chore: import upstream snapshot with attribution

.github/scripts/check_notebooks.py

@@ -0,0 +1,61 @@
+import subprocess
+import sys
+from pathlib import Path
+
+import nbformat
+
+
+def get_changed_notebooks(base_ref: str = "origin/main") -> list[Path]:
+    """
+    Returns a list of changed notebook paths in the current git branch
+    compared to the specified base reference.
+    """
+    result = subprocess.run(
+        ["git", "diff", "--name-only", base_ref, "--", "*.ipynb"],
+        capture_output=True,
+        text=True,
+        check=True,
+    )
+    return [Path(line.strip()) for line in result.stdout.splitlines() if line.strip()]
+
+
+def is_valid_notebook(path: Path) -> bool:
+    """
+    Checks if the notebook at the given path is valid by attempting to read it
+    with nbformat.
+    """
+    try:
+        with open(path, "r", encoding="utf-8") as f:
+            nbformat.read(f, as_version=4)
+        return True
+    except Exception as e:
+        print(f"{path}: INVALID - {e}")
+        return False
+
+
+def main() -> None:
+    """
+    Main function to validate the format of changed notebooks.
+    """
+    changed_notebooks = get_changed_notebooks()
+    if not changed_notebooks:
+        print("No changed .ipynb files to validate.")
+        sys.exit(0)
+
+    print(f"Validating {len(changed_notebooks)} notebook(s)...")
+    errors = 0
+    for path in changed_notebooks:
+        if not path.exists():
+            continue  # skip deleted files
+        if not is_valid_notebook(path):
+            errors += 1
+
+    if errors:
+        print(f"{errors} invalid notebook(s) found.")
+        sys.exit(1)
+    else:
+        print("All changed notebooks are valid.")
+
+
+if __name__ == "__main__":
+    main()