README: replace vague cross-app section with actual code dependencies

List specific model imports, glue services, internal APIs, and
domain events that cart code actually references.

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

README.md

@@ -46,13 +46,26 @@ shared/                 # Submodule → git.rose-ash.com/coop/shared.git
 glue/                   # Submodule → git.rose-ash.com/coop/glue.git
 ```
 
-## Cross-App Integration
+## Dependencies
 
-- **Internal API:** `GET /internal/cart/summary` returns cart count + total for the current session/user. Called by blog and market context processors.
-- **Calendar entries:** Checkout marks CalendarEntries (events domain) as "ordered" via `glue/services/order_lifecycle.py` — not by direct model write.
-- **Payment confirmation:** When SumUp payment confirms, entries are marked "provisional" via the same glue service.
-- **Domain events:** Emits `order.created` and `order.paid` events for observability.
-- **Login adoption:** Anonymous cart/entries are adopted when `user.logged_in` event fires (handled by `glue/handlers/login_handlers.py`).
+**Cross-app model imports:**
+- `market.models.market.Product, CartItem` — cart services, checkout, API
+- `market.models.market_place.MarketPlace` — checkout page-config resolution, API page filtering
+- `events.models.calendars.CalendarEntry, Calendar` — checkout, API summary, calendar cart services
+- `blog.models.ghost_content.Post` — `app.py` context processor, API page-slug lookup
+
+**Glue services:**
+- `glue.services.order_lifecycle.claim_entries_for_order` — checkout marks entries as "ordered"
+- `glue.services.order_lifecycle.confirm_entries_for_order` — payment confirmation marks entries "provisional"
+- `glue.services.order_lifecycle.get_entries_for_order` — checkout return page loads entries
+- `glue.services.navigation.get_navigation_tree` — context processor builds site nav
+
+**Internal APIs:**
+- Exposes `GET /internal/cart/summary` — cart count + total for current session/user
+
+**Domain events:**
+- `checkout.py` emits `order.created` via `shared.events.emit_event`
+- `check_sumup_status.py` emits `order.paid` via `shared.events.emit_event`
 
 ## Checkout Flow