diff --git a/agents-api.php b/agents-api.php
index 3382ce1..1aa3537 100644
--- a/agents-api.php
+++ b/agents-api.php
@@ -48,6 +48,7 @@
 require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-package-artifacts-registry.php';
 require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-package-artifact-status.php';
 require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-package-artifact-hasher.php';
+require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-workspace-preload-artifact.php';
 require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-package-installed-artifact.php';
 require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-package-update-plan.php';
 require_once AGENTS_API_PATH . 'src/Packages/class-wp-agent-package-update-planner.php';
@@ -84,6 +85,7 @@
 require_once AGENTS_API_PATH . 'src/Registry/register-agents.php';
 require_once AGENTS_API_PATH . 'src/Registry/register-agent-runtime-bundle-importer.php';
 require_once AGENTS_API_PATH . 'src/Packages/register-agent-package-artifacts.php';
+add_action( 'wp_agent_package_artifacts_init', array( 'WP_Agent_Workspace_Preload_Artifact', 'register' ) );
 require_once AGENTS_API_PATH . 'src/Workspace/class-wp-agent-workspace-scope.php';
 require_once AGENTS_API_PATH . 'src/Workspace/class-wp-agent-safe-execution-workspace.php';
 require_once AGENTS_API_PATH . 'src/Workspace/register-safe-execution-workspace.php';
diff --git a/src/Packages/class-wp-agent-workspace-preload-artifact.php b/src/Packages/class-wp-agent-workspace-preload-artifact.php
new file mode 100644
index 0000000..a257934
--- /dev/null
+++ b/src/Packages/class-wp-agent-workspace-preload-artifact.php
@@ -0,0 +1,187 @@
+<?php
+/**
+ * Generic workspace preload package artifact contract.
+ *
+ * @package AgentsAPI
+ */
+
+defined( 'ABSPATH' ) || exit;
+
+if ( ! class_exists( 'WP_Agent_Workspace_Preload_Artifact' ) ) {
+	/**
+	 * Normalizes and validates portable workspace preload artifacts.
+	 */
+	final class WP_Agent_Workspace_Preload_Artifact {
+
+		public const TYPE   = 'agent-runtime/workspace-preload';
+		public const SCHEMA = 'agent-runtime/workspace-preload/v1';
+
+		/**
+		 * Registers the generic workspace preload artifact type.
+		 *
+		 * @return void
+		 */
+		public static function register(): void {
+			wp_register_agent_package_artifact_type(
+				self::TYPE,
+				array(
+					'label'             => 'Workspace preload',
+					'description'       => 'Portable repository declarations for runtimes that can pre-materialize coding workspaces.',
+					'validate_callback' => array( self::class, 'validate' ),
+					'import_callback'   => array( self::class, 'import' ),
+					'meta'              => array(
+						'schema'       => self::SCHEMA,
+						'materializer' => 'runtime',
+					),
+				)
+			);
+		}
+
+		/**
+		 * Validates a workspace preload artifact payload.
+		 *
+		 * @param WP_Agent_Package_Artifact $artifact Artifact declaration.
+		 * @param array<string,mixed>       $context  Consumer context.
+		 * @return array<string,mixed>|WP_Error Normalized contract or validation error.
+		 */
+		public static function validate( WP_Agent_Package_Artifact $artifact, array $context = array() ) {
+			return self::normalized_from_context( $artifact, $context );
+		}
+
+		/**
+		 * Imports a workspace preload artifact as a runtime materialization contract.
+		 *
+		 * Core does not clone, mount, or persist workspaces. Runtime adopters consume
+		 * the returned contract and decide how to materialize repositories safely.
+		 *
+		 * @param WP_Agent_Package_Artifact $artifact Artifact declaration.
+		 * @param array<string,mixed>       $context  Consumer context.
+		 * @return array<string,mixed>|WP_Error Normalized import contract or validation error.
+		 */
+		public static function import( WP_Agent_Package_Artifact $artifact, array $context = array() ) {
+			$contract = self::normalized_from_context( $artifact, $context );
+			if ( is_wp_error( $contract ) ) {
+				return $contract;
+			}
+
+			return array(
+				'status'   => 'materialization-contract',
+				'artifact' => $contract,
+			);
+		}
+
+		/**
+		 * Normalizes raw payload into the stable workspace preload contract.
+		 *
+		 * @param array<string,mixed> $payload Raw payload.
+		 * @return array<string,mixed>|WP_Error Normalized payload or validation error.
+		 */
+		public static function normalize_payload( array $payload ) {
+			$repositories = $payload['repositories'] ?? null;
+			if ( ! is_array( $repositories ) ) {
+				return new WP_Error( 'wp_agent_workspace_preload_repositories_invalid', 'Workspace preload payload requires a repositories array.' );
+			}
+
+			$normalized = array();
+			foreach ( $repositories as $index => $repository ) {
+				if ( ! is_array( $repository ) ) {
+					return new WP_Error( 'wp_agent_workspace_preload_repository_invalid', 'Workspace preload repository entries must be objects.', array( 'index' => $index ) );
+				}
+
+				$name = self::string_value( $repository['name'] ?? '' );
+				$url  = self::string_value( $repository['url'] ?? '' );
+				$ref  = self::string_value( $repository['ref'] ?? '' );
+
+				if ( '' === $name || sanitize_title( $name ) !== $name ) {
+					return new WP_Error( 'wp_agent_workspace_preload_repository_name_invalid', 'Workspace preload repository name must be a non-empty slug.', array( 'index' => $index ) );
+				}
+
+				if ( '' === $url || ! self::is_supported_repository_url( $url ) ) {
+					return new WP_Error( 'wp_agent_workspace_preload_repository_url_invalid', 'Workspace preload repository url must be an HTTPS or SSH Git URL.', array( 'index' => $index ) );
+				}
+
+				$entry = array(
+					'name' => $name,
+					'url'  => $url,
+				);
+
+				if ( '' !== $ref ) {
+					$entry['ref'] = $ref;
+				}
+
+				$normalized[] = $entry;
+			}
+
+			if ( array() === $normalized ) {
+				return new WP_Error( 'wp_agent_workspace_preload_repositories_empty', 'Workspace preload payload requires at least one repository.' );
+			}
+
+			$result = array(
+				'schema'       => self::SCHEMA,
+				'repositories' => $normalized,
+			);
+
+			if ( isset( $payload['meta'] ) && is_array( $payload['meta'] ) ) {
+				$result['meta'] = self::string_keyed_array( $payload['meta'] );
+			}
+
+			return $result;
+		}
+
+		/**
+		 * Extracts and normalizes payload from an artifact callback context.
+		 *
+		 * @param WP_Agent_Package_Artifact $artifact Artifact declaration.
+		 * @param array<string,mixed>       $context  Consumer context.
+		 * @return array<string,mixed>|WP_Error Normalized contract or validation error.
+		 */
+		private static function normalized_from_context( WP_Agent_Package_Artifact $artifact, array $context ) {
+			$target  = is_array( $context['target'] ?? null ) ? self::string_keyed_array( $context['target'] ) : array();
+			$payload = is_array( $context['payload'] ?? null ) ? self::string_keyed_array( $context['payload'] ) : ( is_array( $target['payload'] ?? null ) ? self::string_keyed_array( $target['payload'] ) : array() );
+			if ( array() === $payload ) {
+				return new WP_Error( 'wp_agent_workspace_preload_payload_missing', 'Workspace preload artifact callbacks require a payload array.', array( 'artifact' => $artifact->get_slug() ) );
+			}
+
+			$normalized = self::normalize_payload( $payload );
+			if ( is_wp_error( $normalized ) ) {
+				return $normalized;
+			}
+
+			return array(
+				'type'    => self::TYPE,
+				'slug'    => $artifact->get_slug(),
+				'source'  => $artifact->get_source(),
+				'payload' => $normalized,
+			);
+		}
+
+		private static function is_supported_repository_url( string $url ): bool {
+			return str_starts_with( $url, 'https://' ) || preg_match( '/^git@[A-Za-z0-9._-]+:[A-Za-z0-9._\/-]+\.git$/', $url );
+		}
+
+		private static function string_value( mixed $value ): string {
+			if ( is_scalar( $value ) || $value instanceof Stringable ) {
+				return trim( (string) $value );
+			}
+
+			return '';
+		}
+
+		/**
+		 * @param array<mixed> $values Raw values.
+		 * @return array<string,mixed>
+		 */
+		private static function string_keyed_array( array $values ): array {
+			$prepared = array();
+			foreach ( $values as $key => $value ) {
+				if ( is_string( $key ) ) {
+					$prepared[ $key ] = $value;
+				}
+			}
+
+			return $prepared;
+		}
+
+		private function __construct() {}
+	}
+}
diff --git a/tests/workspace-preload-artifact-smoke.php b/tests/workspace-preload-artifact-smoke.php
new file mode 100644
index 0000000..642a23a
--- /dev/null
+++ b/tests/workspace-preload-artifact-smoke.php
@@ -0,0 +1,102 @@
+<?php
+/**
+ * Pure-PHP smoke test for the workspace preload package artifact contract.
+ *
+ * Run with: php tests/workspace-preload-artifact-smoke.php
+ *
+ * @package AgentsAPI\Tests
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	define( 'ABSPATH', __DIR__ . '/' );
+}
+
+if ( ! class_exists( 'WP_Error' ) ) {
+	class WP_Error {
+		private string $code;
+		private string $message;
+		private $data;
+
+		public function __construct( string $code = '', string $message = '', $data = null ) {
+			$this->code    = $code;
+			$this->message = $message;
+			$this->data    = $data;
+		}
+
+		public function get_error_code(): string {
+			return $this->code;
+		}
+
+		public function get_error_message(): string {
+			return $this->message;
+		}
+
+		public function get_error_data() {
+			return $this->data;
+		}
+	}
+}
+
+$failures = array();
+$passes   = 0;
+
+echo "agents-api-workspace-preload-artifact-smoke\n";
+
+require_once __DIR__ . '/agents-api-smoke-helpers.php';
+agents_api_smoke_require_module();
+do_action( 'init' );
+
+echo "\n[1] Core registers the generic workspace preload artifact type:\n";
+$type = wp_get_agent_package_artifact_type( 'agent-runtime/workspace-preload' );
+agents_api_smoke_assert_equals( true, $type instanceof WP_Agent_Package_Artifact_Type, 'artifact type is registered', $failures, $passes );
+agents_api_smoke_assert_equals( 'agent-runtime/workspace-preload/v1', $type->get_meta()['schema'] ?? '', 'artifact type advertises the stable schema', $failures, $passes );
+
+$artifact = new WP_Agent_Package_Artifact(
+	array(
+		'type'   => 'agent-runtime/workspace-preload',
+		'slug'   => 'review-repos',
+		'source' => 'extensions/agent-runtime/workspace-preload/review-repos.json',
+	)
+);
+
+$payload = array(
+	'repositories' => array(
+		array(
+			'name' => 'static-site-importer',
+			'url'  => 'https://github.com/chubes4/static-site-importer.git',
+		),
+		array(
+			'name' => 'private-runtime',
+			'url'  => 'git@github.a8c.com:Automattic/private-runtime.git',
+			'ref'  => 'trunk',
+		),
+	),
+);
+
+echo "\n[2] Validation normalizes repository preload payloads without materializing them:\n";
+$validated = WP_Agent_Package_Artifact_Callbacks::validate( $artifact, array( 'target' => array( 'payload' => $payload ) ) );
+agents_api_smoke_assert_equals( false, is_wp_error( $validated ), 'valid payload passes validation', $failures, $passes );
+agents_api_smoke_assert_equals( 'agent-runtime/workspace-preload', $validated['type'] ?? '', 'validated contract keeps the generic artifact type', $failures, $passes );
+agents_api_smoke_assert_equals( 'agent-runtime/workspace-preload/v1', $validated['payload']['schema'] ?? '', 'validated payload carries schema version', $failures, $passes );
+agents_api_smoke_assert_equals( 'trunk', $validated['payload']['repositories'][1]['ref'] ?? '', 'repository refs are preserved for runtime materializers', $failures, $passes );
+
+echo "\n[3] Import returns a runtime materialization contract, not a product-specific side effect:\n";
+$imported = WP_Agent_Package_Artifact_Callbacks::import( $artifact, array( 'target' => array( 'payload' => $payload ) ) );
+agents_api_smoke_assert_equals( 'materialization-contract', $imported['status'] ?? '', 'import status identifies a materialization contract', $failures, $passes );
+agents_api_smoke_assert_equals( 'review-repos', $imported['artifact']['slug'] ?? '', 'import contract identifies the artifact slug', $failures, $passes );
+
+echo "\n[4] Invalid repository declarations fail before runtime adoption:\n";
+$invalid = WP_Agent_Workspace_Preload_Artifact::normalize_payload(
+	array(
+		'repositories' => array(
+			array(
+				'name' => 'Bad Name',
+				'url'  => 'file:///tmp/repo',
+			),
+		),
+	)
+);
+agents_api_smoke_assert_equals( true, is_wp_error( $invalid ), 'invalid repository payload returns WP_Error', $failures, $passes );
+agents_api_smoke_assert_equals( 'wp_agent_workspace_preload_repository_name_invalid', $invalid->get_error_code(), 'invalid names are rejected before urls are considered', $failures, $passes );
+
+agents_api_smoke_finish( 'Agents API workspace preload artifact contract', $failures, $passes );