refactor: establish standalone application boundary

app/tests/frontend_test_helpers.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+
+APP_ROOT = Path(__file__).resolve().parents[1]
+FRONTEND_ROOT = APP_ROOT / "frontend"
+PAGE_MOUNT_MARKER = "    <!-- Registered page fragments mount here. -->\n"
+
+
+def registered_frontend_fragments() -> list[str]:
+    registry = (FRONTEND_ROOT / "pages.config.js").read_text(encoding="utf-8")
+    return re.findall(
+        r'^\s*\["[^"]+", "(/pages/[^"]+/page\.html(?:\?[^"]*)?)", \[',
+        registry,
+        re.MULTILINE,
+    )
+
+
+def registered_frontend_runtime_scripts() -> list[str]:
+    registry = (FRONTEND_ROOT / "pages.config.js").read_text(encoding="utf-8")
+    block = re.search(r"const runtimeScripts = \[(.*?)\n  \];", registry, re.DOTALL)
+    if not block:
+        raise AssertionError("runtimeScripts registry is missing")
+    return re.findall(r'^\s*"([^"]+)",$', block.group(1), re.MULTILINE)
+
+
+def assembled_frontend_document() -> str:
+    shell = (FRONTEND_ROOT / "index.html").read_text(encoding="utf-8")
+    if shell.count(PAGE_MOUNT_MARKER) != 1:
+        raise AssertionError("index.html must contain exactly one page mount marker")
+    fragments = []
+    for url in registered_frontend_fragments():
+        relative = url.split("?", 1)[0].lstrip("/")
+        fragments.append((FRONTEND_ROOT / relative).read_text(encoding="utf-8"))
+    return shell.replace(PAGE_MOUNT_MARKER, "".join(fragments))
+
+
+def assembled_frontend_runtime() -> str:
+    chunks = []
+    for url in registered_frontend_runtime_scripts():
+        relative = url.split("?", 1)[0].lstrip("/")
+        if relative.startswith("vendor/"):
+            continue
+        chunks.append((FRONTEND_ROOT / relative).read_text(encoding="utf-8"))
+    return "\n".join(chunks)