fix: use invoicing role contact for invoice email

tuttle/app/invoicing/intent.py

@@ -581,7 +581,7 @@ def send_reminder_by_mail(self, invoice: Invoice) -> IntentResult[None]:
         try:
             user = self._user_data_source.get_user()
             client = invoice.contract.client
-            contact = client.invoicing_contact if client else None
+            contact = client.invoice_recipient_contact if client else None
             greeting = contact.name if contact and contact.name else client.name
             recipient = contact.email if contact and contact.email else None
             if not recipient:
@@ -643,7 +643,7 @@ def send_invoice_by_mail(self, invoice: Invoice) -> IntentResult[None]:
             user = self._user_data_source.get_user()
             # open email client with message pre-filled
             client = invoice.contract.client
-            contact = client.invoicing_contact if client else None
+            contact = client.invoice_recipient_contact if client else None
             greeting = contact.name if contact and contact.name else client.name
             recipient = contact.email if contact and contact.email else None
 

tuttle/invoicing.py

@@ -184,7 +184,7 @@ def generate_invoice_email(
     Returns None when no contact email is available.
     """
     client = invoice.client
-    contact = client.invoicing_contact if client else None
+    contact = client.invoice_recipient_contact if client else None
     greeting = contact.first_name if contact and contact.first_name else client.name
     recipient = contact.email if contact and contact.email else None
 

tuttle/model.py

@@ -372,18 +372,34 @@ class Client(RpcMixin, SQLModel, table=True):
         sa_relationship_kwargs={"lazy": "subquery", "cascade": "all, delete-orphan"},
     )
 
+    @property
+    def invoice_recipient_contact(self) -> Optional[Contact]:
+        """Contact to use for invoice delivery.
+
+        Prefer the legacy direct invoicing contact, but also support the
+        many-to-many contact association used by the current contact UI.
+        """
+        if self.invoicing_contact:
+            return self.invoicing_contact
+        for association in self.client_contacts:
+            if (association.role or "").strip().casefold() == "invoicing":
+                return association.contact
+        return None
+
     @property
     def invoice_recipient_name(self) -> str:
         """Name to use on invoices: contact name if available, else client name."""
-        if self.invoicing_contact and self.invoicing_contact.name:
-            return self.invoicing_contact.name
+        contact = self.invoice_recipient_contact
+        if contact and contact.name:
+            return contact.name
         return self.name
 
     @property
     def invoice_recipient_address(self) -> Optional["Address"]:
         """Address for invoices: prefer contact address, fall back to client address."""
-        if self.invoicing_contact and self.invoicing_contact.address:
-            return self.invoicing_contact.address
+        contact = self.invoice_recipient_contact
+        if contact and contact.address:
+            return contact.address
         return self.address
 
 

tuttle_tests/test_invoice.py

@@ -13,13 +13,16 @@
 from tuttle.model import (
     Address,
     Client,
+    ClientContact,
+    Contact,
     Contract,
     ContractCharge,
     Invoice,
     InvoiceItem,
     InvoiceNote,
     Project,
     TaxCategory,
+    User,
 )
 from tuttle.time import ChargeBasis, ContractType, Cycle, TimeUnit
 
@@ -63,6 +66,31 @@ def test_invoice():
     assert the_invoice.total == Decimal(1800)
 
 
+def test_generate_invoice_email_uses_invoicing_role_contact():
+    """Clients with many-to-many invoicing contacts can still send invoices."""
+    contact = Contact(first_name="Jill", last_name="Invoice", email="billing@example.com")
+    client = Client(name="Client Corp")
+    client.client_contacts.append(ClientContact(client=client, contact=contact, role=" invoicing "))
+    contract = Contract(
+        title="Retainer",
+        client=client,
+        rate=Decimal("100"),
+        currency="EUR",
+        unit=TimeUnit.hour,
+        units_per_workday=8,
+        term_of_payment=14,
+        billing_cycle=Cycle.monthly,
+    )
+    invoice = Invoice(number="INV-1", date=datetime.date(2026, 7, 29), contract=contract)
+    user = User(first_name="Harry", last_name="Tuttle")
+
+    email = invoicing.generate_invoice_email(invoice, user)
+
+    assert email is not None
+    assert email["recipient"] == "billing@example.com"
+    assert "Dear Jill" in email["body"]
+
+
 def test_generate_invoice(
     demo_projects,
     demo_calendar_timetracking,