrency is disabled.
* The site uses WPML with two languages, so we must preserve language behavior.
* We still need WooCommerce Multilingual & Multicurrency active because the catalogue uses WooCommerce products, product categories, attributes, and filters.

The issue is that WCML still sends these response headers on guest catalogue/filter pages:

Set-Cookie: wcml_client_currency=...
Set-Cookie: wcml_client_currency_language=...

On Cloudways/Varnish, any `Set-Cookie` response header prevents the first guest response from being cached. This means product category/filter pages require extra PHP hits before Varnish can serve a HIT.

We tested a targeted MU plugin that removes only these two WCML currency `Set-Cookie` headers on guest WooCommerce catalogue pages, while preserving any other cookies such as WPML language cookies.

This is the MU plugin we tested:

<?php
/**
* Plugin Name: Strip WCML Currency Cookies for Catalogue Cache
* Description: Removes unnecessary WCML currency Set-Cookie headers for guest catalogue pages so Varnish can cache first responses.
*/

add_action( 'template_redirect', function () {
if ( is_admin() || is_user_logged_in() || wp_doing_ajax() ) {
return;
}

if ( function_exists( 'is_cart' ) && ( is_cart() || is_checkout() || is_account_page() ) ) {
return;
}

$is_catalogue_context =
( function_exists( 'is_shop' ) && is_shop() ) ||
( function_exists( 'is_product' ) && is_product() ) ||
( function_exists( 'is_product_category' ) && is_product_category() ) ||
( function_exists( 'is_product_tag' ) && is_product_tag() ) ||
is_tax( get_object_taxonomies( 'product' ) );

if ( ! $is_catalogue_context ) {
return;
}

add_action( 'shutdown', function () {
if ( headers_sent() ) {
return;
}

$headers = headers_list();

header_remove( 'Set-Cookie' );

foreach ( $headers as $header ) {
if ( stripos( $header, 'Set-Cookie:' ) !== 0 ) {
continue;
}

if (
stripos( $header, 'wcml_client_currency=' ) !== false ||
stripos( $header, 'wcml_client_currency_language=' ) !== false
) {
continue;
}

header( $header, false );
}
}, 9999 );
}, 20 );

What the plugin is intended to do:
1. Run only on frontend guest requests.
2. Skip logged-in users, admin, AJAX, cart, checkout, and account pages.
3. Run only on WooCommerce catalogue contexts:
- shop
- product page
- product category
- product tag
- product taxonomies / filters
4. Temporarily remove all Set-Cookie headers.
5. Re-add every Set-Cookie header except:
- wcml_client_currency
- wcml_client_currency_language
6. Preserve other cookies, especially WPML language behavior.

We are not trying to disable WPML language cookies, and we are not trying to remove all cookies. We only want to stop the two WCML currency cookies because this site has no pricing, no cart, no checkout, and no currency switching.

Could you please review this approach and confirm:

1. Is this safe for a catalogue-only WooCommerce site using WPML in two languages?
2. Could removing only these two `Set-Cookie` headers cause any product/category/attribute translation issue?
3. Is there a more official WPML/WCML hook to prevent these two currency cookies from being sent in the first place?
4. Would your suggested filters be safer than this header-level removal?

Suggested filters from your previous reply:

add_filter( 'wcml_enable_multi_currency', '__return_false' );
add_filter( 'wcml_load_multi_currency', '__return_false' );
add_filter( 'wcml_multi_currency_is_enabled', '__return_false' );

Our preference would be to prevent WCML from sending the cookies at source, but we need to keep WooCommerce multilingual catalogue functionality active.

Best,
Xavier