diff --git a/shared/sx/helpers.py b/shared/sx/helpers.py
index bd7aebe..fb4dd73 100644
--- a/shared/sx/helpers.py
+++ b/shared/sx/helpers.py
@@ -427,15 +427,20 @@ async def render_to_sx_with_env(__name: str, extra_env: dict, **kwargs: Any) ->
     """Like ``render_to_sx`` but merges *extra_env* into the evaluation
     environment before eval.  Used by ``register_sx_layout`` so .sx
     defcomps can read ctx values as free variables.
+
+    Uses ``async_eval_slot_to_sx`` (not ``async_eval_to_sx``) so the
+    top-level component body is expanded server-side — free variables
+    from *extra_env* are resolved during expansion rather than being
+    serialized as unresolved symbols for the client.
     """
     from .jinja_bridge import get_component_env, _get_request_context
-    from .async_eval import async_eval_to_sx
+    from .async_eval import async_eval_slot_to_sx
 
     ast = _build_component_ast(__name, **kwargs)
     env = dict(get_component_env())
     env.update(extra_env)
     ctx = _get_request_context()
-    return await async_eval_to_sx(ast, env, ctx)
+    return await async_eval_slot_to_sx(ast, env, ctx)
 
 
 async def render_to_sx(__name: str, **kwargs: Any) -> str:
diff --git a/shared/sx/templates/layout.sx b/shared/sx/templates/layout.sx
index 11b1dd4..b18bf7b 100644
--- a/shared/sx/templates/layout.sx
+++ b/shared/sx/templates/layout.sx
@@ -146,32 +146,24 @@
     (when auth-menu
       (div :class "p-3 border-t border-stone-200" auth-menu))))
 
-;; ---------------------------------------------------------------------------
-;; Root header/mobile wrappers — read ctx values from env free variables
-;; Used by register_sx_layout so .sx defcomps compose without Python
-;; ---------------------------------------------------------------------------
-
-(defcomp ~root-header (&key oob)
-  (~header-row-sx :cart-mini cart-mini :blog-url blog-url :site-title site-title
-                   :app-label app-label :nav-tree nav-tree :auth-menu auth-menu
-                   :nav-panel nav-panel :settings-url settings-url :is-admin is-admin
-                   :oob oob))
-
-(defcomp ~root-mobile ()
-  (~mobile-root-nav :nav-tree nav-tree :auth-menu auth-menu))
-
 ;; ---------------------------------------------------------------------------
 ;; Built-in layout defcomps — used by register_sx_layout("root", ...)
+;; Free variables (cart-mini, blog-url, etc.) come from _ctx_to_env().
 ;; ---------------------------------------------------------------------------
 
 (defcomp ~layout-root-full ()
-  (~root-header))
+  (~header-row-sx :cart-mini cart-mini :blog-url blog-url :site-title site-title
+                   :app-label app-label :nav-tree nav-tree :auth-menu auth-menu
+                   :nav-panel nav-panel :settings-url settings-url :is-admin is-admin))
 
 (defcomp ~layout-root-oob ()
-  (~oob-header-sx :parent-id "root-header-child" :row (~root-header)))
+  (~oob-header-sx :parent-id "root-header-child"
+    :row (~header-row-sx :cart-mini cart-mini :blog-url blog-url :site-title site-title
+                          :app-label app-label :nav-tree nav-tree :auth-menu auth-menu
+                          :nav-panel nav-panel :settings-url settings-url :is-admin is-admin)))
 
 (defcomp ~layout-root-mobile ()
-  (~root-mobile))
+  (~mobile-root-nav :nav-tree nav-tree :auth-menu auth-menu))
 
 (defcomp ~error-content (&key errnum message image)
   (div :class "text-center p-8 max-w-lg mx-auto"