fix: price parsing with currency symbol

src/Pricing/Engine.php

@@ -888,9 +888,10 @@ public static function price_get_addon_total( $price_array ) {
 					continue;
 				}
 
-				$the_price = floatval( $price['price'] );
+				$the_price = self::normalize_price_value( $price['price'] );
+				$qty       = isset( $price['quantity'] ) ? self::normalize_price_value( $price['quantity'] ) : 0;
 
-				$total_addon += ( $the_price * $price['quantity'] );
+				$total_addon += ( $the_price * $qty );
 
 				/*
 				if( $price['type'] == 'quantities' || $price['type'] == 'bulkquantity' ) {
@@ -913,14 +914,42 @@ public static function price_get_cart_fee_total( $price_array ) {
 			foreach ( $price_array as $price ) {
 
 				if ( $price['apply'] == 'cart_fee' ) {
-					$total_cart_fee += $price['price'];
+					$total_cart_fee += self::normalize_price_value( $price['price'] );
 				}
 			}
 		}
 
 		return $total_cart_fee;
 	}
 
+	/**
+	 * Coerce a raw addon price value to a float.
+	 *
+	 * Admins occasionally type currency symbols, spaces, or trailing labels
+	 * into the price field (e.g. "$10", "10 USD"). PHP 8+ raises a fatal
+	 * TypeError if such a value is added to an int, so any value that flows
+	 * into pricing arithmetic must be normalized first.
+	 *
+	 * Delegates to wc_format_decimal() so locale separators (e.g. "1.000,50"
+	 * on European stores) and currency symbols are stripped consistently with
+	 * the rest of WooCommerce's price handling.
+	 *
+	 * @param mixed $value Raw price value as stored in field meta.
+	 * @return float
+	 */
+	private static function normalize_price_value( $value ) {
+
+		if ( is_int( $value ) || is_float( $value ) ) {
+			return (float) $value;
+		}
+
+		if ( ! is_scalar( $value ) ) {
+			return 0.0;
+		}
+
+		return (float) wc_format_decimal( (string) $value );
+	}
+
 	// Get total quantities
 	public static function price_get_total_quantities( $ppom_fields_post, $product_id ) {
 

tests/unit/src/Pricing/test-pricing-engine.php

@@ -144,6 +144,109 @@ public function test_price_get_cart_fee_total_empty() {
 		$this->assertSame( 0, Engine::price_get_cart_fee_total( array() ) );
 	}
 
+	/**
+	 * Regression for #642 — admin saved a cart-fee addon price as "$10".
+	 *
+	 * Prior to the fix, summing the int accumulator with the string "$10" raised
+	 * a fatal TypeError on PHP 8+, taking down the whole cart/checkout. After
+	 * the fix the leading currency symbol is stripped and the value is parsed
+	 * as 10.
+	 *
+	 * @return void
+	 */
+	public function test_price_get_cart_fee_total_normalizes_currency_prefixed_string() {
+		$total = Engine::price_get_cart_fee_total(
+			array(
+				array( 'apply' => 'cart_fee', 'price' => '$10' ),
+				array( 'apply' => 'cart_fee', 'price' => ' 5.50' ),
+				array( 'apply' => 'cart_fee', 'price' => 'USD 2' ),
+			)
+		);
+
+		$this->assertEqualsWithDelta( 17.5, $total, 0.0001 );
+	}
+
+	/**
+	 * Regression for #642 — trailing junk after the number must not crash.
+	 *
+	 * "10abc" was the second example from the bug report. PHP's float cast
+	 * already handles a trailing non-numeric tail, but we assert it here so a
+	 * future refactor cannot silently break the contract.
+	 *
+	 * @return void
+	 */
+	public function test_price_get_cart_fee_total_truncates_trailing_non_numeric() {
+		$total = Engine::price_get_cart_fee_total(
+			array(
+				array( 'apply' => 'cart_fee', 'price' => '10abc' ),
+			)
+		);
+
+		$this->assertEqualsWithDelta( 10.0, $total, 0.0001 );
+	}
+
+	/**
+	 * Non-scalar / unparseable values must degrade to 0 rather than throw.
+	 *
+	 * @return void
+	 */
+	public function test_price_get_cart_fee_total_handles_unparseable_values() {
+		$total = Engine::price_get_cart_fee_total(
+			array(
+				array( 'apply' => 'cart_fee', 'price' => 'free' ),
+				array( 'apply' => 'cart_fee', 'price' => null ),
+				array( 'apply' => 'cart_fee', 'price' => array( 'unexpected' ) ),
+				array( 'apply' => 'cart_fee', 'price' => 7 ),
+			)
+		);
+
+		$this->assertEqualsWithDelta( 7.0, $total, 0.0001 );
+	}
+
+	/**
+	 * Same regression coverage for the addon-apply path so both helpers stay
+	 * symmetric.
+	 *
+	 * @return void
+	 */
+	public function test_price_get_addon_total_normalizes_currency_prefixed_string() {
+		$total = Engine::price_get_addon_total(
+			array(
+				array(
+					'apply'    => 'addon',
+					'price'    => '$10',
+					'quantity' => 2,
+				),
+				array(
+					'apply'    => 'addon',
+					'price'    => '5abc',
+					'quantity' => 1,
+				),
+			)
+		);
+
+		$this->assertEqualsWithDelta( 25.0, $total, 0.0001 );
+	}
+
+	/**
+	 * A non-numeric quantity must not crash the addon sum either.
+	 *
+	 * @return void
+	 */
+	public function test_price_get_addon_total_handles_non_numeric_quantity() {
+		$total = Engine::price_get_addon_total(
+			array(
+				array(
+					'apply'    => 'addon',
+					'price'    => 4,
+					'quantity' => '3x',
+				),
+			)
+		);
+
+		$this->assertEqualsWithDelta( 12.0, $total, 0.0001 );
+	}
+
 	/**
 	 * @return void
 	 */