feat: make email optional for under-16 participants except applicant

config/services.yaml

@@ -302,7 +302,6 @@ services:
                 - 'App\Form\Service\ParticipantDropOffFieldHandler'
                 - 'App\Form\Service\ParticipantRentalInsuranceFieldHandler'
                 - 'App\Form\Service\ParticipantLicensePlateFieldHandler'
-                - 'App\Form\Service\ParticipantEmailFieldHandler'
                 # Complex handlers with dependencies - use service references
                 - '@App\Form\Service\ParticipantDateOfBirthFieldHandler'
                 - '@App\Form\Service\ParticipantTransportationDiscountReplacementFieldHandler'

docs/bpn-xml-api-reference.md

@@ -167,11 +167,19 @@ fails on `Telefon-Mobil` and `Nationalität` because its `Vorgang_Details` recor
 `telefonprivat` and no `nationalitaet`.
 
 **Participants are held to less than the Anmelder** (measured 2026-09-16 on 2036, travel 12500, from a
-real step-3 `Anfrage`). Once a room is present, every `teilnehmer` needs a `Mail-Adresse`, children
-included: without `kommunikation` the answer is `650 … 1.Teilnehmer-Mail-Adresse, 2.Teilnehmer-Mail-Adresse`.
-`telefonmobil` and an empty `anschrift` pass for participants. An email identical to the Anmelder's is
-accepted. The field list above (Strasse, Plz, Ort, Telefon-Mobil for every participant) was measured on
-the placeholder records and is stricter than what BusPro applies to ordinary participants.
+real step-3 `Anfrage`). `telefonmobil` and an empty `anschrift` pass for participants. The field list
+above (Strasse, Plz, Ort, Telefon-Mobil for every participant) was measured on the placeholder records and
+is stricter than what BusPro applies to ordinary participants.
+
+**The participant `Mail-Adresse` is BusPro configuration, not a fixed rule.** Until 2026-10-13 every
+`teilnehmer` needed one once a room was present, children included: without it the answer was
+`650 … 1.Teilnehmer-Mail-Adresse, 2.Teilnehmer-Mail-Adresse`, while an email identical to the Anmelder's
+was accepted. On 2026-10-15 the requirement was switched off on the test system, and the same requests
+(no `email`, no `kommunikation`, an empty `<email/>`, adults and children, with and without a travelling
+Anmelder) all pass with an unchanged price. BusPro now accepts a participant without an email at any age,
+so the rule MyE&P applies (required from 16, and for the applicant at any age) is enforced only by
+`ParticipantDto` and `BookingDto` validation. Production needs the same configuration before under-16s
+without an email can be booked there.
 
 **The Anmelder does not have to travel.** An `<anmelder>` that matches no `teilnehmer` (a parent booking
 for their children) returns `möglich` with the same price as the control where the Anmelder is

src/BusProNet/DataProcessor/BookingPayloadBuilder.php

@@ -285,7 +285,7 @@ class BookingPayloadBuilder
             $participantData = [
                 '@id' => $index + 1,
                 'status' => self::DEFAULT_PARTICIPANT_STATUS,
-            ] + $this->buildPersonalDataPayload($participant, $applicantSource->email, true);
+            ] + $this->buildPersonalDataPayload($participant, true);
 
             // Add body dimensions
             if (null !== $participant->height) {
@@ -387,16 +387,12 @@ class BookingPayloadBuilder
      * Maps one person's personal data onto the payload shape shared by anmelder and teilnehmer.
      *
      * @param ParticipantDto $person               The applicant or participant to map
-     * @param string|null    $fallbackEmail        Used when the person has none of their own. BusPro
-     *                                             requires a Mail-Adresse for every participant once
-     *                                             a room is present and rejects the Anfrage with 650
-     *                                             otherwise, but accepts one shared with the Anmelder
      * @param bool           $alwaysIncludeAddress Participants always carry the anschrift structure
      *                                             even when empty; the anmelder only when set
      *
      * @return array<string, mixed>
      */
-    private function buildPersonalDataPayload(ParticipantDto $person, ?string $fallbackEmail = null, bool $alwaysIncludeAddress = false): array
+    private function buildPersonalDataPayload(ParticipantDto $person, bool $alwaysIncludeAddress = false): array
     {
         $data = [
             'name' => $person->lastName,
@@ -421,9 +417,9 @@ class BookingPayloadBuilder
             ];
         }
 
-        $email = null !== $person->email && '' !== trim($person->email)
-            ? $person->email
-            : $fallbackEmail;
+        // A participant may come without an email (under-16s, see ParticipantDto::$email), and
+        // BusPro accepts that, so a blank is sent as a blank rather than borrowing the applicant's.
+        $email = null !== $person->email && '' !== trim($person->email) ? $person->email : null;
 
         if (null !== $email || null !== $person->mobile) {
             $data['kommunikation'] = [];

src/Form/BookingParticipantType.php

@@ -210,9 +210,7 @@ class BookingParticipantType extends AbstractType
         if ($this->fieldStateProvider->shouldIncludeField('email', $bookingDto, $participantIndex)) {
             $form->add('email', EmailType::class, $this->mergeFieldState([
                 'label' => 'E-Mail',
-                // Required for every participant (BPN 650); EditFieldStateProvider clears it
-                // again for internal agency bookings, where staff may leave data blank.
-                'required' => true,
+                'required' => false,
                 'property_path' => 'participant.email',
                 'attr' => [
                     'autocomplete' => 'leave-me-alone-chrome',

src/Form/Model/BookingDto.php

@@ -213,6 +213,50 @@ class BookingDto
         $this->applicantTravels = true;
     }
 
+    /**
+     * Whether the participant at $index has to supply an email address.
+     *
+     * Everyone does except an under-16 who is not the applicant; BusPro itself accepts a blank
+     * for any participant. Validation enforces this in two parts, the Assert\When on
+     * ParticipantDto::$email (age) and validateFirstParticipantApplicant() (the applicant), and
+     * this is the same rule in one place for the field state. A participant that does not exist
+     * yet counts as needing one, matching the "unknown counts as an adult" stance of isChild().
+     */
+    public function requiresParticipantEmail(int $index): bool
+    {
+        $participant = $this->getParticipant($index);
+
+        if (null === $participant || false === $participant->isChild()) {
+            return true;
+        }
+
+        return 0 === $index && true === $this->isFirstParticipantApplicant();
+    }
+
+    /**
+     * The applicant's email address, wherever the applicant is held.
+     *
+     * - participant[0] where they are the applicant
+     * - create, split: the separate applicant block
+     * - edit, split: the loaded booking's anmelder, since $applicant is only filled in create mode
+     */
+    public function getApplicantEmail(): ?string
+    {
+        if (true === $this->isFirstParticipantApplicant()) {
+            $email = $this->getParticipant(0)?->email;
+        } elseif (self::MODE_CREATE === $this->getMode()) {
+            $email = $this->applicant?->email;
+        } else {
+            $email = $this->booking?->applicant?->communication->email;
+        }
+
+        if (null === $email || '' === trim($email)) {
+            return null;
+        }
+
+        return trim($email);
+    }
+
     /**
      * Whether participant[0] is also the applicant.
      *
@@ -311,18 +355,19 @@ class BookingDto
     }
 
     /**
-     * Requires a complete address from participant[0] only where they are the applicant.
+     * Requires a complete address and an email from participant[0] only where they are the applicant.
      *
-     * BusPro does not require an anschrift from an ordinary participant, so on a split booking
-     * the traveller at index 0 is not asked for one.
+     * BusPro asks neither of an ordinary participant, so on a split booking the traveller at index 0
+     * is not asked for an address, and an under-16 there may leave the email blank.
      */
     #[Assert\Callback(groups: ['strict_required'])]
-    public function validateFirstParticipantAddress(ExecutionContextInterface $context): void
+    public function validateFirstParticipantApplicant(ExecutionContextInterface $context): void
     {
         if (false === $this->isFirstParticipantApplicant()) {
             return;
         }
 
+        $this->getParticipant(0)?->validateApplicantEmail($context, 'participants[0].');
         $this->getParticipant(0)?->validateAddressFields($context, 'participants[0].');
     }
 

src/Form/Model/ParticipantDto.php

@@ -80,11 +80,17 @@ class ParticipantDto
     #[Assert\NotNull(message: 'Bitte angeben', groups: ['strict_required'])]
     public ?\DateTimeImmutable $dateOfBirth = null;
 
-    // Every participant needs an email address: BusPro rejects the step-3 Anfrage with 650
-    // otherwise, children included. Under-16s have the applicant's address pre-filled by
-    // ParticipantEmailFieldHandler and may override it, but may not leave it blank.
+    // BusPro accepts a participant without an email address, so this is the only gate. Under-16s
+    // may leave it blank, everyone else needs one. An under-16 applicant needs one as well; that
+    // case depends on the booking and is enforced by BookingDto::validateFirstParticipantApplicant()
+    // and ParticipantEditDto::validateApplicant(). It stays a property constraint so the missing-field
+    // labels keep their order (see BookingEditPreFlightChecker).
     #[Assert\Email(message: 'Bitte eine gültige E-Mail Adresse angeben', mode: 'strict', groups: ['booking_edit', 'booking_create'])]
-    #[Assert\NotBlank(message: 'Bitte angeben', groups: ['strict_required'])]
+    #[Assert\When(
+        expression: 'not this.isChild()',
+        constraints: [new Assert\NotBlank(message: 'Bitte angeben')],
+        groups: ['strict_required'],
+    )]
     public ?string $email = null;
 
     public ?string $mobile = null;
@@ -530,6 +536,28 @@ class ParticipantDto
         }
     }
 
+    /**
+     * Validates that this person, as the booking's contact, has an email address.
+     *
+     * The property constraint on $email already holds everyone aged 16 or older (and anyone
+     * without a date of birth) to it, so this only adds the under-16 contact and never reports
+     * the same field twice. Like validateAddressFields(), the callers decide who the contact is.
+     */
+    public function validateApplicantEmail(ExecutionContextInterface $context, string $pathPrefix = ''): void
+    {
+        if (false === $this->isChild()) {
+            return;
+        }
+
+        if (null !== $this->email && false === u($this->email)->trim()->isEmpty()) {
+            return;
+        }
+
+        $context->buildViolation('Bitte angeben')
+            ->atPath($pathPrefix.'email')
+            ->addViolation();
+    }
+
     /**
      * Validates that this person has a complete address.
      *

src/Form/Model/ParticipantEditDto.php

@@ -93,13 +93,13 @@ class ParticipantEditDto
     }
 
     /**
-     * Requires a complete address from the participant form's applicant only.
+     * Requires a complete address and an email from the participant form's applicant only.
      *
-     * Mirrors BookingDto::validateFirstParticipantAddress() for the per-participant form, which
+     * Mirrors BookingDto::validateFirstParticipantApplicant() for the per-participant form, which
      * binds this wrapper rather than the booking.
      */
     #[Assert\Callback(groups: ['strict_required'])]
-    public function validateApplicantAddress(ExecutionContextInterface $context): void
+    public function validateApplicant(ExecutionContextInterface $context): void
     {
         if (false === $this->participant->isApplicant()) {
             return;
@@ -109,6 +109,7 @@ class ParticipantEditDto
             return;
         }
 
+        $this->participant->validateApplicantEmail($context, 'participant.');
         $this->participant->validateAddressFields($context, 'participant.');
     }
 
@@ -117,7 +118,11 @@ class ParticipantEditDto
      *
      * Exempt from validation:
      * - The applicant: can share an email with dependents they're booking for
-     * - Children (under 16): Can share email addresses with adults
+     * - Children (under 16): Can share email addresses with adults, or have none at all
+     *
+     * Where the applicant does not travel they are not among the participants, so their address
+     * is checked separately: an adult traveller may not reuse it, just as on an ordinary booking
+     * an adult may not reuse participant[0]'s.
      *
      * Email comparison is case-insensitive and whitespace is normalized.
      */
@@ -140,7 +145,7 @@ class ParticipantEditDto
             return;
         }
 
-        // Skip if email is null or empty (handled by @Email and @NotBlank constraints)
+        // Nothing to compare. Whether a blank is allowed is the property constraint's business.
         if (null === $this->participant->email || u($this->participant->email)->trim()->isEmpty()) {
             return;
         }
@@ -178,5 +183,17 @@ class ParticipantEditDto
                 return;
             }
         }
+
+        if (true === $this->bookingContext->isFirstParticipantApplicant()) {
+            return;
+        }
+
+        $applicantEmail = $this->bookingContext->getApplicantEmail();
+
+        if (null !== $applicantEmail && $normalizedEmail === u($applicantEmail)->lower()->toString()) {
+            $context->buildViolation('Diese E-Mail Adresse wird bereits von der anmeldenden Person verwendet')
+                ->atPath('participant.email')
+                ->addViolation();
+        }
     }
 }

src/Form/Service/Condition/RequiresOwnEmailCondition.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Form\Service\Condition;
+
+use App\Form\Model\BookingDto;
+use App\Form\Service\Contract\FieldConditionInterface;
+
+/**
+ * Condition that mirrors BookingDto::requiresParticipantEmail() into the field state layer.
+ *
+ * It deliberately holds no logic of its own, so the mandatory marker rendered next to the field
+ * is derived from the same method that describes what validation enforces, rather than from a
+ * second, independently maintained composition of age and applicant conditions.
+ */
+class RequiresOwnEmailCondition implements FieldConditionInterface
+{
+    /**
+     * Evaluates whether the participant has to supply an email address of their own.
+     *
+     * @param BookingDto           $bookingDto       The current booking data (create or edit)
+     * @param int                  $participantIndex The index of the participant being evaluated
+     * @param array<string, mixed> $formData         Current form data (unused)
+     *
+     * @return bool True if the participant needs their own email address
+     */
+    public function evaluate(BookingDto $bookingDto, int $participantIndex, array $formData): bool
+    {
+        return $bookingDto->requiresParticipantEmail($participantIndex);
+    }
+
+    /**
+     * The rule reads the date of birth, so the state has to be recalculated when it changes.
+     *
+     * @return string[] Array containing 'dateOfBirth'
+     */
+    public function getDependentFields(): array
+    {
+        return ['dateOfBirth'];
+    }
+
+    public function getDescription(): string
+    {
+        return 'Checks if the participant needs an email address of their own';
+    }
+}

src/Form/Service/CreateFieldStateProvider.php

@@ -21,6 +21,7 @@ use App\Form\Service\Condition\FirstParticipantReadOnlyCondition;
 use App\Form\Service\Condition\MultipleParticipantsCondition;
 use App\Form\Service\Condition\RentalInsuranceAvailableCondition;
 use App\Form\Service\Condition\RentalSelectionCondition;
+use App\Form\Service\Condition\RequiresOwnEmailCondition;
 use App\Form\Service\Condition\RoomSelectionCondition;
 use App\Form\Service\Condition\ServiceSubTypeCondition;
 use App\Form\Service\Condition\SingleRoomTypeCondition;
@@ -112,10 +113,9 @@ class CreateFieldStateProvider extends AbstractFieldStateProvider
             'static_text' => $firstParticipantReadOnlyCondition,
         ];
 
-        // Every participant needs an email address, children included (BPN 650), so
-        // requiredness is the form type's base option and not a condition here.
         $this->fieldStateConditions['email'] = [
             'static_text' => $firstParticipantReadOnlyCondition,
+            'required' => new RequiresOwnEmailCondition(),
         ];
 
         // Mobile field: static text for first participant (when read-only). Mandatory only for the

src/Form/Service/EditFieldStateProvider.php

@@ -20,6 +20,7 @@ use App\Form\Service\Condition\PersonalDataMutabilityCondition;
 use App\Form\Service\Condition\PickupsMutabilityCondition;
 use App\Form\Service\Condition\RentalInsuranceAvailableCondition;
 use App\Form\Service\Condition\RentalSelectionCondition;
+use App\Form\Service\Condition\RequiresOwnEmailCondition;
 use App\Form\Service\Condition\RoomSelectionCondition;
 use App\Form\Service\Condition\ServiceSubTypeCondition;
 use App\Form\Service\Condition\SkiPassSelectionCondition;
@@ -92,7 +93,10 @@ class EditFieldStateProvider extends AbstractFieldStateProvider
         // data optional throughout.
         $this->fieldStateConditions['email'] = [
             'static_text' => $firstParticipantReadOnlyCondition,
-            'required' => CompositeCondition::not($internalAgencyBookingCondition),
+            'required' => CompositeCondition::and(
+                CompositeCondition::not($internalAgencyBookingCondition),
+                new RequiresOwnEmailCondition(),
+            ),
         ];
 
         // Address fields - render as static text if first participant in non-internal agency OR participant not mutable

src/Form/Service/ParticipantEmailFieldHandler.php

@@ -1,110 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\Form\Service;
-
-use App\Form\Model\BookingDto;
-use App\Form\Model\ParticipantDto;
-use App\Form\Service\Abstract\AbstractParticipantFieldHandler;
-
-/**
- * Handles the email field, pre-filling the applicant's address for under-16 participants.
- *
- * BusPro requires a Mail-Adresse for every participant once a room is present and rejects the
- * step-3 Anfrage with 650 otherwise, children included. It does accept an address identical to
- * the Anmelder's, so children inherit the applicant's rather than being asked for one they
- * typically do not have. The value stays editable and stays mandatory. This happens in the
- * create flow only; in edit mode the handler just stores what was submitted.
- *
- * The copy only ever fills a blank, so an address somebody typed is never overwritten. A later
- * correction to the applicant's own address therefore does not propagate to children who already
- * inherited the previous one.
- *
- * Depends on dateOfBirth: whether a participant counts as a child is only known once their date
- * of birth has been processed.
- */
-class ParticipantEmailFieldHandler extends AbstractParticipantFieldHandler
-{
-    public function getFieldName(): string
-    {
-        return 'email';
-    }
-
-    /**
-     * @return string[]
-     */
-    public function getDependencies(): array
-    {
-        return ['dateOfBirth'];
-    }
-
-    /**
-     * @param array<string, mixed> $submittedData    The submitted participant form data
-     * @param BookingDto           $bookingDto       The booking DTO to update (create or edit)
-     * @param int                  $participantIndex The index of the participant being processed
-     */
-    public function processField(array $submittedData, BookingDto $bookingDto, int $participantIndex): void
-    {
-        $participant = $this->getParticipant($bookingDto, $participantIndex);
-
-        if (false === $participant instanceof ParticipantDto) {
-            return;
-        }
-
-        $submitted = $this->getFieldValue($submittedData, $this->getFieldName());
-
-        if (true === is_string($submitted)) {
-            $participant->email = '' !== trim($submitted) ? trim($submitted) : null;
-        }
-
-        $this->applyApplicantEmail($bookingDto, $participant);
-    }
-
-    /**
-     * Copies the applicant's address onto a child who has none of their own.
-     */
-    public function applyApplicantEmail(BookingDto $bookingDto, ParticipantDto $participant): void
-    {
-        // Create mode only. An existing booking already carries whatever BusPro accepted, a
-        // blank may be intended where personal data is optional, and participant[0] is not
-        // reliably the applicant there.
-        if (BookingDto::MODE_CREATE !== $bookingDto->getMode()) {
-            return;
-        }
-
-        if (false === $participant->isChild()) {
-            return;
-        }
-
-        $applicantEmail = $this->resolveApplicantEmail($bookingDto);
-
-        if (null === $applicantEmail) {
-            return;
-        }
-
-        // The applicant themselves never inherits, and on an ordinary booking that is participant[0].
-        if (true === $participant->isApplicant() && true === $bookingDto->applicantTravels) {
-            return;
-        }
-
-        if (null === $participant->email || '' === trim($participant->email)) {
-            $participant->email = $applicantEmail;
-        }
-    }
-
-    private function resolveApplicantEmail(BookingDto $bookingDto): ?string
-    {
-        $applicant = $bookingDto->applicantTravels
-            ? ($bookingDto->participants[0] ?? null)
-            : $bookingDto->applicant;
-
-        $email = $applicant?->email;
-
-        if (null === $email || '' === trim($email)) {
-            return null;
-        }
-
-        return trim($email);
-    }
-}

src/Form/Service/ParticipantFieldHandlerRegistry.php

@@ -250,9 +250,6 @@ class ParticipantFieldHandlerRegistry
     {
         // Define fields that may be reassigned by handlers and need syncing
         $serviceFields = [
-            // Not a service: ParticipantEmailFieldHandler pre-fills a child's blank email from
-            // the applicant, and without syncing it back the form would bind the blank over it.
-            'email',
             'transportationOutbound',
             'transportationInbound',
             'insurance',

tests/BusProNet/DataProcessor/BookingPayloadBuilderTest.php

@@ -13,7 +13,7 @@ use App\Form\Model\ParticipantDto;
 use PHPUnit\Framework\TestCase;
 
 /**
- * Covers who the <anmelder> block is built from, and the participant email fallback.
+ * Covers who the <anmelder> block is built from, and that a participant's blank email stays blank.
  */
 class BookingPayloadBuilderTest extends TestCase
 {
@@ -69,7 +69,7 @@ class BookingPayloadBuilderTest extends TestCase
         $this->assertArrayNotHasKey('idadresse', $payload['anmelder']);
     }
 
-    public function testParticipantWithoutEmailInheritsTheApplicants(): void
+    public function testParticipantWithoutEmailIsSentWithoutOne(): void
     {
         $bookingDto = $this->createBookingDto();
         $bookingDto->applicantTravels = false;
@@ -78,10 +78,10 @@ class BookingPayloadBuilderTest extends TestCase
 
         $payload = $this->builder->buildCreatePayload($bookingDto, 'BUCHUNG');
 
-        $this->assertSame(
-            'e[email protected]',
-            $payload['teilnehmerliste']['teilnehmer'][0]['kommunikation']['email'],
-            'BusPro rejects a participant without a Mail-Adresse with 650, but accepts a shared one'
+        $this->assertArrayNotHasKey(
+            'email',
+            $payload['teilnehmerliste']['teilnehmer'][0]['kommunikation'],
+            'BusPro accepts a participant without a Mail-Adresse; the applicant\'s must not be borrowed'
         );
     }
 

tests/Form/Model/BookingDtoTest.php

@@ -429,6 +429,97 @@ class BookingDtoTest extends TestCase
         $this->assertSame(['participants[0].address'], $this->collectFirstParticipantAddressPaths($dto));
     }
 
+    public function testChildApplicantWithoutEmailIsReportedOnce(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->participants[0] = $this->createParticipantWithoutEmail(10);
+
+        $this->assertSame(
+            ['participants[0].email'],
+            $this->collectFirstParticipantEmailPaths($dto),
+            'The applicant is the booking contact and needs an email at any age'
+        );
+    }
+
+    public function testChildAtIndexZeroOfASplitBookingMayLeaveTheEmailBlank(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->applicantTravels = false;
+        $dto->participants[0] = $this->createParticipantWithoutEmail(10);
+
+        $this->assertSame([], $this->collectFirstParticipantEmailPaths($dto));
+    }
+
+    public function testAdultAtIndexZeroOfASplitBookingStillNeedsAnEmail(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->applicantTravels = false;
+        $dto->participants[0] = $this->createParticipantWithoutEmail(30);
+
+        $this->assertSame(['participants[0].email'], $this->collectFirstParticipantEmailPaths($dto));
+    }
+
+    public function testApplicantEmailComesFromParticipantZeroWhenTheApplicantTravels(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->participants[0]->email = ' [email protected] ';
+        $dto->applicant = new ParticipantDto();
+        $dto->applicant->email = '[email protected]';
+
+        $this->assertSame('[email protected]', $dto->getApplicantEmail());
+    }
+
+    public function testApplicantEmailComesFromTheApplicantBlockOnACreateModeSplit(): void
+    {
+        $dto = $this->createCreateModeDto();
+        $dto->participants[0]->email = '[email protected]';
+        $dto->applicantTravels = false;
+        $dto->applicant = new ParticipantDto();
+        $dto->applicant->email = '[email protected]';
+
+        $this->assertSame('[email protected]', $dto->getApplicantEmail());
+    }
+
+    public function testApplicantEmailComesFromTheAnmelderOnAnEditModeSplit(): void
+    {
+        $dto = $this->createEditModeDto(100, 200);
+        $dto->participants[0]->email = '[email protected]';
+        $dto->booking->applicant->communication->email = '[email protected]';
+
+        $this->assertSame('[email protected]', $dto->getApplicantEmail());
+    }
+
+    /**
+     * Ages relative to today, since isChild() measures against the current date.
+     */
+    private function createParticipantWithoutEmail(int $years): ParticipantDto
+    {
+        $participant = new ParticipantDto();
+        $participant->index = 0;
+        $participant->dateOfBirth = (new \DateTimeImmutable('today'))->modify(sprintf('-%d years', $years));
+        $participant->address = $this->createAddress();
+
+        return $participant;
+    }
+
+    /**
+     * @return list<string>
+     */
+    private function collectFirstParticipantEmailPaths(BookingDto $dto): array
+    {
+        $validator = Validation::createValidatorBuilder()->enableAttributeMapping()->getValidator();
+        $violations = $validator->validate($dto, null, ['booking_create', 'strict_required']);
+
+        $paths = [];
+        foreach ($violations as $violation) {
+            if ('participants[0].email' === $violation->getPropertyPath()) {
+                $paths[] = $violation->getPropertyPath();
+            }
+        }
+
+        return $paths;
+    }
+
     /**
      * @return list<string>
      */

tests/Form/Model/ParticipantEditDtoTest.php

@@ -909,7 +909,7 @@ class ParticipantEditDtoTest extends TestCase
      * available ski pass. Ski pass validation depends on the travel actually offering
      * passes, so a travel without them is a distinct fixture, not the default.
      */
-    public function testChildWithoutEmailFailsStrictValidation(): void
+    public function testChildWithoutEmailPassesStrictValidation(): void
     {
         $bookingDto = $this->createBookingDtoWithParticipants([
             $this->createAdultParticipant('[email protected]'),
@@ -918,14 +918,10 @@ class ParticipantEditDtoTest extends TestCase
 
         $violations = $this->validateStrict($bookingDto, 1);
 
-        $this->assertSame(
-            ['Bitte angeben'],
-            $this->emailRequiredMessages($violations),
-            'BusPro requires a Mail-Adresse for every participant, children included'
-        );
+        $this->assertSame([], $this->emailRequiredMessages($violations));
     }
 
-    public function testChildWithNullEmailFailsStrictValidation(): void
+    public function testChildWithNullEmailPassesStrictValidation(): void
     {
         $child = $this->createChildParticipant('');
         $child->email = null;
@@ -937,7 +933,7 @@ class ParticipantEditDtoTest extends TestCase
 
         $violations = $this->validateStrict($bookingDto, 1);
 
-        $this->assertSame(['Bitte angeben'], $this->emailRequiredMessages($violations));
+        $this->assertSame([], $this->emailRequiredMessages($violations));
     }
 
     public function testChildSharingTheApplicantsEmailPassesStrictValidation(): void
@@ -952,7 +948,7 @@ class ParticipantEditDtoTest extends TestCase
         $this->assertSame(
             [],
             $this->emailRequiredMessages($violations),
-            'A child inherits the applicant address, which BusPro accepts'
+            'A child may use the applicant\'s address instead of leaving it blank'
         );
     }
 
@@ -1021,6 +1017,99 @@ class ParticipantEditDtoTest extends TestCase
         $this->assertSame(['Bitte angeben'], $this->emailRequiredMessages($violations));
     }
 
+    public function testChildAtIndexZeroOfASplitBookingMayLeaveTheEmailBlank(): void
+    {
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createChildParticipant(''),
+        ]);
+        $bookingDto->applicantTravels = false;
+
+        $violations = $this->validateStrict($bookingDto, 0);
+
+        $this->assertSame(
+            [],
+            $this->emailRequiredMessages($violations),
+            'Where the applicant does not travel, participant[0] is an ordinary traveller'
+        );
+    }
+
+    public function testAdultAtIndexZeroOfASplitBookingStillNeedsAnEmail(): void
+    {
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createAdultParticipant(''),
+        ]);
+        $bookingDto->applicantTravels = false;
+
+        $violations = $this->validateStrict($bookingDto, 0);
+
+        $this->assertSame(['Bitte angeben'], $this->emailRequiredMessages($violations));
+    }
+
+    public function testAdultTravellerMayNotReuseTheNonTravellingApplicantsEmail(): void
+    {
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createAdultParticipant('[email protected]'),
+        ]);
+        $bookingDto->applicantTravels = false;
+        $bookingDto->applicant = $this->createValidParticipant(new \DateTimeImmutable('1980-01-01'), '[email protected]');
+
+        $violations = $this->validator->validate(
+            new ParticipantEditDto(participant: $bookingDto->participants[0], bookingContext: $bookingDto),
+            null,
+            ['booking_create']
+        );
+
+        $this->assertCount(1, $violations);
+        $this->assertSame('participant.email', $violations->get(0)->getPropertyPath());
+        $this->assertSame(
+            'Diese E-Mail Adresse wird bereits von der anmeldenden Person verwendet',
+            $violations->get(0)->getMessage()
+        );
+    }
+
+    public function testChildTravellerMayReuseTheNonTravellingApplicantsEmail(): void
+    {
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createChildParticipant('[email protected]'),
+        ]);
+        $bookingDto->applicantTravels = false;
+        $bookingDto->applicant = $this->createValidParticipant(new \DateTimeImmutable('1980-01-01'), '[email protected]');
+
+        $violations = $this->validator->validate(
+            new ParticipantEditDto(participant: $bookingDto->participants[0], bookingContext: $bookingDto),
+            null,
+            ['booking_create']
+        );
+
+        $this->assertCount(0, $violations);
+    }
+
+    public function testAdultTravellerMayNotReuseTheAnmelderEmailOfASplitBookingInEditMode(): void
+    {
+        $applicant = new PersonalData();
+        $applicant->personId = 100;
+        $applicant->communication->email = '[email protected]';
+
+        $bookingDto = $this->createBookingDtoWithParticipants([
+            $this->createAdultParticipant('[email protected]'),
+        ]);
+        $bookingDto->booking = new Booking();
+        $bookingDto->booking->applicant = $applicant;
+        $bookingDto->participants[0]->personId = 200;
+
+        $violations = $this->validator->validate(
+            new ParticipantEditDto(participant: $bookingDto->participants[0], bookingContext: $bookingDto),
+            null,
+            ['booking_edit']
+        );
+
+        $this->assertCount(1, $violations);
+        $this->assertSame(
+            'Diese E-Mail Adresse wird bereits von der anmeldenden Person verwendet',
+            $violations->get(0)->getMessage()
+        );
+    }
+
     public function testDependentTurningExactlySixteenRequiresEmail(): void
     {
         $participant = $this->createAdultParticipant('');
@@ -1036,7 +1125,7 @@ class ParticipantEditDtoTest extends TestCase
         $this->assertSame(['Bitte angeben'], $this->emailRequiredMessages($violations));
     }
 
-    public function testDependentOneDayShortOfSixteenStillRequiresEmail(): void
+    public function testDependentOneDayShortOfSixteenDoesNotRequireEmail(): void
     {
         $participant = $this->createAdultParticipant('');
         $participant->dateOfBirth = (new \DateTimeImmutable('today'))->modify('-16 years')->modify('+1 day');
@@ -1048,7 +1137,7 @@ class ParticipantEditDtoTest extends TestCase
 
         $violations = $this->validateStrict($bookingDto, 1);
 
-        $this->assertSame(['Bitte angeben'], $this->emailRequiredMessages($violations));
+        $this->assertSame([], $this->emailRequiredMessages($violations));
     }
 
     /**

tests/Form/Service/CreateFieldStateProviderTest.php

@@ -74,14 +74,69 @@ class CreateFieldStateProviderTest extends TestCase
         );
     }
 
-    public function testEmailIsRequiredForEveryParticipantIncludingChildren(): void
+    public function testEmailIsNotRequiredForNonApplicantChild(): void
     {
         $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
 
-        $this->assertArrayNotHasKey(
-            'required',
-            $this->provider->getFieldState('email', $bookingDto, 1),
-            'Requiredness is the form type base option now that it is unconditional'
+        $this->assertFalse(
+            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
+            'A child travelling with an applicant does not need an email address of their own'
+        );
+    }
+
+    public function testEmailIsRequiredForNonApplicantAdult(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('1990-01-01'));
+
+        $this->assertTrue($this->provider->getFieldState('email', $bookingDto, 1)['required']);
+    }
+
+    public function testEmailIsRequiredForTheApplicantEvenAsAChild(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $bookingDto->participants[0]->dateOfBirth = new \DateTimeImmutable('2015-01-01');
+
+        $this->assertTrue(
+            $this->provider->getFieldState('email', $bookingDto, 0)['required'],
+            'The applicant is the booking contact and always has to be reachable'
+        );
+    }
+
+    public function testEmailIsNotRequiredForAChildAtIndexZeroWhenTheApplicantDoesNotTravel(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $bookingDto->participants[0]->dateOfBirth = new \DateTimeImmutable('2015-01-01');
+        $bookingDto->applicantTravels = false;
+
+        $this->assertFalse(
+            $this->provider->getFieldState('email', $bookingDto, 0)['required'],
+            'On a split booking participant[0] is an ordinary traveller'
+        );
+    }
+
+    public function testEmailIsRequiredWhenDateOfBirthIsUnknown(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $bookingDto->participants[1]->dateOfBirth = null;
+
+        $this->assertTrue(
+            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
+            'An unknown age counts as an adult'
+        );
+    }
+
+    public function testEmailRequirementFlipsWhenDateOfBirthChanges(): void
+    {
+        $bookingDto = $this->createBookingDtoWithApplicantAndDependent(new \DateTimeImmutable('2015-01-01'));
+        $dependent = $bookingDto->participants[1];
+
+        $this->assertFalse($this->provider->getFieldState('email', $bookingDto, 1)['required']);
+
+        $dependent->dateOfBirth = new \DateTimeImmutable('1990-01-01');
+
+        $this->assertTrue(
+            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
+            'Correcting a child date of birth to an adult one must reinstate the requirement'
         );
     }
 

tests/Form/Service/EditFieldStateProviderTest.php

@@ -31,14 +31,11 @@ class EditFieldStateProviderTest extends TestCase
         $this->assertTrue($this->provider->getFieldState('email', $bookingDto, 1)['required']);
     }
 
-    public function testEmailIsRequiredForNonApplicantChild(): void
+    public function testEmailIsNotRequiredForNonApplicantChild(): void
     {
         $bookingDto = $this->createBookingDto(new \DateTimeImmutable('2015-01-01'), false);
 
-        $this->assertTrue(
-            $this->provider->getFieldState('email', $bookingDto, 1)['required'],
-            'BusPro requires a Mail-Adresse for every participant, children included'
-        );
+        $this->assertFalse($this->provider->getFieldState('email', $bookingDto, 1)['required']);
     }
 
     public function testEmailIsNotRequiredForInternalAgencyBookingsEvenForAdults(): void

tests/Form/Service/ParticipantEmailFieldHandlerTest.php

@@ -1,162 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\Tests\Form\Service;
-
-use App\BusProNet\Model\Booking;
-use App\BusProNet\Model\Travel;
-use App\BusProNet\XmlLoader\AgencyLoader;
-use App\Form\Model\BookingDto;
-use App\Form\Model\ParticipantDto;
-use App\Form\Service\ParticipantDateOfBirthFieldHandler;
-use App\Form\Service\ParticipantEmailFieldHandler;
-use App\Form\Service\ParticipantFieldHandlerRegistry;
-use PHPUnit\Framework\TestCase;
-use Psr\Log\NullLogger;
-
-class ParticipantEmailFieldHandlerTest extends TestCase
-{
-    private ParticipantEmailFieldHandler $handler;
-
-    protected function setUp(): void
-    {
-        $this->handler = new ParticipantEmailFieldHandler();
-    }
-
-    public function testChildWithoutEmailInheritsTheApplicants(): void
-    {
-        $bookingDto = $this->createBookingDto();
-
-        $this->handler->processField(['email' => ''], $bookingDto, 1);
-
-        $this->assertSame('[email protected]', $bookingDto->participants[1]->email);
-    }
-
-    public function testChildKeepsAnEmailThatWasTypedIn(): void
-    {
-        $bookingDto = $this->createBookingDto();
-
-        $this->handler->processField(['email' => '[email protected]'], $bookingDto, 1);
-
-        $this->assertSame(
-            '[email protected]',
-            $bookingDto->participants[1]->email,
-            'The pre-filled address stays overridable'
-        );
-    }
-
-    public function testAdultWithoutEmailDoesNotInherit(): void
-    {
-        $bookingDto = $this->createBookingDto();
-        $bookingDto->participants[1]->dateOfBirth = new \DateTimeImmutable('1990-01-01');
-
-        $this->handler->processField(['email' => ''], $bookingDto, 1);
-
-        $this->assertNull(
-            $bookingDto->participants[1]->email,
-            'An adult supplies their own address; NotBlank reports the gap'
-        );
-    }
-
-    public function testApplicantDoesNotInheritFromThemselves(): void
-    {
-        $bookingDto = $this->createBookingDto();
-        $bookingDto->participants[0]->dateOfBirth = new \DateTimeImmutable('2015-01-01');
-
-        $this->handler->processField(['email' => ''], $bookingDto, 0);
-
-        $this->assertNull($bookingDto->participants[0]->email);
-    }
-
-    public function testChildAtIndexZeroInheritsWhenTheApplicantDoesNotTravel(): void
-    {
-        $bookingDto = $this->createBookingDto();
-        $bookingDto->applicantTravels = false;
-        $bookingDto->applicant = $this->createParticipant('[email protected]', '1981-03-16');
-        $bookingDto->participants[0]->dateOfBirth = new \DateTimeImmutable('2015-01-01');
-
-        $this->handler->processField(['email' => ''], $bookingDto, 0);
-
-        $this->assertSame('[email protected]', $bookingDto->participants[0]->email);
-    }
-
-    public function testEditModeNeverPreFills(): void
-    {
-        $bookingDto = $this->createBookingDto();
-        $bookingDto->booking = new Booking();
-
-        $this->handler->processField(['email' => ''], $bookingDto, 1);
-
-        $this->assertNull(
-            $bookingDto->participants[1]->email,
-            'participant[0] is not reliably the applicant in edit mode, and a blank may be intended'
-        );
-    }
-
-    public function testEditModeLeavesAnInternalAgencyChildWithoutEmail(): void
-    {
-        $bookingDto = $this->createBookingDto();
-        $bookingDto->booking = new Booking();
-        $bookingDto->agencyCode = AgencyLoader::INTERNAL_AGENCY_CODE;
-
-        $this->handler->processField(['email' => ''], $bookingDto, 1);
-
-        $this->assertNull($bookingDto->participants[1]->email);
-    }
-
-    public function testHandlerRunsAfterDateOfBirth(): void
-    {
-        $this->assertSame(
-            ['dateOfBirth'],
-            $this->handler->getDependencies(),
-            'Whether someone counts as a child is only known once their DOB is processed'
-        );
-    }
-
-    /**
-     * The handler runs in PRE_SUBMIT and writes to the DTO, but the form then binds the submitted
-     * data over it. Only fields the registry syncs back survive, so the pre-filled address has to
-     * reappear in the returned data - otherwise the blank wins and the field renders empty.
-     */
-    public function testPreFilledEmailIsSyncedBackIntoTheSubmittedData(): void
-    {
-        $bookingDto = $this->createBookingDto();
-        $registry = new ParticipantFieldHandlerRegistry([
-            new ParticipantDateOfBirthFieldHandler(new NullLogger()),
-            new ParticipantEmailFieldHandler(),
-        ]);
-
-        $synced = $registry->processFieldsForParticipantAndSync(['email' => ''], $bookingDto, 1);
-
-        $this->assertSame('[email protected]', $bookingDto->participants[1]->email);
-        $this->assertSame(
-            '[email protected]',
-            $synced['email'],
-            'Without the sync the form binds the blank back over the pre-filled address'
-        );
-    }
-
-    private function createBookingDto(): BookingDto
-    {
-        $bookingDto = new BookingDto(new Travel(), 1);
-        $bookingDto->participants = [
-            $this->createParticipant('[email protected]', '1980-01-01'),
-            $this->createParticipant('', '2015-01-01'),
-        ];
-        $bookingDto->participants[0]->index = 0;
-        $bookingDto->participants[1]->index = 1;
-        $bookingDto->participants[1]->email = null;
-
-        return $bookingDto;
-    }
-
-    private function createParticipant(string $email, string $dateOfBirth): ParticipantDto
-    {
-        $participant = new ParticipantDto();
-        $participant->email = '' !== $email ? $email : null;
-        $participant->dateOfBirth = new \DateTimeImmutable($dateOfBirth);
-
-        return $participant;
-    }
-}