CLAUDE.md

@@ -100,6 +100,7 @@ All test classes extend `tests/Unit/TestCase.php`, which handles `Monkey\setUp()
 - When mocking `$wpdb`, set `$mock->prefix = 'wp_'` explicitly — it is a public property, not a method
 
 ### Adding a Feature
+0. **If the feature touches `Schema.php`, bump both the `Version:` header and `USC_VERSION` in `unsupervised-schedular.php`.** `Plugin::boot()` only re-runs `Installer`/`dbDelta` when the stored `us_schedular_version` differs, so a schema change without a version bump never reaches existing sites and inserts into new columns fail silently.
 1. Write the feature doc in `docs/features/<feature-name>.md` (data model, API, classes, test paths).
 2. Create a domain package under `src/<Domain>/` containing all classes for that feature.
 3. Add template(s) under `templates/` if needed.

src/Auth/InviteRepository.php

@@ -11,8 +11,12 @@ class InviteRepository {
 		$this->table = $db->prefix . 'us_invites';
 	}
 
+	/**
+	 * Persist an invite. Returns the new row id, or 0 when the insert failed —
+	 * callers must not hand out a registration link for an unstored token.
+	 */
 	public function insert( Invite $invite ): int {
-		$this->db->insert(
+		$result = $this->db->insert(
 			$this->table,
 			[
 				'email'            => $invite->email,
@@ -29,7 +33,7 @@ class InviteRepository {
 			[ '%s', '%s', '%s', '%s', '%s', '%d', '%d', '%s', '%s', '%s' ]
 		);
 
-		return $this->db->insert_id;
+		return false === $result ? 0 : $this->db->insert_id;
 	}
 
 	public function findByToken( string $token ): ?Invite {

src/Auth/RegistrationController.php

@@ -20,8 +20,9 @@ class RegistrationController {
 		}
 
 		$newInviteUrl = '';
+		$inviteError  = '';
 		if ( isset( $_POST['usc_action'] ) && check_admin_referer( 'usc_invite_action' ) ) {
-			$newInviteUrl = $this->handleFormAction();
+			[ $newInviteUrl, $inviteError ] = $this->handleFormAction();
 		}
 
 		$pendingInvites      = $this->invites->findPending();
@@ -32,11 +33,14 @@ class RegistrationController {
 	}
 
 	/**
-	 * Handle a posted admin action. Returns the registration link for a freshly
+	 * Handle a posted admin action. Returns `[link, error]`: the registration
-	 * created invite — the only time it can be shown, since just the token's hash
+	 * link for a freshly created invite — the only time it can be shown, since
-	 * is stored — or an empty string for every other action.
+	 * just the token's hash is stored — or an error message when creation
+	 * failed; both empty for every other action.
+	 *
+	 * @return array{string, string}
 	 */
-	private function handleFormAction(): string {
+	private function handleFormAction(): array {
 		// Nonce is verified by the caller (renderPage) before this method runs.
 		// phpcs:disable WordPress.Security.NonceVerification.Missing
 		$action = sanitize_key( Val::string( wp_unslash( $_POST['usc_action'] ?? '' ) ) );
@@ -49,42 +53,46 @@ class RegistrationController {
 			$email = sanitize_email( Val::string( wp_unslash( $_POST['email'] ?? '' ) ) );
 
 			if (
-				is_email( $email )
+				! is_email( $email )
-				&& false === email_exists( $email )
+				|| false !== email_exists( $email )
-				&& null === $this->invites->findPendingByEmail( $email )
+				|| null !== $this->invites->findPendingByEmail( $email )
 			) {
-				$rawToken = wp_generate_password( 32, false );
+				return [ '', esc_html__( 'Could not create the invite: enter a valid email address that has no account and no pending invite.', 'unsupervised-schedular' ) ];
-
-				$this->invites->insert(
-					new Invite(
-						email:     $email,
-						token:     Invite::hashToken( $rawToken ),
-						invitedBy: get_current_user_id(),
-					)
-				);
-
-				return $this->registrationLink( $rawToken );
 			}
+
+			$rawToken = wp_generate_password( 32, false );
+
+			$id = $this->invites->insert(
+				new Invite(
+					email:     $email,
+					token:     Invite::hashToken( $rawToken ),
+					invitedBy: get_current_user_id(),
+				)
+			);
+
+			return $this->linkOrError( $id, $rawToken );
 		}
 
 		if ( 'group_invite' === $action ) {
 			$expiresAt = $this->normalizeExpiry( sanitize_text_field( Val::string( wp_unslash( $_POST['expires_at'] ?? '' ) ) ) );
 
-			if ( null !== $expiresAt ) {
+			if ( null === $expiresAt ) {
-				$rawToken = wp_generate_password( 32, false );
+				return [ '', esc_html__( 'Could not create the group link: choose an expiry date of today or later.', 'unsupervised-schedular' ) ];
-
-				$this->invites->insert(
-					new Invite(
-						email:     '',
-						token:     Invite::hashToken( $rawToken ),
-						invitedBy: get_current_user_id(),
-						kind:      Invite::KIND_GROUP,
-						expiresAt: $expiresAt,
-					)
-				);
-
-				return $this->registrationLink( $rawToken );
 			}
+
+			$rawToken = wp_generate_password( 32, false );
+
+			$id = $this->invites->insert(
+				new Invite(
+					email:     '',
+					token:     Invite::hashToken( $rawToken ),
+					invitedBy: get_current_user_id(),
+					kind:      Invite::KIND_GROUP,
+					expiresAt: $expiresAt,
+				)
+			);
+
+			return $this->linkOrError( $id, $rawToken );
 		}
 
 		if ( 'revoke' === $action ) {
@@ -95,7 +103,22 @@ class RegistrationController {
 		}
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 
-		return '';
+		return [ '', '' ];
+	}
+
+	/**
+	 * The registration link for a stored invite, or an error when the insert
+	 * failed — a link must never be shown for a token that was not persisted,
+	 * since it could only ever dead-end as "invalid or expired".
+	 *
+	 * @return array{string, string}
+	 */
+	private function linkOrError( int $insertedId, string $rawToken ): array {
+		if ( $insertedId <= 0 ) {
+			return [ '', esc_html__( 'Could not save the invite. Deactivate and reactivate the plugin to update the database, then try again.', 'unsupervised-schedular' ) ];
+		}
+
+		return [ $this->registrationLink( $rawToken ), '' ];
 	}
 
 	/**

templates/admin/invites.php

@@ -10,12 +10,19 @@ if (! defined('ABSPATH')) {
  * @var int    $registrationPageId
  * @var string $registrationPageUrl
  * @var string $newInviteUrl One-time registration link for a just-created invite.
+ * @var string $inviteError  Error message when invite creation failed.
  */
 ?>
 <div class="wrap">
     <h1><?php esc_html_e('Invites', 'unsupervised-schedular'); ?></h1>
     <p class="description"><?php esc_html_e('Invite a student by email, then send them the registration link. They complete signup and accept any required policies through the [us_student_register] page.', 'unsupervised-schedular'); ?></p>
 
+    <?php if ($inviteError !== '') : ?>
+        <div class="notice notice-error inline">
+            <p><?php echo esc_html($inviteError); ?></p>
+        </div>
+    <?php endif; ?>
+
     <?php if ($newInviteUrl !== '') : ?>
         <div class="notice notice-success inline">
             <p><?php esc_html_e('Invite created. Copy the registration link now — for security it is not stored and cannot be shown again. To re-send a lost link, revoke the invite and create a new one.', 'unsupervised-schedular'); ?></p>

tests/Unit/Auth/InviteRepositoryTest.php

@@ -46,6 +46,16 @@ class InviteRepositoryTest extends TestCase
         self::assertSame(5, $this->repo->insert(new Invite('[email protected]', 'tok123', invitedBy: 2)));
     }
 
+    public function testInsertReturnsZeroWhenDbInsertFails(): void
+    {
+        Functions\expect('current_time')->with('mysql')->andReturn('2026-06-02 09:00:00');
+
+        $this->db->shouldReceive('insert')->once()->andReturn(false);
+        $this->db->insert_id = 99; // Stale id from an earlier insert must not leak out.
+
+        self::assertSame(0, $this->repo->insert(new Invite('[email protected]', 'tok123')));
+    }
+
     public function testInsertPersistsGroupKindAndExpiry(): void
     {
         Functions\expect('current_time')->with('mysql')->andReturn('2026-06-02 09:00:00');

unsupervised-schedular.php

@@ -3,7 +3,7 @@
  * Plugin Name: Unsupervised Scheduler
  * Plugin URI:  https://unsupervised.ca
  * Description: Instructor/student lesson scheduling for WordPress.
- * Version:     1.0.0-rc.2
+ * Version:     1.0.0-rc.3
  * Requires at least: 6.2
  * Requires PHP: 8.1
  * Author:      Unsupervised
@@ -20,7 +20,7 @@ if (! defined('ABSPATH')) {
     exit;
 }
 
-define('USC_VERSION', '1.0.0-rc.2');
+define('USC_VERSION', '1.0.0-rc.3');
 define('USC_PLUGIN_FILE', __FILE__);
 define('USC_PLUGIN_DIR', plugin_dir_path(__FILE__));
 define('USC_PLUGIN_URL', plugin_dir_url(__FILE__));