Domain isolation: replace cross-domain imports with service calls

Replace direct Post query and CartItem imports with typed service calls.
Market registers all 4 services via domain_services_fn with has() guards.

Key changes:
- app.py: use domain_services_fn, Post query → services.blog,
  CartItem → services.cart, MarketPlace+Post join → separate queries,
  glue navigation → shared navigation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -18,46 +18,38 @@ async def market_context() -> dict:
     Market app context processor.
 
     - menu_items: direct DB query via glue layer
-    - cart_count/cart_total: direct DB query (same shared DB)
+    - cart_count/cart_total: via cart service (shared DB)
     """
     from shared.infrastructure.context import base_context
-    from glue.services.navigation import get_navigation_tree
+    from shared.services.navigation import get_navigation_tree
     from shared.infrastructure.cart_identity import current_cart_identity
-    from models.market import CartItem
-    from sqlalchemy.orm import selectinload
+    from shared.services.registry import services
 
     ctx = await base_context()
 
     ctx["menu_items"] = await get_navigation_tree(g.s)
 
-    # Cart data: query shared DB directly (avoids stale cross-app API responses)
+    # Cart data via service (replaces direct CartItem query)
     ident = current_cart_identity()
-    cart_filters = [CartItem.deleted_at.is_(None)]
-    if ident["user_id"] is not None:
-        cart_filters.append(CartItem.user_id == ident["user_id"])
-    else:
-        cart_filters.append(CartItem.session_id == ident["session_id"])
-
-    cart_result = await g.s.execute(
-        select(CartItem)
-        .where(*cart_filters)
-        .options(selectinload(CartItem.product))
+    summary = await services.cart.cart_summary(
+        g.s, user_id=ident["user_id"], session_id=ident["session_id"],
     )
-    cart_items = cart_result.scalars().all()
-
-    from bp.cart.services import total
-    ctx["cart"] = list(cart_items)
-    ctx["cart_count"] = sum(ci.quantity for ci in cart_items)
-    ctx["cart_total"] = total(cart_items) or 0
+    ctx["cart"] = summary.items
+    ctx["cart_count"] = summary.count
+    ctx["cart_total"] = float(summary.total)
 
     return ctx
 
 
 def create_app() -> "Quart":
     from models.market_place import MarketPlace
-    from shared.models.ghost_content import Post
+    from services import register_domain_services
 
-    app = create_base_app("market", context_fn=market_context)
+    app = create_base_app(
+        "market",
+        context_fn=market_context,
+        domain_services_fn=register_domain_services,
+    )
 
     # App-specific templates override shared templates
     app_templates = str(Path(__file__).resolve().parent / "templates")
@@ -100,12 +92,8 @@ def create_app() -> "Quart":
         if not post_slug or not market_slug:
             return
 
-        # Load post by slug
-        post = (
-            await g.s.execute(
-                select(Post).where(Post.slug == post_slug)
-            )
-        ).scalar_one_or_none()
+        # Load post by slug via blog service
+        post = await services.blog.get_post_by_slug(g.s, post_slug)
         if not post:
             abort(404)
 
@@ -147,23 +135,22 @@ def create_app() -> "Quart":
     # --- Root route: market listing ---
     @app.get("/")
     async def markets_listing():
-        rows = (
-            await g.s.execute(
-                select(MarketPlace, Post)
-                .join(
-                    Post,
-                    (MarketPlace.container_type == "page")
-                    & (MarketPlace.container_id == Post.id),
-                )
-                .where(MarketPlace.deleted_at.is_(None))
-                .order_by(MarketPlace.name)
-            )
-        ).all()
+        result = await g.s.execute(
+            select(MarketPlace)
+            .where(MarketPlace.deleted_at.is_(None), MarketPlace.container_type == "page")
+            .order_by(MarketPlace.name)
+        )
+        all_markets = result.scalars().all()
 
-        # Attach the joined post to each market for template access
+        # Resolve page posts via blog service
+        post_ids = list({m.container_id for m in all_markets})
+        posts_by_id = {
+            p.id: p
+            for p in await services.blog.get_posts_by_ids(g.s, post_ids)
+        }
         markets = []
-        for market, post in rows:
-            market.page = post
+        for market in all_markets:
+            market.page = posts_by_id.get(market.container_id)
             markets.append(market)
 
         html = await render_template(