fix(loyalty): cross-store enrollment, card scoping, i18n flicker

Fix duplicate card creation when the same email enrolls at different
stores under the same merchant, and implement cross-location-aware
enrollment behavior.

- Cross-location enabled (default): one card per customer per merchant.
  Re-enrolling at another store returns the existing card with a
  "works at all our locations" message + store list.
- Cross-location disabled: one card per customer per store. Enrolling
  at a different store creates a separate card for that store.

Changes:
- Migration loyalty_004: replace (merchant_id, customer_id) unique
  index with (enrolled_at_store_id, customer_id). Per-merchant
  uniqueness enforced at application layer when cross-location enabled.
- card_service.resolve_customer_id: cross-store email lookup via
  merchant_id param to find existing cardholders at other stores.
- card_service.enroll_customer: branch duplicate check on
  allow_cross_location_redemption setting.
- card_service.search_card_for_store: cross-store email search when
  cross-location enabled so staff at store2 can find cards from store1.
- card_service.get_card_by_customer_and_store: new service method.
- storefront enrollment: catch LoyaltyCardAlreadyExistsException,
  return existing card with already_enrolled flag, locations, and
  cross-location context. Server-rendered i18n via Jinja2 tojson.
- enroll-success.html: conditional cross-store/single-store messaging,
  server-rendered translations and context, i18n_modules block added.
- dashboard.html, history.html: replace $t() with server-side _() to
  fix i18n flicker across all storefront templates.
- Fix device-mobile icon → phone icon.
- 4 new i18n keys in 4 locales (en, fr, de, lb).
- Docs: updated data-model, business-logic, production-launch-plan,
  user-journeys with cross-location behavior and E2E test checklist.
- 12 new unit tests + 3 new integration tests (334 total pass).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/loyalty/docs/business-logic.md

@@ -214,14 +214,25 @@ Uses PKCS#7 signed `.pkpass` files and APNs push notifications.
 
 ## Cross-Store Redemption
 
-When `allow_cross_location_redemption` is enabled in merchant settings:
+The `allow_cross_location_redemption` merchant setting controls both card scoping and enrollment behavior:
 
-- Cards are scoped to the **merchant** (not individual stores)
+### When enabled (default)
+
+- **One card per customer per merchant** — enforced at the application layer
 - Customer can earn stamps at Store A and redeem at Store B
 - Each transaction records which `store_id` it occurred at
 - The `enrolled_at_store_id` field tracks where the customer first enrolled
+- If a customer tries to enroll at a second store, the system returns their existing card with a message showing all available locations
 
-When disabled, stamp/point operations are restricted to the enrollment store.
+### When disabled
+
+- **One card per customer per store** — each store under the merchant issues its own card
+- Stamp/point operations are restricted to the card's enrollment store
+- A customer can hold separate cards at different stores under the same merchant
+- Re-enrolling at the **same** store returns the existing card
+- Enrolling at a **different** store creates a new card scoped to that store
+
+**Database constraint:** Unique index on `(enrolled_at_store_id, customer_id)` prevents duplicate cards at the same store regardless of the cross-location setting.
 
 ## Enrollment Flow
 
@@ -229,21 +240,25 @@ When disabled, stamp/point operations are restricted to the enrollment store.
 
 Staff enrolls customer via terminal:
 1. Enter customer email (and optional name)
-2. System resolves or creates customer record
+2. System resolves customer — checks the current store first, then searches across all stores under the merchant for an existing cardholder with the same email
-3. Creates loyalty card with unique card number and QR code
+3. If the customer already has a card (per-merchant or per-store, depending on the cross-location setting), raises `LoyaltyCardAlreadyExistsException`
-4. Creates `CARD_CREATED` transaction
+4. Otherwise creates loyalty card with unique card number and QR code
-5. Awards welcome bonus points (if configured) via `WELCOME_BONUS` transaction
+5. Creates `CARD_CREATED` transaction
-6. Creates Google Wallet object and Apple Wallet serial
+6. Awards welcome bonus points (if configured) via `WELCOME_BONUS` transaction
-7. Returns card details with "Add to Wallet" URLs
+7. Creates Google Wallet object and Apple Wallet serial
+8. Returns card details with "Add to Wallet" URLs
 
 ### Self-Enrollment (Public)
 
 Customer enrolls via public page (if `allow_self_enrollment` enabled):
 1. Customer visits `/loyalty/join` page
-2. Enters email and name
+2. Enters email, name, and optional birthday
-3. System creates customer + card
+3. System resolves customer (cross-store lookup for existing cardholders under the same merchant)
-4. Redirected to success page with card number
+4. If already enrolled: returns existing card with success page showing location info
-5. Can add to Google/Apple Wallet from success page
+   - Cross-location enabled: "Your card works at all our locations" + store list
+   - Cross-location disabled: "Your card is registered at {original_store}"
+5. If new: creates customer + card, redirected to success page with card number
+6. Can add to Google/Apple Wallet from success page
 
 ## Scheduled Tasks
 

app/modules/loyalty/docs/data-model.md

@@ -120,14 +120,21 @@ Merchant-wide loyalty program configuration. One program per merchant, shared ac
 
 ### LoyaltyCard
 
-Customer loyalty card linking a customer to a merchant's program. One card per customer per merchant.
+Customer loyalty card linking a customer to a merchant's program.
+
+**Card uniqueness depends on the `allow_cross_location_redemption` merchant setting:**
+
+- **Cross-location enabled (default):** One card per customer per merchant. The application layer enforces this by checking all stores under the merchant before creating a card. Re-enrolling at another store returns the existing card.
+- **Cross-location disabled:** One card per customer per store. A customer can hold separate cards at different stores under the same merchant, each scoped to its enrollment store.
+
+**Database constraint:** Unique index on `(enrolled_at_store_id, customer_id)` — always enforced. The per-merchant uniqueness (cross-location enabled) is enforced at the application layer in `card_service.enroll_customer`.
 
 | Field | Type | Description |
 |-------|------|-------------|
 | `merchant_id` | FK | Links to program's merchant |
 | `customer_id` | FK | Card owner |
 | `program_id` | FK | Associated program |
-| `enrolled_at_store_id` | FK | Store where customer enrolled |
+| `enrolled_at_store_id` | FK | Store where customer enrolled (part of unique constraint) |
 | `card_number` | String (unique) | Formatted XXXX-XXXX-XXXX |
 | `qr_code_data` | String (unique) | URL-safe token for QR codes |
 | `stamp_count` | Integer | Current stamp count |

app/modules/loyalty/docs/production-launch-plan.md

@@ -40,11 +40,14 @@ This is the active execution plan for taking the Loyalty module to production. I
 ```
 loyalty_002 (existing)
 loyalty_003 — CHECK constraints (points_balance >= 0, stamp_count >= 0, etc.)
-loyalty_004 — seed 28 notification email templates
+loyalty_004 — relax card uniqueness: replace (merchant_id, customer_id) unique index
-loyalty_005 — add columns: last_expiration_warning_at, last_reengagement_at on cards;
+              with (enrolled_at_store_id, customer_id) for cross-location support
+loyalty_005 — seed 28 notification email templates
+loyalty_006 — add columns: last_expiration_warning_at, last_reengagement_at on cards;
               acting_admin_id on transactions
-loyalty_006 — terms_cms_page_slug on programs
+loyalty_007 — terms_cms_page_slug on programs
-loyalty_007 — birth_date on customers (P0 — Phase 1.4 fix, dropped data bug)
+
+customers_003 — birth_date on customers (Phase 1.4 fix, dropped data bug)
 ```
 
 ---
@@ -82,7 +85,7 @@ All 8 decisions locked. No external blockers.
 #### 1.4 Fix dropped birthday data (P0 bug)
 **Background:** The enrollment form (`enroll.html:87`) collects a birthday, the schema accepts `customer_birthday` (`schemas/card.py:34`), and `card_service.resolve_customer_id` has the parameter (`card_service.py:172`) — but the call to `customer_service.create_customer_for_enrollment` at `card_service.py:215-222` does not pass it, and the `Customer` model has no `birth_date` column at all. Every enrollment silently loses the birthday. Not live yet, so no backfill needed.
 
-- New migration `loyalty_007_add_customer_birth_date.py` (or place under customers module if that's the convention) adds `birth_date: Date | None` to `customers`.
+- Migration `customers_003_add_birth_date.py` adds `birth_date: Date | None` to `customers`.
 - Update `customer_service.create_customer_for_enrollment` to accept and persist `birth_date`.
 - Update `card_service.py:215-222` to pass `customer_birthday` through, with `date.fromisoformat()` parsing and validation (must be a real past date, sensible age range).
 - Update `customer_service.update_customer` to allow backfill.
@@ -114,7 +117,7 @@ All 8 decisions locked. No external blockers.
 - New `app/modules/loyalty/tasks/notifications.py` with `@shared_task(name="loyalty.send_notification_email", bind=True, max_retries=3, default_retry_delay=60)`.
 - Opens fresh `SessionLocal`, calls `EmailService(db).send_template(...)`, retries on SMTP errors.
 
-#### 2.3 Seed templates `loyalty_004`
+#### 2.3 Seed templates `loyalty_005`
 - 7 templates × 4 locales (en, fr, de, lb) = **28 rows** in `email_templates`.
 - Template codes: `loyalty_enrollment`, `loyalty_welcome_bonus`, `loyalty_points_expiring`, `loyalty_points_expired`, `loyalty_reward_ready`, `loyalty_birthday`, `loyalty_reengagement`.
 - **Copywriting needs sign-off** before applying to prod.
@@ -123,7 +126,7 @@ All 8 decisions locked. No external blockers.
 - In `card_service.enroll_customer_for_store` (~lines 480-540), call notification service **after** `db.commit()`.
 
 #### 2.5 Wire expiration warning into expiration task
-- Migration `loyalty_005` adds `last_expiration_warning_at` to prevent duplicates.
+- Migration `loyalty_006` adds `last_expiration_warning_at` to prevent duplicates.
 - In rewritten `tasks/point_expiration.py` (see 3.1), find cards 14 days from expiry, fire warning, stamp timestamp.
 - **Validation:** time-mocked test — fires once at 14-day mark.
 
@@ -137,7 +140,7 @@ All 8 decisions locked. No external blockers.
 
 #### 2.8 Re-engagement Celery beat task
 - Weekly schedule. Finds cards inactive > N days (default 60, configurable).
-- Throttled via `last_reengagement_at` (added in `loyalty_005`) — once per quarter per card.
+- Throttled via `last_reengagement_at` (added in `loyalty_006`) — once per quarter per card.
 
 ---
 
@@ -163,7 +166,7 @@ All 8 decisions locked. No external blockers.
 ### Phase 4 — Accessibility & T&C *(2d)*
 
 #### 4.1 T&C via store CMS integration
-- Migration `loyalty_006`: add `terms_cms_page_slug: str | None` to `loyalty_programs`.
+- Migration `loyalty_007`: add `terms_cms_page_slug: str | None` to `loyalty_programs`.
 - Update `schemas/program.py` (`ProgramCreate`, `ProgramUpdate`).
 - `program-form.html:251` — CMS page picker scoped to the program's owning store.
 - `enroll.html:99-160` — resolve slug to CMS page URL/content; legacy `terms_text` fallback.
@@ -224,7 +227,7 @@ All 8 decisions locked. No external blockers.
 - **Admin "act on behalf"** (`routes/api/admin.py`):
   - `POST /admin/loyalty/merchants/{merchant_id}/cards/bulk/deactivate` (etc.)
   - Shared service layer; route stamps `acting_admin_id` in audit log
-- New `loyalty_transactions.acting_admin_id` column in `loyalty_005`.
+- New `loyalty_transactions.acting_admin_id` column in `loyalty_006`.
 
 #### 6.5 Manual override: restore expired points
 - `POST /admin/loyalty/cards/{card_id}/restore_points` with `{points, reason}`.

app/modules/loyalty/docs/user-journeys.md

@@ -792,3 +792,109 @@ flowchart TD
     There is no feature gating on loyalty program creation — you can test them in
     either order. Journey 0 is listed second because domain setup is about URL
     presentation, not a functional prerequisite for the loyalty module.
+
+---
+
+## Pre-Launch E2E Test Checklist (Fashion Group)
+
+Manual end-to-end checklist using Fashion Group (merchant 2: FASHIONHUB + FASHIONOUTLET).
+Covers all customer-facing flows including the cross-store enrollment and redemption features
+added in the Phase 1 production launch hardening.
+
+### Pre-requisite: Program Setup (Journey 1)
+
+If Fashion Group doesn't have a loyalty program yet:
+
+1. Login as `jane.owner@fashiongroup.com` at `http://localhost:8000/platforms/loyalty/store/FASHIONHUB/login`
+2. Navigate to: `http://localhost:8000/platforms/loyalty/store/FASHIONHUB/loyalty/settings`
+3. Create program (hybrid or points), set welcome bonus, enable self-enrollment
+4. Verify Cross-Location Redemption is **enabled** in merchant settings
+
+### Test 1: Customer Self-Enrollment (Journey 4)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 1.1 | Visit `http://localhost:8000/platforms/loyalty/storefront/FASHIONHUB/loyalty/join` | Enrollment form loads, no console errors |
+| 1.2 | Fill in: fresh email, name, **birthday** → Submit | Redirected to success page with card number |
+| 1.3 | Check DB: `SELECT birth_date FROM customers WHERE email = '...'` | `birth_date` is set (not NULL) |
+| 1.4 | Enroll **without** birthday (different email) | Success, `birth_date` is NULL (no crash) |
+
+### Test 2: Cross-Store Re-Enrollment (Cross-Location Enabled)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 2.1 | Visit `http://localhost:8000/platforms/loyalty/storefront/FASHIONOUTLET/loyalty/join` | Enrollment form loads |
+| 2.2 | Submit with the **same email** from Test 1 | Success page shows **"You're already a member!"** |
+| 2.3 | Check: store list shown | Blue box: "Your card works at all our locations:" with Fashion Hub + Fashion Outlet listed |
+| 2.4 | Check: same card number as Test 1 | Card number matches (no duplicate created) |
+| 2.5 | Check DB: `SELECT COUNT(*) FROM loyalty_cards WHERE customer_id = ...` | Exactly 1 card |
+| 2.6 | Re-enroll at FASHIONHUB (same store as original) | Same behavior: "already a member" + locations |
+| 2.7 | Refresh the success page | Message persists, no flicker, no untranslated i18n keys |
+
+### Test 3: Staff Operations — Stamps/Points (Journeys 2 & 3)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 3.1 | Login as `jane.owner@fashiongroup.com` at FASHIONHUB | Login succeeds |
+| 3.2 | Open terminal: `.../store/FASHIONHUB/loyalty/terminal` | Terminal loads |
+| 3.3 | Look up card by card number | Card found, balance displayed |
+| 3.4 | Look up card by customer email | Card found (same result) |
+| 3.5 | Add stamp (or earn points with purchase amount) | Count/balance updates |
+| 3.6 | Add stamp again immediately (within cooldown) | Rejected: cooldown active |
+
+### Test 4: Cross-Store Redemption (Journey 8)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 4.1 | Staff at FASHIONHUB adds stamps/points to the card | Balance updated |
+| 4.2 | Login as staff at FASHIONOUTLET (e.g., `diana.stylist@fashiongroup.com` or `jane.owner`) | Login succeeds |
+| 4.3 | Open terminal: `.../store/FASHIONOUTLET/loyalty/terminal` | Terminal loads |
+| 4.4 | Look up card **by email** | Card found (cross-store email search) |
+| 4.5 | Look up card **by card number** | Card found |
+| 4.6 | Redeem reward (if enough stamps/points) | Redemption succeeds |
+| 4.7 | View card detail | Transaction history shows entries from both FASHIONHUB and FASHIONOUTLET |
+
+### Test 5: Customer Views Status (Journey 5)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 5.1 | Login as the customer at storefront | Customer dashboard loads |
+| 5.2 | Dashboard: `.../storefront/FASHIONHUB/account/loyalty` | Shows balance, available rewards |
+| 5.3 | History: `.../storefront/FASHIONHUB/account/loyalty/history` | Shows transactions from both stores |
+
+### Test 6: Void/Return (Journey 7)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 6.1 | Staff at FASHIONHUB opens terminal, looks up card | Card found |
+| 6.2 | Void a stamp or points transaction | Balance adjusted |
+| 6.3 | Check transaction history | Void transaction appears, linked to original |
+
+### Test 7: Admin Oversight (Journey 6)
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 7.1 | Login as `samir.boulahtit@gmail.com` (admin) | Admin dashboard loads |
+| 7.2 | Programs: `.../admin/loyalty/programs` | Fashion Group program visible |
+| 7.3 | Fashion Group detail: `.../admin/loyalty/merchants/2` | Cards, transactions, stats appear correctly |
+| 7.4 | Fashion Group settings: `.../admin/loyalty/merchants/2/settings` | Cross-location toggle visible and correct |
+
+### Test 8: Cross-Location Disabled Behavior
+
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 8.1 | Admin disables Cross-Location Redemption for Fashion Group | Setting saved |
+| 8.2 | Enroll a **new email** at FASHIONHUB | New card created for FASHIONHUB |
+| 8.3 | Enroll **same email** at FASHIONOUTLET | **New card created** for FASHIONOUTLET (separate card) |
+| 8.4 | Enroll **same email** at FASHIONHUB again | "Already a member" — shows "Your card is registered at Fashion Hub" (single store, no list) |
+| 8.5 | Staff at FASHIONOUTLET searches by email | Only finds the FASHIONOUTLET card (no cross-store search) |
+| 8.6 | Re-enable Cross-Location Redemption when done | Restore default state |
+
+### Key Things to Watch
+
+- [ ] Birthday persisted after enrollment (check DB)
+- [ ] No i18n flicker or console warnings on success page
+- [ ] Cross-store email search works in the terminal (cross-location enabled)
+- [ ] "Already a member" message shows correct locations/store based on cross-location setting
+- [ ] No duplicate cards created under same merchant (when cross-location enabled)
+- [ ] Rate limiting: rapid-fire stamp calls eventually return 429

app/modules/loyalty/locales/de.json

@@ -135,6 +135,10 @@
       "view_dashboard": "Mein Treue-Dashboard anzeigen",
       "continue_shopping": "Weiter einkaufen"
     },
+    "already_enrolled_title": "Sie sind bereits Mitglied!",
+    "cross_location_message": "Ihre Karte gilt an allen unseren Standorten:",
+    "single_location_message": "Ihre Karte ist bei {store_name} registriert",
+    "available_locations": "Nutzen Sie Ihre Karte an allen unseren Standorten:",
     "errors": {
       "load_failed": "Programminformationen konnten nicht geladen werden",
       "email_exists": "Diese E-Mail ist bereits in unserem Treueprogramm registriert.",

app/modules/loyalty/locales/en.json

@@ -135,6 +135,10 @@
       "view_dashboard": "View My Loyalty Dashboard",
       "continue_shopping": "Continue Shopping"
     },
+    "already_enrolled_title": "You're already a member!",
+    "cross_location_message": "Your card works at all our locations:",
+    "single_location_message": "Your card is registered at {store_name}",
+    "available_locations": "Use your card at all our locations:",
     "errors": {
       "load_failed": "Failed to load program information",
       "email_exists": "This email is already registered in our loyalty program.",

app/modules/loyalty/locales/fr.json

@@ -135,6 +135,10 @@
       "view_dashboard": "Voir mon tableau de bord fidélité",
       "continue_shopping": "Continuer mes achats"
     },
+    "already_enrolled_title": "Vous êtes déjà membre !",
+    "cross_location_message": "Votre carte est valable dans tous nos points de vente :",
+    "single_location_message": "Votre carte est enregistrée chez {store_name}",
+    "available_locations": "Utilisez votre carte dans tous nos points de vente :",
     "errors": {
       "load_failed": "Impossible de charger les informations du programme",
       "email_exists": "Cet e-mail est déjà inscrit dans notre programme de fidélité.",

app/modules/loyalty/locales/lb.json

@@ -135,6 +135,10 @@
       "view_dashboard": "Mäin Treie-Dashboard kucken",
       "continue_shopping": "Weider akafen"
     },
+    "already_enrolled_title": "Dir sidd schonn Member!",
+    "cross_location_message": "Är Kaart gëllt an all eise Standuerter:",
+    "single_location_message": "Är Kaart ass bei {store_name} registréiert",
+    "available_locations": "Benotzt Är Kaart an all eise Standuerter:",
     "errors": {
       "load_failed": "Programminformatiounen konnten net gelueden ginn",
       "email_exists": "Dës E-Mail ass schonn an eisem Treieprogramm registréiert.",

app/modules/loyalty/migrations/versions/loyalty_004_relax_card_uniqueness.py

@@ -0,0 +1,59 @@
+"""loyalty 004 - relax card uniqueness for cross-location support
+
+Replace the (merchant_id, customer_id) and (customer_id, program_id)
+unique indexes with (enrolled_at_store_id, customer_id). This allows
+merchants with cross-location redemption DISABLED to issue one card per
+store per customer, while merchants with it ENABLED enforce the
+per-merchant constraint in the application layer.
+
+Revision ID: loyalty_004
+Revises: loyalty_003
+Create Date: 2026-04-10
+"""
+from alembic import op
+
+revision = "loyalty_004"
+down_revision = "loyalty_003"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Drop the old per-merchant unique indexes
+    op.drop_index("idx_loyalty_card_merchant_customer", table_name="loyalty_cards")
+    op.drop_index("idx_loyalty_card_customer_program", table_name="loyalty_cards")
+
+    # Keep a non-unique index on (merchant_id, customer_id) for lookups
+    op.create_index(
+        "idx_loyalty_card_merchant_customer",
+        "loyalty_cards",
+        ["merchant_id", "customer_id"],
+        unique=False,
+    )
+
+    # New unique constraint: one card per customer per store (always valid)
+    op.create_index(
+        "idx_loyalty_card_store_customer",
+        "loyalty_cards",
+        ["enrolled_at_store_id", "customer_id"],
+        unique=True,
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("idx_loyalty_card_store_customer", table_name="loyalty_cards")
+    op.drop_index("idx_loyalty_card_merchant_customer", table_name="loyalty_cards")
+
+    # Restore original unique indexes
+    op.create_index(
+        "idx_loyalty_card_merchant_customer",
+        "loyalty_cards",
+        ["merchant_id", "customer_id"],
+        unique=True,
+    )
+    op.create_index(
+        "idx_loyalty_card_customer_program",
+        "loyalty_cards",
+        ["customer_id", "program_id"],
+        unique=True,
+    )

app/modules/loyalty/models/loyalty_card.py

@@ -255,11 +255,14 @@ class LoyaltyCard(Base, TimestampMixin, SoftDeleteMixin):
         cascade="all, delete-orphan",
     )
 
-    # Indexes - one card per customer per merchant
+    # Indexes
+    # One card per customer per store (always enforced at DB level).
+    # Per-merchant uniqueness (when cross-location is enabled) is enforced
+    # by the application layer in enroll_customer().
     __table_args__ = (
-        Index("idx_loyalty_card_merchant_customer", "merchant_id", "customer_id", unique=True),
+        Index("idx_loyalty_card_store_customer", "enrolled_at_store_id", "customer_id", unique=True),
+        Index("idx_loyalty_card_merchant_customer", "merchant_id", "customer_id"),
         Index("idx_loyalty_card_merchant_active", "merchant_id", "is_active"),
-        Index("idx_loyalty_card_customer_program", "customer_id", "program_id", unique=True),
         # Balances must never go negative — guards against direct SQL writes
         # bypassing the service layer's clamping logic.
         CheckConstraint("points_balance >= 0", name="ck_loyalty_cards_points_balance_nonneg"),

app/modules/loyalty/routes/api/store.py

@@ -540,11 +540,18 @@ def enroll_customer(
     """
     store_id = current_user.token_store_id
 
+    # Resolve merchant_id for cross-store customer lookup
+    from app.modules.tenancy.services.store_service import store_service
+
+    store = store_service.get_store_by_id_optional(db, store_id)
+    merchant_id = store.merchant_id if store else None
+
     customer_id = card_service.resolve_customer_id(
         db,
         customer_id=data.customer_id,
         email=data.email,
         store_id=store_id,
+        merchant_id=merchant_id,
     )
 
     card = card_service.enroll_customer_for_store(db, customer_id, store_id)

app/modules/loyalty/routes/api/storefront.py

@@ -19,6 +19,7 @@ from sqlalchemy.orm import Session
 from app.api.deps import get_current_customer_api
 from app.core.database import get_db
 from app.modules.customers.schemas import CustomerContext
+from app.modules.loyalty.exceptions import LoyaltyCardAlreadyExistsException
 from app.modules.loyalty.schemas import (
     CardEnrollRequest,
     CardResponse,
@@ -88,6 +89,7 @@ def self_enroll(
         customer_id=data.customer_id,
         email=data.email,
         store_id=store.id,
+        merchant_id=store.merchant_id,
         create_if_missing=True,
         customer_name=data.customer_name,
         customer_phone=data.customer_phone,
@@ -96,10 +98,45 @@ def self_enroll(
 
     logger.info(f"Self-enrollment for customer {customer_id} at store {store.subdomain}")
 
-    card = card_service.enroll_customer_for_store(db, customer_id, store.id)
+    # Build merchant context for the response (locations, cross-location flag)
+    settings = program_service.get_merchant_settings(db, store.merchant_id)
+    allow_cross_location = (
+        settings.allow_cross_location_redemption if settings else True
+    )
+    locations = program_service.get_merchant_locations(db, store.merchant_id)
+    location_list = [
+        {"id": loc.id, "name": loc.name}
+        for loc in locations
+    ]
+
+    already_enrolled = False
+    try:
+        card = card_service.enroll_customer_for_store(db, customer_id, store.id)
+    except LoyaltyCardAlreadyExistsException:
+        # Customer already has a card — return it instead of erroring out.
+        # For cross-location=true this is the normal re-enroll-at-another-store
+        # path; for cross-location=false this is a same-store re-enroll.
+        already_enrolled = True
+        if allow_cross_location:
+            card = card_service.get_card_by_customer_and_merchant(
+                db, customer_id, store.merchant_id
+            )
+        else:
+            card = card_service.get_card_by_customer_and_store(
+                db, customer_id, store.id
+            )
+
     program = card.program
     wallet_urls = wallet_service.get_add_to_wallet_urls(db, card)
 
+    # Resolve the name of the original enrollment store
+    enrolled_at_store_name = None
+    if card.enrolled_at_store_id:
+        for loc in locations:
+            if loc.id == card.enrolled_at_store_id:
+                enrolled_at_store_name = loc.name
+                break
+
     return {
         "card": CardResponse(
             id=card.id,
@@ -122,6 +159,10 @@ def self_enroll(
             has_apple_wallet=bool(card.apple_serial_number),
         ),
         "wallet_urls": wallet_urls,
+        "already_enrolled": already_enrolled,
+        "allow_cross_location": allow_cross_location,
+        "enrolled_at_store_name": enrolled_at_store_name,
+        "merchant_locations": location_list,
     }
 
 

app/modules/loyalty/routes/pages/storefront.py

@@ -133,6 +133,7 @@ async def loyalty_self_enrollment(
 async def loyalty_enrollment_success(
     request: Request,
     card: str = Query(None, description="Card number"),
+    already: str = Query(None, description="Already enrolled flag"),
     db: Session = Depends(get_db),
 ):
     """
@@ -149,6 +150,27 @@ async def loyalty_enrollment_success(
 
     context = get_storefront_context(request, db=db)
     context["enrolled_card_number"] = card
+
+    # Provide merchant locations and cross-location flag server-side so
+    # the template doesn't depend on sessionStorage surviving refreshes.
+    store = getattr(request.state, "store", None)
+    if store:
+        from app.modules.loyalty.services import program_service
+
+        settings = program_service.get_merchant_settings(db, store.merchant_id)
+        locations = program_service.get_merchant_locations(db, store.merchant_id)
+        context["server_already_enrolled"] = already == "1"
+        context["server_allow_cross_location"] = (
+            settings.allow_cross_location_redemption if settings else True
+        )
+        context["server_merchant_locations"] = [
+            {"id": loc.id, "name": loc.name} for loc in locations
+        ]
+    else:
+        context["server_already_enrolled"] = False
+        context["server_allow_cross_location"] = True
+        context["server_merchant_locations"] = []
+
     return templates.TemplateResponse(
         "loyalty/storefront/enroll-success.html",
         context,

app/modules/loyalty/services/card_service.py

@@ -119,6 +119,23 @@ class CardService:
             .first()
         )
 
+    def get_card_by_customer_and_store(
+        self,
+        db: Session,
+        customer_id: int,
+        store_id: int,
+    ) -> LoyaltyCard | None:
+        """Get a customer's card for a specific store."""
+        return (
+            db.query(LoyaltyCard)
+            .options(joinedload(LoyaltyCard.program))
+            .filter(
+                LoyaltyCard.customer_id == customer_id,
+                LoyaltyCard.enrolled_at_store_id == store_id,
+            )
+            .first()
+        )
+
     def get_card_by_customer_and_program(
         self,
         db: Session,
@@ -166,6 +183,7 @@ class CardService:
         customer_id: int | None,
         email: str | None,
         store_id: int,
+        merchant_id: int | None = None,
         create_if_missing: bool = False,
         customer_name: str | None = None,
         customer_phone: str | None = None,
@@ -179,6 +197,7 @@ class CardService:
             customer_id: Direct customer ID (used if provided)
             email: Customer email to look up
             store_id: Store ID for scoping the email lookup
+            merchant_id: Merchant ID for cross-store loyalty card lookup
             create_if_missing: If True, create customer when email not found
                 (used for self-enrollment)
             customer_name: Full name for customer creation
@@ -196,6 +215,9 @@ class CardService:
             return customer_id
 
         if email:
+            from app.modules.customers.models.customer import (
+                Customer as CustomerModel,
+            )
             from app.modules.customers.services.customer_service import (
                 customer_service,
             )
@@ -210,6 +232,29 @@ class CardService:
                     db.flush()
                 return customer.id
 
+            # Customers are store-scoped, but loyalty cards are merchant-scoped.
+            # Check if this email already has a card under the same merchant at
+            # a different store — if so, reuse that customer_id so the duplicate
+            # check in enroll_customer() fires correctly.
+            if merchant_id:
+                existing_cardholder = (
+                    db.query(CustomerModel)
+                    .join(
+                        LoyaltyCard,
+                        CustomerModel.id == LoyaltyCard.customer_id,
+                    )
+                    .filter(
+                        CustomerModel.email == email.lower(),
+                        LoyaltyCard.merchant_id == merchant_id,
+                    )
+                    .first()
+                )
+                if existing_cardholder:
+                    if customer_birthday and not existing_cardholder.birth_date:
+                        existing_cardholder.birth_date = customer_birthday
+                        db.flush()
+                    return existing_cardholder.id
+
             if create_if_missing:
                 # Parse name into first/last
                 first_name = customer_name or ""
@@ -347,18 +392,45 @@ class CardService:
 
         merchant_id = store.merchant_id
 
-        # Try card number
+        # Try card number — always merchant-scoped
         card = self.get_card_by_number(db, query)
         if card and card.merchant_id == merchant_id:
             return card
 
-        # Try customer email
+        # Try customer email — first at this store
         customer = customer_service.get_customer_by_email(db, store_id, query)
         if customer:
             card = self.get_card_by_customer_and_merchant(db, customer.id, merchant_id)
             if card:
                 return card
 
+        # Cross-store email search: the customer may have enrolled at a
+        # different store under the same merchant.  Only search when
+        # cross-location redemption is enabled.
+        from app.modules.customers.models.customer import Customer as CustomerModel
+        from app.modules.loyalty.services.program_service import program_service
+
+        settings = program_service.get_merchant_settings(db, merchant_id)
+        cross_location_enabled = (
+            settings.allow_cross_location_redemption if settings else True
+        )
+        if cross_location_enabled:
+            cross_store_customer = (
+                db.query(CustomerModel)
+                .join(LoyaltyCard, CustomerModel.id == LoyaltyCard.customer_id)
+                .filter(
+                    CustomerModel.email == query.lower(),
+                    LoyaltyCard.merchant_id == merchant_id,
+                )
+                .first()
+            )
+            if cross_store_customer:
+                card = self.get_card_by_customer_and_merchant(
+                    db, cross_store_customer.id, merchant_id
+                )
+                if card:
+                    return card
+
         return None
 
     def list_cards(
@@ -479,10 +551,32 @@ class CardService:
         if not program.is_active:
             raise LoyaltyProgramInactiveException(program.id)
 
-        # Check if customer already has a card
+        # Check for duplicate enrollment — the scope depends on whether
-        existing = self.get_card_by_customer_and_merchant(db, customer_id, merchant_id)
+        # cross-location redemption is enabled for this merchant.
-        if existing:
+        from app.modules.loyalty.services.program_service import program_service
-            raise LoyaltyCardAlreadyExistsException(customer_id, program.id)
+
+        settings = program_service.get_merchant_settings(db, merchant_id)
+        if settings and not settings.allow_cross_location_redemption:
+            # Per-store cards: only block if the customer already has a card
+            # at THIS specific store.  Cards at other stores are allowed.
+            if enrolled_at_store_id:
+                existing = (
+                    db.query(LoyaltyCard)
+                    .filter(
+                        LoyaltyCard.customer_id == customer_id,
+                        LoyaltyCard.enrolled_at_store_id == enrolled_at_store_id,
+                    )
+                    .first()
+                )
+                if existing:
+                    raise LoyaltyCardAlreadyExistsException(customer_id, program.id)
+        else:
+            # Cross-location enabled (default): one card per merchant
+            existing = self.get_card_by_customer_and_merchant(
+                db, customer_id, merchant_id
+            )
+            if existing:
+                raise LoyaltyCardAlreadyExistsException(customer_id, program.id)
 
         # Create the card
         card = LoyaltyCard(

app/modules/loyalty/static/storefront/js/loyalty-enroll.js

@@ -81,10 +81,21 @@ function customerLoyaltyEnroll() {
                         sessionStorage.setItem('loyalty_wallet_urls', JSON.stringify(response.wallet_urls));
                     }
 
-                    // Redirect to success page
+                    // Store enrollment context for the success page
+                    sessionStorage.setItem('loyalty_enroll_context', JSON.stringify({
+                        already_enrolled: response.already_enrolled || false,
+                        allow_cross_location: response.allow_cross_location ?? true,
+                        enrolled_at_store_name: response.enrolled_at_store_name || null,
+                        merchant_locations: response.merchant_locations || [],
+                    }));
+
+                    // Redirect to success page — pass already_enrolled in the
+                    // URL so the message survives page refreshes (sessionStorage
+                    // is supplementary for the location list).
                     const currentPath = window.location.pathname;
+                    const alreadyFlag = response.already_enrolled ? '&already=1' : '';
                     const successUrl = currentPath.replace(/\/join\/?$/, '/join/success') +
-                        '?card=' + encodeURIComponent(cardNumber);
+                        '?card=' + encodeURIComponent(cardNumber) + alreadyFlag;
                     window.location.href = successUrl;
                 }
             } catch (error) {

app/modules/loyalty/templates/loyalty/storefront/dashboard.html

@@ -105,12 +105,12 @@
                             <template x-if="(card?.points_balance || 0) >= reward.points_required">
                                 <span class="inline-flex items-center text-sm font-medium text-green-600">
                                     <span x-html="$icon('check-circle', 'w-4 h-4 mr-1')"></span>
-                                    <span x-text="$t('loyalty.storefront.dashboard.ready_to_redeem')"></span>
+                                    <span>{{ _('loyalty.storefront.dashboard.ready_to_redeem') }}</span>
                                 </span>
                             </template>
                             <template x-if="(card?.points_balance || 0) < reward.points_required">
                                 <span class="text-sm text-gray-500"
-                                      x-text="$t('loyalty.storefront.dashboard.x_more_to_go', {count: reward.points_required - (card?.points_balance || 0)})">
+                                      x-text="'{{ _('loyalty.storefront.dashboard.x_more_to_go') }}'.replace('{count}', reward.points_required - (card?.points_balance || 0))">
                                 </span>
                             </template>
                         </div>
@@ -208,14 +208,14 @@
             <template x-if="walletUrls.apple_wallet_url">
                 <a :href="walletUrls.apple_wallet_url" target="_blank" rel="noopener"
                    class="w-full flex items-center justify-center px-4 py-3 bg-black text-white rounded-lg hover:bg-gray-800 transition-colors">
-                    <span x-html="$icon('device-mobile', 'w-5 h-5 mr-2')"></span>
+                    <span x-html="$icon('phone', 'w-5 h-5 mr-2')"></span>
                     {{ _('loyalty.loyalty.wallet.apple') }}
                 </a>
             </template>
             <template x-if="walletUrls.google_wallet_url">
                 <a :href="walletUrls.google_wallet_url" target="_blank" rel="noopener"
                    class="w-full flex items-center justify-center px-4 py-3 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors">
-                    <span x-html="$icon('device-mobile', 'w-5 h-5 mr-2')"></span>
+                    <span x-html="$icon('phone', 'w-5 h-5 mr-2')"></span>
                     {{ _('loyalty.loyalty.wallet.google') }}
                 </a>
             </template>

app/modules/loyalty/templates/loyalty/storefront/enroll-success.html

@@ -3,6 +3,7 @@
 
 {% block title %}{{ _('loyalty.enrollment.success.title') }} - {{ store.name }}{% endblock %}
 
+{% block i18n_modules %}['loyalty']{% endblock %}
 {% block alpine_data %}customerLoyaltyEnrollSuccess(){% endblock %}
 
 {% block content %}
@@ -16,7 +17,10 @@
             </div>
         </div>
 
-        <h1 class="text-3xl font-bold text-gray-900 dark:text-white mb-2">{{ _('loyalty.enrollment.success.title') }}</h1>
+        <h1 class="text-3xl font-bold text-gray-900 dark:text-white mb-2"
+            x-text="enrollContext.already_enrolled ? i18nStrings.already_enrolled_title : i18nStrings.success_title">
+            {{ _('loyalty.enrollment.success.title') }}
+        </h1>
         <p class="text-gray-600 dark:text-gray-400 mb-8">{{ _('loyalty.enrollment.success.message') }}</p>
 
         <!-- Card Number Display -->
@@ -33,14 +37,14 @@
                     <template x-if="walletUrls.apple_wallet_url">
                         <a :href="walletUrls.apple_wallet_url" target="_blank" rel="noopener"
                            class="w-full flex items-center justify-center px-4 py-3 bg-black text-white rounded-lg hover:bg-gray-800 transition-colors">
-                            <span x-html="$icon('device-mobile', 'w-5 h-5 mr-2')"></span>
+                            <span x-html="$icon('phone', 'w-5 h-5 mr-2')"></span>
                             {{ _('loyalty.loyalty.wallet.apple') }}
                         </a>
                     </template>
                     <template x-if="walletUrls.google_wallet_url">
                         <a :href="walletUrls.google_wallet_url" target="_blank" rel="noopener"
                            class="w-full flex items-center justify-center px-4 py-3 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors">
-                            <span x-html="$icon('device-mobile', 'w-5 h-5 mr-2')"></span>
+                            <span x-html="$icon('phone', 'w-5 h-5 mr-2')"></span>
                             {{ _('loyalty.loyalty.wallet.google') }}
                         </a>
                     </template>
@@ -48,6 +52,41 @@
             </div>
         </div>
 
+        <!-- Cross-location info -->
+        <template x-if="enrollContext.already_enrolled || (enrollContext.merchant_locations?.length > 1 && enrollContext.allow_cross_location)">
+            <div class="bg-blue-50 dark:bg-blue-900/30 border border-blue-200 dark:border-blue-800 rounded-lg p-4 mb-8 text-left">
+                <template x-if="enrollContext.already_enrolled && enrollContext.allow_cross_location">
+                    <div>
+                        <p class="font-medium text-blue-800 dark:text-blue-200 mb-2" x-text="i18nStrings.cross_location_message"></p>
+                        <ul class="space-y-1">
+                            <template x-for="loc in enrollContext.merchant_locations" :key="loc.id">
+                                <li class="flex items-center text-sm text-blue-700 dark:text-blue-300">
+                                    <span x-html="$icon('map-pin', 'w-4 h-4 mr-2 flex-shrink-0')"></span>
+                                    <span x-text="loc.name"></span>
+                                </li>
+                            </template>
+                        </ul>
+                    </div>
+                </template>
+                <template x-if="enrollContext.already_enrolled && !enrollContext.allow_cross_location">
+                    <p class="text-sm text-blue-700 dark:text-blue-300" x-text="i18nStrings.single_location_message.replace('{store_name}', enrollContext.enrolled_at_store_name || '')"></p>
+                </template>
+                <template x-if="!enrollContext.already_enrolled && enrollContext.merchant_locations?.length > 1 && enrollContext.allow_cross_location">
+                    <div>
+                        <p class="font-medium text-blue-800 dark:text-blue-200 mb-2" x-text="i18nStrings.available_locations"></p>
+                        <ul class="space-y-1">
+                            <template x-for="loc in enrollContext.merchant_locations" :key="loc.id">
+                                <li class="flex items-center text-sm text-blue-700 dark:text-blue-300">
+                                    <span x-html="$icon('map-pin', 'w-4 h-4 mr-2 flex-shrink-0')"></span>
+                                    <span x-text="loc.name"></span>
+                                </li>
+                            </template>
+                        </ul>
+                    </div>
+                </template>
+            </div>
+        </template>
+
         <!-- Next Steps -->
         <div class="bg-white dark:bg-gray-800 rounded-lg shadow p-6 text-left mb-8">
             <h2 class="font-semibold text-gray-900 dark:text-white mb-4">{{ _('loyalty.enrollment.success.next_steps_title') }}</h2>
@@ -89,6 +128,20 @@ function customerLoyaltyEnrollSuccess() {
     return {
         ...storefrontLayoutData(),
         walletUrls: { google_wallet_url: null, apple_wallet_url: null },
+        // Server-rendered context — no flicker, survives refreshes
+        enrollContext: {
+            already_enrolled: {{ server_already_enrolled|tojson }},
+            allow_cross_location: {{ server_allow_cross_location|tojson }},
+            enrolled_at_store_name: null,
+            merchant_locations: {{ server_merchant_locations|tojson }},
+        },
+        i18nStrings: {
+            success_title: {{ _('loyalty.enrollment.success.title')|tojson }},
+            already_enrolled_title: {{ _('loyalty.enrollment.already_enrolled_title')|tojson }},
+            cross_location_message: {{ _('loyalty.enrollment.cross_location_message')|tojson }},
+            single_location_message: {{ _('loyalty.enrollment.single_location_message')|tojson }},
+            available_locations: {{ _('loyalty.enrollment.available_locations')|tojson }},
+        },
 
         init() {
             // Read wallet URLs saved during enrollment (no auth needed)
@@ -101,6 +154,20 @@ function customerLoyaltyEnrollSuccess() {
             } catch (e) {
                 console.log('Could not load wallet URLs:', e.message);
             }
+
+            // Merge sessionStorage context (has enrolled_at_store_name from
+            // the enrollment API response) into the server-rendered defaults
+            try {
+                const ctx = sessionStorage.getItem('loyalty_enroll_context');
+                if (ctx) {
+                    const parsed = JSON.parse(ctx);
+                    if (parsed.enrolled_at_store_name) {
+                        this.enrollContext.enrolled_at_store_name = parsed.enrolled_at_store_name;
+                    }
+                }
+            } catch (e) {
+                console.log('Could not load enroll context:', e.message);
+            }
         }
     };
 }

app/modules/loyalty/templates/loyalty/storefront/history.html

@@ -93,7 +93,7 @@
                 {{ _('loyalty.storefront.history.previous') }}
             </button>
             <span class="text-sm text-gray-500 dark:text-gray-400"
-                  x-text="$t('loyalty.storefront.history.page_x_of_y', {page: pagination.page, pages: pagination.pages})">
+                  x-text="'{{ _('loyalty.storefront.history.page_x_of_y') }}'.replace('{page}', pagination.page).replace('{pages}', pagination.pages)">
             </span>
             <button @click="nextPage()" :disabled="pagination.page >= pagination.pages"
                     class="px-3 py-1 text-sm border border-gray-300 dark:border-gray-600 rounded hover:bg-gray-50 dark:hover:bg-gray-700 disabled:opacity-50">

app/modules/loyalty/tests/integration/test_store_api.py

@@ -830,3 +830,248 @@ class TestAdjustPointsRoleGate:
         assert response.status_code == 200
         data = response.json()
         assert data["success"] is True
+
+
+# ============================================================================
+# Item 4: Cross-store enrollment
+# ============================================================================
+
+
+@pytest.fixture
+def cross_store_setup(db, loyalty_platform):
+    """Setup with two stores under the same merchant for cross-store tests.
+
+    Creates: merchant → store1 + store2 (each with its own user),
+    program, customer at store1 with card.
+    """
+    from app.modules.customers.models.customer import Customer
+    from app.modules.tenancy.models import Merchant, Store
+    from app.modules.tenancy.models.store import StoreUser
+    from app.modules.tenancy.models.store_platform import StorePlatform
+    from middleware.auth import AuthManager
+
+    auth = AuthManager()
+    uid = uuid.uuid4().hex[:8]
+
+    # Owner for store1
+    owner1 = User(
+        email=f"xs1own_{uid}@test.com",
+        username=f"xs1own_{uid}",
+        hashed_password=auth.hash_password("storepass123"),
+        role="merchant_owner",
+        is_active=True,
+        is_email_verified=True,
+    )
+    db.add(owner1)
+    db.commit()
+    db.refresh(owner1)
+
+    merchant = Merchant(
+        name=f"Cross-Store Merchant {uid}",
+        owner_user_id=owner1.id,
+        contact_email=owner1.email,
+        is_active=True,
+        is_verified=True,
+    )
+    db.add(merchant)
+    db.commit()
+    db.refresh(merchant)
+
+    # Store 1
+    store1 = Store(
+        merchant_id=merchant.id,
+        store_code=f"XS1_{uid.upper()}",
+        subdomain=f"xs1{uid}",
+        name=f"Cross Store 1 {uid}",
+        is_active=True,
+        is_verified=True,
+    )
+    db.add(store1)
+    db.commit()
+    db.refresh(store1)
+
+    su1 = StoreUser(store_id=store1.id, user_id=owner1.id, is_active=True)
+    db.add(su1)
+    sp1 = StorePlatform(store_id=store1.id, platform_id=loyalty_platform.id)
+    db.add(sp1)
+    db.commit()
+
+    # Separate user for store2 (login always binds to user's first store)
+    owner2 = User(
+        email=f"xs2own_{uid}@test.com",
+        username=f"xs2own_{uid}",
+        hashed_password=auth.hash_password("storepass123"),
+        role="merchant_owner",
+        is_active=True,
+        is_email_verified=True,
+    )
+    db.add(owner2)
+    db.commit()
+    db.refresh(owner2)
+
+    # Store 2
+    store2 = Store(
+        merchant_id=merchant.id,
+        store_code=f"XS2_{uid.upper()}",
+        subdomain=f"xs2{uid}",
+        name=f"Cross Store 2 {uid}",
+        is_active=True,
+        is_verified=True,
+    )
+    db.add(store2)
+    db.commit()
+    db.refresh(store2)
+
+    su2 = StoreUser(store_id=store2.id, user_id=owner2.id, is_active=True)
+    db.add(su2)
+    sp2 = StorePlatform(store_id=store2.id, platform_id=loyalty_platform.id)
+    db.add(sp2)
+    db.commit()
+
+    # Customer at store1
+    customer_email = f"xscust_{uid}@test.com"
+    customer = Customer(
+        email=customer_email,
+        first_name="Cross",
+        last_name="StoreCustomer",
+        hashed_password="!unused!",  # noqa: SEC001
+        customer_number=f"XSC-{uid.upper()}",
+        store_id=store1.id,
+        is_active=True,
+    )
+    db.add(customer)
+    db.commit()
+    db.refresh(customer)
+
+    # Program
+    program = LoyaltyProgram(
+        merchant_id=merchant.id,
+        loyalty_type=LoyaltyType.POINTS.value,
+        points_per_euro=10,
+        welcome_bonus_points=0,
+        minimum_redemption_points=100,
+        minimum_purchase_cents=0,
+        cooldown_minutes=0,
+        max_daily_stamps=10,
+        require_staff_pin=False,
+        card_name="Cross Store Rewards",
+        card_color="#4F46E5",
+        is_active=True,
+        points_rewards=[],
+    )
+    db.add(program)
+    db.commit()
+    db.refresh(program)
+
+    # Card enrolled at store1
+    card = LoyaltyCard(
+        merchant_id=merchant.id,
+        program_id=program.id,
+        customer_id=customer.id,
+        enrolled_at_store_id=store1.id,
+        is_active=True,
+        last_activity_at=datetime.now(UTC),
+    )
+    db.add(card)
+    db.commit()
+    db.refresh(card)
+
+    return {
+        "owner1": owner1,
+        "owner2": owner2,
+        "merchant": merchant,
+        "store1": store1,
+        "store2": store2,
+        "customer": customer,
+        "customer_email": customer_email,
+        "program": program,
+        "card": card,
+    }
+
+
+@pytest.fixture
+def cross_store_headers_store2(client, cross_store_setup):
+    """JWT auth headers bound to store2 (via owner2 who only belongs to store2)."""
+    owner2 = cross_store_setup["owner2"]
+    response = client.post(
+        "/api/v1/store/auth/login",
+        json={"email_or_username": owner2.username, "password": "storepass123"},
+    )
+    assert response.status_code == 200
+    token = response.json()["access_token"]
+    return {"Authorization": f"Bearer {token}"}
+
+
+@pytest.mark.integration
+@pytest.mark.api
+@pytest.mark.loyalty
+class TestCrossStoreEnrollment:
+    """Integration tests for enrollment across stores under the same merchant."""
+
+    def test_enroll_same_email_at_store2_returns_409(
+        self, client, cross_store_headers_store2, cross_store_setup
+    ):
+        """With cross-location enabled (default), enrolling the same email
+        at store2 returns 409 because the customer already has a card under
+        this merchant."""
+        response = client.post(
+            f"{BASE}/cards/enroll",
+            json={"email": cross_store_setup["customer_email"]},
+            headers=cross_store_headers_store2,
+        )
+        assert response.status_code == 409
+
+    def test_enroll_new_customer_at_store2_succeeds(
+        self, client, cross_store_headers_store2, cross_store_setup, db
+    ):
+        """A fresh customer at store2 (no existing card) enrolls normally."""
+        from app.modules.customers.models.customer import Customer
+
+        # Pre-create a customer at store2 (store API requires existing customer)
+        store2 = cross_store_setup["store2"]
+        new_customer = Customer(
+            email=f"newcust_{uuid.uuid4().hex[:8]}@test.com",
+            first_name="New",
+            last_name="Customer",
+            hashed_password="!unused!",  # noqa: SEC001
+            customer_number=f"NEW-{uuid.uuid4().hex[:6].upper()}",
+            store_id=store2.id,
+            is_active=True,
+        )
+        db.add(new_customer)
+        db.commit()
+        db.refresh(new_customer)
+
+        response = client.post(
+            f"{BASE}/cards/enroll",
+            json={"customer_id": new_customer.id},
+            headers=cross_store_headers_store2,
+        )
+        assert response.status_code == 201
+        data = response.json()
+        assert data["card_number"] is not None
+
+    def test_enroll_cross_location_disabled_allows_store2_card(
+        self, client, cross_store_headers_store2, cross_store_setup, db
+    ):
+        """With cross-location disabled, enrolling the same email at store2
+        creates a second card for that store."""
+        # Disable cross-location
+        from app.modules.loyalty.services.program_service import program_service
+
+        settings = program_service.get_or_create_merchant_settings(
+            db, cross_store_setup["merchant"].id
+        )
+        settings.allow_cross_location_redemption = False
+        db.commit()
+
+        response = client.post(
+            f"{BASE}/cards/enroll",
+            json={"email": cross_store_setup["customer_email"]},
+            headers=cross_store_headers_store2,
+        )
+        assert response.status_code == 201
+        data = response.json()
+        assert data["card_number"] is not None
+        # Different card from the original
+        assert data["id"] != cross_store_setup["card"].id

app/modules/loyalty/tests/unit/test_card_service.py

@@ -153,6 +153,69 @@ class TestSearchCardForStore:
         result = self.service.search_card_for_store(db, test_store.id, "nobody@nowhere.com")
         assert result is None
 
+    def test_search_email_finds_cross_store_card(self, db, loyalty_store_setup):
+        """Email search at store2 finds a card enrolled at store1 when
+        cross-location is enabled."""
+        setup = loyalty_store_setup
+        customer = setup["customer"]
+        card = setup["card"]
+        merchant = setup["merchant"]
+
+        from app.modules.tenancy.models import Store
+
+        store2 = Store(
+            merchant_id=merchant.id,
+            store_code=f"XSRCH_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"xsrch{uuid.uuid4().hex[:6]}",
+            name="Cross Search Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+
+        # Cross-location is enabled by default — should find the card
+        result = self.service.search_card_for_store(
+            db, store2.id, customer.email
+        )
+        assert result is not None
+        assert result.id == card.id
+
+    def test_search_email_no_cross_store_when_disabled(
+        self, db, loyalty_store_setup
+    ):
+        """Email search at store2 does NOT find cross-store cards when
+        cross-location is disabled."""
+        setup = loyalty_store_setup
+        customer = setup["customer"]
+        merchant = setup["merchant"]
+
+        from app.modules.loyalty.services.program_service import program_service
+
+        settings = program_service.get_or_create_merchant_settings(
+            db, merchant.id
+        )
+        settings.allow_cross_location_redemption = False
+        db.commit()
+
+        from app.modules.tenancy.models import Store
+
+        store2 = Store(
+            merchant_id=merchant.id,
+            store_code=f"NOSRCH_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"nosrch{uuid.uuid4().hex[:6]}",
+            name="No Cross Search Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+
+        result = self.service.search_card_for_store(
+            db, store2.id, customer.email
+        )
+        assert result is None
+
 
 @pytest.mark.unit
 @pytest.mark.loyalty
@@ -405,3 +468,232 @@ class TestReactivateCardAudit:
 
         card = self.service.reactivate_card(db, test_loyalty_card.id)
         assert card.is_active is True
+
+
+@pytest.mark.unit
+@pytest.mark.loyalty
+class TestGetCardByCustomerAndStore:
+    """Tests for the per-store card lookup."""
+
+    def setup_method(self):
+        self.service = CardService()
+
+    def test_finds_card_at_store(self, db, loyalty_store_setup):
+        """Returns card when customer has one at the given store."""
+        setup = loyalty_store_setup
+        result = self.service.get_card_by_customer_and_store(
+            db, setup["customer"].id, setup["store"].id
+        )
+        assert result is not None
+        assert result.id == setup["card"].id
+
+    def test_returns_none_at_different_store(self, db, loyalty_store_setup):
+        """Returns None when customer has no card at the given store."""
+        from app.modules.tenancy.models import Store
+
+        setup = loyalty_store_setup
+        store2 = Store(
+            merchant_id=setup["merchant"].id,
+            store_code=f"NOCARD_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"nocard{uuid.uuid4().hex[:6]}",
+            name="No Card Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+
+        result = self.service.get_card_by_customer_and_store(
+            db, setup["customer"].id, store2.id
+        )
+        assert result is None
+
+
+@pytest.mark.unit
+@pytest.mark.loyalty
+class TestCrossStoreEnrollment:
+    """
+    Tests for cross-store enrollment with merchant_id-aware resolution.
+
+    The customer model is store-scoped, but loyalty cards are merchant-scoped.
+    When a customer enrolls at store1 and then at store2 (same merchant),
+    resolve_customer_id should find the existing customer from store1 via
+    the cross-store loyalty card lookup.
+    """
+
+    def setup_method(self):
+        self.service = CardService()
+
+    def test_resolve_finds_existing_cardholder_across_stores(
+        self, db, loyalty_store_setup
+    ):
+        """Same email at a different store returns the original customer_id
+        when merchant_id is provided and they already have a card."""
+        setup = loyalty_store_setup
+        merchant = setup["merchant"]
+        customer = setup["customer"]  # Already has a card at store1
+
+        # Create a second store under the same merchant
+        from app.modules.tenancy.models import Store
+
+        store2 = Store(
+            merchant_id=merchant.id,
+            store_code=f"SECOND_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"second{uuid.uuid4().hex[:6]}",
+            name="Second Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+        db.refresh(store2)
+
+        # Resolve with the same email at store2 — should find
+        # the existing customer from store1 via the loyalty card join
+        result = self.service.resolve_customer_id(
+            db,
+            customer_id=None,
+            email=customer.email,
+            store_id=store2.id,
+            merchant_id=merchant.id,
+            create_if_missing=True,
+        )
+
+        assert result == customer.id
+
+    def test_resolve_without_merchant_id_creates_new_customer(
+        self, db, loyalty_store_setup
+    ):
+        """Without merchant_id, the cross-store lookup is skipped and
+        a new customer is created at the new store."""
+        setup = loyalty_store_setup
+        merchant = setup["merchant"]
+        customer = setup["customer"]
+
+        from app.modules.tenancy.models import Store
+
+        store2 = Store(
+            merchant_id=merchant.id,
+            store_code=f"NOMID_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"nomid{uuid.uuid4().hex[:6]}",
+            name="No Merchant ID Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+
+        result = self.service.resolve_customer_id(
+            db,
+            customer_id=None,
+            email=customer.email,
+            store_id=store2.id,
+            # No merchant_id — cross-store lookup skipped
+            create_if_missing=True,
+            customer_name="New Customer",
+        )
+
+        assert result != customer.id  # Different customer created
+
+    def test_enroll_cross_location_enabled_rejects_duplicate(
+        self, db, loyalty_store_setup
+    ):
+        """With cross-location enabled (default), enrolling the same
+        customer_id at a different store raises AlreadyExists."""
+        from app.modules.loyalty.exceptions import (
+            LoyaltyCardAlreadyExistsException,
+        )
+
+        setup = loyalty_store_setup
+        merchant = setup["merchant"]
+        customer = setup["customer"]  # Already has a card
+
+        from app.modules.tenancy.models import Store
+
+        store2 = Store(
+            merchant_id=merchant.id,
+            store_code=f"DUP_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"dup{uuid.uuid4().hex[:6]}",
+            name="Dup Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+
+        with pytest.raises(LoyaltyCardAlreadyExistsException):
+            self.service.enroll_customer_for_store(
+                db, customer.id, store2.id
+            )
+
+    def test_enroll_cross_location_disabled_allows_second_card(
+        self, db, loyalty_store_setup
+    ):
+        """With cross-location disabled, the same customer can enroll
+        at a different store and get a separate card."""
+        setup = loyalty_store_setup
+        merchant = setup["merchant"]
+        customer = setup["customer"]
+
+        # Disable cross-location
+        from app.modules.loyalty.services.program_service import (
+            program_service,
+        )
+
+        settings = program_service.get_or_create_merchant_settings(
+            db, merchant.id
+        )
+        settings.allow_cross_location_redemption = False
+        db.commit()
+
+        from app.modules.tenancy.models import Store
+
+        store2 = Store(
+            merchant_id=merchant.id,
+            store_code=f"XLOC_{uuid.uuid4().hex[:6].upper()}",
+            subdomain=f"xloc{uuid.uuid4().hex[:6]}",
+            name="Cross-Loc Store",
+            is_active=True,
+            is_verified=True,
+        )
+        db.add(store2)
+        db.commit()
+        db.refresh(store2)
+
+        # Should succeed — different store, cross-location disabled
+        card2 = self.service.enroll_customer_for_store(
+            db, customer.id, store2.id
+        )
+        assert card2.enrolled_at_store_id == store2.id
+        assert card2.merchant_id == merchant.id
+        assert card2.customer_id == customer.id
+        # Original card still exists
+        assert setup["card"].id != card2.id
+
+    def test_enroll_cross_location_disabled_rejects_same_store(
+        self, db, loyalty_store_setup
+    ):
+        """With cross-location disabled, re-enrolling at the SAME store
+        still raises AlreadyExists."""
+        from app.modules.loyalty.exceptions import (
+            LoyaltyCardAlreadyExistsException,
+        )
+
+        setup = loyalty_store_setup
+        merchant = setup["merchant"]
+        customer = setup["customer"]
+
+        from app.modules.loyalty.services.program_service import (
+            program_service,
+        )
+
+        settings = program_service.get_or_create_merchant_settings(
+            db, merchant.id
+        )
+        settings.allow_cross_location_redemption = False
+        db.commit()
+
+        with pytest.raises(LoyaltyCardAlreadyExistsException):
+            self.service.enroll_customer_for_store(
+                db, customer.id, setup["store"].id
+            )