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/tests/test_sx_helpers.py

@@ -0,0 +1,74 @@
+"""Tests for shared sx helper functions (call_url, get_asset_url, etc.)."""
+from __future__ import annotations
+
+from shared.sx.helpers import call_url, get_asset_url
+
+
+# ---------------------------------------------------------------------------
+# call_url
+# ---------------------------------------------------------------------------
+
+class TestCallUrl:
+    def test_callable_url_fn(self):
+        ctx = {"blog_url": lambda path: f"https://blog.example.com{path}"}
+        assert call_url(ctx, "blog_url", "/posts/") == "https://blog.example.com/posts/"
+
+    def test_callable_default_path(self):
+        ctx = {"blog_url": lambda path: f"https://blog.example.com{path}"}
+        assert call_url(ctx, "blog_url") == "https://blog.example.com/"
+
+    def test_string_url(self):
+        ctx = {"blog_url": "https://blog.example.com"}
+        assert call_url(ctx, "blog_url", "/posts/") == "https://blog.example.com/posts/"
+
+    def test_string_url_default_path(self):
+        ctx = {"blog_url": "https://blog.example.com"}
+        assert call_url(ctx, "blog_url") == "https://blog.example.com/"
+
+    def test_missing_key(self):
+        ctx = {}
+        assert call_url(ctx, "blog_url", "/x") == "/x"
+
+    def test_none_value(self):
+        ctx = {"blog_url": None}
+        assert call_url(ctx, "blog_url", "/x") == "/x"
+
+    def test_callable_with_empty_path(self):
+        ctx = {"cart_url": lambda path: f"https://cart.example.com{path}"}
+        assert call_url(ctx, "cart_url", "") == "https://cart.example.com"
+
+
+# ---------------------------------------------------------------------------
+# get_asset_url
+# ---------------------------------------------------------------------------
+
+class TestGetAssetUrl:
+    def test_callable_asset_url(self):
+        ctx = {"asset_url": lambda path: f"https://cdn.example.com/static{path}"}
+        result = get_asset_url(ctx)
+        # Should strip the trailing path component
+        assert "cdn.example.com" in result
+
+    def test_string_asset_url(self):
+        ctx = {"asset_url": "https://cdn.example.com/static"}
+        assert get_asset_url(ctx) == "https://cdn.example.com/static"
+
+    def test_missing_asset_url(self):
+        ctx = {}
+        assert get_asset_url(ctx) == ""
+
+    def test_none_asset_url(self):
+        ctx = {"asset_url": None}
+        assert get_asset_url(ctx) == ""
+
+    def test_callable_returns_path_only(self):
+        # au("") → "/static", rsplit("/",1)[0] → "" (splits on leading /)
+        ctx = {"asset_url": lambda path: f"/static{path}"}
+        result = get_asset_url(ctx)
+        assert result == ""
+
+    def test_callable_with_nested_path(self):
+        # au("") → "/assets/static", rsplit("/",1)[0] → "/assets"
+        ctx = {"asset_url": lambda path: f"/assets/static{path}"}
+        result = get_asset_url(ctx)
+        assert result == "/assets"