diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-includes/Requests/src/Response/Headers.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/Requests/src/Response/Headers.php	Fri Sep 05 18:40:08 2025 +0200
@@ -0,0 +1,127 @@
+<?php
+/**
+ * Case-insensitive dictionary, suitable for HTTP headers
+ *
+ * @package Requests
+ */
+
+namespace WpOrg\Requests\Response;
+
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Utility\CaseInsensitiveDictionary;
+use WpOrg\Requests\Utility\FilteredIterator;
+
+/**
+ * Case-insensitive dictionary, suitable for HTTP headers
+ *
+ * @package Requests
+ */
+class Headers extends CaseInsensitiveDictionary {
+	/**
+	 * Get the given header
+	 *
+	 * Unlike {@see \WpOrg\Requests\Response\Headers::getValues()}, this returns a string. If there are
+	 * multiple values, it concatenates them with a comma as per RFC2616.
+	 *
+	 * Avoid using this where commas may be used unquoted in values, such as
+	 * Set-Cookie headers.
+	 *
+	 * @param string $offset Name of the header to retrieve.
+	 * @return string|null Header value
+	 */
+	public function offsetGet($offset) {
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		if (!isset($this->data[$offset])) {
+			return null;
+		}
+
+		return $this->flatten($this->data[$offset]);
+	}
+
+	/**
+	 * Set the given item
+	 *
+	 * @param string $offset Item name
+	 * @param string $value Item value
+	 *
+	 * @throws \WpOrg\Requests\Exception On attempting to use dictionary as list (`invalidset`)
+	 */
+	public function offsetSet($offset, $value) {
+		if ($offset === null) {
+			throw new Exception('Object is a dictionary, not a list', 'invalidset');
+		}
+
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		if (!isset($this->data[$offset])) {
+			$this->data[$offset] = [];
+		}
+
+		$this->data[$offset][] = $value;
+	}
+
+	/**
+	 * Get all values for a given header
+	 *
+	 * @param string $offset Name of the header to retrieve.
+	 * @return array|null Header values
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not valid as an array key.
+	 */
+	public function getValues($offset) {
+		if (!is_string($offset) && !is_int($offset)) {
+			throw InvalidArgument::create(1, '$offset', 'string|int', gettype($offset));
+		}
+
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		if (!isset($this->data[$offset])) {
+			return null;
+		}
+
+		return $this->data[$offset];
+	}
+
+	/**
+	 * Flattens a value into a string
+	 *
+	 * Converts an array into a string by imploding values with a comma, as per
+	 * RFC2616's rules for folding headers.
+	 *
+	 * @param string|array $value Value to flatten
+	 * @return string Flattened value
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or an array.
+	 */
+	public function flatten($value) {
+		if (is_string($value)) {
+			return $value;
+		}
+
+		if (is_array($value)) {
+			return implode(',', $value);
+		}
+
+		throw InvalidArgument::create(1, '$value', 'string|array', gettype($value));
+	}
+
+	/**
+	 * Get an iterator for the data
+	 *
+	 * Converts the internally stored values to a comma-separated string if there is more
+	 * than one value for a key.
+	 *
+	 * @return \ArrayIterator
+	 */
+	public function getIterator() {
+		return new FilteredIterator($this->data, [$this, 'flatten']);
+	}
+}