Make rich 404 resilient to cross-service failures

Build a minimal context directly instead of relying on
get_template_context() which runs the full context processor chain
including cross-service fragment fetches. Each step (base_context,
fragments, post hydration) is independently try/excepted so the page
renders with whatever is available.

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

shared/browser/app/errors.py

@@ -83,53 +83,72 @@ async def _rich_error_page(errnum: str, message: str, image: str | None = None)
         return None
 
     try:
-        # If the app's url_value_preprocessor didn't run (no route match),
-        # manually extract the first path segment as a candidate slug and
-        # try to hydrate post data so context processors can use it.
+        from shared.sexp.jinja_bridge import render
+        from shared.sexp.helpers import full_page, call_url
+
+        # Build a minimal context — avoid get_template_context() which
+        # calls cross-service fragment fetches that may fail.
+        from shared.infrastructure.context import base_context
+        try:
+            ctx = await base_context()
+        except Exception:
+            ctx = {"base_title": "Rose Ash", "asset_url": "/static"}
+
+        # Try to fetch fragments, but don't fail if they're unreachable
+        try:
+            from shared.infrastructure.fragments import fetch_fragments
+            from shared.infrastructure.cart_identity import current_cart_identity
+            user = getattr(g, "user", None)
+            ident = current_cart_identity()
+            cart_params = {}
+            if ident["user_id"] is not None:
+                cart_params["user_id"] = ident["user_id"]
+            if ident["session_id"] is not None:
+                cart_params["session_id"] = ident["session_id"]
+            cart_mini_html, auth_menu_html, nav_tree_html = await fetch_fragments([
+                ("cart", "cart-mini", cart_params or None),
+                ("account", "auth-menu", {"email": user.email} if user else None),
+                ("blog", "nav-tree", {"app_name": current_app.name, "path": request.path}),
+            ])
+            ctx["cart_mini_html"] = cart_mini_html
+            ctx["auth_menu_html"] = auth_menu_html
+            ctx["nav_tree_html"] = nav_tree_html
+        except Exception:
+            ctx.setdefault("cart_mini_html", "")
+            ctx.setdefault("auth_menu_html", "")
+            ctx.setdefault("nav_tree_html", "")
+
+        # Try to hydrate post data from slug if not already available
         segments = [s for s in request.path.strip("/").split("/") if s]
         slug = segments[0] if segments else None
+        post_data = getattr(g, "post_data", None)
 
-        if slug and not getattr(g, "post_data", None):
-            # Set g.post_slug / g.page_slug so app context processors
-            # (inject_post, etc.) can pick it up.
-            from shared.infrastructure.data_client import fetch_data
-            raw = await fetch_data(
-                "blog", "post-by-slug",
-                params={"slug": slug},
-                required=False,
-            )
-            if raw:
-                g.post_slug = slug
-                g.page_slug = slug  # cart uses page_slug
-                g.post_data = {
-                    "post": {
-                        "id": raw["id"],
-                        "title": raw["title"],
-                        "slug": raw["slug"],
-                        "feature_image": raw.get("feature_image"),
-                        "status": raw["status"],
-                        "visibility": raw["visibility"],
-                    },
-                }
-                # Also set page_post for cart app
-                from shared.contracts.dtos import PostDTO, dto_from_dict
-                post_dto = dto_from_dict(PostDTO, raw)
-                if post_dto and getattr(post_dto, "is_page", False):
-                    g.page_post = post_dto
-
-        # Build template context (runs app context processors → fragments)
-        from shared.sexp.page import get_template_context
-        ctx = await get_template_context()
-
-        # Build headers: root header + post header if available
-        from shared.sexp.jinja_bridge import render
-        from shared.sexp.helpers import (
-            root_header_html, call_url, full_page,
-        )
+        if slug and not post_data:
+            try:
+                from shared.infrastructure.data_client import fetch_data
+                raw = await fetch_data(
+                    "blog", "post-by-slug",
+                    params={"slug": slug},
+                    required=False,
+                )
+                if raw:
+                    post_data = {
+                        "post": {
+                            "id": raw["id"],
+                            "title": raw["title"],
+                            "slug": raw["slug"],
+                            "feature_image": raw.get("feature_image"),
+                        },
+                    }
+            except Exception:
+                pass
 
+        # Root header (site nav bar)
+        from shared.sexp.helpers import root_header_html
         hdr = root_header_html(ctx)
 
-        post = ctx.get("post") or {}
+        # Post breadcrumb if we resolved a post
+        post = (post_data or {}).get("post") or ctx.get("post") or {}
         if post.get("slug"):
             title = (post.get("title") or "")[:160]
             feature_image = post.get("feature_image")