diff --git a/.env.example b/.env.example
new file mode 100644
index 00000000..00f2b847
--- /dev/null
+++ b/.env.example
@@ -0,0 +1,33 @@
+# Checkout Kit sample storefront configuration.
+# Copy this file to .env, fill in local values, then run:
+# scripts/setup_storefront_env
+# Optional Apple Pay and Customer Account API values can stay blank.
+#
+# Do not commit real values from .env or generated platform config files.
+
+# Storefront details
+STOREFRONT_DOMAIN=your-store.myshopify.com
+STOREFRONT_ACCESS_TOKEN=your-public-storefront-access-token
+# Optional Apple Pay merchant identifier used by accelerated checkout flows.
+STOREFRONT_MERCHANT_IDENTIFIER=
+
+# Storefront API version
+API_VERSION=2026-04
+
+# Customer Account API (optional)
+CUSTOMER_ACCOUNT_API_CLIENT_ID=
+CUSTOMER_ACCOUNT_API_SHOP_ID=
+CUSTOMER_ACCOUNT_API_VERSION=2026-04
+
+# Buyer identity defaults used by sample apps
+EMAIL=checkout-kit@example.com
+ADDRESS_1=650 King Street
+ADDRESS_2=Shopify HQ
+CITY=Toronto
+COMPANY=Shopify
+COUNTRY=CA
+FIRST_NAME=Evelyn
+LAST_NAME=Hartley
+PROVINCE=ON
+ZIP=M5V 1M7
+PHONE=+14165550100
diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index ae63d3ed..8a917e41 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -50,6 +50,11 @@ dev check
 
 Platform-scoped commands are available as `dev android <command>`, `dev swift <command>`, and `dev react-native <command>` (or `dev rn`). Protocol schema/model commands are available as `dev protocol <command>`. For cross-platform changes, use `dev lint`, `dev test`, `dev check`, `dev format`, and `dev build`.
 
+Sample app storefront configuration is generated from the repo-root `.env`.
+Shopify employees get this through `dev up`. External contributors can copy
+`.env.example` to `.env`, fill in local storefront values, then run
+`scripts/setup_storefront_env` from the repo root.
+
 ---
 
 ## Swift (`platforms/swift/`)
diff --git a/.github/workflows/android-test.yml b/.github/workflows/android-test.yml
index 41e89565..01bc389f 100644
--- a/.github/workflows/android-test.yml
+++ b/.github/workflows/android-test.yml
@@ -47,8 +47,10 @@ jobs:
           cache: 'gradle'
 
       - name: Setup sample app environment
-        run: cp .env.example .env
-        working-directory: platforms/android/samples/MobileBuyIntegration
+        run: ${{ github.workspace }}/scripts/setup_storefront_env --skip-optional-prompts
+        env:
+          STOREFRONT_DOMAIN: example.myshopify.com
+          STOREFRONT_ACCESS_TOKEN: test-token
 
       - name: Build Sample App
         run: ./gradlew assembleDebug
diff --git a/.github/workflows/rn-test-android.yml b/.github/workflows/rn-test-android.yml
index 6f026b35..c913a02a 100644
--- a/.github/workflows/rn-test-android.yml
+++ b/.github/workflows/rn-test-android.yml
@@ -58,10 +58,12 @@ jobs:
         env:
           GRADLE_OPTS: -Xmx4g -XX:MaxMetaspaceSize=768m
           JAVA_HOME: ${{ steps.setup-java.outputs.path }}
+          STOREFRONT_DOMAIN: example.myshopify.com
+          STOREFRONT_ACCESS_TOKEN: test-token
         run: |
           echo "JAVA_HOME: $JAVA_HOME"
           java -version
           javac -version
-          echo "STOREFRONT_DOMAIN=myshopify.com" > sample/.env
+          ${{ github.workspace }}/scripts/setup_storefront_env --skip-optional-prompts
           pnpm module build
           pnpm sample test:android --no-daemon
diff --git a/.github/workflows/swift-build-samples.yml b/.github/workflows/swift-build-samples.yml
index df8067e0..0821942c 100644
--- a/.github/workflows/swift-build-samples.yml
+++ b/.github/workflows/swift-build-samples.yml
@@ -13,3 +13,4 @@ jobs:
     with:
       test-path: ./Scripts/build_samples
       job-name: Build Sample Apps
+      setup-storefront-env: true
diff --git a/.github/workflows/swift-test-workflow.yml b/.github/workflows/swift-test-workflow.yml
index 14153b36..73210794 100644
--- a/.github/workflows/swift-test-workflow.yml
+++ b/.github/workflows/swift-test-workflow.yml
@@ -8,6 +8,10 @@ on:
         required: false
         type: string
         default: Run
+      setup-storefront-env:
+        required: false
+        type: boolean
+        default: false
 
 permissions:
   contents: read
@@ -68,5 +72,12 @@ jobs:
           echo "CURRENT_SIMULATOR_UUID=$CURRENT_SIMULATOR_UUID" >> $GITHUB_ENV
           echo ""
 
+      - name: Setup sample app storefront configuration
+        if: ${{ inputs.setup-storefront-env }}
+        env:
+          STOREFRONT_DOMAIN: example.myshopify.com
+          STOREFRONT_ACCESS_TOKEN: test-token
+        run: ${{ github.workspace }}/scripts/setup_storefront_env --skip-optional-prompts
+
       - name: Run Tests
         run: ${{ inputs.test-path }}
diff --git a/platforms/android/samples/MobileBuyIntegration/.env.example b/platforms/android/samples/MobileBuyIntegration/.env.example
deleted file mode 100644
index 0e3a417d..00000000
--- a/platforms/android/samples/MobileBuyIntegration/.env.example
+++ /dev/null
@@ -1,14 +0,0 @@
-STOREFRONT_DOMAIN=<yourdomainhere.myshopify.com>
-STOREFRONT_ACCESS_TOKEN=<storefront access token>
-API_VERSION=2026-04
-
-CUSTOMER_ACCOUNT_API_CLIENT_ID=<configured customer account api client id>
-CUSTOMER_ACCOUNT_API_REDIRECT_URI=shop.<shop id>.app://callback
-
-CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL=https://shopify.com/<shop id>/account/customer/api/<api version>/graphql
-CUSTOMER_ACCOUNT_API_AUTH_BASE_URL=https://shopify.com/authentication/<shop id>
-
-# Demo buyer identity used when the "Prefill checkout" toggle is enabled in Settings.
-# Phone must be in E.164 format (+1XXXXXXXXXX for Canada).
-PREFILL_EMAIL=test.buyer@example.com
-PREFILL_PHONE=+16135550123
diff --git a/platforms/android/samples/MobileBuyIntegration/README.md b/platforms/android/samples/MobileBuyIntegration/README.md
index ded94669..16edb0ed 100644
--- a/platforms/android/samples/MobileBuyIntegration/README.md
+++ b/platforms/android/samples/MobileBuyIntegration/README.md
@@ -66,13 +66,14 @@ Do not edit files in `app/build/generated/source/apollo/` by hand. Update `.grap
 
 ## Setup
 
-From this directory:
+From the repo root:
 
 ```sh
 cp .env.example .env
+scripts/setup_storefront_env
 ```
 
-Edit `.env`:
+Edit the repo-root `.env`:
 
 ```text
 STOREFRONT_DOMAIN=your-store.myshopify.com
@@ -84,19 +85,21 @@ Optional values enable Customer Account API and buyer identity demo flows:
 
 ```text
 CUSTOMER_ACCOUNT_API_CLIENT_ID=your-client-id
-CUSTOMER_ACCOUNT_API_REDIRECT_URI=shop.<shop id>.app://callback
-CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL=https://shopify.com/<shop id>/account/customer/api/<api version>/graphql
-CUSTOMER_ACCOUNT_API_AUTH_BASE_URL=https://shopify.com/authentication/<shop id>
-PREFILL_EMAIL=test.buyer@example.com
-PREFILL_PHONE=+16135550123
+CUSTOMER_ACCOUNT_API_SHOP_ID=your-shop-id
+CUSTOMER_ACCOUNT_API_VERSION=2026-04
+EMAIL=test.buyer@example.com
+PHONE=+16135550123
 ```
 
+The setup script generates this sample's local `.env`.
+
 Open the project in Android Studio, sync Gradle, then build and run.
 
 ## Updating the Storefront API version
 
-1. Update `API_VERSION` in `.env`.
-2. Download the schema with Rover. This introspects your store's Storefront API and writes `schema.graphqls` into `app/src/main/graphql/`.
+1. Update `API_VERSION` in the repo-root `.env`.
+2. Run `scripts/setup_storefront_env` from the repo root.
+3. Download the schema with Rover. This introspects your store's Storefront API and writes `schema.graphqls` into `app/src/main/graphql/`.
 
    ```sh
    rover graph introspect \
@@ -105,7 +108,7 @@ Open the project in Android Studio, sync Gradle, then build and run.
      --output "app/src/main/graphql/schema.graphqls"
    ```
 
-3. Update GraphQL operations in `app/src/main/graphql/` if the schema changed. For example, add a product field to `FetchProducts.graphql` before regenerating types:
+4. Update GraphQL operations in `app/src/main/graphql/` if the schema changed. For example, add a product field to `FetchProducts.graphql` before regenerating types:
 
    ```graphql
    query FetchProducts(...) {
diff --git a/platforms/android/samples/MobileBuyIntegration/app/build.gradle b/platforms/android/samples/MobileBuyIntegration/app/build.gradle
index 24679cb9..4427db88 100644
--- a/platforms/android/samples/MobileBuyIntegration/app/build.gradle
+++ b/platforms/android/samples/MobileBuyIntegration/app/build.gradle
@@ -20,6 +20,11 @@ def loadProperties() {
 
 def properties = loadProperties()
 
+def propertyOrDefault = { String key, String defaultValue ->
+    def value = properties.getProperty(key)
+    return value?.trim() ? value.trim() : defaultValue
+}
+
 // Storefront API
 def storefrontDomain = properties.getProperty("STOREFRONT_DOMAIN")
 def accessToken = properties.getProperty("STOREFRONT_ACCESS_TOKEN")
@@ -27,14 +32,28 @@ def apiVersion = properties.getProperty("API_VERSION", "2026-04")
 
 // Customer Account API
 def customerAccountApiClientId = properties.getProperty("CUSTOMER_ACCOUNT_API_CLIENT_ID")
+def customerAccountApiShopId = properties.getProperty("CUSTOMER_ACCOUNT_API_SHOP_ID")
+def customerAccountApiVersion = propertyOrDefault("CUSTOMER_ACCOUNT_API_VERSION", "unstable")
 def customerAccountApiRedirectUri = properties.getProperty("CUSTOMER_ACCOUNT_API_REDIRECT_URI")
 
 def customerAccountApiGraphQLBaseUrl = properties.getProperty("CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL")
 def customerAccountApiAuthBaseUrl = properties.getProperty("CUSTOMER_ACCOUNT_API_AUTH_BASE_URL")
 
+if (!customerAccountApiRedirectUri && customerAccountApiShopId) {
+    customerAccountApiRedirectUri = "shop.${customerAccountApiShopId}.app://callback"
+}
+
+if (!customerAccountApiGraphQLBaseUrl && customerAccountApiShopId) {
+    customerAccountApiGraphQLBaseUrl = "https://shopify.com/${customerAccountApiShopId}/account/customer/api/${customerAccountApiVersion}/graphql"
+}
+
+if (!customerAccountApiAuthBaseUrl && customerAccountApiShopId) {
+    customerAccountApiAuthBaseUrl = "https://shopify.com/authentication/${customerAccountApiShopId}"
+}
+
 // Demo buyer identity (prefill toggle in Settings)
-def prefillEmail = properties.getProperty("PREFILL_EMAIL", "test.buyer@example.com")
-def prefillPhone = properties.getProperty("PREFILL_PHONE", "+16135550123")
+def prefillEmail = properties.getProperty("EMAIL", properties.getProperty("PREFILL_EMAIL", "test.buyer@example.com"))
+def prefillPhone = properties.getProperty("PHONE", properties.getProperty("PREFILL_PHONE", "+14165550100"))
 
 if (!storefrontDomain || !accessToken) {
     println("**** Please add a .env file with STOREFRONT_DOMAIN and STOREFRONT_ACCESS_TOKEN set *****")
diff --git a/platforms/android/samples/README.md b/platforms/android/samples/README.md
index 42f62677..badf78c8 100644
--- a/platforms/android/samples/README.md
+++ b/platforms/android/samples/README.md
@@ -8,13 +8,14 @@ This directory contains Android sample apps for Checkout Kit.
 
 ## Setup
 
-From `platforms/android/samples/MobileBuyIntegration`:
+From the repo root:
 
 ```sh
 cp .env.example .env
+scripts/setup_storefront_env
 ```
 
-Fill in:
+Fill `.env` with:
 
 - `STOREFRONT_DOMAIN`
 - `STOREFRONT_ACCESS_TOKEN`
@@ -22,4 +23,6 @@ Fill in:
 - Optional Customer Account API values
 - Optional demo buyer identity values
 
+The setup script generates `platforms/android/samples/MobileBuyIntegration/.env`.
+
 Open `MobileBuyIntegration` in Android Studio, sync Gradle, then build and run the `app` target.
diff --git a/platforms/android/scripts/apollo_download_schema b/platforms/android/scripts/apollo_download_schema
index d8ab6283..28b61809 100755
--- a/platforms/android/scripts/apollo_download_schema
+++ b/platforms/android/scripts/apollo_download_schema
@@ -3,44 +3,66 @@ set -euo pipefail
 
 cd samples/MobileBuyIntegration
 
-if [ ! -f ".env" ]; then
+ENV_FILE=".env"
+
+if [ ! -f "$ENV_FILE" ]; then
   echo "❌ .env file not found in samples/MobileBuyIntegration/"
-  echo "   Run 'cp .env.example .env' and fill in your credentials."
+  echo "   Run scripts/setup_storefront_env from the repo root."
   exit 1
 fi
 
-npx -y dotenv-cli -e .env -- sh -c '
-  DOMAIN="$STOREFRONT_DOMAIN"
-  TOKEN="$STOREFRONT_ACCESS_TOKEN"
-  VERSION="$API_VERSION"
-
-  if [ -z "$DOMAIN" ]; then
-    echo "❌ STOREFRONT_DOMAIN is not set. Check your .env file."
-    exit 1
-  fi
-  if [ -z "$TOKEN" ]; then
-    echo "❌ STOREFRONT_ACCESS_TOKEN is not set. Check your .env file."
-    exit 1
-  fi
-  if [ -z "$VERSION" ]; then
-    echo "❌ API_VERSION is not set. Check your .env file."
-    echo "   Add API_VERSION=2026-04 to your .env"
-    exit 1
-  fi
-
-  echo "📡 Downloading schema for MobileBuyIntegration..."
-  echo "   Domain: $DOMAIN"
-  echo "   API Version: $VERSION"
-
-  rover graph introspect \
-    "https://$DOMAIN/api/$VERSION/graphql" \
-    --header="X-Shopify-Storefront-Access-Token: $TOKEN" \
-    --output "app/src/main/graphql/schema.graphqls"
-
-  if [ $? -eq 0 ]; then
-    echo "✅ Schema downloaded to app/src/main/graphql/schema.graphqls"
-  else
-    echo "❌ Schema download failed. Check your network connection and credentials."
-    exit 1
-  fi
-'
+read_env_value() {
+  local key="$1"
+  awk -v key="$key" '
+    /^[[:space:]]*#/ || /^[[:space:]]*\/\// || /^[[:space:]]*$/ { next }
+    $0 !~ /=/ { next }
+    {
+      line = $0
+      sub(/^[[:space:]]*/, "", line)
+      candidate = line
+      sub(/=.*/, "", candidate)
+      sub(/[[:space:]]*$/, "", candidate)
+      if (candidate == key) {
+        value = substr(line, index(line, "=") + 1)
+        gsub(/^[[:space:]]+|[[:space:]]+$/, "", value)
+        if (value ~ /^".*"$/ || value ~ /^'\''.*'\''$/) {
+          value = substr(value, 2, length(value) - 2)
+        }
+        print value
+        exit
+      }
+    }
+  ' "$ENV_FILE"
+}
+
+DOMAIN="$(read_env_value STOREFRONT_DOMAIN)"
+TOKEN="$(read_env_value STOREFRONT_ACCESS_TOKEN)"
+VERSION="$(read_env_value API_VERSION)"
+
+if [ -z "$DOMAIN" ]; then
+  echo "❌ STOREFRONT_DOMAIN is not set. Check your .env file."
+  exit 1
+fi
+if [ -z "$TOKEN" ]; then
+  echo "❌ STOREFRONT_ACCESS_TOKEN is not set. Check your .env file."
+  exit 1
+fi
+if [ -z "$VERSION" ]; then
+  echo "❌ API_VERSION is not set. Check your .env file."
+  echo "   Add API_VERSION=2026-04 to your .env"
+  exit 1
+fi
+
+echo "📡 Downloading schema for MobileBuyIntegration..."
+echo "   Domain: $DOMAIN"
+echo "   API Version: $VERSION"
+
+if rover graph introspect \
+  "https://$DOMAIN/api/$VERSION/graphql" \
+  --header="X-Shopify-Storefront-Access-Token: $TOKEN" \
+  --output "app/src/main/graphql/schema.graphqls"; then
+  echo "✅ Schema downloaded to app/src/main/graphql/schema.graphqls"
+else
+  echo "❌ Schema download failed. Check your network connection and credentials."
+  exit 1
+fi
diff --git a/platforms/android/scripts/setup_env.sh b/platforms/android/scripts/setup_env.sh
index 013a5a2e..952b0a04 100755
--- a/platforms/android/scripts/setup_env.sh
+++ b/platforms/android/scripts/setup_env.sh
@@ -1,57 +1,7 @@
 #!/bin/bash
 
-# Function to create .env file for a sample app
-create_env_file() {
-	local app_name="$1"
-	local env_path="./samples/${app_name}/.env"
+set -e
 
-	if [ ! -f "$env_path" ]; then
-		echo "Creating ${app_name} .env file..."
-		cat >"$env_path" <<EOF
-STOREFRONT_DOMAIN=${STOREFRONT_DOMAIN}
-STOREFRONT_ACCESS_TOKEN=${STOREFRONT_ACCESS_TOKEN}
-EOF
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
-		# Add optional authentication configuration if provided
-		if [ -n "$SHOP_ID" ] && [ -n "$CUSTOMER_ACCOUNT_API_CLIENT_ID" ]; then
-			cat >>"$env_path" <<EOF
-
-CUSTOMER_ACCOUNT_API_CLIENT_ID=${CUSTOMER_ACCOUNT_API_CLIENT_ID}
-CUSTOMER_ACCOUNT_API_REDIRECT_URI=shop.${SHOP_ID}.app://callback
-
-CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL=https://shopify.com/${SHOP_ID}/account/customer/api/${CUSTOMER_ACCOUNT_API_VERSION}/graphql
-CUSTOMER_ACCOUNT_API_AUTH_BASE_URL=https://shopify.com/authentication/${SHOP_ID}
-EOF
-		fi
-		echo "✓ Created ${app_name} .env file"
-	fi
-}
-
-# Prompt for Shopify credentials
-echo "Setting up .env files for sample apps..."
-echo "Please provide your Shopify storefront credentials:"
-read -p "Storefront Domain (e.g., yourstore.myshopify.com): " STOREFRONT_DOMAIN
-read -p "Storefront Access Token: " STOREFRONT_ACCESS_TOKEN
-
-if [ -z "$STOREFRONT_DOMAIN" ] || [ -z "$STOREFRONT_ACCESS_TOKEN" ]; then
-	echo "Error: Both storefront domain and access token are required."
-	exit 1
-fi
-
-# Optional authentication configuration
-echo ""
-echo "Optional: Customer Account API configuration (needed for authentication features)"
-echo "Press Enter to skip if you don't need authentication features."
-read -p "Shop ID (optional): " SHOP_ID
-read -p "Customer Account API Client ID (optional): " CUSTOMER_ACCOUNT_API_CLIENT_ID
-read -p "Customer Account API Version (default: unstable): " CUSTOMER_ACCOUNT_API_VERSION
-
-# Set default API version if not provided
-if [ -z "$CUSTOMER_ACCOUNT_API_VERSION" ]; then
-	CUSTOMER_ACCOUNT_API_VERSION="unstable"
-fi
-
-# Create .env files for both sample apps
-create_env_file "MobileBuyIntegration"
-
-echo "✓ Sample app .env files are ready!"
+exec "$SCRIPT_DIR/../../../scripts/setup_storefront_env" "$@"
diff --git a/platforms/react-native/CONTRIBUTING.md b/platforms/react-native/CONTRIBUTING.md
index d2c5f691..e91f8344 100644
--- a/platforms/react-native/CONTRIBUTING.md
+++ b/platforms/react-native/CONTRIBUTING.md
@@ -188,16 +188,22 @@ pnpm pod-install sample/ios
 pnpm module build
 ```
 
-### Update the dotenv file
+### Update sample configuration
 
-Replace the details in the `sample/.env.example` file and rename it to
-`sample/.env`
+From the repo root, copy the shared example and generate platform-local config:
+
+```sh
+cp .env.example .env
+scripts/setup_storefront_env
+```
+
+Fill `.env` with your local storefront values:
 
 ```
 # Storefront Details
 STOREFRONT_DOMAIN="YOUR_STORE.myshopify.com"
 STOREFRONT_ACCESS_TOKEN="YOUR_PUBLIC_STOREFRONT_ACCESS_TOKEN"
-STOREFRONT_VERSION="2025-07"
+API_VERSION="2026-04"
 ```
 
 ### Start the sample app
diff --git a/platforms/react-native/README.md b/platforms/react-native/README.md
index 08b66c79..28afede3 100644
--- a/platforms/react-native/README.md
+++ b/platforms/react-native/README.md
@@ -217,11 +217,11 @@ Here's an example of how to get started with Apollo:
 
 ```tsx
 import {ApolloClient, gql, ApolloProvider} from '@apollo/client';
-import {STOREFRONT_NAME, STOREFRONT_ACCESS_TOKEN} from '@env';
+import {API_VERSION, STOREFRONT_DOMAIN, STOREFRONT_ACCESS_TOKEN} from '@env';
 
 // Create a new instance of the ApolloClient
 const client = new ApolloClient({
-  uri: `https://${STOREFRONT_NAME}.myshopify.com/api/2025-07/graphql.json`,
+  uri: `https://${STOREFRONT_DOMAIN}/api/${API_VERSION}/graphql.json`,
   headers: {
     'X-Shopify-Storefront-Access-Token': STOREFRONT_ACCESS_TOKEN,
   },
diff --git a/platforms/react-native/__mocks__/react-native-config.ts b/platforms/react-native/__mocks__/react-native-config.ts
index 31dd0e60..e1d9a022 100644
--- a/platforms/react-native/__mocks__/react-native-config.ts
+++ b/platforms/react-native/__mocks__/react-native-config.ts
@@ -1,6 +1,7 @@
 module.exports = {
   __esModule: true,
   default: {
+    API_VERSION: '2026-04',
     CUSTOMER_ACCOUNT_API_SHOP_ID: 'test-shop-123',
     CUSTOMER_ACCOUNT_API_CLIENT_ID: 'test-client-456',
   },
diff --git a/platforms/react-native/sample/.env.example b/platforms/react-native/sample/.env.example
deleted file mode 100644
index adaf5d9f..00000000
--- a/platforms/react-native/sample/.env.example
+++ /dev/null
@@ -1,24 +0,0 @@
-# Storefront Details
-STOREFRONT_DOMAIN="YOUR_STORE.myshopify.com"
-STOREFRONT_ACCESS_TOKEN="YOUR_PUBLIC_STOREFRONT_ACCESS_TOKEN"
-STOREFRONT_MERCHANT_IDENTIFIER=example.merchant.com.shopify
-
-# Storefront API version
-STOREFRONT_VERSION="2025-07"
-
-# Prefilled buyer information
-EMAIL="checkout-kit@shopify.com"
-ADDRESS_1="650 King Street"
-ADDRESS_2="Shopify HQ"
-CITY="Toronto"
-COMPANY="Shopify"
-COUNTRY="CA"
-FIRST_NAME="Evelyn"
-LAST_NAME="Hartley"
-PROVINCE="ON"
-ZIP="M5V 1M7"
-PHONE="1-888-746-7439"
-
-# Customer Account API (for OAuth authentication)
-CUSTOMER_ACCOUNT_API_CLIENT_ID="YOUR_CUSTOMER_ACCOUNT_API_CLIENT_ID"
-CUSTOMER_ACCOUNT_API_SHOP_ID="YOUR_SHOP_ID"
diff --git a/platforms/react-native/sample/@types/env.d.ts b/platforms/react-native/sample/@types/env.d.ts
index d995b75e..aa80478f 100644
--- a/platforms/react-native/sample/@types/env.d.ts
+++ b/platforms/react-native/sample/@types/env.d.ts
@@ -1,7 +1,9 @@
 declare module '@env' {
   export const STOREFRONT_DOMAIN: string;
   export const STOREFRONT_ACCESS_TOKEN: string;
-  export const STOREFRONT_VERSION: string;
+  export const API_VERSION: string | undefined;
+  export const STOREFRONT_VERSION: string | undefined;
+  export const STOREFRONT_MERCHANT_IDENTIFIER: string | undefined;
 
   export const EMAIL: string;
   export const ADDRESS_1: string;
diff --git a/platforms/react-native/sample/src/App.tsx b/platforms/react-native/sample/src/App.tsx
index 9cb13abf..6c7ebe5e 100644
--- a/platforms/react-native/sample/src/App.tsx
+++ b/platforms/react-native/sample/src/App.tsx
@@ -46,23 +46,22 @@ import {useShopifyEventHandlers} from './hooks/useCheckoutEventHandlers';
 
 const log = createDebugLogger('ENV');
 
-function quote(str: string | undefined) {
-  return `"${str}"`;
+function configured(value: string | undefined) {
+  return value ? 'configured' : 'missing';
 }
 
+const storefrontApiVersion = env.API_VERSION ?? env.STOREFRONT_VERSION;
+
 console.groupCollapsed('ENV');
-log('STOREFRONT_DOMAIN:', quote(env.STOREFRONT_DOMAIN));
-log(
-  'STOREFRONT_ACCESS_TOKEN:',
-  '*'.repeat(8) + env.STOREFRONT_ACCESS_TOKEN?.slice(-4),
-);
-log('STOREFRONT_VERSION:', quote(env.STOREFRONT_VERSION));
+log('STOREFRONT_DOMAIN:', configured(env.STOREFRONT_DOMAIN));
+log('STOREFRONT_ACCESS_TOKEN:', configured(env.STOREFRONT_ACCESS_TOKEN));
+log('API_VERSION:', configured(storefrontApiVersion));
 log(
   'STOREFRONT_MERCHANT_IDENTIFIER:',
-  quote(env.STOREFRONT_MERCHANT_IDENTIFIER),
+  configured(env.STOREFRONT_MERCHANT_IDENTIFIER),
 );
-log('EMAIL:', quote(env.EMAIL));
-log('PHONE:', quote(env.PHONE));
+log('EMAIL:', configured(env.EMAIL));
+log('PHONE:', configured(env.PHONE));
 console.groupEnd();
 
 export type RootStackParamList = {
@@ -87,7 +86,7 @@ const AccountStack = createNativeStackNavigator<AccountStackParamList>();
 export const cache = new InMemoryCache();
 
 const client = new ApolloClient({
-  uri: `https://${env.STOREFRONT_DOMAIN}/api/${env.STOREFRONT_VERSION}/graphql.json`,
+  uri: `https://${env.STOREFRONT_DOMAIN}/api/${storefrontApiVersion}/graphql.json`,
   cache,
   headers: {
     'Content-Type': 'application/json',
diff --git a/platforms/swift/Samples/MobileBuyIntegration/README.md b/platforms/swift/Samples/MobileBuyIntegration/README.md
index 4f5c3de0..3b95a5b1 100644
--- a/platforms/swift/Samples/MobileBuyIntegration/README.md
+++ b/platforms/swift/Samples/MobileBuyIntegration/README.md
@@ -63,36 +63,39 @@ Do not edit files in `Generated/` by hand. Update `.graphql` files and regenerat
 
 ## Setup
 
-From `platforms/swift`:
+From the repo root:
 
 ```sh
-cp Samples/MobileBuyIntegration/Storefront.xcconfig.example \
-  Samples/MobileBuyIntegration/Storefront.xcconfig
+cp .env.example .env
+scripts/setup_storefront_env
 ```
 
-Edit `Storefront.xcconfig`:
+Edit `.env`:
 
 ```text
-STOREFRONT_DOMAIN = your-store.myshopify.com
-STOREFRONT_ACCESS_TOKEN = your-token
-API_VERSION = 2026-04
+STOREFRONT_DOMAIN=your-store.myshopify.com
+STOREFRONT_ACCESS_TOKEN=your-token
+API_VERSION=2026-04
 ```
 
 Optional values enable Customer Account API and buyer identity demo flows:
 
 ```text
-CUSTOMER_ACCOUNT_API_CLIENT_ID = your-client-id
-CUSTOMER_ACCOUNT_API_SHOP_ID = your-shop-id
-EMAIL = test.buyer@example.com
-PHONE = +16135550123
+CUSTOMER_ACCOUNT_API_CLIENT_ID=your-client-id
+CUSTOMER_ACCOUNT_API_SHOP_ID=your-shop-id
+EMAIL=test.buyer@example.com
+PHONE=+16135550123
 ```
 
+The setup script generates this sample's `Storefront.xcconfig`.
+
 Open the project in Xcode, let Swift Package Manager resolve dependencies, then build and run.
 
 ## Updating the Storefront API version
 
-1. Update `API_VERSION` in `Storefront.xcconfig`.
-2. Download the schema with Rover. This introspects your store's Storefront API and writes `schema.<version>.graphqls` into the sample app directory.
+1. Update `API_VERSION` in the repo-root `.env`.
+2. Run `scripts/setup_storefront_env` from the repo root.
+3. Download the schema with Rover. This introspects your store's Storefront API and writes `schema.<version>.graphqls` into the sample app directory.
 
    ```sh
    rover graph introspect \
@@ -101,7 +104,7 @@ Open the project in Xcode, let Swift Package Manager resolve dependencies, then
      --output "schema.$API_VERSION.graphqls"
    ```
 
-3. Update `.graphql` operations if the schema changed. For example, add a product field to `MobileBuyIntegration/Sources/Api/Queries/GetProducts.graphql` before regenerating types:
+4. Update `.graphql` operations if the schema changed. For example, add a product field to `MobileBuyIntegration/Sources/Api/Queries/GetProducts.graphql` before regenerating types:
 
    ```graphql
    query GetProducts(...) {
diff --git a/platforms/swift/Samples/MobileBuyIntegration/Scripts/generate_entitlements.sh b/platforms/swift/Samples/MobileBuyIntegration/Scripts/generate_entitlements.sh
index 8a284e34..067f8901 100755
--- a/platforms/swift/Samples/MobileBuyIntegration/Scripts/generate_entitlements.sh
+++ b/platforms/swift/Samples/MobileBuyIntegration/Scripts/generate_entitlements.sh
@@ -20,4 +20,4 @@ fi
 
 sed "s/{STOREFRONT_DOMAIN}/$STOREFRONT_DOMAIN?mode=developer/g" "$TEMPLATE_FILE" > "$OUTPUT_FILE"
 
-echo "Success: Entitlements file generated at $OUTPUT_FILE with domain $STOREFRONT_DOMAIN"
+echo "Success: Entitlements file generated at $OUTPUT_FILE"
diff --git a/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig.example b/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig.example
deleted file mode 100644
index fcb81ae6..00000000
--- a/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig.example
+++ /dev/null
@@ -1,29 +0,0 @@
-// --- Storefront
-// --- Find your Storefront API access token under:
-// ----- https://admin.shopify.com/store/{STOREFRONT}/settings/apps/development/{APP_ID}/api_credentials
-
-STOREFRONT_DOMAIN = <INSERT_STOREFRONT_DOMAIN>
-STOREFRONT_ACCESS_TOKEN = <INSERT_STOREFRONT_ACCESS_TOKEN>
-STOREFRONT_MERCHANT_IDENTIFIER = <INSERT_STOREFRONT_MERCHANT_IDENTIFIER>
-
-// --- Customer Account API (optional)
-// --- Find these under your Headless app configuration:
-// ----- https://admin.shopify.com/store/{STOREFRONT}/settings/apps/development/{APP_ID}
-CUSTOMER_ACCOUNT_API_CLIENT_ID = <INSERT_CLIENT_ID>
-CUSTOMER_ACCOUNT_API_SHOP_ID = <INSERT_SHOP_ID>
-
-// --- Buyer preference data
-EMAIL = test-checkout-sdk@shopify.com
-
-FIRST_NAME = Test
-LAST_NAME = Test
-
-ADDRESS_1 = The Cloak & Dagger
-ADDRESS_2 = 1st Street Southeast
-CITY = Calgary
-COUNTRY = CA
-PROVINCE = AB
-ZIP = T1X 0L3
-PHONE = +155565708743
-
-API_VERSION = 2026-04
diff --git a/platforms/swift/Samples/README.md b/platforms/swift/Samples/README.md
index bf27c831..1b3c98c9 100644
--- a/platforms/swift/Samples/README.md
+++ b/platforms/swift/Samples/README.md
@@ -16,14 +16,14 @@ This directory contains iOS sample apps for Checkout Kit.
 
 ## MobileBuyIntegration
 
-From `platforms/swift`:
+From the repo root:
 
 ```sh
-cp Samples/MobileBuyIntegration/Storefront.xcconfig.example \
-  Samples/MobileBuyIntegration/Storefront.xcconfig
+cp .env.example .env
+scripts/setup_storefront_env
 ```
 
-Fill in:
+Fill `.env` with:
 
 - `STOREFRONT_DOMAIN`
 - `STOREFRONT_ACCESS_TOKEN`
@@ -31,26 +31,30 @@ Fill in:
 - Optional Customer Account API values
 - Optional demo buyer identity values
 
-Open `Samples/Samples.xcworkspace` or `Samples/MobileBuyIntegration/MobileBuyIntegration.xcodeproj` in Xcode, then build and run the `MobileBuyIntegration` scheme.
+The setup script generates `platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig`.
+
+Open `platforms/swift/Samples/Samples.xcworkspace` or `platforms/swift/Samples/MobileBuyIntegration/MobileBuyIntegration.xcodeproj` in Xcode, then build and run the `MobileBuyIntegration` scheme.
 
 The project generates associated-domain entitlements from `Storefront.xcconfig` during the Xcode build pre-action.
 
 ## ShopifyAcceleratedCheckoutsApp
 
-From `platforms/swift`:
+From the repo root:
 
 ```sh
-cp Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig.example \
-  Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig
+cp .env.example .env
+scripts/setup_storefront_env
 ```
 
-Fill in:
+Fill `.env` with:
 
 - `STOREFRONT_DOMAIN`
 - `STOREFRONT_ACCESS_TOKEN`
 - `API_VERSION`
 
-Open `Samples/Samples.xcworkspace` or `Samples/ShopifyAcceleratedCheckoutsApp/ShopifyAcceleratedCheckoutsApp.xcodeproj` in Xcode, then build and run the `ShopifyAcceleratedCheckoutsApp` scheme.
+The setup script generates `platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig`.
+
+Open `platforms/swift/Samples/Samples.xcworkspace` or `platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/ShopifyAcceleratedCheckoutsApp.xcodeproj` in Xcode, then build and run the `ShopifyAcceleratedCheckoutsApp` scheme.
 
 ## Troubleshooting
 
@@ -58,6 +62,6 @@ If the build pre-action fails, Xcode usually shows `exited with status code 1`.
 
 | Build log output | Cause | Fix |
 | --- | --- | --- |
-| `grep: Storefront.xcconfig: No such file or directory` | The sample config file is missing. | Copy `.xcconfig.example` to `Storefront.xcconfig`. |
+| `grep: Storefront.xcconfig: No such file or directory` | The sample config file is missing. | Run `scripts/setup_storefront_env` from the repo root. |
 | `Error: STOREFRONT_DOMAIN is not set in Storefront.xcconfig` | `STOREFRONT_DOMAIN` is blank. | Set your shop domain without `https://`. |
 | Associated domains do not work at runtime | Domain or app association is wrong. | Verify your custom storefront domain, app ID, and Universal Links setup. |
diff --git a/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/.gitignore b/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/.gitignore
deleted file mode 100644
index 299cebcd..00000000
--- a/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-!Storefront.xcconfig.example
\ No newline at end of file
diff --git a/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig.example b/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig.example
deleted file mode 100644
index aea5720c..00000000
--- a/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig.example
+++ /dev/null
@@ -1,10 +0,0 @@
-// --- Storefront
-// --- Find your Storefront API access token under:
-// ----- https://admin.shopify.com/store/{STOREFRONT}/settings/apps/development/{APP_ID}/api_credentials
-
-// Configuration settings file format documentation can be found at:
-// https://help.apple.com/xcode/#/dev745c5c974
-
-STOREFRONT_DOMAIN = shopify.my-shopify.com
-STOREFRONT_ACCESS_TOKEN = 123456
-API_VERSION = 2026-04
diff --git a/platforms/swift/Scripts/build_samples b/platforms/swift/Scripts/build_samples
index 499ca62f..b39040e2 100755
--- a/platforms/swift/Scripts/build_samples
+++ b/platforms/swift/Scripts/build_samples
@@ -1,11 +1,17 @@
- #!/usr/bin/env bash
+#!/usr/bin/env bash
 
-set -ex
-set -eo pipefail
+set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../../.." && pwd)"
+SAMPLES_DIR="$SCRIPT_DIR/../Samples"
 
-cd Samples/
+if ! "$REPO_ROOT/scripts/setup_storefront_env" --check; then
+    echo "Run dev up from the repo root to sync sample app storefront configuration."
+    exit 1
+fi
+
+cd "$SAMPLES_DIR"
 
 EMPTY_ENTITLEMENTS="""
 <?xml version=\"1.0\" encoding=\"UTF-8\"?>
@@ -17,17 +23,18 @@ EMPTY_ENTITLEMENTS="""
 
 build_app() {
     if [[ ! -f "$1/Storefront.xcconfig" ]]; then
-        cp "$1/Storefront.xcconfig.example" "$1/Storefront.xcconfig"
+        echo "Missing Storefront.xcconfig for $1. Run dev up from the repo root."
+        exit 1
     fi
 
     # Create an empty entitlements file if it doesn't already exist
     if [[ ! -f "$1/$1/$1.entitlements" ]]; then
-        echo $EMPTY_ENTITLEMENTS > "$1/$1/$1.entitlements"
+        printf '%s\n' "$EMPTY_ENTITLEMENTS" > "$1/$1/$1.entitlements"
     else
         echo "Entitlements file already exists for $1 project."
     fi
 
-    $SCRIPT_DIR/xcode_run "clean build" $1 
+    "$SCRIPT_DIR/xcode_run" "clean build" "$1"
 }
 
 build_app MobileBuyIntegration
diff --git a/platforms/swift/Scripts/ensure_storefront_config b/platforms/swift/Scripts/ensure_storefront_config
index e7dc924b..c87a9047 100755
--- a/platforms/swift/Scripts/ensure_storefront_config
+++ b/platforms/swift/Scripts/ensure_storefront_config
@@ -1,14 +1,7 @@
- #!/usr/bin/env bash
+#!/usr/bin/env bash
 
 set -e
 
-if [ ! -f "./samples/MobileBuyIntegration/Storefront.xcconfig" ]; then
-  echo """
-    Error: Your project is missing a Storefront.xcconfig file.
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
-    Replace the STOREFRONT_DOMAIN and STOREFRONT_ACCESS_TOKEN environment variables in \"samples/MobileBuyIntegration/Storefront.xcconfig.example\" and rename the file to \"Storefront.xcconfig\" to get started.
-
-    If you don't have a Shopify app setup, go to https://admin.shopify.com/settings/apps/development to configure an application for your storefront which will give you access to the Storefront API.
-  """
-  exit 1;
-fi
+exec "$SCRIPT_DIR/../../../scripts/setup_storefront_env" "$@"
diff --git a/scripts/setup_storefront_env b/scripts/setup_storefront_env
new file mode 100755
index 00000000..77d5c939
--- /dev/null
+++ b/scripts/setup_storefront_env
@@ -0,0 +1,749 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+
+ROOT_ENV="${ROOT_DIR}/.env"
+ANDROID_ENV="${ROOT_DIR}/platforms/android/samples/MobileBuyIntegration/.env"
+SWIFT_MOBILE_XCCONFIG="${ROOT_DIR}/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig"
+SWIFT_ACCELERATED_XCCONFIG="${ROOT_DIR}/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig"
+REACT_NATIVE_ENV="${ROOT_DIR}/platforms/react-native/sample/.env"
+
+DEFAULT_API_VERSION="2026-04"
+DEFAULT_CUSTOMER_ACCOUNT_API_VERSION="2026-04"
+
+usage() {
+  cat <<EOF
+Usage: scripts/setup_storefront_env [--check] [--skip-optional-prompts|--prompt-optional]
+
+Creates or checks sample app storefront configuration from the repo-root .env.
+This command prints file paths and status only; it never prints configured values.
+
+By default, interactive setup prompts for missing optional Apple Pay and Customer
+Account API values. Use --skip-optional-prompts for automation paths that should
+only prompt for required storefront values.
+EOF
+}
+
+mode="sync"
+prompt_optional_values="true"
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --check)
+      mode="check"
+      ;;
+    --skip-optional-prompts)
+      prompt_optional_values="false"
+      ;;
+    --prompt-optional)
+      prompt_optional_values="true"
+      ;;
+    -h | --help)
+      usage
+      exit 0
+      ;;
+    *)
+      usage >&2
+      exit 1
+      ;;
+  esac
+  shift
+done
+
+trim() {
+  sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//'
+}
+
+strip_outer_quotes() {
+  local value
+  value="$(printf '%s' "$1" | trim)"
+
+  case "$value" in
+    \"*\")
+      value="${value#\"}"
+      value="${value%\"}"
+      ;;
+    \'*\')
+      value="${value#\'}"
+      value="${value%\'}"
+      ;;
+  esac
+
+  printf '%s' "$value"
+}
+
+read_env_value() {
+  local key="$1"
+  local file="$2"
+  local raw_value
+
+  if [[ ! -f "$file" ]]; then
+    return 0
+  fi
+
+  raw_value="$(awk -v key="$key" '
+    /^[[:space:]]*#/ || /^[[:space:]]*\/\// || /^[[:space:]]*$/ { next }
+    $0 !~ /=/ { next }
+    {
+      line = $0
+      sub(/^[[:space:]]*/, "", line)
+      candidate = line
+      sub(/=.*/, "", candidate)
+      sub(/[[:space:]]*$/, "", candidate)
+      if (candidate == key) {
+        value = substr(line, index(line, "=") + 1)
+        print value
+        exit
+      }
+    }
+  ' "$file")"
+
+  strip_outer_quotes "$raw_value"
+}
+
+env_has_key() {
+  local key="$1"
+  local file="$2"
+
+  [[ -f "$file" ]] || return 1
+
+  awk -v key="$key" '
+    /^[[:space:]]*#/ || /^[[:space:]]*\/\// || /^[[:space:]]*$/ { next }
+    $0 !~ /=/ { next }
+    {
+      line = $0
+      sub(/^[[:space:]]*/, "", line)
+      candidate = line
+      sub(/=.*/, "", candidate)
+      sub(/[[:space:]]*$/, "", candidate)
+      if (candidate == key) {
+        found = 1
+        exit
+      }
+    }
+    END { exit found ? 0 : 1 }
+  ' "$file"
+}
+
+is_missing_required_value() {
+  local value="$1"
+
+  [[ -z "$value" ]] ||
+    [[ "$value" == \<*\> ]] ||
+    [[ "$value" == "YOUR_"* ]] ||
+    [[ "$value" == "your-store.myshopify.com" ]] ||
+    [[ "$value" == "your-public-storefront-access-token" ]]
+}
+
+is_placeholder_value() {
+  local value="$1"
+
+  [[ "$value" == \<*\> ]] ||
+    [[ "$value" == "YOUR_"* ]] ||
+    [[ "$value" == "INSERT_"* ]] ||
+    [[ "$value" == *"INSERT_"* ]] ||
+    [[ "$value" == "your-store.myshopify.com" ]] ||
+    [[ "$value" == "your-public-storefront-access-token" ]]
+}
+
+env_fallback() {
+  local key="$1"
+  printf '%s' "${!key:-}"
+}
+
+first_config_value() {
+  local value
+  for value in "$@"; do
+    if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+      printf '%s' "$value"
+      return 0
+    fi
+  done
+}
+
+required_config_value() {
+  local key="$1"
+  local file_value
+  local env_value
+
+  file_value="$(read_env_value "$key" "$ROOT_ENV")"
+  if ! is_missing_required_value "$file_value"; then
+    printf '%s' "$file_value"
+    return 0
+  fi
+
+  env_value="$(env_fallback "$key")"
+  if ! is_missing_required_value "$env_value"; then
+    printf '%s' "$env_value"
+  fi
+}
+
+root_or_source_value() {
+  local key="$1"
+  shift
+  local root_value
+
+  if env_has_key "$key" "$ROOT_ENV"; then
+    root_value="$(read_env_value "$key" "$ROOT_ENV")"
+    if ! is_placeholder_value "$root_value"; then
+      printf '%s' "$root_value"
+      return 0
+    fi
+  fi
+
+  first_config_value "$@"
+}
+
+root_or_source_nonempty_value() {
+  local key="$1"
+  shift
+  local root_value
+
+  if env_has_key "$key" "$ROOT_ENV"; then
+    root_value="$(read_env_value "$key" "$ROOT_ENV")"
+    if [[ -n "$root_value" ]] && ! is_placeholder_value "$root_value"; then
+      printf '%s' "$root_value"
+      return 0
+    fi
+  fi
+
+  first_config_value "$@"
+}
+
+root_has_canonical_keys() {
+  local key
+
+  for key in \
+    STOREFRONT_DOMAIN \
+    STOREFRONT_ACCESS_TOKEN \
+    STOREFRONT_MERCHANT_IDENTIFIER \
+    API_VERSION \
+    CUSTOMER_ACCOUNT_API_CLIENT_ID \
+    CUSTOMER_ACCOUNT_API_SHOP_ID \
+    CUSTOMER_ACCOUNT_API_VERSION \
+    EMAIL \
+    ADDRESS_1 \
+    ADDRESS_2 \
+    CITY \
+    COMPANY \
+    COUNTRY \
+    FIRST_NAME \
+    LAST_NAME \
+    PROVINCE \
+    ZIP \
+    PHONE; do
+    env_has_key "$key" "$ROOT_ENV" || return 1
+  done
+}
+
+customer_account_api_version_needs_default() {
+  local value
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_VERSION "$ROOT_ENV")"
+  [[ -z "$value" ]] || is_placeholder_value "$value"
+}
+
+optional_values_need_prompt() {
+  [[ "$prompt_optional_values" == "true" ]] &&
+    [[ -t 0 ]] &&
+    (
+      [[ -z "$STOREFRONT_MERCHANT_IDENTIFIER_VALUE" ]] ||
+        [[ -z "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE" ]] ||
+        [[ -z "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE" ]]
+    )
+}
+
+fill_optional_values_from_environment() {
+  local value
+  local updated="false"
+
+  if [[ -z "$STOREFRONT_MERCHANT_IDENTIFIER_VALUE" ]]; then
+    value="$(env_fallback STOREFRONT_MERCHANT_IDENTIFIER)"
+    if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+      STOREFRONT_MERCHANT_IDENTIFIER_VALUE="$value"
+      updated="true"
+    fi
+  fi
+
+  if [[ -z "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE" ]]; then
+    value="$(env_fallback CUSTOMER_ACCOUNT_API_CLIENT_ID)"
+    if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+      CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE="$value"
+      updated="true"
+    fi
+  fi
+
+  if [[ -z "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE" ]]; then
+    value="$(env_fallback CUSTOMER_ACCOUNT_API_SHOP_ID)"
+    if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+      CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE="$value"
+      updated="true"
+    fi
+  fi
+
+  [[ "$updated" == "true" ]]
+}
+
+derive_customer_account_api_shop_id() {
+  local value
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_SHOP_ID "$ANDROID_ENV")"
+  if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+    printf '%s' "$value"
+    return 0
+  fi
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_REDIRECT_URI "$ANDROID_ENV")"
+  case "$value" in
+    shop.*.app://callback)
+      value="${value#shop.}"
+      value="${value%.app://callback}"
+      if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+        printf '%s' "$value"
+        return 0
+      fi
+      ;;
+  esac
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_AUTH_BASE_URL "$ANDROID_ENV")"
+  case "$value" in
+    https://shopify.com/authentication/*)
+      value="${value#https://shopify.com/authentication/}"
+      if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+        printf '%s' "$value"
+        return 0
+      fi
+      ;;
+  esac
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL "$ANDROID_ENV")"
+  case "$value" in
+    https://shopify.com/*/account/customer/api/*/graphql)
+      value="${value#https://shopify.com/}"
+      value="${value%%/account/customer/api/*}"
+      if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+        printf '%s' "$value"
+      fi
+      ;;
+  esac
+}
+
+derive_customer_account_api_version() {
+  local value
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_VERSION "$ANDROID_ENV")"
+  if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+    printf '%s' "$value"
+    return 0
+  fi
+
+  value="$(read_env_value CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL "$ANDROID_ENV")"
+  case "$value" in
+    https://shopify.com/*/account/customer/api/*/graphql)
+      value="${value#*/account/customer/api/}"
+      value="${value%/graphql}"
+      if [[ -n "$value" ]] && ! is_placeholder_value "$value"; then
+        printf '%s' "$value"
+      fi
+      ;;
+  esac
+}
+
+prompt_required() {
+  local label="$1"
+  local value=""
+
+  if [[ ! -t 0 ]]; then
+    echo "Storefront configuration requires interactive setup. Run scripts/setup_storefront_env in a terminal." >&2
+    exit 1
+  fi
+
+  while [[ -z "$value" ]]; do
+    read -r -s -p "${label}: " value
+    echo
+    value="$(printf '%s' "$value" | trim)"
+  done
+
+  printf '%s' "$value"
+}
+
+prompt_optional() {
+  local label="$1"
+  local value=""
+
+  if [[ ! -t 0 ]]; then
+    return 0
+  fi
+
+  read -r -s -p "${label} (optional, press Enter to skip): " value
+  echo
+  printf '%s' "$value" | trim
+}
+
+load_values() {
+  STOREFRONT_DOMAIN_VALUE="$(first_config_value \
+    "$(required_config_value STOREFRONT_DOMAIN)" \
+    "$(read_env_value STOREFRONT_DOMAIN "$ANDROID_ENV")" \
+    "$(read_env_value STOREFRONT_DOMAIN "$REACT_NATIVE_ENV")" \
+    "$(read_env_value STOREFRONT_DOMAIN "$SWIFT_MOBILE_XCCONFIG")" \
+    "$(read_env_value STOREFRONT_DOMAIN "$SWIFT_ACCELERATED_XCCONFIG")")"
+
+  STOREFRONT_ACCESS_TOKEN_VALUE="$(first_config_value \
+    "$(required_config_value STOREFRONT_ACCESS_TOKEN)" \
+    "$(read_env_value STOREFRONT_ACCESS_TOKEN "$ANDROID_ENV")" \
+    "$(read_env_value STOREFRONT_ACCESS_TOKEN "$REACT_NATIVE_ENV")" \
+    "$(read_env_value STOREFRONT_ACCESS_TOKEN "$SWIFT_MOBILE_XCCONFIG")" \
+    "$(read_env_value STOREFRONT_ACCESS_TOKEN "$SWIFT_ACCELERATED_XCCONFIG")")"
+
+  API_VERSION_VALUE="$(first_config_value \
+    "$(read_env_value API_VERSION "$ROOT_ENV")" \
+    "$(read_env_value STOREFRONT_VERSION "$ROOT_ENV")" \
+    "$(env_fallback API_VERSION)" \
+    "$(env_fallback STOREFRONT_VERSION)" \
+    "$(read_env_value API_VERSION "$ANDROID_ENV")" \
+    "$(read_env_value API_VERSION "$REACT_NATIVE_ENV")" \
+    "$(read_env_value STOREFRONT_VERSION "$REACT_NATIVE_ENV")" \
+    "$(read_env_value API_VERSION "$SWIFT_MOBILE_XCCONFIG")" \
+    "$(read_env_value API_VERSION "$SWIFT_ACCELERATED_XCCONFIG")" \
+    "$DEFAULT_API_VERSION")"
+
+  STOREFRONT_MERCHANT_IDENTIFIER_VALUE="$(root_or_source_value STOREFRONT_MERCHANT_IDENTIFIER \
+    "$(env_fallback STOREFRONT_MERCHANT_IDENTIFIER)" \
+    "$(read_env_value STOREFRONT_MERCHANT_IDENTIFIER "$ANDROID_ENV")" \
+    "$(read_env_value STOREFRONT_MERCHANT_IDENTIFIER "$REACT_NATIVE_ENV")" \
+    "$(read_env_value STOREFRONT_MERCHANT_IDENTIFIER "$SWIFT_MOBILE_XCCONFIG")")"
+
+  CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE="$(root_or_source_value CUSTOMER_ACCOUNT_API_CLIENT_ID \
+    "$(env_fallback CUSTOMER_ACCOUNT_API_CLIENT_ID)" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_CLIENT_ID "$ANDROID_ENV")" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_CLIENT_ID "$REACT_NATIVE_ENV")" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_CLIENT_ID "$SWIFT_MOBILE_XCCONFIG")")"
+
+  CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE="$(root_or_source_value CUSTOMER_ACCOUNT_API_SHOP_ID \
+    "$(env_fallback CUSTOMER_ACCOUNT_API_SHOP_ID)" \
+    "$(derive_customer_account_api_shop_id)" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_SHOP_ID "$REACT_NATIVE_ENV")" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_SHOP_ID "$SWIFT_MOBILE_XCCONFIG")")"
+
+  CUSTOMER_ACCOUNT_API_VERSION_VALUE="$(root_or_source_nonempty_value CUSTOMER_ACCOUNT_API_VERSION \
+    "$(env_fallback CUSTOMER_ACCOUNT_API_VERSION)" \
+    "$(derive_customer_account_api_version)" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_VERSION "$REACT_NATIVE_ENV")" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_VERSION "$SWIFT_MOBILE_XCCONFIG")" \
+    "$(read_env_value CUSTOMER_ACCOUNT_API_VERSION "$SWIFT_ACCELERATED_XCCONFIG")" \
+    "$DEFAULT_CUSTOMER_ACCOUNT_API_VERSION")"
+
+  EMAIL_VALUE="$(root_or_source_value EMAIL "$(env_fallback EMAIL)" "$(read_env_value EMAIL "$ANDROID_ENV")" "$(read_env_value PREFILL_EMAIL "$ANDROID_ENV")" "$(read_env_value EMAIL "$REACT_NATIVE_ENV")" "$(read_env_value EMAIL "$SWIFT_MOBILE_XCCONFIG")" "checkout-kit@example.com")"
+  ADDRESS_1_VALUE="$(root_or_source_value ADDRESS_1 "$(env_fallback ADDRESS_1)" "$(read_env_value ADDRESS_1 "$REACT_NATIVE_ENV")" "$(read_env_value ADDRESS_1 "$SWIFT_MOBILE_XCCONFIG")" "650 King Street")"
+  ADDRESS_2_VALUE="$(root_or_source_value ADDRESS_2 "$(env_fallback ADDRESS_2)" "$(read_env_value ADDRESS_2 "$REACT_NATIVE_ENV")" "$(read_env_value ADDRESS_2 "$SWIFT_MOBILE_XCCONFIG")" "Shopify HQ")"
+  CITY_VALUE="$(root_or_source_value CITY "$(env_fallback CITY)" "$(read_env_value CITY "$REACT_NATIVE_ENV")" "$(read_env_value CITY "$SWIFT_MOBILE_XCCONFIG")" "Toronto")"
+  COMPANY_VALUE="$(root_or_source_value COMPANY "$(env_fallback COMPANY)" "$(read_env_value COMPANY "$REACT_NATIVE_ENV")" "$(read_env_value COMPANY "$SWIFT_MOBILE_XCCONFIG")" "Shopify")"
+  COUNTRY_VALUE="$(root_or_source_value COUNTRY "$(env_fallback COUNTRY)" "$(read_env_value COUNTRY "$REACT_NATIVE_ENV")" "$(read_env_value COUNTRY "$SWIFT_MOBILE_XCCONFIG")" "CA")"
+  FIRST_NAME_VALUE="$(root_or_source_value FIRST_NAME "$(env_fallback FIRST_NAME)" "$(read_env_value FIRST_NAME "$REACT_NATIVE_ENV")" "$(read_env_value FIRST_NAME "$SWIFT_MOBILE_XCCONFIG")" "Evelyn")"
+  LAST_NAME_VALUE="$(root_or_source_value LAST_NAME "$(env_fallback LAST_NAME)" "$(read_env_value LAST_NAME "$REACT_NATIVE_ENV")" "$(read_env_value LAST_NAME "$SWIFT_MOBILE_XCCONFIG")" "Hartley")"
+  PROVINCE_VALUE="$(root_or_source_value PROVINCE "$(env_fallback PROVINCE)" "$(read_env_value PROVINCE "$REACT_NATIVE_ENV")" "$(read_env_value PROVINCE "$SWIFT_MOBILE_XCCONFIG")" "ON")"
+  ZIP_VALUE="$(root_or_source_value ZIP "$(env_fallback ZIP)" "$(read_env_value ZIP "$REACT_NATIVE_ENV")" "$(read_env_value ZIP "$SWIFT_MOBILE_XCCONFIG")" "M5V 1M7")"
+  PHONE_VALUE="$(root_or_source_value PHONE "$(env_fallback PHONE)" "$(read_env_value PHONE "$ANDROID_ENV")" "$(read_env_value PREFILL_PHONE "$ANDROID_ENV")" "$(read_env_value PHONE "$REACT_NATIVE_ENV")" "$(read_env_value PHONE "$SWIFT_MOBILE_XCCONFIG")" "+14165550100")"
+}
+
+collect_missing_values() {
+  fill_optional_values_from_environment || true
+
+  if is_missing_required_value "$STOREFRONT_DOMAIN_VALUE"; then
+    STOREFRONT_DOMAIN_VALUE="$(prompt_required "Storefront domain")"
+  fi
+
+  if is_missing_required_value "$STOREFRONT_ACCESS_TOKEN_VALUE"; then
+    STOREFRONT_ACCESS_TOKEN_VALUE="$(prompt_required "Storefront access token")"
+  fi
+
+  if [[ "$prompt_optional_values" == "true" && -z "$STOREFRONT_MERCHANT_IDENTIFIER_VALUE" ]]; then
+    STOREFRONT_MERCHANT_IDENTIFIER_VALUE="$(prompt_optional "Apple Pay merchant identifier")"
+  fi
+
+  if [[ "$prompt_optional_values" == "true" && -z "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE" ]]; then
+    CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE="$(prompt_optional "Customer Account API client ID")"
+  fi
+
+  if [[ "$prompt_optional_values" == "true" && -z "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE" ]]; then
+    CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE="$(prompt_optional "Customer Account API shop ID")"
+  fi
+}
+
+write_env_assignment() {
+  printf '%s=%s\n' "$1" "$2"
+}
+
+write_quoted_env_assignment() {
+  local value="${2//\"/\\\"}"
+  printf '%s="%s"\n' "$1" "$value"
+}
+
+write_xcconfig_assignment() {
+  printf '%s = %s\n' "$1" "$2"
+}
+
+generate_root_env() {
+  cat <<EOF
+# Checkout Kit sample storefront configuration.
+# Edit this file, then run scripts/setup_storefront_env to sync platform config.
+# Do not commit real values from this file.
+
+# Storefront details
+EOF
+  write_env_assignment STOREFRONT_DOMAIN "$STOREFRONT_DOMAIN_VALUE"
+  write_env_assignment STOREFRONT_ACCESS_TOKEN "$STOREFRONT_ACCESS_TOKEN_VALUE"
+  echo "# Optional Apple Pay merchant identifier used by accelerated checkout flows."
+  write_env_assignment STOREFRONT_MERCHANT_IDENTIFIER "$STOREFRONT_MERCHANT_IDENTIFIER_VALUE"
+  cat <<EOF
+
+# Storefront API version
+EOF
+  write_env_assignment API_VERSION "$API_VERSION_VALUE"
+  cat <<EOF
+
+# Customer Account API (optional)
+EOF
+  write_env_assignment CUSTOMER_ACCOUNT_API_CLIENT_ID "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE"
+  write_env_assignment CUSTOMER_ACCOUNT_API_SHOP_ID "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE"
+  write_env_assignment CUSTOMER_ACCOUNT_API_VERSION "$CUSTOMER_ACCOUNT_API_VERSION_VALUE"
+  cat <<EOF
+
+# Buyer identity defaults used by sample apps
+EOF
+  write_env_assignment EMAIL "$EMAIL_VALUE"
+  write_env_assignment ADDRESS_1 "$ADDRESS_1_VALUE"
+  write_env_assignment ADDRESS_2 "$ADDRESS_2_VALUE"
+  write_env_assignment CITY "$CITY_VALUE"
+  write_env_assignment COMPANY "$COMPANY_VALUE"
+  write_env_assignment COUNTRY "$COUNTRY_VALUE"
+  write_env_assignment FIRST_NAME "$FIRST_NAME_VALUE"
+  write_env_assignment LAST_NAME "$LAST_NAME_VALUE"
+  write_env_assignment PROVINCE "$PROVINCE_VALUE"
+  write_env_assignment ZIP "$ZIP_VALUE"
+  write_env_assignment PHONE "$PHONE_VALUE"
+}
+
+generate_platform_env_header() {
+  cat <<EOF
+# Generated from repo-root .env by scripts/setup_storefront_env.
+# Do not edit directly; update .env and rerun scripts/setup_storefront_env.
+
+EOF
+}
+
+generate_xcconfig_header() {
+  cat <<EOF
+// Generated from repo-root .env by scripts/setup_storefront_env.
+// Do not edit directly; update .env and rerun scripts/setup_storefront_env.
+
+EOF
+}
+
+generate_android_env() {
+  generate_platform_env_header
+  write_env_assignment STOREFRONT_DOMAIN "$STOREFRONT_DOMAIN_VALUE"
+  write_env_assignment STOREFRONT_ACCESS_TOKEN "$STOREFRONT_ACCESS_TOKEN_VALUE"
+  write_env_assignment API_VERSION "$API_VERSION_VALUE"
+
+  cat <<EOF
+
+# Customer Account API (optional)
+EOF
+  write_env_assignment CUSTOMER_ACCOUNT_API_CLIENT_ID "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE"
+  write_env_assignment CUSTOMER_ACCOUNT_API_SHOP_ID "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE"
+  write_env_assignment CUSTOMER_ACCOUNT_API_VERSION "$CUSTOMER_ACCOUNT_API_VERSION_VALUE"
+
+  if [[ -n "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE" && -n "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE" ]]; then
+    write_env_assignment CUSTOMER_ACCOUNT_API_REDIRECT_URI "shop.${CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE}.app://callback"
+    write_env_assignment CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL "https://shopify.com/${CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE}/account/customer/api/${CUSTOMER_ACCOUNT_API_VERSION_VALUE}/graphql"
+    write_env_assignment CUSTOMER_ACCOUNT_API_AUTH_BASE_URL "https://shopify.com/authentication/${CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE}"
+  fi
+
+  cat <<EOF
+
+# Buyer identity defaults
+EOF
+  write_env_assignment EMAIL "$EMAIL_VALUE"
+  write_env_assignment PHONE "$PHONE_VALUE"
+}
+
+generate_react_native_env() {
+  generate_platform_env_header
+  write_quoted_env_assignment STOREFRONT_DOMAIN "$STOREFRONT_DOMAIN_VALUE"
+  write_quoted_env_assignment STOREFRONT_ACCESS_TOKEN "$STOREFRONT_ACCESS_TOKEN_VALUE"
+  write_quoted_env_assignment STOREFRONT_MERCHANT_IDENTIFIER "$STOREFRONT_MERCHANT_IDENTIFIER_VALUE"
+  write_quoted_env_assignment API_VERSION "$API_VERSION_VALUE"
+
+  cat <<EOF
+
+# Buyer identity defaults
+EOF
+  write_quoted_env_assignment EMAIL "$EMAIL_VALUE"
+  write_quoted_env_assignment ADDRESS_1 "$ADDRESS_1_VALUE"
+  write_quoted_env_assignment ADDRESS_2 "$ADDRESS_2_VALUE"
+  write_quoted_env_assignment CITY "$CITY_VALUE"
+  write_quoted_env_assignment COMPANY "$COMPANY_VALUE"
+  write_quoted_env_assignment COUNTRY "$COUNTRY_VALUE"
+  write_quoted_env_assignment FIRST_NAME "$FIRST_NAME_VALUE"
+  write_quoted_env_assignment LAST_NAME "$LAST_NAME_VALUE"
+  write_quoted_env_assignment PROVINCE "$PROVINCE_VALUE"
+  write_quoted_env_assignment ZIP "$ZIP_VALUE"
+  write_quoted_env_assignment PHONE "$PHONE_VALUE"
+
+  cat <<EOF
+
+# Customer Account API (optional)
+EOF
+  write_quoted_env_assignment CUSTOMER_ACCOUNT_API_CLIENT_ID "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE"
+  write_quoted_env_assignment CUSTOMER_ACCOUNT_API_SHOP_ID "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE"
+}
+
+generate_swift_mobile_xcconfig() {
+  generate_xcconfig_header
+  write_xcconfig_assignment STOREFRONT_DOMAIN "$STOREFRONT_DOMAIN_VALUE"
+  write_xcconfig_assignment STOREFRONT_ACCESS_TOKEN "$STOREFRONT_ACCESS_TOKEN_VALUE"
+  write_xcconfig_assignment STOREFRONT_MERCHANT_IDENTIFIER "$STOREFRONT_MERCHANT_IDENTIFIER_VALUE"
+  write_xcconfig_assignment API_VERSION "$API_VERSION_VALUE"
+
+  cat <<EOF
+
+// Customer Account API (optional)
+EOF
+  write_xcconfig_assignment CUSTOMER_ACCOUNT_API_CLIENT_ID "$CUSTOMER_ACCOUNT_API_CLIENT_ID_VALUE"
+  write_xcconfig_assignment CUSTOMER_ACCOUNT_API_SHOP_ID "$CUSTOMER_ACCOUNT_API_SHOP_ID_VALUE"
+
+  cat <<EOF
+
+// Buyer identity defaults
+EOF
+  write_xcconfig_assignment EMAIL "$EMAIL_VALUE"
+  write_xcconfig_assignment ADDRESS_1 "$ADDRESS_1_VALUE"
+  write_xcconfig_assignment ADDRESS_2 "$ADDRESS_2_VALUE"
+  write_xcconfig_assignment CITY "$CITY_VALUE"
+  write_xcconfig_assignment COMPANY "$COMPANY_VALUE"
+  write_xcconfig_assignment COUNTRY "$COUNTRY_VALUE"
+  write_xcconfig_assignment FIRST_NAME "$FIRST_NAME_VALUE"
+  write_xcconfig_assignment LAST_NAME "$LAST_NAME_VALUE"
+  write_xcconfig_assignment PROVINCE "$PROVINCE_VALUE"
+  write_xcconfig_assignment ZIP "$ZIP_VALUE"
+  write_xcconfig_assignment PHONE "$PHONE_VALUE"
+}
+
+generate_swift_accelerated_xcconfig() {
+  generate_xcconfig_header
+  write_xcconfig_assignment STOREFRONT_DOMAIN "$STOREFRONT_DOMAIN_VALUE"
+  write_xcconfig_assignment STOREFRONT_ACCESS_TOKEN "$STOREFRONT_ACCESS_TOKEN_VALUE"
+  write_xcconfig_assignment API_VERSION "$API_VERSION_VALUE"
+}
+
+ensure_root_env() {
+  load_values
+
+  if [[ "$mode" == "check" ]]; then
+    if [[ ! -f "$ROOT_ENV" ]]; then
+      echo "Missing storefront configuration: .env" >&2
+      exit 1
+    fi
+
+    if is_missing_required_value "$(read_env_value STOREFRONT_DOMAIN "$ROOT_ENV")" ||
+      is_missing_required_value "$(read_env_value STOREFRONT_ACCESS_TOKEN "$ROOT_ENV")"; then
+      echo "Root .env is missing required storefront configuration." >&2
+      exit 1
+    fi
+
+    if ! root_has_canonical_keys; then
+      echo "Root .env is missing canonical storefront configuration keys." >&2
+      exit 1
+    fi
+
+    if customer_account_api_version_needs_default; then
+      echo "Root .env has a blank Customer Account API version." >&2
+      exit 1
+    fi
+
+    return 0
+  fi
+
+  local root_needs_write="false"
+  if [[ ! -f "$ROOT_ENV" ]]; then
+    root_needs_write="true"
+    echo "Creating root storefront configuration at .env."
+  elif is_missing_required_value "$(read_env_value STOREFRONT_DOMAIN "$ROOT_ENV")" ||
+    is_missing_required_value "$(read_env_value STOREFRONT_ACCESS_TOKEN "$ROOT_ENV")"; then
+    root_needs_write="true"
+    echo "Updating root storefront configuration at .env."
+  elif ! root_has_canonical_keys; then
+    root_needs_write="true"
+    echo "Normalizing root storefront configuration at .env."
+  elif customer_account_api_version_needs_default; then
+    root_needs_write="true"
+    echo "Normalizing root storefront configuration at .env."
+  fi
+
+  if [[ "$root_needs_write" == "true" ]]; then
+    collect_missing_values
+    generate_root_env >"$ROOT_ENV"
+  elif fill_optional_values_from_environment; then
+    echo "Updating optional storefront configuration at .env."
+    generate_root_env >"$ROOT_ENV"
+  elif optional_values_need_prompt; then
+    echo "Updating optional storefront configuration at .env."
+    collect_missing_values
+    generate_root_env >"$ROOT_ENV"
+  fi
+
+  load_values
+}
+
+write_generated_files() {
+  generate_android_env >"$ANDROID_ENV"
+  generate_swift_mobile_xcconfig >"$SWIFT_MOBILE_XCCONFIG"
+  generate_swift_accelerated_xcconfig >"$SWIFT_ACCELERATED_XCCONFIG"
+  generate_react_native_env >"$REACT_NATIVE_ENV"
+
+  echo "Synced sample app storefront configuration files."
+}
+
+check_generated_file() {
+  local path="$1"
+  local generator="$2"
+  local expected
+
+  expected="$(mktemp)"
+  "$generator" >"$expected"
+
+  if [[ ! -f "$path" ]] || ! cmp -s "$path" "$expected"; then
+    rm -f "$expected"
+    echo "Missing or stale storefront configuration: ${path#"$ROOT_DIR/"}" >&2
+    return 1
+  fi
+
+  rm -f "$expected"
+  return 0
+}
+
+check_generated_files() {
+  local failed="false"
+
+  check_generated_file "$ANDROID_ENV" generate_android_env || failed="true"
+  check_generated_file "$SWIFT_MOBILE_XCCONFIG" generate_swift_mobile_xcconfig || failed="true"
+  check_generated_file "$SWIFT_ACCELERATED_XCCONFIG" generate_swift_accelerated_xcconfig || failed="true"
+  check_generated_file "$REACT_NATIVE_ENV" generate_react_native_env || failed="true"
+
+  if [[ "$failed" == "true" ]]; then
+    exit 1
+  fi
+
+  echo "Sample app storefront configuration is up to date."
+}
+
+ensure_root_env
+
+if [[ "$mode" == "check" ]]; then
+  check_generated_files
+else
+  write_generated_files
+fi
diff --git a/scripts/test_setup_storefront_env b/scripts/test_setup_storefront_env
new file mode 100755
index 00000000..698bbceb
--- /dev/null
+++ b/scripts/test_setup_storefront_env
@@ -0,0 +1,278 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+
+fixtures=()
+
+cleanup() {
+  local fixture
+  if [[ "${#fixtures[@]}" -eq 0 ]]; then
+    return
+  fi
+
+  for fixture in "${fixtures[@]}"; do
+    rm -rf "$fixture"
+  done
+}
+
+trap cleanup EXIT
+
+fail() {
+  echo "test_setup_storefront_env: $1" >&2
+  exit 1
+}
+
+make_fixture() {
+  local fixture
+  fixture="$(mktemp -d "${TMPDIR:-/tmp}/checkout-kit-storefront-env.XXXXXX")"
+  fixtures+=("$fixture")
+
+  mkdir -p \
+    "$fixture/scripts" \
+    "$fixture/platforms/android/samples/MobileBuyIntegration" \
+    "$fixture/platforms/react-native/sample" \
+    "$fixture/platforms/swift/Samples/MobileBuyIntegration" \
+    "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp"
+
+  cp "$REPO_ROOT/scripts/setup_storefront_env" "$fixture/scripts/setup_storefront_env"
+  chmod +x "$fixture/scripts/setup_storefront_env"
+
+  printf '%s\n' "$fixture"
+}
+
+assert_file_exists() {
+  [[ -f "$1" ]] || fail "expected generated file is missing"
+}
+
+assert_contains() {
+  local path="$1"
+  local pattern="$2"
+
+  grep -Fq "$pattern" "$path" || fail "expected generated file content was not found: $path: $pattern"
+}
+
+assert_not_contains() {
+  local path="$1"
+  local pattern="$2"
+
+  if grep -Fq "$pattern" "$path"; then
+    fail "unexpected generated file content was found"
+  fi
+}
+
+assert_output_is_sanitized() {
+  local output_path="$1"
+  local value
+
+  for value in \
+    synthetic-store.example.myshopify.com \
+    synthetic-token \
+    synthetic-merchant \
+    synthetic-client \
+    synthetic-shop \
+    migrated-store.example.myshopify.com \
+    migrated-token \
+    migrated-client \
+    migrated-shop; do
+    if grep -Fq "$value" "$output_path"; then
+      fail "command output included a configured value"
+    fi
+  done
+}
+
+test_sync_and_check() {
+  local fixture output
+  fixture="$(make_fixture)"
+  output="$fixture/output.log"
+
+  STOREFRONT_DOMAIN=synthetic-store.example.myshopify.com \
+    STOREFRONT_ACCESS_TOKEN=synthetic-token \
+    STOREFRONT_MERCHANT_IDENTIFIER=synthetic-merchant \
+    CUSTOMER_ACCOUNT_API_CLIENT_ID=synthetic-client \
+    CUSTOMER_ACCOUNT_API_SHOP_ID=synthetic-shop \
+    "$fixture/scripts/setup_storefront_env" >"$output" 2>&1
+
+  assert_output_is_sanitized "$output"
+  assert_file_exists "$fixture/.env"
+  assert_file_exists "$fixture/platforms/android/samples/MobileBuyIntegration/.env"
+  assert_file_exists "$fixture/platforms/react-native/sample/.env"
+  assert_file_exists "$fixture/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig"
+  assert_file_exists "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig"
+  assert_not_contains "$fixture/platforms/android/samples/MobileBuyIntegration/.env" "STOREFRONT_MERCHANT_IDENTIFIER"
+  assert_not_contains "$fixture/platforms/react-native/sample/.env" "CUSTOMER_ACCOUNT_API_VERSION"
+  assert_not_contains "$fixture/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig" "CUSTOMER_ACCOUNT_API_VERSION"
+  assert_not_contains "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig" "STOREFRONT_MERCHANT_IDENTIFIER"
+  assert_not_contains "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig" "CUSTOMER_ACCOUNT_API_CLIENT_ID"
+  assert_not_contains "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig" "EMAIL"
+
+  "$fixture/scripts/setup_storefront_env" --check >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+
+  awk '
+    /^API_VERSION=/ { print "API_VERSION=2026-01"; next }
+    { print }
+  ' "$fixture/.env" >"$fixture/.env.next"
+  mv "$fixture/.env.next" "$fixture/.env"
+
+  "$fixture/scripts/setup_storefront_env" >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+  assert_contains "$fixture/platforms/android/samples/MobileBuyIntegration/.env" "API_VERSION=2026-01"
+  assert_contains "$fixture/platforms/react-native/sample/.env" "API_VERSION=\"2026-01\""
+  assert_contains "$fixture/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig" "API_VERSION = 2026-01"
+  assert_contains "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig" "API_VERSION = 2026-01"
+
+  printf '%s\n' "stale" >"$fixture/platforms/android/samples/MobileBuyIntegration/.env"
+  if "$fixture/scripts/setup_storefront_env" --check >"$output" 2>&1; then
+    fail "stale generated config passed --check"
+  fi
+  assert_output_is_sanitized "$output"
+}
+
+test_required_values_only() {
+  local fixture output
+  fixture="$(make_fixture)"
+  output="$fixture/output.log"
+
+  STOREFRONT_DOMAIN=synthetic-store.example.myshopify.com \
+    STOREFRONT_ACCESS_TOKEN=synthetic-token \
+    "$fixture/scripts/setup_storefront_env" --skip-optional-prompts >"$output" 2>&1
+
+  assert_output_is_sanitized "$output"
+  assert_file_exists "$fixture/.env"
+  assert_contains "$fixture/.env" "STOREFRONT_MERCHANT_IDENTIFIER="
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_CLIENT_ID="
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_SHOP_ID="
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_VERSION=2026-04"
+  assert_contains "$fixture/platforms/android/samples/MobileBuyIntegration/.env" "CUSTOMER_ACCOUNT_API_VERSION=2026-04"
+  assert_not_contains "$fixture/platforms/react-native/sample/.env" "CUSTOMER_ACCOUNT_API_VERSION"
+  assert_not_contains "$fixture/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig" "CUSTOMER_ACCOUNT_API_VERSION"
+  assert_not_contains "$fixture/platforms/swift/Samples/ShopifyAcceleratedCheckoutsApp/Storefront.xcconfig" "CUSTOMER_ACCOUNT_API_VERSION"
+
+  "$fixture/scripts/setup_storefront_env" --check >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+}
+
+test_optional_sync_updates_blank_optional_values_after_required_setup() {
+  local fixture output
+  fixture="$(make_fixture)"
+  output="$fixture/output.log"
+
+  STOREFRONT_DOMAIN=synthetic-store.example.myshopify.com \
+    STOREFRONT_ACCESS_TOKEN=synthetic-token \
+    "$fixture/scripts/setup_storefront_env" --skip-optional-prompts >"$output" 2>&1
+
+  assert_output_is_sanitized "$output"
+  assert_contains "$fixture/.env" "STOREFRONT_MERCHANT_IDENTIFIER="
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_CLIENT_ID="
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_SHOP_ID="
+
+  STOREFRONT_MERCHANT_IDENTIFIER=synthetic-merchant \
+    CUSTOMER_ACCOUNT_API_CLIENT_ID=synthetic-client \
+    CUSTOMER_ACCOUNT_API_SHOP_ID=synthetic-shop \
+    "$fixture/scripts/setup_storefront_env" >"$output" 2>&1
+
+  assert_output_is_sanitized "$output"
+  assert_contains "$fixture/.env" "STOREFRONT_MERCHANT_IDENTIFIER=synthetic-merchant"
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_CLIENT_ID=synthetic-client"
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_SHOP_ID=synthetic-shop"
+  assert_contains "$fixture/platforms/react-native/sample/.env" "STOREFRONT_MERCHANT_IDENTIFIER=\"synthetic-merchant\""
+  assert_contains "$fixture/platforms/swift/Samples/MobileBuyIntegration/Storefront.xcconfig" "CUSTOMER_ACCOUNT_API_CLIENT_ID = synthetic-client"
+  assert_contains "$fixture/platforms/android/samples/MobileBuyIntegration/.env" "CUSTOMER_ACCOUNT_API_REDIRECT_URI=shop.synthetic-shop.app://callback"
+}
+
+test_normalizes_existing_root_env() {
+  local fixture output
+  fixture="$(make_fixture)"
+  output="$fixture/output.log"
+
+  cat >"$fixture/.env" <<'EOF'
+STOREFRONT_DOMAIN=synthetic-store.example.myshopify.com
+STOREFRONT_ACCESS_TOKEN=synthetic-token
+EOF
+
+  if "$fixture/scripts/setup_storefront_env" --check >"$output" 2>&1; then
+    fail "non-canonical root .env passed --check"
+  fi
+  assert_output_is_sanitized "$output"
+
+  "$fixture/scripts/setup_storefront_env" --skip-optional-prompts >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_VERSION=2026-04"
+  assert_contains "$fixture/.env" "EMAIL=checkout-kit@example.com"
+
+  "$fixture/scripts/setup_storefront_env" --check >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+}
+
+test_blank_customer_account_api_version_defaults() {
+  local fixture output
+  fixture="$(make_fixture)"
+  output="$fixture/output.log"
+
+  cat >"$fixture/.env" <<'EOF'
+STOREFRONT_DOMAIN=synthetic-store.example.myshopify.com
+STOREFRONT_ACCESS_TOKEN=synthetic-token
+STOREFRONT_MERCHANT_IDENTIFIER=
+API_VERSION=2026-04
+CUSTOMER_ACCOUNT_API_CLIENT_ID=synthetic-client
+CUSTOMER_ACCOUNT_API_SHOP_ID=synthetic-shop
+CUSTOMER_ACCOUNT_API_VERSION=
+EMAIL=checkout-kit@example.com
+ADDRESS_1=650 King Street
+ADDRESS_2=Shopify HQ
+CITY=Toronto
+COMPANY=Shopify
+COUNTRY=CA
+FIRST_NAME=Evelyn
+LAST_NAME=Hartley
+PROVINCE=ON
+ZIP=M5V 1M7
+PHONE=+14165550100
+EOF
+
+  "$fixture/scripts/setup_storefront_env" --skip-optional-prompts >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_VERSION=2026-04"
+  assert_contains "$fixture/platforms/android/samples/MobileBuyIntegration/.env" "CUSTOMER_ACCOUNT_API_VERSION=2026-04"
+  assert_contains "$fixture/platforms/android/samples/MobileBuyIntegration/.env" "/2026-04/graphql"
+}
+
+test_migration_from_platform_config() {
+  local fixture output android_env
+  fixture="$(make_fixture)"
+  output="$fixture/output.log"
+  android_env="$fixture/platforms/android/samples/MobileBuyIntegration/.env"
+
+  cat >"$android_env" <<'EOF'
+STOREFRONT_DOMAIN=migrated-store.example.myshopify.com
+STOREFRONT_ACCESS_TOKEN=migrated-token
+CUSTOMER_ACCOUNT_API_CLIENT_ID=migrated-client
+CUSTOMER_ACCOUNT_API_REDIRECT_URI=shop.migrated-shop.app://callback
+CUSTOMER_ACCOUNT_API_GRAPHQL_BASE_URL=https://shopify.com/migrated-shop/account/customer/api/2026-04/graphql
+EMAIL=migrated@example.com
+PHONE=+15555550100
+EOF
+
+  "$fixture/scripts/setup_storefront_env" >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+
+  assert_file_exists "$fixture/.env"
+  assert_contains "$fixture/.env" "API_VERSION=2026-04"
+  assert_contains "$fixture/.env" "CUSTOMER_ACCOUNT_API_VERSION=2026-04"
+
+  "$fixture/scripts/setup_storefront_env" --check >"$output" 2>&1
+  assert_output_is_sanitized "$output"
+}
+
+test_sync_and_check
+test_required_values_only
+test_optional_sync_updates_blank_optional_values_after_required_setup
+test_normalizes_existing_root_env
+test_blank_customer_account_api_version_defaults
+test_migration_from_platform_config
+
+echo "setup_storefront_env synthetic tests passed."