diff --git a/frontend/i18n/locales/fr.json b/frontend/i18n/locales/fr.json
index 5744828..cf7bc63 100644
--- a/frontend/i18n/locales/fr.json
+++ b/frontend/i18n/locales/fr.json
@@ -168,13 +168,18 @@
                     "prospect": "Prospect",
                     "delivery": "Adresse de livraison",
                     "billing": "Facturation",
+                    "addressType": "Type d'adresse",
+                    "addressTypeProspect": "Prospect",
+                    "addressTypeDelivery": "Livraison",
+                    "addressTypeBilling": "Facturation",
+                    "addressTypeDeliveryBilling": "Adresse + Facturation",
                     "categories": "Catégorie",
                     "country": "Pays",
                     "postalCode": "Code postal",
                     "city": "Ville",
                     "street": "Adresse",
                     "streetComplement": "Adresse complémentaire",
-                    "sites": "Sites Starseed",
+                    "sites": "Sites",
                     "contacts": "Contact(s) rattaché(s)",
                     "billingEmail": "Email de facturation",
                     "remove": "Supprimer l'adresse",
diff --git a/frontend/modules/commercial/components/ClientAddressBlock.vue b/frontend/modules/commercial/components/ClientAddressBlock.vue
index ee6e08b..1745a4b 100644
--- a/frontend/modules/commercial/components/ClientAddressBlock.vue
+++ b/frontend/modules/commercial/components/ClientAddressBlock.vue
@@ -10,34 +10,53 @@
             @click="$emit('remove')"
         />
 
-        <!-- Usage de l'adresse : Prospect exclusif de Livraison/Facturation
-             (RG-1.06/07/08). L'exclusivite est appliquee au toggle (cocher l'un
-             decoche l'autre) plutot qu'en masquant les options. -->
-        <MalioCheckbox
-            :model-value="model.isProspect"
-            :label="t('commercial.clients.form.address.prospect')"
-            group-class="self-center"
+        <!-- Usage de l'adresse : Select unique (plus simple pour l'utilisateur)
+             remplacant les 3 cases. Les options encodent les combinaisons valides
+             (exclusivite Prospect, RG-1.06/07/08) ; le back recoit toujours les
+             drapeaux isProspect / isDelivery / isBilling (aucune RG modifiee). -->
+        <MalioSelect
+            :model-value="addressType"
+            :options="addressTypeOptions"
+            :label="t('commercial.clients.form.address.addressType')"
             :readonly="readonly"
-            @update:model-value="(v: boolean) => toggleFlag('isProspect', v)"
-        />
-        <MalioCheckbox
-            :model-value="model.isDelivery"
-            :label="t('commercial.clients.form.address.delivery')"
-            group-class="self-center"
-            :readonly="readonly"
-            @update:model-value="(v: boolean) => toggleFlag('isDelivery', v)"
-        />
-        <MalioCheckbox
-            :model-value="model.isBilling"
-            :label="t('commercial.clients.form.address.billing')"
-            group-class="self-center"
-            :readonly="readonly"
-            @update:model-value="(v: boolean) => toggleFlag('isBilling', v)"
+            :required="true"
+            @update:model-value="onAddressTypeChange"
         />
 
-        <!-- Cellule vide : laisse un trou en position 4 (ligne 1) pour que
-             Categorie reparte au debut de la ligne suivante. -->
-        <div aria-hidden="true" />
+        <!-- Sites Starseed : multiselect a tags (>= 1 obligatoire, RG-1.10). -->
+        <MalioSelectCheckbox
+            :model-value="model.siteIris"
+            :options="siteOptions"
+            :label="t('commercial.clients.form.address.sites')"
+            :display-tag="true"
+            :readonly="readonly"
+            :required="true"
+            @update:model-value="(v: (string | number)[]) => update('siteIris', v.map(String))"
+        />
+
+        <MalioSelectCheckbox
+            :model-value="model.contactIris"
+            :options="contactOptions"
+            :label="t('commercial.clients.form.address.contacts')"
+            :display-tag="true"
+            :readonly="readonly"
+            @update:model-value="(v: (string | number)[]) => update('contactIris', v.map(String))"
+        />
+
+        <!-- Email de facturation : ligne 1 colonne 4, visible/obligatoire
+             seulement si Facturation (RG-1.11). Sinon un filler comble la
+             colonne pour que Categorie reparte au debut de la ligne 2. -->
+        <MalioInputEmail
+            v-if="isBillingEmailRequired(model)"
+            :model-value="model.billingEmail"
+            :label="t('commercial.clients.form.address.billingEmail')"
+            :required="true"
+            :readonly="readonly"
+            :lowercase="true"
+            :error="errors?.billingEmail"
+            @update:model-value="(v: string) => update('billingEmail', v)"
+        />
+        <div v-else aria-hidden="true" />
 
         <MalioSelectCheckbox
             :model-value="model.categoryIris"
@@ -134,47 +153,15 @@
             />
         </div>
 
-        <!-- Sites Starseed : cases a cocher inline (>= 1 obligatoire, RG-1.10). -->
-        <div class="flex justify-between">
-            <MalioCheckbox
-                v-for="site in siteOptions"
-                :key="site.value"
-                :model-value="model.siteIris.includes(site.value)"
-                :label="site.label"
-                group-class="w-auto self-center"
-                :readonly="readonly"
-                @update:model-value="(v: boolean) => toggleSite(site.value, v)"
-            />
-        </div>
-
-        <MalioSelectCheckbox
-            :model-value="model.contactIris"
-            :options="contactOptions"
-            :label="t('commercial.clients.form.address.contacts')"
-            :display-tag="true"
-            :readonly="readonly"
-            @update:model-value="(v: (string | number)[]) => update('contactIris', v.map(String))"
-        />
-
-        <!-- Email de facturation : visible/obligatoire seulement si Facturation
-             est coche (RG-1.11). -->
-        <MalioInputText
-            v-if="isBillingEmailRequired(model)"
-            :model-value="model.billingEmail"
-            :label="t('commercial.clients.form.address.billingEmail')"
-            :required="true"
-            :readonly="readonly"
-            :error="errors?.billingEmail"
-            @update:model-value="(v: string) => update('billingEmail', v)"
-        />
     </div>
 </template>
 
 <script setup lang="ts">
 import {
-    applyProspectExclusivity,
+    addressFlagsFromType,
+    addressTypeFromFlags,
     isBillingEmailRequired,
-    type AddressFlagsDraft,
+    type AddressType,
 } from '~/modules/commercial/utils/clientFormRules'
 import { useAddressAutocomplete, type AddressSuggestion } from '~/shared/composables/useAddressAutocomplete'
 import type { CategoryOption, RefOption } from '~/modules/commercial/composables/useClientReferentials'
@@ -213,6 +200,23 @@ const autocomplete = useAddressAutocomplete()
 
 const model = computed(() => props.modelValue)
 
+// Type d'adresse (Select unique) derive des drapeaux back. null tant qu'aucun
+// drapeau n'est pose -> champ vide + bouton « Valider » bloque (cf. parent).
+const addressType = computed<AddressType | null>(() => addressTypeFromFlags(model.value))
+
+const addressTypeOptions = computed<RefOption[]>(() => [
+    { value: 'prospect', label: t('commercial.clients.form.address.addressTypeProspect') },
+    { value: 'delivery', label: t('commercial.clients.form.address.addressTypeDelivery') },
+    { value: 'billing', label: t('commercial.clients.form.address.addressTypeBilling') },
+    { value: 'delivery_billing', label: t('commercial.clients.form.address.addressTypeDeliveryBilling') },
+])
+
+/** Applique le type choisi en repercutant les 3 drapeaux back (immutabilite). */
+function onAddressTypeChange(value: string | number | null): void {
+    if (value === null) return
+    emit('update:modelValue', { ...props.modelValue, ...addressFlagsFromType(value as AddressType) })
+}
+
 // Mode degrade : service BAN indisponible → Ville/Adresse en saisie libre.
 const degraded = ref(false)
 // Villes proposees par la BAN (alimentees a la saisie du code postal).
@@ -254,25 +258,6 @@ function update<K extends keyof AddressFormDraft>(field: K, value: AddressFormDr
     emit('update:modelValue', { ...props.modelValue, [field]: value })
 }
 
-/** Coche/decoche un site Starseed rattache a l'adresse (M2M par IRI, RG-1.10). */
-function toggleSite(siteIri: string, selected: boolean): void {
-    const current = props.modelValue.siteIris
-    const next = selected
-        ? [...current, siteIri]
-        : current.filter(iri => iri !== siteIri)
-    update('siteIris', next)
-}
-
-/** Applique l'exclusivite Prospect / (Livraison|Facturation) au changement. */
-function toggleFlag(field: keyof AddressFlagsDraft, value: boolean): void {
-    const flags = applyProspectExclusivity(
-        { isProspect: model.value.isProspect, isDelivery: model.value.isDelivery, isBilling: model.value.isBilling },
-        field,
-        value,
-    )
-    emit('update:modelValue', { ...props.modelValue, ...flags })
-}
-
 /** Bascule définitivement en mode degrade et previent le parent (toast unique). */
 function enterDegraded(): void {
     if (!degraded.value) {
diff --git a/frontend/modules/commercial/components/ClientContactBlock.vue b/frontend/modules/commercial/components/ClientContactBlock.vue
index e270138..1531966 100644
--- a/frontend/modules/commercial/components/ClientContactBlock.vue
+++ b/frontend/modules/commercial/components/ClientContactBlock.vue
@@ -37,6 +37,7 @@
             :model-value="model.email"
             :label="t('commercial.clients.form.contact.email')"
             :readonly="readonly"
+            :lowercase="true"
             :error="errors?.email"
             @update:model-value="(v: string) => update('email', v)"
         />
diff --git a/frontend/modules/commercial/pages/clients/[id]/edit.vue b/frontend/modules/commercial/pages/clients/[id]/edit.vue
index 7cbd718..b5387f2 100644
--- a/frontend/modules/commercial/pages/clients/[id]/edit.vue
+++ b/frontend/modules/commercial/pages/clients/[id]/edit.vue
@@ -410,6 +410,7 @@ import {
     type MainFormDraft,
 } from '~/modules/commercial/utils/clientEdit'
 import {
+    addressTypeFromFlags,
     buildClientFormTabKeys,
     hasAllRequiredAccountingFields,
     hasAtLeastOneValidContact,
@@ -789,7 +790,8 @@ const canValidateAddresses = computed(() =>
     addresses.value.length > 0
     && addresses.value.every((a) => {
         const filledBillingEmail = a.billingEmail !== null && a.billingEmail.trim() !== ''
-        return a.siteIris.length >= 1
+        return addressTypeFromFlags(a) !== null
+            && a.siteIris.length >= 1
             && a.categoryIris.length >= 1
             && (!isBillingEmailRequired(a) || filledBillingEmail)
     }),
diff --git a/frontend/modules/commercial/pages/clients/new.vue b/frontend/modules/commercial/pages/clients/new.vue
index c248499..720f40e 100644
--- a/frontend/modules/commercial/pages/clients/new.vue
+++ b/frontend/modules/commercial/pages/clients/new.vue
@@ -380,6 +380,7 @@ import { computed, onMounted, reactive, ref, watch } from 'vue'
 import { useClientReferentials, type RefOption } from '~/modules/commercial/composables/useClientReferentials'
 import { useClientFormErrors } from '~/modules/commercial/composables/useClientFormErrors'
 import {
+    addressTypeFromFlags,
     buildClientFormTabKeys,
     CLIENT_FORM_PLACEHOLDER_TABS,
     hasAllRequiredAccountingFields,
@@ -749,12 +750,14 @@ const countryOptions: RefOption[] = [
     { value: 'Espagne', label: 'Espagne' },
 ]
 
-// RG-1.10 (>= 1 site) + RG-1.11 (email facturation si Facturation) sur chaque adresse.
+// Type d'adresse (Select) obligatoire + RG-1.10 (>= 1 site) + RG-1.11 (email
+// facturation si Facturation) sur chaque adresse.
 const canValidateAddresses = computed(() =>
     addresses.value.length > 0
     && addresses.value.every((a) => {
         const filledBillingEmail = a.billingEmail !== null && a.billingEmail.trim() !== ''
-        return a.siteIris.length >= 1
+        return addressTypeFromFlags(a) !== null
+            && a.siteIris.length >= 1
             && a.categoryIris.length >= 1
             && (!isBillingEmailRequired(a) || filledBillingEmail)
     }),
diff --git a/frontend/modules/commercial/utils/__tests__/clientFormRules.spec.ts b/frontend/modules/commercial/utils/__tests__/clientFormRules.spec.ts
index 34da52c..c8929c9 100644
--- a/frontend/modules/commercial/utils/__tests__/clientFormRules.spec.ts
+++ b/frontend/modules/commercial/utils/__tests__/clientFormRules.spec.ts
@@ -1,5 +1,7 @@
 import { describe, it, expect } from 'vitest'
 import {
+    addressFlagsFromType,
+    addressTypeFromFlags,
     applyProspectExclusivity,
     buildClientFormTabKeys,
     canSelectDeliveryOrBilling,
@@ -197,6 +199,32 @@ describe('isBillingEmailRequired (RG-1.11)', () => {
     })
 })
 
+describe('type d\'adresse (Select front) <-> drapeaux back', () => {
+    it('addressFlagsFromType mappe chaque type vers les bons drapeaux', () => {
+        expect(addressFlagsFromType('prospect')).toEqual({ isProspect: true, isDelivery: false, isBilling: false })
+        expect(addressFlagsFromType('delivery')).toEqual({ isProspect: false, isDelivery: true, isBilling: false })
+        expect(addressFlagsFromType('billing')).toEqual({ isProspect: false, isDelivery: false, isBilling: true })
+        expect(addressFlagsFromType('delivery_billing')).toEqual({ isProspect: false, isDelivery: true, isBilling: true })
+    })
+
+    it('addressTypeFromFlags reconstruit le type (Prospect prioritaire, livraison+facturation groupes)', () => {
+        expect(addressTypeFromFlags({ isProspect: true, isDelivery: false, isBilling: false })).toBe('prospect')
+        expect(addressTypeFromFlags({ isProspect: false, isDelivery: true, isBilling: false })).toBe('delivery')
+        expect(addressTypeFromFlags({ isProspect: false, isDelivery: false, isBilling: true })).toBe('billing')
+        expect(addressTypeFromFlags({ isProspect: false, isDelivery: true, isBilling: true })).toBe('delivery_billing')
+    })
+
+    it('addressTypeFromFlags retourne null quand aucun drapeau (amorce vierge -> bouton bloque)', () => {
+        expect(addressTypeFromFlags({ isProspect: false, isDelivery: false, isBilling: false })).toBeNull()
+    })
+
+    it('aller-retour type -> drapeaux -> type stable pour les 4 types', () => {
+        for (const type of ['prospect', 'delivery', 'billing', 'delivery_billing'] as const) {
+            expect(addressTypeFromFlags(addressFlagsFromType(type))).toBe(type)
+        }
+    })
+})
+
 describe('regles type de reglement (RG-1.12 / RG-1.13)', () => {
     it('banque obligatoire si VIREMENT', () => {
         expect(isBankRequiredForPaymentType('VIREMENT')).toBe(true)
diff --git a/frontend/modules/commercial/utils/clientFormRules.ts b/frontend/modules/commercial/utils/clientFormRules.ts
index 7fee6a4..ea838b4 100644
--- a/frontend/modules/commercial/utils/clientFormRules.ts
+++ b/frontend/modules/commercial/utils/clientFormRules.ts
@@ -187,6 +187,45 @@ export function isBillingEmailRequired(flags: AddressFlagsDraft): boolean {
     return flags.isBilling
 }
 
+/**
+ * Type d'adresse expose a l'utilisateur (Select unique remplacant les trois
+ * cases a cocher). Sucre purement front : le back continue de recevoir les
+ * drapeaux isProspect / isDelivery / isBilling (aucune RG modifiee). Les seules
+ * combinaisons proposees respectent l'exclusivite Prospect (RG-1.06/07/08).
+ */
+export type AddressType = 'prospect' | 'delivery' | 'billing' | 'delivery_billing'
+
+/**
+ * Mappe le type d'adresse choisi vers les trois drapeaux back.
+ * « Adresse + Facturation » = livraison ET facturation sur la meme adresse.
+ */
+export function addressFlagsFromType(type: AddressType): AddressFlagsDraft {
+    switch (type) {
+        case 'prospect':
+            return { isProspect: true, isDelivery: false, isBilling: false }
+        case 'delivery':
+            return { isProspect: false, isDelivery: true, isBilling: false }
+        case 'billing':
+            return { isProspect: false, isDelivery: false, isBilling: true }
+        case 'delivery_billing':
+            return { isProspect: false, isDelivery: true, isBilling: true }
+    }
+}
+
+/**
+ * Reconstruit le type d'adresse a partir des drapeaux (consultation / edition
+ * d'une adresse persistee, ou amorce vierge). Retourne null si aucun drapeau
+ * n'est positionne — le Select reste alors a saisir (et bloque la validation).
+ */
+export function addressTypeFromFlags(flags: AddressFlagsDraft): AddressType | null {
+    if (flags.isProspect) return 'prospect'
+    if (flags.isDelivery && flags.isBilling) return 'delivery_billing'
+    if (flags.isDelivery) return 'delivery'
+    if (flags.isBilling) return 'billing'
+
+    return null
+}
+
 /** Code stable du type de reglement « virement » (cf. PaymentType.code, RG-1.12). */
 const PAYMENT_TYPE_TRANSFER = 'VIREMENT'