Consolidate post header/menu system into shared infrastructure

Replace duplicated _post_header_html, _oob_header_html, and header-child
components across blog/events/market/errors with shared sexpr components
(~post-label, ~page-cart-badge, ~oob-header, ~header-child, ~error-content)
and shared Python helpers (post_header_html, oob_header_html,
header_child_html, error_content_html). App-specific logic (blog container-nav
wrapping, admin cog, events calendar links) preserved via thin wrappers.

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

blog/sexp/header.sexpr

@@ -1,22 +1,8 @@
 ;; Blog header components
 
-(defcomp ~blog-oob-header (&key parent-id child-id row-html)
-  (div :id parent-id :hx-swap-oob "outerHTML" :class "w-full"
-    (div :class "w-full" (raw! row-html)
-      (div :id child-id))))
-
 (defcomp ~blog-header-label ()
   (div))
 
-(defcomp ~blog-post-label (&key feature-image title)
-  (<> (when feature-image (img :src feature-image :class "h-8 w-8 rounded-full object-cover border border-stone-300 flex-shrink-0"))
-    (span title)))
-
-(defcomp ~blog-post-cart-link (&key href count)
-  (a :href href :class "relative inline-flex items-center gap-1.5 px-3 py-1.5 text-sm rounded-full border border-emerald-300 bg-emerald-50 text-emerald-800 hover:bg-emerald-100 transition"
-    (i :class "fa fa-shopping-cart" :aria-hidden "true")
-    (span count)))
-
 (defcomp ~blog-container-nav (&key container-nav-html)
   (div :class "flex flex-col sm:flex-row sm:items-center gap-2 border-r border-stone-200 mr-2 sm:max-w-2xl"
     :id "entries-calendars-nav-wrapper" (raw! container-nav-html)))

blog/sexp/sexp_components.py

@@ -15,6 +15,8 @@ from markupsafe import escape
 from shared.sexp.jinja_bridge import render, load_service_components
 from shared.sexp.helpers import (
     call_url, get_asset_url, root_header_html,
+    post_header_html as _shared_post_header_html,
+    oob_header_html,
     search_mobile_html, search_desktop_html,
     full_page, oob_page,
 )
@@ -24,14 +26,10 @@ load_service_components(os.path.dirname(os.path.dirname(__file__)))
 
 
 # ---------------------------------------------------------------------------
-# OOB header helper
+# OOB header helper — delegates to shared
 # ---------------------------------------------------------------------------
 
-def _oob_header_html(parent_id: str, child_id: str, row_html: str) -> str:
-    """Wrap a header row in OOB div with child placeholder."""
-    return render("blog-oob-header",
-        parent_id=parent_id, child_id=child_id, row_html=row_html,
-    )
+_oob_header_html = oob_header_html
 
 
 # ---------------------------------------------------------------------------
@@ -48,59 +46,40 @@ def _blog_header_html(ctx: dict, *, oob: bool = False) -> str:
 
 
 # ---------------------------------------------------------------------------
-# Post header helpers
+# Post header helpers — thin wrapper over shared post_header_html
 # ---------------------------------------------------------------------------
 
 def _post_header_html(ctx: dict, *, oob: bool = False) -> str:
-    """Build the post-level header row."""
-    post = ctx.get("post") or {}
-    slug = post.get("slug", "")
-    title = (post.get("title") or "")[:160]
-    feature_image = post.get("feature_image")
+    """Build the post-level header row (blog-specific: container-nav wrapping + admin cog)."""
+    overrides: dict = {}
 
-    label_html = render("blog-post-label",
-        feature_image=feature_image, title=title,
-    )
-
-    nav_parts = []
-    page_cart_count = ctx.get("page_cart_count", 0)
-    if page_cart_count and page_cart_count > 0:
-        cart_href = call_url(ctx, "cart_url", f"/{slug}/")
-        nav_parts.append(render("blog-post-cart-link",
-            href=cart_href, count=str(page_cart_count),
-        ))
-
-    # Container nav fragments (calendars, markets)
+    # Blog wraps container_nav_html in border styling
     container_nav = ctx.get("container_nav_html", "")
     if container_nav:
-        nav_parts.append(render("blog-container-nav",
+        overrides["container_nav_html"] = render("blog-container-nav",
             container_nav_html=container_nav,
-        ))
+        )
 
-    # Admin link
-    from quart import url_for as qurl, g, request
+    # Admin cog link
+    from quart import url_for as qurl, request
+    post = ctx.get("post") or {}
+    slug = post.get("slug", "")
     rights = ctx.get("rights") or {}
     has_admin = rights.get("admin") if isinstance(rights, dict) else getattr(rights, "admin", False)
-    if has_admin:
+    if has_admin and slug:
         select_colours = ctx.get("select_colours", "")
         styles = ctx.get("styles") or {}
         nav_btn = styles.get("nav_button", "") if isinstance(styles, dict) else getattr(styles, "nav_button", "")
         admin_href = qurl("blog.post.admin.admin", slug=slug)
         is_admin_page = "/admin" in request.path
-        nav_parts.append(render("nav-link",
+        overrides["post_admin_nav_html"] = render("nav-link",
             href=admin_href, hx_select="#main-panel", icon="fa fa-cog",
             aclass=f"{nav_btn} {select_colours}",
             select_colours=select_colours, is_selected=is_admin_page,
-        ))
+        )
 
-    nav_html = "".join(nav_parts)
-    link_href = call_url(ctx, "blog_url", f"/{slug}/")
-
-    return render("menu-row",
-        id="post-row", level=1,
-        link_href=link_href, link_label_html=label_html,
-        nav_html=nav_html, child_id="post-header-child", oob=oob,
-    )
+    effective_ctx = {**ctx, **overrides} if overrides else ctx
+    return _shared_post_header_html(effective_ctx, oob=oob)
 
 
 # ---------------------------------------------------------------------------