diff --git a/src/BusProNet/DataProcessor/PickupPlanningTransformer.php b/src/BusProNet/DataProcessor/PickupPlanningTransformer.php
index 34b4081..131e424 100644
--- a/src/BusProNet/DataProcessor/PickupPlanningTransformer.php
+++ b/src/BusProNet/DataProcessor/PickupPlanningTransformer.php
@@ -4,6 +4,13 @@ declare(strict_types=1);
 
 namespace App\BusProNet\DataProcessor;
 
+/**
+ * Transforms raw pickup planning data into structured travel-indexed pickup information.
+ *
+ * Processes JSON payload from the CMS pickup planning endpoint, filtering for outbound
+ * trips (HIN direction) and grouping pickups by travel code. Each pickup includes city,
+ * location, and datetime, sorted chronologically per travel code.
+ */
 class PickupPlanningTransformer
 {
     /**
diff --git a/src/EventListener/AccessDeniedListener.php b/src/EventListener/AccessDeniedListener.php
index c7284b1..26c18e8 100644
--- a/src/EventListener/AccessDeniedListener.php
+++ b/src/EventListener/AccessDeniedListener.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\EventListener;
 
 use Psr\Log\LoggerInterface;
@@ -9,6 +11,14 @@ use Symfony\Component\HttpKernel\Event\ExceptionEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\Security\Core\Exception\AccessDeniedException;
 
+/**
+ * Converts AccessDeniedException to user-friendly flash messages.
+ *
+ * Logs access denials and adds appropriate flash messages: "Please log in" for
+ * anonymous users, or "Access denied" for authenticated users. Clears target
+ * path for authenticated denials to prevent redirect loops. OAuth2 routes are
+ * logged but allowed to pass through without modification.
+ */
 class AccessDeniedListener implements EventSubscriberInterface
 {
     public function __construct(
diff --git a/src/EventListener/AuthorizationCodeListener.php b/src/EventListener/AuthorizationCodeListener.php
index 7ea7548..9271364 100644
--- a/src/EventListener/AuthorizationCodeListener.php
+++ b/src/EventListener/AuthorizationCodeListener.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\EventListener;
 
 use App\Entity\User;
@@ -13,6 +15,14 @@ use Symfony\Component\HttpFoundation\RequestStack;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 
+/**
+ * Handles OAuth2 authorization code grant flow.
+ *
+ * Automatically approves authorization requests for authenticated users without
+ * consent prompts. Redirects anonymous users to login. For external OAuth2
+ * requests (flagged via session), logs out the user after authorization to
+ * prevent session hijacking.
+ */
 #[AsEventListener(event: OAuth2Events::AUTHORIZATION_REQUEST_RESOLVE, method: 'onAuthorizationRequestResolve')]
 class AuthorizationCodeListener
 {
diff --git a/src/Form/Service/ParticipantTransportationDiscountReplacementFieldHandler.php b/src/Form/Service/ParticipantTransportationDiscountReplacementFieldHandler.php
index 48f81c2..5781b23 100644
--- a/src/Form/Service/ParticipantTransportationDiscountReplacementFieldHandler.php
+++ b/src/Form/Service/ParticipantTransportationDiscountReplacementFieldHandler.php
@@ -10,6 +10,18 @@ use App\Form\Model\BookingDto;
 use App\Form\Service\Abstract\AbstractParticipantFieldHandler;
 use App\Service\ServiceAvailabilityCalculator;
 
+/**
+ * Handles automatic replacement of discounted transportation based on booking rules.
+ *
+ * This virtual field handler enforces the business rule that discounted self-organized
+ * transportation (PKW with negative price) is only available when both outbound AND
+ * inbound travel use PKW. When inbound changes to BUS, the outbound PKW is automatically
+ * replaced with the regular (non-discounted) PKW variant.
+ *
+ * Conversely, when inbound changes back to PKW, this handler restores the discounted
+ * variant if availability permits. Baby participants (age <= 2) are excluded from
+ * discounted transportation restoration.
+ */
 class ParticipantTransportationDiscountReplacementFieldHandler extends AbstractParticipantFieldHandler
 {
     public function __construct(
diff --git a/src/Logger/DatabaseHandler.php b/src/Logger/DatabaseHandler.php
index a8bf7b8..61a78f0 100644
--- a/src/Logger/DatabaseHandler.php
+++ b/src/Logger/DatabaseHandler.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Logger;
 
 use App\Entity\LogEntry;
@@ -7,6 +9,12 @@ use Doctrine\ORM\EntityManagerInterface;
 use Monolog\Handler\AbstractProcessingHandler;
 use Monolog\LogRecord;
 
+/**
+ * Monolog handler that persists log entries to the database.
+ *
+ * Writes log records to the LogEntry entity, replacing message placeholders
+ * with context values. Includes channel, context, and extra data for auditing.
+ */
 class DatabaseHandler extends AbstractProcessingHandler
 {
     public function __construct(private readonly EntityManagerInterface $entityManager)
diff --git a/src/Logger/RequestInfoProcessor.php b/src/Logger/RequestInfoProcessor.php
index cacc11e..2610fa9 100644
--- a/src/Logger/RequestInfoProcessor.php
+++ b/src/Logger/RequestInfoProcessor.php
@@ -1,11 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Logger;
 
 use Monolog\Attribute\AsMonologProcessor;
 use Monolog\LogRecord;
 use Symfony\Component\HttpFoundation\RequestStack;
 
+/**
+ * Enriches log records with HTTP request context.
+ *
+ * Adds the current request URI and method to the log record's extra data,
+ * enabling correlation of log entries with specific HTTP requests.
+ */
 #[AsMonologProcessor]
 class RequestInfoProcessor
 {
diff --git a/src/Logger/UserDataProcessor.php b/src/Logger/UserDataProcessor.php
index b980abd..973f8dc 100644
--- a/src/Logger/UserDataProcessor.php
+++ b/src/Logger/UserDataProcessor.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Logger;
 
 use App\Entity\User;
@@ -8,6 +10,12 @@ use Monolog\LogRecord;
 use Symfony\Bundle\SecurityBundle\Security;
 use Symfony\Component\Security\Core\Authentication\Token\SwitchUserToken;
 
+/**
+ * Enriches log records with current user information.
+ *
+ * Adds username and roles to log entries for audit trails. Handles CLI context
+ * (system user), anonymous requests, and user impersonation via SwitchUserToken.
+ */
 #[AsMonologProcessor]
 class UserDataProcessor
 {
diff --git a/src/Security/BpnAuthenticator.php b/src/Security/BpnAuthenticator.php
index 3c28f51..962d40b 100644
--- a/src/Security/BpnAuthenticator.php
+++ b/src/Security/BpnAuthenticator.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Security;
 
 use App\BusProNet\ApiClient;
@@ -22,6 +24,13 @@ use Symfony\Component\Security\Http\Authenticator\Passport\SelfValidatingPasspor
 use Symfony\Component\Security\Http\EntryPoint\AuthenticationEntryPointInterface;
 use Symfony\Component\Security\Http\Util\TargetPathTrait;
 
+/**
+ * Authenticates users against the BPN API.
+ *
+ * Validates credentials via BPN's getPersonalData endpoint, creates or updates
+ * local User entities, and retrieves CRM attributes (roles, hotel codes) for
+ * authorization. Passwords are stored encrypted with RSA for subsequent API calls.
+ */
 class BpnAuthenticator extends AbstractLoginFormAuthenticator implements AuthenticationEntryPointInterface
 {
     use TargetPathTrait;
diff --git a/src/Security/Crypt.php b/src/Security/Crypt.php
index df597f0..6b34814 100644
--- a/src/Security/Crypt.php
+++ b/src/Security/Crypt.php
@@ -1,10 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Security;
 
 use Spatie\Crypto\Rsa\PrivateKey;
 use Spatie\Crypto\Rsa\PublicKey;
 
+/**
+ * RSA encryption/decryption utilities for secure credential storage.
+ *
+ * Uses asymmetric encryption to store BPN API passwords securely. Private key
+ * encrypts data for storage, public key decrypts for API calls. Also provides
+ * signing/verification for message integrity.
+ */
 class Crypt
 {
     public function __construct(private readonly string $path)
diff --git a/src/Security/Voter/BookingVoter.php b/src/Security/Voter/BookingVoter.php
index b8a742e..75c47c9 100644
--- a/src/Security/Voter/BookingVoter.php
+++ b/src/Security/Voter/BookingVoter.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Security\Voter;
 
 use App\BusProNet\Model\Booking;
@@ -7,6 +9,13 @@ use App\Entity\User;
 use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
 use Symfony\Component\Security\Core\Authorization\Voter\Voter;
 
+/**
+ * Determines access permissions for booking operations.
+ *
+ * Enforces ownership check via personId matching. VIEW access requires ownership,
+ * EDIT access additionally requires the booking to be in an editable state
+ * (determined by booking.isEditable()).
+ */
 class BookingVoter extends Voter
 {
     public const VIEW = 'VIEW';
diff --git a/src/Twig/AppExtension.php b/src/Twig/AppExtension.php
index b942f81..b12ada0 100644
--- a/src/Twig/AppExtension.php
+++ b/src/Twig/AppExtension.php
@@ -1,11 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Twig;
 
 use Twig\Extension\AbstractExtension;
 use Twig\TwigFilter;
 use Twig\TwigFunction;
 
+/**
+ * Twig extension registering booking-related filters and functions.
+ *
+ * Provides filters for formatting (file_size, format_money, format_service_price)
+ * and mapping (map_gender, map_status, map_country, map_nationality), plus
+ * functions for field state checking and participant eligibility.
+ */
 class AppExtension extends AbstractExtension
 {
     public function getFilters(): array
diff --git a/src/Twig/AppRuntime.php b/src/Twig/AppRuntime.php
index cabf7c0..9269e88 100644
--- a/src/Twig/AppRuntime.php
+++ b/src/Twig/AppRuntime.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Twig;
 
 use App\BusProNet\DataProvider\CountryDataProvider;
@@ -14,6 +16,13 @@ use Twig\Environment;
 use Twig\Extension\RuntimeExtensionInterface;
 use Twig\Extra\Intl\IntlExtension;
 
+/**
+ * Runtime implementation for AppExtension's filters and functions.
+ *
+ * Provides formatting utilities (money, file size, service prices), code-to-label
+ * mapping for display (gender, status, country), and field state introspection
+ * for conditional rendering in templates.
+ */
 class AppRuntime implements RuntimeExtensionInterface
 {
     public function __construct(
diff --git a/src/Validator/Constraints/Participant.php b/src/Validator/Constraints/Participant.php
index 660e618..fb08dae 100644
--- a/src/Validator/Constraints/Participant.php
+++ b/src/Validator/Constraints/Participant.php
@@ -1,9 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Validator\Constraints;
 
 use Symfony\Component\Validator\Constraint;
 
+/**
+ * Validates participant data for cross-field consistency.
+ *
+ * Applied as a class-level constraint on ParticipantDto to enforce business rules
+ * that depend on multiple fields (e.g., requiring pickup when bus transport is selected).
+ */
 #[\Attribute]
 class Participant extends Constraint
 {
diff --git a/src/Validator/Constraints/ParticipantValidator.php b/src/Validator/Constraints/ParticipantValidator.php
index 068ee23..fb71fad 100644
--- a/src/Validator/Constraints/ParticipantValidator.php
+++ b/src/Validator/Constraints/ParticipantValidator.php
@@ -1,11 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Validator\Constraints;
 
 use App\Form\Model\ParticipantDto;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 
+/**
+ * Validates cross-field constraints on participant data.
+ *
+ * Enforces business rules that require examining multiple fields together,
+ * such as requiring a pickup location when bus transportation is selected.
+ */
 class ParticipantValidator extends ConstraintValidator
 {
     public function validate(mixed $value, Constraint $constraint): void
diff --git a/src/Validator/Constraints/PromoVoucherValidator.php b/src/Validator/Constraints/PromoVoucherValidator.php
index 07bef5d..1daf5e9 100644
--- a/src/Validator/Constraints/PromoVoucherValidator.php
+++ b/src/Validator/Constraints/PromoVoucherValidator.php
@@ -11,6 +11,13 @@ use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
+/**
+ * Validates promotional voucher codes against the BPN API.
+ *
+ * Verifies that promo codes are valid for the current travel, checks minimum price
+ * thresholds, and validates code availability. Uses the participant's calculated
+ * total price (including room and all selected services) for threshold comparison.
+ */
 class PromoVoucherValidator extends ConstraintValidator
 {
     public function __construct(
diff --git a/src/Validator/Constraints/PurchaseVoucherValidator.php b/src/Validator/Constraints/PurchaseVoucherValidator.php
index cf1e6cd..b644a47 100644
--- a/src/Validator/Constraints/PurchaseVoucherValidator.php
+++ b/src/Validator/Constraints/PurchaseVoucherValidator.php
@@ -10,6 +10,12 @@ use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
+/**
+ * Validates purchase voucher codes against the BPN API.
+ *
+ * Verifies that voucher codes exist and have remaining balance. Unlike promo
+ * vouchers, purchase vouchers do not require travel or price context validation.
+ */
 class PurchaseVoucherValidator extends ConstraintValidator
 {
     public function __construct(
diff --git a/src/Validator/Constraints/RoomSelection.php b/src/Validator/Constraints/RoomSelection.php
index c3f9f3e..a4a2eea 100644
--- a/src/Validator/Constraints/RoomSelection.php
+++ b/src/Validator/Constraints/RoomSelection.php
@@ -6,6 +6,13 @@ namespace App\Validator\Constraints;
 
 use Symfony\Component\Validator\Constraint;
 
+/**
+ * Validates room selection requirements for bookings.
+ *
+ * Applied as a class-level constraint on BookingDto to ensure valid room
+ * configurations: at least one room must be selected, and baby rooms
+ * cannot be booked without accompanying regular rooms.
+ */
 #[\Attribute]
 class RoomSelection extends Constraint
 {
diff --git a/src/Validator/Constraints/RoomSelectionValidator.php b/src/Validator/Constraints/RoomSelectionValidator.php
index 20eee44..806a007 100644
--- a/src/Validator/Constraints/RoomSelectionValidator.php
+++ b/src/Validator/Constraints/RoomSelectionValidator.php
@@ -10,6 +10,12 @@ use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
+/**
+ * Validates room selection business rules for bookings.
+ *
+ * Enforces that at least one room is selected and that baby rooms (BABY code)
+ * are only booked in combination with regular rooms, not standalone.
+ */
 class RoomSelectionValidator extends ConstraintValidator
 {
     public function validate(mixed $value, Constraint $constraint): void