Eliminate Python page helpers from orders — pure .sx defpages with IO primitives

Orders defpages now fetch data via (service ...) and generate URLs via
(url-for ...) and (route-prefix) directly in .sx. No Python middleman.

- Add url-for, route-prefix IO primitives to shared/sx/primitives_io.py
- Add generic register()/\_\_getattr\_\_ to ServiceRegistry for dynamic services
- Create OrdersPageService with list_page_data/detail_page_data methods
- Rewrite orders.sx defpages to use IO primitives + defcomp calls
- Remove ~320 lines of Python page helpers from orders/sxc/pages/__init__.py
- Convert :data env merge to use kebab-case keys for SX symbol access

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

shared/services/registry.py

@@ -15,6 +15,8 @@ Usage::
 """
 from __future__ import annotations
 
+from typing import Any
+
 from shared.contracts.protocols import (
     CalendarService,
     MarketService,
@@ -36,6 +38,7 @@ class _ServiceRegistry:
         self._market: MarketService | None = None
         self._cart: CartService | None = None
         self._federation: FederationService | None = None
+        self._extra: dict[str, Any] = {}
 
     # -- calendar -------------------------------------------------------------
     @property
@@ -81,10 +84,27 @@ class _ServiceRegistry:
     def federation(self, impl: FederationService) -> None:
         self._federation = impl
 
+    # -- generic registration --------------------------------------------------
+    def register(self, name: str, impl: Any) -> None:
+        """Register a service by name (for services without typed properties)."""
+        self._extra[name] = impl
+
+    def __getattr__(self, name: str) -> Any:
+        # Fallback to _extra dict for dynamically registered services
+        try:
+            extra = object.__getattribute__(self, "_extra")
+            if name in extra:
+                return extra[name]
+        except AttributeError:
+            pass
+        raise AttributeError(f"No service registered as: {name}")
+
     # -- introspection --------------------------------------------------------
     def has(self, name: str) -> bool:
         """Check whether a domain service is registered."""
-        return getattr(self, f"_{name}", None) is not None
+        if getattr(self, f"_{name}", None) is not None:
+            return True
+        return name in self._extra
 
 
 # Module-level singleton — import this everywhere.

shared/sx/pages.py

@@ -184,7 +184,9 @@ async def execute_page(
     if page_def.data_expr is not None:
         data_result = await async_eval(page_def.data_expr, env, ctx)
         if isinstance(data_result, dict):
-            env.update(data_result)
+            # Merge with kebab-case keys so SX symbols can reference them
+            for k, v in data_result.items():
+                env[k.replace("_", "-")] = v
 
     # Render content slot (required)
     content_sx = await _eval_slot(page_def.content_expr, env, ctx)

shared/sx/primitives_io.py

@@ -43,6 +43,8 @@ IO_PRIMITIVES: frozenset[str] = frozenset({
     "g",
     "csrf-token",
     "abort",
+    "url-for",
+    "route-prefix",
 })
 
 
@@ -345,6 +347,34 @@ async def _io_abort(
     abort(status, message)
 
 
+async def _io_url_for(
+    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
+) -> str:
+    """``(url-for "endpoint" :key val ...)`` → url_for(endpoint, **kwargs).
+
+    Generates a URL for the given endpoint.  Keyword args become URL
+    parameters (kebab-case converted to snake_case).
+    """
+    if not args:
+        raise ValueError("url-for requires an endpoint name")
+    from quart import url_for
+    endpoint = str(args[0])
+    clean = {k.replace("-", "_"): v for k, v in _clean_kwargs(kwargs).items()}
+    # Convert numeric values for int URL params
+    for k, v in clean.items():
+        if isinstance(v, str) and v.isdigit():
+            clean[k] = int(v)
+    return url_for(endpoint, **clean)
+
+
+async def _io_route_prefix(
+    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
+) -> str:
+    """``(route-prefix)`` → current route prefix string."""
+    from shared.utils import route_prefix
+    return route_prefix()
+
+
 _IO_HANDLERS: dict[str, Any] = {
     "frag": _io_frag,
     "query": _io_query,
@@ -359,4 +389,6 @@ _IO_HANDLERS: dict[str, Any] = {
     "g": _io_g,
     "csrf-token": _io_csrf_token,
     "abort": _io_abort,
+    "url-for": _io_url_for,
+    "route-prefix": _io_route_prefix,
 }