diff --git a/shared/sx/ref/boundary-app.sx b/shared/sx/ref/boundary-app.sx
index 213e1c0..e559e31 100644
--- a/shared/sx/ref/boundary-app.sx
+++ b/shared/sx/ref/boundary-app.sx
@@ -1,9 +1,12 @@
 ;; ==========================================================================
 ;; boundary-app.sx — Deployment-specific boundary declarations
 ;;
-;; Layout context I/O primitives for THIS deployment's service architecture.
+;; I/O primitives specific to THIS deployment's architecture:
+;; inter-service communication, framework bindings, domain concepts,
+;; and layout context providers.
+;;
 ;; These are NOT part of the SX language contract — a different deployment
-;; would declare different layout contexts here.
+;; would declare different primitives here.
 ;;
 ;; The core SX I/O contract lives in boundary.sx.
 ;; Per-service page helpers live in {service}/sx/boundary.sx.
@@ -11,7 +14,92 @@
 
 
 ;; --------------------------------------------------------------------------
-;; Layout context providers — deployment-specific I/O
+;; Inter-service communication — microservice architecture
+;; --------------------------------------------------------------------------
+
+(define-io-primitive "frag"
+  :params (service frag-type &key)
+  :returns "string"
+  :async true
+  :doc "Fetch cross-service HTML fragment."
+  :context :request)
+
+(define-io-primitive "query"
+  :params (service query-name &key)
+  :returns "any"
+  :async true
+  :doc "Fetch data from another service via internal HTTP."
+  :context :request)
+
+(define-io-primitive "action"
+  :params (service action-name &key)
+  :returns "any"
+  :async true
+  :doc "Call an action on another service via internal HTTP."
+  :context :request)
+
+(define-io-primitive "service"
+  :params (service-or-method &rest args &key)
+  :returns "any"
+  :async true
+  :doc "Call a domain service method. Two-arg: (service svc method). One-arg: (service method) uses bound handler service."
+  :context :request)
+
+
+;; --------------------------------------------------------------------------
+;; Framework bindings — Quart/Jinja2/HTMX specifics
+;; --------------------------------------------------------------------------
+
+(define-io-primitive "htmx-request?"
+  :params ()
+  :returns "boolean"
+  :async true
+  :doc "True if current request has HX-Request header."
+  :context :request)
+
+(define-io-primitive "g"
+  :params (key)
+  :returns "any"
+  :async true
+  :doc "Read a value from the Quart request-local g object."
+  :context :request)
+
+(define-io-primitive "jinja-global"
+  :params (key &rest default)
+  :returns "any"
+  :async false
+  :doc "Read a Jinja environment global."
+  :context :request)
+
+
+;; --------------------------------------------------------------------------
+;; Domain concepts — navigation, relations
+;; --------------------------------------------------------------------------
+
+(define-io-primitive "nav-tree"
+  :params ()
+  :returns "list"
+  :async true
+  :doc "Navigation tree as list of node dicts."
+  :context :request)
+
+(define-io-primitive "get-children"
+  :params (&key parent-type parent-id)
+  :returns "list"
+  :async true
+  :doc "Fetch child entities for a parent."
+  :context :request)
+
+(define-io-primitive "relations-from"
+  :params (entity-type)
+  :returns "list"
+  :async false
+  :doc "List of RelationDef dicts for an entity type."
+  :context :config)
+
+
+;; --------------------------------------------------------------------------
+;; Layout context providers — per-service header/page context
 ;; --------------------------------------------------------------------------
 
 ;; Shared across all services (root layout)
diff --git a/shared/sx/ref/boundary.sx b/shared/sx/ref/boundary.sx
index 24f6e39..4bd0ecf 100644
--- a/shared/sx/ref/boundary.sx
+++ b/shared/sx/ref/boundary.sx
@@ -5,7 +5,7 @@
 ;; This is the LANGUAGE contract — not deployment-specific.
 ;;
 ;; Pure primitives (Tier 1) are declared in primitives.sx.
-;; Deployment-specific I/O (layout contexts) lives in boundary-app.sx.
+;; Deployment-specific I/O lives in boundary-app.sx.
 ;; Per-service page helpers live in {service}/sx/boundary.sx.
 ;;
 ;; Format:
@@ -28,38 +28,11 @@
 
 ;; --------------------------------------------------------------------------
 ;; Tier 2: Core I/O primitives — async, side-effectful, need host context
+;;
+;; These are generic web-platform I/O that any SX web host would provide,
+;; regardless of deployment architecture.
 ;; --------------------------------------------------------------------------
 
-;; Cross-service communication
-
-(define-io-primitive "frag"
-  :params (service frag-type &key)
-  :returns "string"
-  :async true
-  :doc "Fetch cross-service HTML fragment."
-  :context :request)
-
-(define-io-primitive "query"
-  :params (service query-name &key)
-  :returns "any"
-  :async true
-  :doc "Fetch data from another service via internal HTTP."
-  :context :request)
-
-(define-io-primitive "action"
-  :params (service action-name &key)
-  :returns "any"
-  :async true
-  :doc "Call an action on another service via internal HTTP."
-  :context :request)
-
-(define-io-primitive "service"
-  :params (service-or-method &rest args &key)
-  :returns "any"
-  :async true
-  :doc "Call a domain service method. Two-arg: (service svc method). One-arg: (service method) uses bound handler service."
-  :context :request)
-
 ;; Request context
 
 (define-io-primitive "current-user"
@@ -69,13 +42,6 @@
   :doc "Current authenticated user dict, or nil."
   :context :request)
 
-(define-io-primitive "htmx-request?"
-  :params ()
-  :returns "boolean"
-  :async true
-  :doc "True if current request has HX-Request header."
-  :context :request)
-
 (define-io-primitive "request-arg"
   :params (name &rest default)
   :returns "any"
@@ -97,13 +63,6 @@
   :doc "Read a URL view argument from the current request."
   :context :request)
 
-(define-io-primitive "g"
-  :params (key)
-  :returns "any"
-  :async true
-  :doc "Read a value from the Quart request-local g object."
-  :context :request)
-
 (define-io-primitive "csrf-token"
   :params ()
   :returns "string"
@@ -134,22 +93,6 @@
   :doc "Service URL prefix for dev/prod routing."
   :context :request)
 
-;; Navigation and relations
-
-(define-io-primitive "nav-tree"
-  :params ()
-  :returns "list"
-  :async true
-  :doc "Navigation tree as list of node dicts."
-  :context :request)
-
-(define-io-primitive "get-children"
-  :params (&key parent-type parent-id)
-  :returns "list"
-  :async true
-  :doc "Fetch child entities for a parent."
-  :context :request)
-
 ;; Config and host context (sync — no await needed)
 
 (define-io-primitive "app-url"
@@ -170,21 +113,7 @@
   :params (key)
   :returns "any"
   :async false
-  :doc "Read a value from app-config.yaml."
-  :context :config)
-
-(define-io-primitive "jinja-global"
-  :params (key &rest default)
-  :returns "any"
-  :async false
-  :doc "Read a Jinja environment global."
-  :context :request)
-
-(define-io-primitive "relations-from"
-  :params (entity-type)
-  :returns "list"
-  :async false
-  :doc "List of RelationDef dicts for an entity type."
+  :doc "Read a value from host configuration."
   :context :config)