Plan independent BFF and adapt selected Sendico foundations (#34)

README.md

@@ -11,8 +11,9 @@ with `go_router`. Its interface uses the shared theme's colors and typography.
 
 **Authentication, email verification and analytics use dummy services.** No real
 account or session is created, no email is delivered, and no analytics data is
-transmitted. The backend is documentation only. Session/KYC access guards and
-Sendico integration are not implemented.
+transmitted. The backend has an independent Go operational shell; product services
+are not connected. Session/KYC access guards and Sendico integration are not
+implemented.
 
 ## Repository structure
 
@@ -23,7 +24,7 @@ Sendico integration are not implemented.
 | [`sxchnge_theme`](frontend/packages/sxchnge_theme/README.md) | Reusable light/dark themes and bundled Onest font |
 | [`sxchnge_auth`](frontend/packages/sxchnge_auth/README.md) | Shared auth contracts, providers, two-factor page and dummy services |
 | [`sxchnge_analytics`](frontend/packages/sxchnge_analytics/README.md) | Typed journey events, recorder and bounded in-memory dummy analytics |
-| [`backend/`](backend/README.md) | Planned BFF and Sendico integration boundaries |
+| [`backend/`](backend/README.md) | Independent Go BFF starter, adapted foundations and provider integration plan |
 | [`.agents/skills/`](.agents/skills) | Repository agent skills |
 | [`docs/`](docs/implementation.md) | Implementation records and UX measurement contracts |
 
@@ -152,9 +153,9 @@ The intended integration is: **consumer app → sxchnge BFF → supported Sendic
 - The sxchnge organization, backend integration principal and individual customer
   references are distinct identities. Consumers must not share the integration
   account's customer identity.
-- The BFF should use a supported API contract rather than copying Sendico's BFF
-  or depending on its local internal modules. Integration credentials belong in
-  the backend.
+- The BFF uses a supported provider API. Selected Sendico components may be
+  adapted into SXCHNGE-owned code; local Sendico module dependencies are not used.
+  Integration credentials belong in the backend.
 
 Before backend integration, agree on the customer, KYC, eligibility/limits and
 customer-scoped payment contracts for one complete transaction flow. These are
@@ -224,3 +225,14 @@ instructions also support authenticator challenges; actual TOTP enrollment,
 validation and recovery remain backend integration work. See the
 [two-factor UX contract](docs/ux/two-factor.md) and
 [shared auth package](frontend/packages/sxchnge_auth/README.md).
+
+## Backend integration plan
+
+The [BFF architecture and Sendico service audit](docs/architecture/bff.md) defines
+consumer identity, financial-provider boundaries, reusable components, contract
+gaps and delivery phases. Selected Sendico code has been adapted with recorded
+[provenance](backend/PROVENANCE.md); the projects share no runtime modules.
+
+Run `make test-backend`, `make lint-backend` or `make run-backend` from the root.
+The starter exposes health and unconfigured readiness only. Authentication,
+persistence and live financial operations remain the next implementation phases.