fix: support CloudPath subclasses in normalize_path and file_browser

[BillionClaw]

Fix: Support CloudPath subclasses in path normalization

Problem

Custom cloudpathlib providers (e.g., SMBPath) that subclass CloudPath were not recognized by marimo's path handling because normalize_path and the file browser used a fragile module-name check:

if path.__class__.__module__.startswith("cloudpathlib"):

This only matched the built-in S3Path, GSPath, AzurePath etc., but not user-created subclasses whose module would be their own package (e.g., mypackage.smbpath).

As a result, os.path.normpath was called on cloud paths, corrupting URI schemes like smb://server/share into smb:/server/share.

Solution

Replace the module-name check with isinstance(path, CloudPath), which correctly identifies all subclasses of CloudPath. The old module-name check is kept as a fallback for backward compatibility.

Changes

• marimo/_utils/paths.py: normalize_path() now uses isinstance(path, CloudPath) with a try/except ImportError, falling back to the module-name check
• marimo/_plugins/ui/_impl/file_browser.py: Same isinstance-based check for the cloud storage limit heuristic
• tests/_utils/test_paths.py: Minor comment update to clarify fallback behavior

Testing

All 15 tests in tests/_utils/test_paths.py pass.

Fixes #8868.

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Mar 26, 2026 4:47am

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