function perspectives_project_detail_page() {
    global $wpdb;
    $project_id = isset($_GET['project_id']) ? intval($_GET['project_id']) : 0;
    $projects_table = $wpdb->prefix . 'perspectives_projects';
    $perspectives_table = $wpdb->prefix . 'perspectives';

    // Check if perspectives table exists
    $perspectives_table_exists = ($wpdb->get_var("SHOW TABLES LIKE '$perspectives_table'") == $perspectives_table);

    // Handle add perspective form
    if (
        $perspectives_table_exists &&
        isset($_POST['add_perspective']) &&
        !empty($_POST['perspective_name']) &&
        !empty($_POST['perspective_type'])
    ) {
        $name = sanitize_text_field($_POST['perspective_name']);
        $type = sanitize_text_field($_POST['perspective_type']);
        $states = isset($_POST['perspective_states']) ? sanitize_text_field($_POST['perspective_states']) : null;
        $is_default = !empty($_POST['perspective_default']) ? 1 : 0;
        $target_project_id = $is_default ? null : $project_id;
        // Only allow user to add non-fixed perspectives
        if ($type === 'fixed') {
            echo '<div class="error"><p>Cannot add new fixed perspectives.</p></div>';
        } else {
            $result = $wpdb->insert($perspectives_table, [
                'project_id' => $target_project_id,
                'name' => $name,
                'type' => $type,
                'states' => $states,
                'default' => $is_default,
                'created_at' => current_time('mysql'),
            ]);
            if ($result === false) {
                echo '<div class="error"><p>Failed to add perspective: ' . esc_html($wpdb->last_error) . '</p></div>';
            } else {
                echo '<div class="updated"><p>Perspective added.</p></div>';
            }
        }
    }

    if (!$project_id) {
        echo '<div class="error"><p>Invalid project.</p></div>';
        return;
    }
    $project = $wpdb->get_row($wpdb->prepare("SELECT * FROM $projects_table WHERE id = %d", $project_id));
    if (!$project) {
        echo '<div class="error"><p>Project not found.</p></div>';
        return;
    }

    $perspectives = [];
    if ($perspectives_table_exists) {
        $perspectives = $wpdb->get_results($wpdb->prepare(
            "SELECT * FROM $perspectives_table WHERE `default` = 1 OR project_id = %d ORDER BY name ASC",
            $project_id
        ));
    }
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