Add invite-only group classes

Group classes can now be marked invite-only (us_offerings.access_mode).
Invite-only classes are hidden from the public catalog and reachable only
when the instructor lets someone in via one of three paths, managed from
My Lessons -> My Group Classes:

- Add students directly: enrols them now with a pending payment.
- Make available: grants registered students access to self-enrol through
  the normal paid flow (multi-select, emailed a notice).
- Invite by email: tokenised registration invite tied to the class for a
  non-account address; after they register the class becomes enrollable.
  Reuses an existing pending invite instead of sending a second link.

New us_group_access table records grants; GET /offerings merges granted
invite-only classes for the caller; enrolment requires a grant
(403 invite_required) and flips it to enrolled on success.

composer test (487), composer lint, composer cs all pass.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/Auth/Invite.php

@@ -51,6 +51,7 @@ class Invite {
 		public readonly ?string $createdAt = null,
 		public readonly string $kind = self::KIND_PERSONAL,
 		public readonly ?string $expiresAt = null,
+		public readonly ?int $offeringId = null,
 		public readonly ?int $id = null,
 	) {}
 
@@ -66,6 +67,7 @@ class Invite {
 			createdAt:      Val::stringOrNull( $row->created_at ?? null ),
 			kind:           '' !== Val::string( $row->kind ?? '' ) ? Val::string( $row->kind ) : self::KIND_PERSONAL,
 			expiresAt:      Val::stringOrNull( $row->expires_at ?? null ),
+			offeringId:     Val::intOrNull( $row->offering_id ?? null ),
 			id:             Val::int( $row->id ),
 		);
 	}
@@ -132,6 +134,7 @@ class Invite {
 			'accepted_user_id' => $this->acceptedUserId,
 			'accepted_at'      => $this->acceptedAt,
 			'expires_at'       => $this->expiresAt,
+			'offering_id'      => $this->offeringId,
 		];
 	}
 }

src/Auth/InviteRepository.php

@@ -23,6 +23,7 @@ class InviteRepository {
 				'token'            => $invite->token,
 				'role'             => $invite->role,
 				'kind'             => $invite->kind,
+				'offering_id'      => $invite->offeringId,
 				'status'           => $invite->status,
 				'invited_by'       => $invite->invitedBy,
 				'accepted_user_id' => $invite->acceptedUserId,
@@ -30,7 +31,7 @@ class InviteRepository {
 				'accepted_at'      => $invite->acceptedAt,
 				'expires_at'       => $invite->expiresAt,
 			],
-			[ '%s', '%s', '%s', '%s', '%s', '%d', '%d', '%s', '%s', '%s' ]
+			[ '%s', '%s', '%s', '%s', '%d', '%s', '%d', '%d', '%s', '%s', '%s' ]
 		);
 
 		return false === $result ? 0 : $this->db->insert_id;

src/Auth/RegistrationMailer.php

@@ -105,6 +105,56 @@ class RegistrationMailer {
 		return (bool) wp_mail( $email, $subject, $body );
 	}
 
+	/**
+	 * Tell a registered student they have been given access to an invite-only
+	 * group class and can now enrol. Returns false when there is no recipient.
+	 */
+	public function sendClassAccessGranted( \WP_User $user, string $className ): bool {
+		if ( '' === (string) $user->user_email ) {
+			return false;
+		}
+
+		$subject = sprintf(
+			/* translators: %s: class title */
+			__( 'You have been invited to %s', 'unsupervised-schedular' ),
+			$className
+		);
+		$body = sprintf(
+			/* translators: 1: class title, 2: site name, 3: login URL */
+			__( "You have been given access to the group class \"%1\$s\" at %2\$s.\n\nLog in and open the group classes page to enrol:\n%3\$s", 'unsupervised-schedular' ),
+			$className,
+			$this->siteName(),
+			wp_login_url()
+		);
+
+		return (bool) wp_mail( $user->user_email, $subject, $body );
+	}
+
+	/**
+	 * Email a tokenised registration link to someone invited to a group class who
+	 * does not yet have an account. Returns false when there is no recipient.
+	 */
+	public function sendClassInvite( string $email, string $link, string $className ): bool {
+		if ( '' === $email ) {
+			return false;
+		}
+
+		$subject = sprintf(
+			/* translators: %s: class title */
+			__( 'You are invited to join %s', 'unsupervised-schedular' ),
+			$className
+		);
+		$body = sprintf(
+			/* translators: 1: class title, 2: site name, 3: registration URL */
+			__( "You have been invited to the group class \"%1\$s\" at %2\$s.\n\nCreate your account using this link, then choose to enrol in the class:\n%3\$s", 'unsupervised-schedular' ),
+			$className,
+			$this->siteName(),
+			$link
+		);
+
+		return (bool) wp_mail( $email, $subject, $body );
+	}
+
 	private function siteName(): string {
 		$name = (string) get_bloginfo( 'name' );
 

src/Auth/RegistrationPage.php

@@ -3,6 +3,7 @@ declare(strict_types=1);
 
 namespace Unsupervised\Schedular\Auth;
 
+use Unsupervised\Schedular\GroupClass\GroupAccessRepository;
 use Unsupervised\Schedular\Payment\StudioSettings;
 use Unsupervised\Schedular\Policy\AcceptanceRepository;
 use Unsupervised\Schedular\Policy\Policy;
@@ -38,6 +39,7 @@ class RegistrationPage {
 		private RegistrationMailer $mailer,
 		private QuestionRepository $questions,
 		private AnswerRepository $answers,
+		private GroupAccessRepository $access,
 	) {}
 
 	/**
@@ -203,6 +205,11 @@ class RegistrationPage {
 		if ( $inviteValid && ! $invite->isGroup() ) {
 			$this->invites->markAccepted( (int) $invite->id, (int) $userId );
 
+			// A personal invite may carry a group-class grant (invited by email);
+			// point any grants for this address at the new account so the class
+			// becomes enrollable for them.
+			$this->access->linkStudentByEmail( $email, (int) $userId );
+
 			wp_set_current_user( (int) $userId );
 			wp_set_auth_cookie( (int) $userId );