Add group-class withdrawal deadline and kind-aware offering form

Group classes now carry an optional per-class withdrawal deadline. Up to
that day a student may withdraw themselves from the class; the withdrawal
frees the seat and voids any pending payment but never issues an account
credit. After the deadline self-withdrawal closes and a studio admin must
withdraw the student by hand (the admin path is never subject to the
deadline). A blank deadline keeps self-withdrawal open indefinitely.

Also make the Add/Edit Offering form show only the fields relevant to the
selected kind: group settings for group classes, weekly reservation for
private lessons. Progressive enhancement — without JS every field renders.

- New nullable us_offerings.withdrawal_deadline column; Offering model gains
  $withdrawalDeadline + isWithdrawalOpen().
- New student endpoint POST /enrollments/{id}/withdraw, gated by the deadline
  (403 withdrawal_closed), ownership-checked, idempotent.
- Front-end group-class page shows a Withdraw button while open.
- No USC_VERSION bump: 1.2.0 is unreleased and accumulates schema changes
  under its section, matching the scheduled-billing and credit features.

Tests: composer test (596), composer lint, composer cs all pass.

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

src/GroupClass/EnrollmentEndpoint.php

@@ -59,6 +59,18 @@ class EnrollmentEndpoint {
 				],
 			]
 		);
+
+		register_rest_route(
+			$route_namespace,
+			'/enrollments/(?P<id>\d+)/withdraw',
+			[
+				[
+					'methods'             => \WP_REST_Server::CREATABLE,
+					'callback'            => [ $this, 'withdraw' ],
+					'permission_callback' => [ $this, 'isLoggedIn' ],
+				],
+			]
+		);
 	}
 
 	public function index( \WP_REST_Request $request ): \WP_REST_Response { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.Found
@@ -148,6 +160,50 @@ class EnrollmentEndpoint {
 		);
 	}
 
+	/**
+	 * Withdraw the current student from a group class they enrolled in. Allowed
+	 * only while the offering's withdrawal deadline is open (a class with no
+	 * deadline set stays open indefinitely); once it passes, the student must
+	 * contact the studio and an admin withdraws them by hand. A timely withdrawal
+	 * frees the seat and voids any still-pending payment but never issues an
+	 * account credit — that is reserved for cancelled lessons.
+	 */
+	public function withdraw( \WP_REST_Request $request ): \WP_REST_Response|\WP_Error {
+		$id         = absint( Val::int( $request->get_param( 'id' ) ) );
+		$enrollment = $this->enrollments->findById( $id );
+
+		if ( null === $enrollment ) {
+			return new \WP_Error( 'not_found', __( 'Enrolment not found.', 'unsupervised-schedular' ), [ 'status' => 404 ] );
+		}
+
+		if ( get_current_user_id() !== $enrollment->studentId ) {
+			return new \WP_Error( 'forbidden', __( 'You cannot withdraw from this class.', 'unsupervised-schedular' ), [ 'status' => 403 ] );
+		}
+
+		if ( Enrollment::STATUS_ACTIVE === $enrollment->status ) {
+			$offering = $this->offerings->findById( $enrollment->offeringId );
+
+			if ( null !== $offering && ! $offering->isWithdrawalOpen( Val::string( current_time( 'Y-m-d' ) ) ) ) {
+				return new \WP_Error(
+					'withdrawal_closed',
+					__( 'Withdrawal for this class has closed. Please contact the studio.', 'unsupervised-schedular' ),
+					[ 'status' => 403 ]
+				);
+			}
+
+			$this->enrollments->updateStatus( $id, Enrollment::STATUS_CANCELLED );
+			$this->payments->voidPending( $enrollment->paymentId );
+		}
+
+		return new \WP_REST_Response(
+			[
+				'id'     => $id,
+				'status' => Enrollment::STATUS_CANCELLED,
+			],
+			200
+		);
+	}
+
 	public function isLoggedIn(): bool {
 		return is_user_logged_in();
 	}

src/Offering/Offering.php

@@ -69,6 +69,7 @@ class Offering {
 		public readonly ?string $termEnd = null,
 		public readonly ?string $classTime = null,
 		public readonly ?string $enrollmentDeadline = null,
+		public readonly ?string $withdrawalDeadline = null,
 		public readonly ?string $scheduleNote = null,
 		public readonly ?string $etransferEmail = null,
 		public readonly ?int $cancellationCutoffHours = null,
@@ -114,6 +115,19 @@ class Offering {
 		return null === $deadline || $today <= $deadline;
 	}
 
+	/**
+	 * Whether a student may still withdraw themselves from this group class on
+	 * `$today` (a `Y-m-d` date). Withdrawal stays open through the end of the
+	 * deadline day. Unlike the enrolment deadline there is no implicit default: a
+	 * class with no withdrawal deadline set stays open to withdrawal for its whole
+	 * life, so the instructor must set a date to lock students in. A withdrawal
+	 * made while open never issues an account credit — it only frees the seat and
+	 * voids any still-pending payment.
+	 */
+	public function isWithdrawalOpen( string $today ): bool {
+		return null === $this->withdrawalDeadline || $today <= $this->withdrawalDeadline;
+	}
+
 	/**
 	 * Normalise a submitted term date to canonical `Y-m-d`, or null when it is
 	 * not a real calendar date. Round-trips through DateTimeImmutable so
@@ -214,6 +228,7 @@ class Offering {
 			termEnd:         Val::stringOrNull( $row->term_end ),
 			classTime:       Val::stringOrNull( $row->class_time ?? null ),
 			enrollmentDeadline: Val::stringOrNull( $row->enrollment_deadline ?? null ),
+			withdrawalDeadline: Val::stringOrNull( $row->withdrawal_deadline ?? null ),
 			scheduleNote:    Val::stringOrNull( $row->schedule_note ),
 			etransferEmail:  Val::stringOrNull( $row->etransfer_email ),
 			cancellationCutoffHours: Val::intOrNull( $row->cancellation_cutoff_hours ),
@@ -249,6 +264,7 @@ class Offering {
 			'term_end'                  => $this->termEnd,
 			'class_time'                => $this->classTime,
 			'enrollment_deadline'       => $this->enrollmentDeadline,
+			'withdrawal_deadline'       => $this->withdrawalDeadline,
 			'schedule_note'             => $this->scheduleNote,
 			'cancellation_cutoff_hours' => $this->cancellationCutoffHours,
 			'access_mode'               => $this->accessMode,

src/Offering/OfferingController.php

@@ -213,6 +213,11 @@ class OfferingController {
 		// day (term_start), applied by Offering::effectiveEnrollmentDeadline().
 		$enrollmentDeadline = Offering::normalizeDate( sanitize_text_field( Val::string( wp_unslash( $_POST['enrollment_deadline'] ?? '' ) ) ) );
 
+		// A blank (or invalid) withdrawal deadline leaves the column NULL, which
+		// keeps self-withdrawal open for the class's whole life
+		// (Offering::isWithdrawalOpen()). A set date closes it after that day.
+		$withdrawalDeadline = Offering::normalizeDate( sanitize_text_field( Val::string( wp_unslash( $_POST['withdrawal_deadline'] ?? '' ) ) ) );
+
 		return new Offering(
 			instructorId:    $this->resolveInstructorId( $instructorId, $manageAll, $existing ),
 			kind:            $kind,
@@ -228,6 +233,7 @@ class OfferingController {
 			termEnd:         $termEnd,
 			classTime:       $classTime,
 			enrollmentDeadline: $enrollmentDeadline,
+			withdrawalDeadline: $withdrawalDeadline,
 			scheduleNote:    $this->nullableText( sanitize_text_field( Val::string( wp_unslash( $_POST['schedule_note'] ?? '' ) ) ) ),
 			etransferEmail:  $this->nullableText( sanitize_email( Val::string( wp_unslash( $_POST['etransfer_email'] ?? '' ) ) ) ),
 			cancellationCutoffHours: $cutoffHours,

src/Offering/OfferingRepository.php

@@ -15,12 +15,12 @@ class OfferingRepository {
 	 * Column formats aligned to {@see columns()} (instructor_id, kind, title,
 	 * description, duration_minutes, price, currency, billing_mode, allow_weekly,
 	 * capacity, term_start, term_end, class_time, enrollment_deadline,
-	 * schedule_note, etransfer_email, cancellation_cutoff_hours, access_mode,
-	 * is_active).
+	 * withdrawal_deadline, schedule_note, etransfer_email,
+	 * cancellation_cutoff_hours, access_mode, is_active).
 	 *
 	 * @var list<string>
 	 */
-	private const COLUMN_FORMATS = [ '%d', '%s', '%s', '%s', '%d', '%f', '%s', '%s', '%d', '%d', '%s', '%s', '%s', '%s', '%s', '%s', '%d', '%s', '%d' ];
+	private const COLUMN_FORMATS = [ '%d', '%s', '%s', '%s', '%d', '%f', '%s', '%s', '%d', '%d', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%d', '%s', '%d' ];
 
 	public function insert( Offering $offering ): int {
 		$this->db->insert(
@@ -63,6 +63,7 @@ class OfferingRepository {
 			'term_end'                  => $offering->termEnd,
 			'class_time'                => $offering->classTime,
 			'enrollment_deadline'       => $offering->enrollmentDeadline,
+			'withdrawal_deadline'       => $offering->withdrawalDeadline,
 			'schedule_note'             => $offering->scheduleNote,
 			'etransfer_email'           => $offering->etransferEmail,
 			'cancellation_cutoff_hours' => $offering->cancellationCutoffHours,

src/Schema.php

@@ -65,6 +65,7 @@ class Schema {
                 term_end         DATE            DEFAULT NULL,
                 class_time       TIME            DEFAULT NULL,
                 enrollment_deadline DATE         DEFAULT NULL,
+                withdrawal_deadline DATE         DEFAULT NULL,
                 schedule_note    VARCHAR(191)    DEFAULT NULL,
                 etransfer_email  VARCHAR(191)    DEFAULT NULL,
                 cancellation_cutoff_hours SMALLINT UNSIGNED DEFAULT NULL,