feat(tenants): add a default address on each consumer grant (T-11)

claude.ai's connector keeps no MCP session between tool calls, so the
Office cannot remember which address a conversation chose. Each consumer
grant now carries a fallback: the Office uses it when a call names none
and has no session binding (tatlock-office T-5, in a parallel round,
reads it).

Migration 008 (down_revision="007") adds
tenant_consumers.default_address — nullable varchar(63) — and a
composite foreign key (tenant_id, default_address) ->
scribe_addresses(owner_tenant, name), so a default always names a real
address in the same tenant. scribe_addresses already carries both a
primary key and a named unique constraint on (owner_tenant, name)
(migration 006), so the composite FK has something to bind to; Postgres's
default MATCH SIMPLE means a NULL default_address never triggers the
check, which is the state every grant but one is left in. The data step
sets jpmschweitzer/office-claude -> claude-ai only if that address exists
at upgrade time (true in production, false in core_api_test, where no
scribe_addresses are seeded) — an UPDATE ... WHERE EXISTS, not a bare
UPDATE, so it is a no-op rather than a failure when absent.
llm_tester/office-claude is untouched and stays null. Downgrade drops the
FK then the column.

TenantConsumer (models.py) gains the column and a matching
ForeignKeyConstraint. TenantsService.get_me now returns a third element,
the caller's own consumer's default_address (looked up only when
caller.consumer is not None — a user-kind caller carries no consumer, so
there is no grant row to hold a default for it) or None. GET /tenants/me
answers it; GET /tenants and its TenantSummary schema are unchanged.

Tests: TestMigration008RoundTrip/ForeignKey/DataStep added to
tests/test_tenants_migration.py (round-trip 007<->008, the FK existing
and refusing an unknown address while allowing null, the data step's
no-op and positive cases). tests/conftest.py gains a
default_address_grant fixture (registers a throwaway address, points a
grant at it, reverses both on teardown). tests/test_tenants.py gains
TestMeDefaultAddress (an office caller with/without a default, a user
caller always null).

Friction found and fixed in the same commit: the new composite FK made
Postgres refuse tests/test_scribe.py's existing clean_scribe_tables
TRUNCATE ("cannot truncate a table referenced in a foreign key
constraint") — the restriction is on the constraint's existence, not on
whether any row's default_address is actually non-null. tenant_consumers
joins that TRUNCATE; CASCADE was rejected because it would silently drop
every grant rather than only addresses, so the four grants
(jpmschweitzer/llm_tester x office-claude/office-gemini) are reinserted
in the same fixture, right after.

Mutation-checked: forcing default_address to null in the controller
fails exactly test_office_caller_with_a_default_sees_it, leaving the
without-a-default and user-caller tests green. Disabling the FK's
creation (and, symmetrically, its drop in downgrade — to keep the
round-trip self-consistent against the live core_api_test schema) fails
test_fk_exists and test_fk_refuses_a_default_naming_an_address_that_does_not_exist,
leaving test_fk_allows_a_null_default_regardless_of_tenant green. Both
mutations reverted; the full suite re-verified green (543 + 11 = 554
passed).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/domains/tenants/controller.py

@@ -51,7 +51,7 @@ class TenantsController(BaseController):
             session: AsyncSession = Depends(get_async_session),
         ):
             try:
-                tenant, consumers = await service.get_me(session, caller)
+                tenant, consumers, default_address = await service.get_me(session, caller)
             except TenantError as error:
                 raise HTTPException(
                     status_code=error.status_code, detail={"code": error.code}
@@ -62,6 +62,7 @@ class TenantsController(BaseController):
                 kind=tenant.kind,
                 status=tenant.status,
                 consumers=consumers,
+                default_address=default_address,
             )
 
         # =====================================================================

src/domains/tenants/models.py

@@ -7,10 +7,25 @@ and `TenantsService.require_tenant` is the one place a caller's tenant is
 checked known, active, and — for an Office caller — granted to the calling
 consumer. SQLAlchemy 2.0 Mapped/mapped_column style, timestamptz, following
 src/domains/book/models.py.
+
+`TenantConsumer.default_address` (migration 008, core-api T-11) is each
+grant's fallback address for a caller that names none and holds no session
+binding — claude.ai's connector keeps no MCP session between tool calls, so
+the Office needs this to answer without one. The composite FK keeps it
+honest: a default always names a real address in the same tenant.
 """
 from datetime import datetime
+from typing import Optional
 
-from sqlalchemy import CheckConstraint, DateTime, ForeignKey, String, Text, func
+from sqlalchemy import (
+    CheckConstraint,
+    DateTime,
+    ForeignKey,
+    ForeignKeyConstraint,
+    String,
+    Text,
+    func,
+)
 from sqlalchemy.orm import Mapped, mapped_column
 
 from src.shared.database import Base
@@ -55,14 +70,26 @@ class Tenant(Base):
 
 
 class TenantConsumer(Base):
-    """A grant: consumer `consumer` may act in tenant `tenant_id`."""
+    """A grant: consumer `consumer` may act in tenant `tenant_id`, with an
+    optional default address (migration 008, core-api T-11) — the composite
+    FK below means a non-null default always names a real
+    `scribe_addresses` row in this same tenant."""
 
     __tablename__ = "tenant_consumers"
+    __table_args__ = (
+        ForeignKeyConstraint(
+            ["tenant_id", "default_address"],
+            ["scribe_addresses.owner_tenant", "scribe_addresses.name"],
+            name="fk_tenant_consumers_default_address",
+        ),
+    )
 
     tenant_id: Mapped[str] = mapped_column(
         String(63), ForeignKey("tenants.id"), primary_key=True
     )
     consumer: Mapped[str] = mapped_column(String(63), primary_key=True)
+    # FK to scribe_addresses (owner_tenant, name) added by migration 008.
+    default_address: Mapped[Optional[str]] = mapped_column(String(63), nullable=True)
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), server_default=func.now(), nullable=False
     )

src/domains/tenants/schemas.py

@@ -5,7 +5,7 @@ Pydantic request/response payloads for the tenant registry (core-api T-8 /
 workspace D-73). No write routes this round — provisioning is later
 (workspace T-195).
 """
-from typing import List
+from typing import List, Optional
 
 from src.shared.base import BaseSchema
 
@@ -21,9 +21,14 @@ class TenantSummary(BaseSchema):
 
 class TenantMeResponse(TenantSummary):
     """`GET /tenants/me` — the caller's own tenant plus the consumers
-    granted in it, the cheap "am I allowed here" probe (D-73)."""
+    granted in it, the cheap "am I allowed here" probe (D-73).
+
+    `default_address` (core-api T-11) is the caller's own consumer's
+    default address, or null — null for a user-kind caller (no consumer to
+    look a default up for) and for an office caller whose grant has none."""
 
     consumers: List[str]
+    default_address: Optional[str] = None
 
 
 class TenantListResponse(BaseSchema):

src/domains/tenants/service.py

@@ -81,9 +81,16 @@ class TenantsService:
 
         return tenant
 
-    async def get_me(self, session: AsyncSession, caller: Caller) -> Tuple[Tenant, List[str]]:
+    async def get_me(
+        self, session: AsyncSession, caller: Caller
+    ) -> Tuple[Tenant, List[str], Optional[str]]:
         """`GET /tenants/me` — through the same helper, so "am I allowed
-        here" shares its answer with every other tenant-scoped call."""
+        here" shares its answer with every other tenant-scoped call.
+
+        The third element is the caller's own consumer's default address
+        (core-api T-11), or None — looked up only for an office caller
+        (`caller.consumer is not None`); a user-kind caller carries no
+        consumer, so there is no grant row to hold a default for it."""
         tenant_id = await self.require_tenant(session, caller)
 
         tenant = await session.get(Tenant, tenant_id)
@@ -93,7 +100,16 @@ class TenantsService:
             .order_by(TenantConsumer.consumer)
         )
         consumers = list((await session.execute(consumers_stmt)).scalars().all())
-        return tenant, consumers
+
+        default_address: Optional[str] = None
+        if caller.consumer is not None:
+            default_address = await session.scalar(
+                select(TenantConsumer.default_address).where(
+                    TenantConsumer.tenant_id == tenant_id,
+                    TenantConsumer.consumer == caller.consumer,
+                )
+            )
+        return tenant, consumers, default_address
 
     async def list_tenants(self, session: AsyncSession, caller: Caller) -> List[Tenant]:
         """