v1.5.0

Writable virtual filesystems

This release expands the host-backed virtual filesystem with guest write support.

Added

• File creation and offset writes
• Appending and truncation
• File and directory deletion
• Directory creation
• File and directory renaming
• Read and write permissions in VFS metadata
• Cache invalidation after filesystem mutations
• Correct guest filesystem errors, including non-empty directory errors

Optional operations have native fallbacks where possible:

• append falls back to an offset write.
• truncate falls back to reading and rewriting the file.
• File rename falls back to copy and delete.

Directory renaming still requires an explicit implementation.

Breaking changes

VirtualFileSystem is now an abstract base class.

Implementations must subclass it and provide:

• stat()
• read()
• list()

Writable implementations may additionally provide write(), delete(),
mkdir(), append(), truncate(), and rename(). Unsupported optional
operations raise NotImplementedError.

Project updates

• Added comprehensive internal and contributor documentation.
• Migrated tests to pytest with parallel execution.
• Improved free-threaded Python testing and wheel builds.
• Reduced CI build and test latency.

Full Changelog: v1.4.0...v1.5.0