diff --git a/functions-cart-checkout-validation-js/schema.graphql b/functions-cart-checkout-validation-js/schema.graphql
index b142caa9..4e01064b 100644
--- a/functions-cart-checkout-validation-js/schema.graphql
+++ b/functions-cart-checkout-validation-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-cart-checkout-validation-rs/schema.graphql b/functions-cart-checkout-validation-rs/schema.graphql
index b142caa9..4e01064b 100644
--- a/functions-cart-checkout-validation-rs/schema.graphql
+++ b/functions-cart-checkout-validation-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-cart-checkout-validation-wasm/schema.graphql b/functions-cart-checkout-validation-wasm/schema.graphql
index b142caa9..4e01064b 100644
--- a/functions-cart-checkout-validation-wasm/schema.graphql
+++ b/functions-cart-checkout-validation-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-cart-transform-js/schema.graphql b/functions-cart-transform-js/schema.graphql
index 4b96d9c3..db80114f 100644
--- a/functions-cart-transform-js/schema.graphql
+++ b/functions-cart-transform-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-cart-transform-rs/schema.graphql b/functions-cart-transform-rs/schema.graphql
index 4b96d9c3..db80114f 100644
--- a/functions-cart-transform-rs/schema.graphql
+++ b/functions-cart-transform-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-cart-transform-wasm/schema.graphql b/functions-cart-transform-wasm/schema.graphql
index 4b96d9c3..db80114f 100644
--- a/functions-cart-transform-wasm/schema.graphql
+++ b/functions-cart-transform-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-delivery-customization-js/schema.graphql b/functions-delivery-customization-js/schema.graphql
index 9e5389a5..e0af177b 100644
--- a/functions-delivery-customization-js/schema.graphql
+++ b/functions-delivery-customization-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-delivery-customization-rs/schema.graphql b/functions-delivery-customization-rs/schema.graphql
index 9e5389a5..e0af177b 100644
--- a/functions-delivery-customization-rs/schema.graphql
+++ b/functions-delivery-customization-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-delivery-customization-wasm/schema.graphql b/functions-delivery-customization-wasm/schema.graphql
index 9e5389a5..e0af177b 100644
--- a/functions-delivery-customization-wasm/schema.graphql
+++ b/functions-delivery-customization-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-discount-js/schema.graphql b/functions-discount-js/schema.graphql
index 2d98ee48..6545540b 100644
--- a/functions-discount-js/schema.graphql
+++ b/functions-discount-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-discount-rs/schema.graphql b/functions-discount-rs/schema.graphql
index 2d98ee48..6545540b 100644
--- a/functions-discount-rs/schema.graphql
+++ b/functions-discount-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-discount-wasm/schema.graphql b/functions-discount-wasm/schema.graphql
index 2d98ee48..6545540b 100644
--- a/functions-discount-wasm/schema.graphql
+++ b/functions-discount-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-discounts-allocator-js/schema.graphql b/functions-discounts-allocator-js/schema.graphql
index cf1c7269..50b8086d 100644
--- a/functions-discounts-allocator-js/schema.graphql
+++ b/functions-discounts-allocator-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-discounts-allocator-rs/schema.graphql b/functions-discounts-allocator-rs/schema.graphql
index cf1c7269..50b8086d 100644
--- a/functions-discounts-allocator-rs/schema.graphql
+++ b/functions-discounts-allocator-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-discounts-allocator-wasm/schema.graphql b/functions-discounts-allocator-wasm/schema.graphql
index cf1c7269..50b8086d 100644
--- a/functions-discounts-allocator-wasm/schema.graphql
+++ b/functions-discounts-allocator-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-fulfillment-constraints-js/schema.graphql b/functions-fulfillment-constraints-js/schema.graphql
index f49dee43..e7f3a10f 100644
--- a/functions-fulfillment-constraints-js/schema.graphql
+++ b/functions-fulfillment-constraints-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-fulfillment-constraints-rs/schema.graphql b/functions-fulfillment-constraints-rs/schema.graphql
index f49dee43..e7f3a10f 100644
--- a/functions-fulfillment-constraints-rs/schema.graphql
+++ b/functions-fulfillment-constraints-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-fulfillment-constraints-wasm/schema.graphql b/functions-fulfillment-constraints-wasm/schema.graphql
index f49dee43..e7f3a10f 100644
--- a/functions-fulfillment-constraints-wasm/schema.graphql
+++ b/functions-fulfillment-constraints-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-local-pickup-delivery-option-generators-js/schema.graphql b/functions-local-pickup-delivery-option-generators-js/schema.graphql
index a11e1e57..57b4382d 100644
--- a/functions-local-pickup-delivery-option-generators-js/schema.graphql
+++ b/functions-local-pickup-delivery-option-generators-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-local-pickup-delivery-option-generators-rs/schema.graphql b/functions-local-pickup-delivery-option-generators-rs/schema.graphql
index a11e1e57..57b4382d 100644
--- a/functions-local-pickup-delivery-option-generators-rs/schema.graphql
+++ b/functions-local-pickup-delivery-option-generators-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-local-pickup-delivery-option-generators-wasm/schema.graphql b/functions-local-pickup-delivery-option-generators-wasm/schema.graphql
index a11e1e57..57b4382d 100644
--- a/functions-local-pickup-delivery-option-generators-wasm/schema.graphql
+++ b/functions-local-pickup-delivery-option-generators-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-location-rules-js/schema.graphql b/functions-location-rules-js/schema.graphql
index b1d8d7ae..1021cc69 100644
--- a/functions-location-rules-js/schema.graphql
+++ b/functions-location-rules-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-location-rules-rs/schema.graphql b/functions-location-rules-rs/schema.graphql
index b1d8d7ae..1021cc69 100644
--- a/functions-location-rules-rs/schema.graphql
+++ b/functions-location-rules-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-location-rules-wasm/schema.graphql b/functions-location-rules-wasm/schema.graphql
index b1d8d7ae..1021cc69 100644
--- a/functions-location-rules-wasm/schema.graphql
+++ b/functions-location-rules-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-order-discounts-js/schema.graphql b/functions-order-discounts-js/schema.graphql
index 4a92363f..14ad7be9 100644
--- a/functions-order-discounts-js/schema.graphql
+++ b/functions-order-discounts-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-order-discounts-rs/schema.graphql b/functions-order-discounts-rs/schema.graphql
index 4a92363f..14ad7be9 100644
--- a/functions-order-discounts-rs/schema.graphql
+++ b/functions-order-discounts-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-order-discounts-wasm/schema.graphql b/functions-order-discounts-wasm/schema.graphql
index 4a92363f..14ad7be9 100644
--- a/functions-order-discounts-wasm/schema.graphql
+++ b/functions-order-discounts-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-payment-customization-js/schema.graphql b/functions-payment-customization-js/schema.graphql
index 0234c1a2..03183f67 100644
--- a/functions-payment-customization-js/schema.graphql
+++ b/functions-payment-customization-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-payment-customization-rs/schema.graphql b/functions-payment-customization-rs/schema.graphql
index 0234c1a2..03183f67 100644
--- a/functions-payment-customization-rs/schema.graphql
+++ b/functions-payment-customization-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-payment-customization-wasm/schema.graphql b/functions-payment-customization-wasm/schema.graphql
index 0234c1a2..03183f67 100644
--- a/functions-payment-customization-wasm/schema.graphql
+++ b/functions-payment-customization-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-pickup-point-delivery-option-generators-js/schema.graphql b/functions-pickup-point-delivery-option-generators-js/schema.graphql
index 531b1066..7f2196d5 100644
--- a/functions-pickup-point-delivery-option-generators-js/schema.graphql
+++ b/functions-pickup-point-delivery-option-generators-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-pickup-point-delivery-option-generators-rs/schema.graphql b/functions-pickup-point-delivery-option-generators-rs/schema.graphql
index 531b1066..7f2196d5 100644
--- a/functions-pickup-point-delivery-option-generators-rs/schema.graphql
+++ b/functions-pickup-point-delivery-option-generators-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-pickup-point-delivery-option-generators-wasm/schema.graphql b/functions-pickup-point-delivery-option-generators-wasm/schema.graphql
index 531b1066..7f2196d5 100644
--- a/functions-pickup-point-delivery-option-generators-wasm/schema.graphql
+++ b/functions-pickup-point-delivery-option-generators-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: unstable
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-product-discounts-js/schema.graphql b/functions-product-discounts-js/schema.graphql
index 49dda5fc..62a5f8c9 100644
--- a/functions-product-discounts-js/schema.graphql
+++ b/functions-product-discounts-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-product-discounts-rs/schema.graphql b/functions-product-discounts-rs/schema.graphql
index 49dda5fc..62a5f8c9 100644
--- a/functions-product-discounts-rs/schema.graphql
+++ b/functions-product-discounts-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-product-discounts-wasm/schema.graphql b/functions-product-discounts-wasm/schema.graphql
index 49dda5fc..62a5f8c9 100644
--- a/functions-product-discounts-wasm/schema.graphql
+++ b/functions-product-discounts-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-shipping-discounts-js/schema.graphql b/functions-shipping-discounts-js/schema.graphql
index 21ca37bd..262b2400 100644
--- a/functions-shipping-discounts-js/schema.graphql
+++ b/functions-shipping-discounts-js/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-shipping-discounts-rs/schema.graphql b/functions-shipping-discounts-rs/schema.graphql
index 21ca37bd..262b2400 100644
--- a/functions-shipping-discounts-rs/schema.graphql
+++ b/functions-shipping-discounts-rs/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot
diff --git a/functions-shipping-discounts-wasm/schema.graphql b/functions-shipping-discounts-wasm/schema.graphql
index 21ca37bd..262b2400 100644
--- a/functions-shipping-discounts-wasm/schema.graphql
+++ b/functions-shipping-discounts-wasm/schema.graphql
@@ -1,3 +1,5 @@
+# api_version: 2026-04
+
 schema {
   query: Input
   mutation: MutationRoot