Add macros, declarative handlers (defhandler), and convert all fragment routes to sx

Phase 1 — Macros: defmacro + quasiquote syntax (`, ,, ,@) in parser,
evaluator, HTML renderer, and JS mirror. Macro type, expansion, and
round-trip serialization.

Phase 2 — Expanded primitives: app-url, url-for, asset-url, config,
format-date, parse-int (pure); service, request-arg, request-path,
nav-tree, get-children (I/O); jinja-global, relations-from (pure).
Updated _io_service to accept (service "registry-name" "method" :kwargs)
with auto kebab→snake conversion. DTO-to-dict now expands datetime fields
into year/month/day convenience keys. Tuple returns converted to lists.

Phase 3 — Declarative handlers: HandlerDef type, defhandler special form,
handler registry (service → name → HandlerDef), async evaluator+renderer
(async_eval.py) that awaits I/O primitives inline within control flow.
Handler loading from .sx files, execute_handler, blueprint factory.

Phase 4 — Convert all fragment routes: 13 Python fragment handlers across
8 services replaced with declarative .sx handler files. All routes.py
simplified to uniform sx dispatch pattern. Two Jinja HTML handlers
(events/container-cards, events/account-page) kept as Python.

New files: shared/sx/async_eval.py, shared/sx/handlers.py,
shared/sx/tests/test_handlers.py, plus 13 handler .sx files under
{service}/sx/handlers/. MarketService.product_by_slug() added.

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

blog/bp/fragments/routes.py

@@ -2,21 +2,22 @@
 
 Exposes sx fragments at ``/internal/fragments/<type>`` for consumption
 by other coop apps via the fragment client.
+
+All handlers are defined declaratively in .sx files under
+``blog/sx/handlers/`` and dispatched via the sx handler registry.
 """
 
 from __future__ import annotations
 
-from quart import Blueprint, Response, g, render_template, request
+from quart import Blueprint, Response, request
 
 from shared.infrastructure.fragments import FRAGMENT_HEADER
-from shared.services.navigation import get_navigation_tree
+from shared.sx.handlers import get_handler, execute_handler
 
 
 def register():
     bp = Blueprint("fragments", __name__, url_prefix="/internal/fragments")
 
-    _handlers: dict[str, object] = {}
-
     @bp.before_request
     async def _require_fragment_header():
         if not request.headers.get(FRAGMENT_HEADER):
@@ -24,138 +25,12 @@ def register():
 
     @bp.get("/<fragment_type>")
     async def get_fragment(fragment_type: str):
-        handler = _handlers.get(fragment_type)
-        if handler is None:
-            return Response("", status=200, content_type="text/sx")
-        result = await handler()
-        return Response(result, status=200, content_type="text/sx")
-
-    # --- nav-tree fragment — returns sx source ---
-    async def _nav_tree_handler():
-        from shared.sx.helpers import sx_call, SxExpr
-        from shared.infrastructure.urls import (
-            blog_url, cart_url, market_url, events_url,
-            federation_url, account_url, artdag_url,
-        )
-
-        app_name = request.args.get("app_name", "")
-        path = request.args.get("path", "/")
-        first_seg = path.strip("/").split("/")[0]
-        menu_items = list(await get_navigation_tree(g.s))
-
-        app_slugs = {
-            "cart": cart_url("/"),
-            "market": market_url("/"),
-            "events": events_url("/"),
-            "federation": federation_url("/"),
-            "account": account_url("/"),
-            "artdag": artdag_url("/"),
-        }
-
-        nav_cls = "whitespace-nowrap flex items-center gap-2 rounded p-2 text-sm"
-
-        item_sxs = []
-        for item in menu_items:
-            href = app_slugs.get(item.slug, blog_url(f"/{item.slug}/"))
-            selected = "true" if (item.slug == first_seg
-                                  or item.slug == app_name) else "false"
-            img = sx_call("img-or-placeholder",
-                            src=getattr(item, "feature_image", None),
-                            alt=getattr(item, "label", item.slug),
-                            size_cls="w-8 h-8 rounded-full object-cover flex-shrink-0")
-            item_sxs.append(sx_call(
-                "blog-nav-item-link",
-                href=href, hx_get=href, selected=selected, nav_cls=nav_cls,
-                img=SxExpr(img), label=getattr(item, "label", item.slug),
-            ))
-
-        # artdag link
-        href = artdag_url("/")
-        selected = "true" if ("artdag" == first_seg
-                              or "artdag" == app_name) else "false"
-        img = sx_call("img-or-placeholder", src=None, alt="art-dag",
-                          size_cls="w-8 h-8 rounded-full object-cover flex-shrink-0")
-        item_sxs.append(sx_call(
-            "blog-nav-item-link",
-            href=href, hx_get=href, selected=selected, nav_cls=nav_cls,
-            img=SxExpr(img), label="art-dag",
-        ))
-
-        if not item_sxs:
-            return sx_call("blog-nav-empty",
-                             wrapper_id="menu-items-nav-wrapper")
-
-        items_frag = "(<> " + " ".join(item_sxs) + ")"
-
-        arrow_cls = "scrolling-menu-arrow-menu-items-container"
-        container_id = "menu-items-container"
-        left_hs = ("on click set #" + container_id
-                    + ".scrollLeft to #" + container_id + ".scrollLeft - 200")
-        scroll_hs = ("on scroll "
-                     "set cls to '" + arrow_cls + "' "
-                     "set arrows to document.getElementsByClassName(cls) "
-                     "set show to (window.innerWidth >= 640 and "
-                     "my.scrollWidth > my.clientWidth) "
-                     "repeat for arrow in arrows "
-                     "if show remove .hidden from arrow add .flex to arrow "
-                     "else add .hidden to arrow remove .flex from arrow end "
-                     "end")
-        right_hs = ("on click set #" + container_id
-                     + ".scrollLeft to #" + container_id + ".scrollLeft + 200")
-
-        return sx_call("scroll-nav-wrapper",
-                         wrapper_id="menu-items-nav-wrapper",
-                         container_id=container_id,
-                         arrow_cls=arrow_cls,
-                         left_hs=left_hs,
-                         scroll_hs=scroll_hs,
-                         right_hs=right_hs,
-                         items=SxExpr(items_frag),
-                         oob=True)
-
-    _handlers["nav-tree"] = _nav_tree_handler
-
-    # --- link-card fragment — returns sx source ---
-    def _blog_link_card_sx(post, link: str) -> str:
-        from shared.sx.helpers import sx_call
-        published = post.published_at.strftime("%d %b %Y") if post.published_at else None
-        return sx_call("link-card",
-                         link=link,
-                         title=post.title,
-                         image=post.feature_image,
-                         icon="fas fa-file-alt",
-                         subtitle=post.custom_excerpt or post.excerpt,
-                         detail=published,
-                         data_app="blog")
-
-    async def _link_card_handler():
-        from services import blog_service
-        from shared.infrastructure.urls import blog_url
-
-        slug = request.args.get("slug", "")
-        keys_raw = request.args.get("keys", "")
-
-        # Batch mode
-        if keys_raw:
-            slugs = [k.strip() for k in keys_raw.split(",") if k.strip()]
-            parts = []
-            for s in slugs:
-                parts.append(f"<!-- fragment:{s} -->")
-                post = await blog_service.get_post_by_slug(g.s, s)
-                if post:
-                    parts.append(_blog_link_card_sx(post, blog_url(f"/{post.slug}")))
-            return "\n".join(parts)
-
-        # Single mode
-        if not slug:
-            return ""
-        post = await blog_service.get_post_by_slug(g.s, slug)
-        if not post:
-            return ""
-        return _blog_link_card_sx(post, blog_url(f"/{post.slug}"))
-
-    _handlers["link-card"] = _link_card_handler
-
-    bp._fragment_handlers = _handlers
+        handler_def = get_handler("blog", fragment_type)
+        if handler_def is not None:
+            result = await execute_handler(
+                handler_def, "blog", args=dict(request.args),
+            )
+            return Response(result, status=200, content_type="text/sx")
+        return Response("", status=200, content_type="text/sx")
 
     return bp