migration: prove standalone maintenance and correct visual evidence

app/tools/README.md

@@ -14,6 +14,13 @@ maintenance command cannot be mistaken for a historical migration rewrite.
 - `python tools/build_architecture_inventory.py [--check]`: generate or verify
   `config/architecture-inventory.json` from the candidate source tree.
 
+Inside the canonical `webapp/app/` checkout, `verify_baseline.py` runs the full preservation
+suite against the retained original baseline and enforces `git diff --check`. In a standalone
+`app/` export where that baseline and Git checkout do not exist, the same command runs all
+candidate-owned tests, skips only `test_preservation_*` comparison modules, and reports the Git
+check as skipped. Product, registry, JavaScript, database, and optional Playwright checks remain
+active in both modes.
+
 ## Acceptance and differential checks
 
 - `run_preservation_runtime.py`: start an isolated original or candidate runtime with an

app/tools/build_architecture_inventory.py

@@ -75,6 +75,14 @@ def css_layers(html: str) -> list[str]:
     return re.findall(r'<link[^>]+rel="stylesheet"[^>]+href="([^"]+)"', html)
 
 
+def source_metrics(path: Path) -> dict[str, int]:
+    text = path.read_text(encoding="utf-8")
+    return {
+        "bytes": len(text.encode("utf-8")),
+        "lines": len(text.splitlines()),
+    }
+
+
 def code_hotspots() -> list[dict[str, Any]]:
     candidates = [
         "backend/application.py",
@@ -99,13 +107,7 @@ def code_hotspots() -> list[dict[str, Any]]:
         path = ROOT / name
         if not path.is_file():
             continue
-        rows.append(
-            {
-                "path": name,
-                "bytes": path.stat().st_size,
-                "lines": len(path.read_text(encoding="utf-8").splitlines()),
-            }
-        )
+        rows.append({"path": name, **source_metrics(path)})
     return sorted(rows, key=lambda item: item["bytes"], reverse=True)
 
 

app/tools/verify_baseline.py

@@ -21,6 +21,39 @@ def run(label: str, command: list[str]) -> None:
     subprocess.run(command, cwd=ROOT, check=True)
 
 
+def python_test_command(preservation_baseline: bool | None = None) -> list[str]:
+    if preservation_baseline is None:
+        preservation_baseline = (ROOT.parent / "static" / "app.js").is_file()
+    if preservation_baseline:
+        return [sys.executable, "-m", "unittest", "discover", "-s", "tests"]
+    modules = [
+        f"tests.{path.stem}"
+        for path in sorted((ROOT / "tests").glob("test_*.py"))
+        if not path.stem.startswith("test_preservation_")
+    ]
+    if not modules:
+        raise RuntimeError("no standalone candidate tests found")
+    return [sys.executable, "-m", "unittest", *modules]
+
+
+def verify_git_diff() -> None:
+    result = subprocess.run(
+        ["git", "rev-parse", "--show-toplevel"],
+        cwd=ROOT,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    if result.returncode != 0:
+        print("\n[patch] skipped: standalone export is not a Git checkout")
+        return
+    repository_root = Path(result.stdout.strip()).resolve()
+    if ROOT != repository_root / "app":
+        print("\n[patch] skipped: standalone export is outside the canonical app path")
+        return
+    run("patch", ["git", "diff", "--check"])
+
+
 def verify_database() -> None:
     database = ROOT / "data" / "review.db"
     if not database.exists():
@@ -97,7 +130,7 @@ def main() -> int:
     )
     args = parser.parse_args()
 
-    run("python", [sys.executable, "-m", "unittest", "discover", "-s", "tests"])
+    run("python", python_test_command())
     run(
         "api-registry",
         [sys.executable, "tools/build_api_registry.py", "--check"],
@@ -117,7 +150,7 @@ def main() -> int:
             "javascript",
             [node, "--check", script.relative_to(ROOT).as_posix()],
         )
-    run("patch", ["git", "diff", "--check"])
+    verify_git_diff()
     verify_database()
 
     if args.e2e: