diff --git a/market/sx/layouts.sx b/market/sx/layouts.sx
index a55828c..e9676d8 100644
--- a/market/sx/layouts.sx
+++ b/market/sx/layouts.sx
@@ -15,7 +15,13 @@
           :title (get __mctx "market-title")
           :top-slug (get __mctx "top-slug")
           :sub-div (get __mctx "sub-slug"))
-        :nav (get __mctx "desktop-nav")
+        :nav (~market-desktop-nav-from-data
+          :categories (get __mctx "categories")
+          :hx-select (get __mctx "hx-select")
+          :select-colours (get __mctx "select-colours")
+          :all-href (get __mctx "all-href")
+          :all-active (get __mctx "all-active")
+          :admin-href (get __mctx "admin-href"))
         :child-id "market-header-child"
         :oob (unquote oob)))))
 
diff --git a/shared/sx/primitives_io.py b/shared/sx/primitives_io.py
index 63fe8e3..09b758d 100644
--- a/shared/sx/primitives_io.py
+++ b/shared/sx/primitives_io.py
@@ -876,10 +876,10 @@ async def _io_events_ticket_type_ctx(
 async def _io_market_header_ctx(
     args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
 ) -> dict[str, Any]:
-    """``(market-header-ctx)`` → dict with market header values.
+    """``(market-header-ctx)`` → dict with market header data.
 
-    Pre-builds desktop-nav and mobile-nav as SxExpr strings using
-    the existing Python helper functions in sxc.pages.layouts.
+    Returns plain data (categories list, hrefs, flags) for the
+    ~market-header-auto macro. Mobile nav is pre-built as SxExpr.
     """
     from quart import g, url_for
     from shared.config import config as get_config
@@ -916,9 +916,9 @@ async def _io_market_header_ctx(
         "category_label": "",
     }
 
-    # Pre-build nav using existing helper functions (lazy import from market service)
-    from sxc.pages.layouts import _desktop_category_nav_sx, _mobile_nav_panel_sx
-    desktop_nav = _desktop_category_nav_sx(mini_ctx, categories, "", "#main-panel")
+    # Build header + mobile nav data via new data-driven helpers
+    from sxc.pages.layouts import _market_header_data, _mobile_nav_panel_sx
+    header_data = _market_header_data(mini_ctx)
     mobile_nav = _mobile_nav_panel_sx(mini_ctx)
 
     return {
@@ -926,7 +926,12 @@ async def _io_market_header_ctx(
         "link-href": link_href,
         "top-slug": "",
         "sub-slug": "",
-        "desktop-nav": SxExpr(desktop_nav) if desktop_nav else "",
+        "categories": header_data.get("categories", []),
+        "hx-select": header_data.get("hx-select", "#main-panel"),
+        "select-colours": header_data.get("select-colours", ""),
+        "all-href": header_data.get("all-href", ""),
+        "all-active": header_data.get("all-active", False),
+        "admin-href": header_data.get("admin-href", ""),
         "mobile-nav": SxExpr(mobile_nav) if mobile_nav else "",
     }
 
diff --git a/sx/sx/layouts.sx b/sx/sx/layouts.sx
index 2f8a4a1..26395e4 100644
--- a/sx/sx/layouts.sx
+++ b/sx/sx/layouts.sx
@@ -73,8 +73,9 @@
                           :sub-nav sub-nav :selected selected))))
 
 (defcomp ~sx-section-layout-oob (&key section sub-label sub-href sub-nav selected)
-  (<> (~sx-sub-row :sub-label sub-label :sub-href sub-href
-                   :sub-nav sub-nav :selected selected :oob true)
+  (<> (~oob-header-sx :parent-id "sx-header-child"
+        :row (~sx-sub-row :sub-label sub-label :sub-href sub-href
+                          :sub-nav sub-nav :selected selected))
     (~sx-header-row
       :nav (~sx-main-nav :section section)
       :oob true)