test(sync): guard hot path from object-store imports

tests/test_edge_sync_hot_path_imports.py

@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+import ast
+from pathlib import Path
+
+HOT_PATH_DIRS = (
+    "algebra",
+    "chat",
+    "generate",
+    "vault",
+    "core/physics",
+)
+
+FORBIDDEN_IMPORTS = (
+    "boto3",
+    "botocore",
+    "core.sync.object_store",
+    "core.sync.s3_store",
+)
+
+
+def _repo_root() -> Path:
+    return Path(__file__).resolve().parents[1]
+
+
+def _python_files(root: Path) -> list[Path]:
+    files: list[Path] = []
+    for rel in HOT_PATH_DIRS:
+        base = root / rel
+        if base.exists():
+            files.extend(base.rglob("*.py"))
+    return files
+
+
+def _imports_for(path: Path) -> set[str]:
+    tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
+    imports: set[str] = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            imports.update(alias.name for alias in node.names)
+        elif isinstance(node, ast.ImportFrom) and node.module:
+            imports.add(node.module)
+    return imports
+
+
+def test_hot_path_has_no_object_store_imports() -> None:
+    offenders: list[str] = []
+    root = _repo_root()
+    for path in _python_files(root):
+        imports = _imports_for(path)
+        for forbidden in FORBIDDEN_IMPORTS:
+            if forbidden in imports or any(name.startswith(forbidden + ".") for name in imports):
+                offenders.append(f"{path.relative_to(root)} imports {forbidden}")
+
+    assert offenders == []