Rebrand sexp → sx across web platform (173 files)

Rename all sexp directories, files, identifiers, and references to sx.
artdag/ excluded (separate media processing DSL).

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

shared/sx/relations.py

@@ -0,0 +1,101 @@
+"""
+Relation registry — declarative entity relationship definitions.
+
+Relations are defined as s-expressions using ``defrelation`` and stored
+in a global registry.  All services load the same definitions at startup
+via ``load_relation_registry()``.
+"""
+
+from __future__ import annotations
+
+from shared.sx.types import RelationDef
+
+
+# ---------------------------------------------------------------------------
+# Registry
+# ---------------------------------------------------------------------------
+
+_RELATION_REGISTRY: dict[str, RelationDef] = {}
+
+
+def register_relation(defn: RelationDef) -> None:
+    """Add a RelationDef to the global registry."""
+    _RELATION_REGISTRY[defn.name] = defn
+
+
+def get_relation(name: str) -> RelationDef | None:
+    """Look up a relation by name (e.g. ``"page->market"``)."""
+    return _RELATION_REGISTRY.get(name)
+
+
+def relations_from(entity_type: str) -> list[RelationDef]:
+    """All relations where *entity_type* is the ``from`` side."""
+    return [d for d in _RELATION_REGISTRY.values() if d.from_type == entity_type]
+
+
+def relations_to(entity_type: str) -> list[RelationDef]:
+    """All relations where *entity_type* is the ``to`` side."""
+    return [d for d in _RELATION_REGISTRY.values() if d.to_type == entity_type]
+
+
+def all_relations() -> list[RelationDef]:
+    """Return all registered relations."""
+    return list(_RELATION_REGISTRY.values())
+
+
+def clear_registry() -> None:
+    """Clear all registered relations (for testing)."""
+    _RELATION_REGISTRY.clear()
+
+
+# ---------------------------------------------------------------------------
+# Built-in relation definitions (s-expression source)
+# ---------------------------------------------------------------------------
+
+_BUILTIN_RELATIONS = '''
+(begin
+
+  (defrelation :page->market
+    :from "page"
+    :to "market"
+    :cardinality :one-to-many
+    :inverse :market->page
+    :nav :submenu
+    :nav-icon "fa fa-shopping-bag"
+    :nav-label "markets")
+
+  (defrelation :page->calendar
+    :from "page"
+    :to "calendar"
+    :cardinality :one-to-many
+    :inverse :calendar->page
+    :nav :submenu
+    :nav-icon "fa fa-calendar"
+    :nav-label "calendars")
+
+  (defrelation :post->calendar_entry
+    :from "post"
+    :to "calendar_entry"
+    :cardinality :many-to-many
+    :inverse :calendar_entry->post
+    :nav :inline
+    :nav-icon "fa fa-file-alt"
+    :nav-label "events")
+
+  (defrelation :page->menu_node
+    :from "page"
+    :to "menu_node"
+    :cardinality :one-to-one
+    :nav :hidden)
+
+)
+'''
+
+
+def load_relation_registry() -> None:
+    """Parse built-in defrelation s-expressions and populate the registry."""
+    from shared.sx.evaluator import evaluate
+    from shared.sx.parser import parse
+
+    tree = parse(_BUILTIN_RELATIONS)
+    evaluate(tree)