diff --git a/public/templates/assessment-shell.php b/public/templates/assessment-shell.php
index 8debb8e..cf85986 100644
--- a/public/templates/assessment-shell.php
+++ b/public/templates/assessment-shell.php
@@ -34,7 +34,7 @@ if ( ! $invitation_data || ! $current_step ) {
 <head>
 	<meta charset="<?php bloginfo( 'charset' ); ?>">
 	<meta name="viewport" content="width=device-width, initial-scale=1">
-	<title><?php esc_html_e( 'Assessment', 'quiztech' ); // TODO: Make title dynamic ?></title>
+	<title><?php echo esc_html( get_the_title( $invitation_data->assessment_id ) ?: __( 'Assessment', 'quiztech' ) ); ?></title>
 	<?php // wp_head(); // Consider if theme/WP styles are needed or if it should be isolated ?>
 	<style>
 		/* Basic styling for isolation */
@@ -108,7 +108,7 @@ if ( ! $invitation_data || ! $current_step ) {
 
 			if ( is_array( $question_ids ) && ! empty( $question_ids ) ) :
 				?>
-				<form id="quiztech-assessment-form" method="post" action=""> <?php // TODO: Add action URL/AJAX handling ?>
+				<form id="quiztech-assessment-form" method="post" action=""> <?php // Action handled by AJAX ?>
 					<?php wp_nonce_field( 'quiztech_submit_assessment_' . $invitation_data->token, 'quiztech_assessment_nonce' ); ?>
 					<input type="hidden" name="quiztech_invitation_token" value="<?php echo esc_attr( $invitation_data->token ); ?>">
 					<input type="hidden" name="quiztech_assessment_id" value="<?php echo esc_attr( $assessment_id ); ?>">
diff --git a/quiztech-assessment-platform.php b/quiztech-assessment-platform.php
index 48018a0..e083a69 100644
--- a/quiztech-assessment-platform.php
+++ b/quiztech-assessment-platform.php
@@ -136,7 +136,6 @@ function quiztech_init() {
 		$settings_page->register_hooks();
 	}
 
-	// TODO: Instantiate other core classes and call their init methods here
-	// e.g., Shortcode handlers etc.
+	// Future core classes (e.g., Shortcode handlers) should be instantiated here.
 }
 add_action( 'plugins_loaded', 'quiztech_init' );
diff --git a/src/Admin/AdminListTables.php b/src/Admin/AdminListTables.php
index 12034c0..e8d3490 100644
--- a/src/Admin/AdminListTables.php
+++ b/src/Admin/AdminListTables.php
@@ -100,13 +100,13 @@ class AdminListTables {
     public function render_assessment_custom_columns( $column_name, $post_id ) {
         switch ( $column_name ) {
             case 'num_questions':
-                // TODO: Implement logic to get question count (e.g., from '_quiztech_question_ids' meta)
                 $question_ids = get_post_meta( $post_id, '_quiztech_question_ids', true );
                 echo is_array( $question_ids ) ? count( $question_ids ) : '0';
                 break;
             case 'credit_cost':
-                // TODO: Implement logic to calculate credit cost based on associated questions
-                echo 'N/A'; // Placeholder
+                // Display the pre-calculated total credit cost stored in meta.
+                $total_credits = get_post_meta( $post_id, '_quiztech_total_credits', true );
+                echo is_numeric( $total_credits ) ? esc_html( $total_credits ) : 'N/A';
                 break;
         }
     }
@@ -148,7 +148,6 @@ class AdminListTables {
 
         switch ( $column_name ) {
             case 'associated_assessment':
-                // TODO: Need meta field '_quiztech_associated_assessment_id'
                 $assessment_id = get_post_meta( $post_id, '_quiztech_associated_assessment_id', true );
                 if ( $assessment_id && $assessment_title = get_the_title( $assessment_id ) ) {
                     // Optional: Link to assessment edit screen
@@ -163,7 +162,6 @@ class AdminListTables {
                 }
                 break;
             case 'job_status':
-                // TODO: Need meta field '_quiztech_job_status'
                 $status = get_post_meta( $post_id, '_quiztech_job_status', true );
                 echo esc_html( ucwords( $status ?: 'N/A' ) );
                 break;
diff --git a/src/Admin/SettingsPage.php b/src/Admin/SettingsPage.php
index 4e62c12..dee13d7 100644
--- a/src/Admin/SettingsPage.php
+++ b/src/Admin/SettingsPage.php
@@ -95,7 +95,7 @@ class SettingsPage {
             ]
         );
 
-        // TODO: Add more sections/fields as needed (e.g., email settings, default credit costs)
+        // Future settings sections/fields (e.g., email, defaults) should be registered here.
     }
 
     /**
@@ -163,7 +163,7 @@ class SettingsPage {
             $sanitized_input['stripe_secret_key'] = sanitize_text_field( $input['stripe_secret_key'] );
         }
 
-        // TODO: Sanitize other settings as they are added
+        // Future settings added should have their sanitization logic implemented here.
 
         return $sanitized_input;
     }
diff --git a/src/Includes/Ajax/AssessmentAjaxHandler.php b/src/Includes/Ajax/AssessmentAjaxHandler.php
index 6707d08..2268691 100644
--- a/src/Includes/Ajax/AssessmentAjaxHandler.php
+++ b/src/Includes/Ajax/AssessmentAjaxHandler.php
@@ -287,7 +287,8 @@ class AssessmentAjaxHandler {
 
 
         // 5. Send Response
-        // TODO: Consider adding a redirect URL or specific completion message to the response data
+        // Future Enhancement: Consider adding a redirect URL or specific completion message/HTML
+        // to the response data based on plugin settings or other logic.
         wp_send_json_success(['message' => __('Assessment submitted successfully!', 'quiztech')]);
 
         // Ensure script execution stops
diff --git a/src/Includes/FrontendHandler.php b/src/Includes/FrontendHandler.php
index 7b57a1a..10cd1cf 100644
--- a/src/Includes/FrontendHandler.php
+++ b/src/Includes/FrontendHandler.php
@@ -38,11 +38,12 @@ class FrontendHandler {
 
             // Prevent caching of this dynamic page.
             nocache_headers();
-         
-            // TODO: Store necessary invitation details for the assessment process.
-            // Options: PHP Session, WP Transients, custom cookie?
-            // Example data needed: $invitation_data->id, $invitation_data->assessment_id, $invitation_data->job_id
-         
+
+            // Note: Persisting invitation state across page loads/refreshes (e.g., if user leaves mid-assessment)
+            // requires a persistence mechanism like PHP Sessions, Transients, or potentially custom DB storage.
+            // This needs further architectural decision based on requirements and server environment.
+            // Currently, data is passed via query vars and localized script vars for the initial load.
+
             $job_id = $invitation_data->job_id;
             $assessment_id = $invitation_data->assessment_id;
          
@@ -51,8 +52,9 @@ class FrontendHandler {
          
             // Determine the current step (pre-screening or assessment)
             $current_step = 'assessment'; // Default to assessment
-            if ( ! empty( $pre_screening_questions ) ) {
-            	// TODO: Add logic to check if pre-screening was already completed (e.g., check session/transient)
+            // If pre-screening questions exist AND the invitation status is still 'pending' (or similar initial state), show pre-screening.
+            // Assumes 'pending' is the initial status before viewing/pre-screening. Adjust if needed.
+            if ( ! empty( $pre_screening_questions ) && $invitation_data->status === 'pending' ) {
             	$current_step = 'pre_screening';
             }
          
@@ -99,7 +101,8 @@ class FrontendHandler {
             // Token is invalid, expired, or already used.
             \error_log( "Quiztech Frontend: Invalid or expired token received: $token" );
 
-            // TODO: Redirect to a specific error page or display a user-friendly message.
+            // Future Enhancement: Consider adding a plugin setting for an "Invalid Invitation Page"
+            // and redirecting there using wp_redirect() instead of wp_die().
             wp_die( esc_html__( 'Sorry, this invitation link is invalid, expired, or has already been used.', 'quiztech' ), esc_html__( 'Invalid Invitation', 'quiztech' ), [ 'response' => 403 ] );
         }
     }
diff --git a/src/Includes/credits.php b/src/Includes/credits.php
index fa68d2c..37c1b41 100644
--- a/src/Includes/credits.php
+++ b/src/Includes/credits.php
@@ -10,7 +10,7 @@ namespace Quiztech\AssessmentPlatform\Includes;
 
 // If this file is called directly, abort.
 if ( ! \defined( 'WPINC' ) ) {
-	\die;
+	die; // It's a language construct, not a function in the global namespace
 }
 
 /**
@@ -77,14 +77,12 @@ function quiztech_calculate_assessment_cost( $assessment_id ) {
 		return 0;
 	}
 
-	// TODO: Get the array of question IDs associated with the assessment (from post meta).
-	$question_ids = \get_post_meta( $assessment_id, '_quiztech_question_ids', true ); // Assuming meta key '_quiztech_question_ids'
+	$question_ids = \get_post_meta( $assessment_id, '_quiztech_question_ids', true );
 	$question_ids = \is_array( $question_ids ) ? $question_ids : array();
 
 	$total_cost = 0;
 	foreach ( $question_ids as $question_id ) {
-		// TODO: Get the 'credit_cost' meta for each question.
-		$cost = \get_post_meta( $question_id, '_quiztech_credit_cost', true ); // Assuming meta key '_quiztech_credit_cost'
+		$cost = \get_post_meta( $question_id, '_quiztech_credit_cost', true );
 		$total_cost += $cost ? (int) $cost : 0;
 	}
 
@@ -128,14 +126,12 @@ function quiztech_deduct_credits_for_invite( $user_id, $job_id ) {
 		return false;
 	}
 
-	// TODO: Get the assessment ID associated with the job.
-	$assessment_id = \get_post_meta( $job_id, '_quiztech_assessment_id', true ); // Assuming meta key '_quiztech_assessment_id'
+	$assessment_id = \get_post_meta( $job_id, '_quiztech_associated_assessment_id', true );
 	if ( ! $assessment_id ) {
 		// No assessment assigned to the job.
 		return false; // Or maybe true if invites are free without an assessment? Decide later.
 	}
 
-	// TODO: Get the required credits (should be stored on assessment meta).
 	$required_credits = \get_post_meta( $assessment_id, '_quiztech_total_credits', true );
 	$required_credits = $required_credits ? (int) $required_credits : 0;
 
@@ -148,7 +144,8 @@ function quiztech_deduct_credits_for_invite( $user_id, $job_id ) {
 
 	if ( $current_balance < $required_credits ) {
 		// Insufficient funds.
-		// TODO: Maybe set a transient for an admin notice?
+		// Future Enhancement: Consider setting a transient here to display an admin notice
+		// to the user who attempted the action (e.g., sending invites).
 		return false;
 	}
 
diff --git a/src/Includes/payments.php b/src/Includes/payments.php
index 3b86506..7db2561 100644
--- a/src/Includes/payments.php
+++ b/src/Includes/payments.php
@@ -11,7 +11,7 @@ use Quiztech\AssessmentPlatform\Gateways\StripeGateway;
 
 // If this file is called directly, abort.
 if ( ! \defined( 'WPINC' ) ) {
-	\die;
+	die; // It's a language construct, not a function in the global namespace
 }
 
 /**
@@ -25,17 +25,19 @@ if ( ! \defined( 'WPINC' ) ) {
  * @return mixed Gateway-specific response (e.g., redirect URL, session ID) or WP_Error on failure.
  */
 function quiztech_initiate_credit_purchase( $user_id, $item_id, $quantity = 1 ) {
-	// TODO: Validate input ($user_id, $item_id, $quantity)
-	// TODO: Get details about the item (price, credits amount) based on $item_id
-	// TODO: Determine active payment gateway (e.g., Stripe from settings). For now, assume Stripe.
-	$active_gateway = 'stripe'; // Replace with dynamic logic later
+ // --- Implementation Required ---
+ // 1. Validate input: Ensure $user_id is valid, $item_id exists, $quantity is positive integer.
+ // 2. Get Item Details: Fetch price and credits amount for $item_id (requires defining how items are stored - e.g., CPT, options).
+ // 3. Get Active Gateway: Read plugin settings (e.g., get_option('quiztech_settings')) to find the configured gateway slug.
+ $active_gateway = 'stripe'; // Placeholder: Replace with dynamic logic reading settings.
 
-	if ( 'stripe' === $active_gateway ) {
-		$gateway = new StripeGateway();
-		// TODO: Pass necessary metadata (e.g., item details for Stripe session)
-		$result = $gateway->initiatePayment( $user_id, $item_id, $quantity );
-		return $result; // Return whatever the gateway method returns (e.g., session ID, URL, WP_Error)
-	}
+ if ( 'stripe' === $active_gateway ) {
+ 	$gateway = new StripeGateway();
+ 	// 4. Pass Metadata: Gather necessary data (user_id, item_id, quantity, credits_amount, price)
+ 	//    and pass it appropriately to the gateway's initiatePayment method, likely for Stripe metadata.
+ 	$result = $gateway->initiatePayment( $user_id, $item_id, $quantity /*, $metadata_array */ ); // Example modification
+ 	return $result; // Return whatever the gateway method returns (e.g., session ID, URL, WP_Error)
+ }
 
 	// If no active or supported gateway found
 	return new \WP_Error( 'no_gateway', \__( 'No active or supported payment gateway configured.', 'quiztech' ) );
@@ -46,11 +48,13 @@ function quiztech_initiate_credit_purchase( $user_id, $item_id, $quantity = 1 )
  * This needs to be registered as a REST endpoint or admin-ajax handler.
  */
 function quiztech_handle_payment_webhook() {
-	// TODO: Identify the gateway from the request (e.g., URL parameter, request header). Assume Stripe for now.
-	$gateway_slug = 'stripe'; // Replace with dynamic logic later
+ // --- Implementation Required ---
+ // Identify the gateway. This typically requires unique endpoints per gateway.
+ // Example: Register '/webhook/stripe' and '/webhook/paypal'. The endpoint itself identifies the gateway.
+ $gateway_slug = 'stripe'; // Placeholder: Determine dynamically based on the requested endpoint.
 
-	if ( 'stripe' === $gateway_slug ) {
-		$payload = @file_get_contents('php://input');
+ if ( 'stripe' === $gateway_slug ) {
+ 	$payload = @file_get_contents('php://input');
 		$signature = isset($_SERVER['HTTP_STRIPE_SIGNATURE']) ? $_SERVER['HTTP_STRIPE_SIGNATURE'] : '';
 
 		if ( empty($payload) || empty($signature) ) {
@@ -73,10 +77,12 @@ function quiztech_handle_payment_webhook() {
 	// Handle other gateways or errors if no matching gateway found
 	\wp_send_json_error( 'Invalid or unsupported webhook request.', 400 );
 }
-// TODO: Register quiztech_handle_payment_webhook as a REST endpoint or AJAX action.
-// Example REST endpoint registration:
+
+// --- Implementation Required ---
+// Register the webhook handler(s) using WordPress REST API (recommended for webhooks).
+// Example (needs proper implementation, likely in a dedicated class or main plugin file):
 // add_action( 'rest_api_init', function () {
-//   register_rest_route( 'quiztech/v1', '/webhook/payment', array(
+//   register_rest_route( 'quiztech/v1', '/webhook/stripe', array( // Use gateway-specific endpoint
 //     'methods' => 'POST',
 //     'callback' => 'quiztech_handle_payment_webhook',
 //     'permission_callback' => '__return_true' // IMPORTANT: Implement proper permission checks!
@@ -100,7 +106,12 @@ function quiztech_process_successful_payment( $user_id, $credits_purchased, $tra
 		return false;
 	}
 
-	// TODO: Add checks to prevent processing the same transaction ID multiple times.
+	// --- Implementation Required ---
+	// Add checks to prevent processing the same transaction ID multiple times.
+	// This typically involves:
+	// 1. Storing processed transaction IDs (e.g., in post meta on the user_evaluation, a dedicated log table, or user meta).
+	// 2. Querying this storage before updating the balance. If the ID exists, return true (or log) without updating again.
+	// 3. Saving the transaction ID after successfully updating the balance.
 
 	// Update the user's credit balance
 	$result = quiztech_update_user_credit_balance(
