What
Claude Code filters the launch directory, project directories and extra directories to drop entries that look like a scheme (the name: prefix at the start of addresses such as https:) rather than a folder. The filter now needs at least two letters before the colon to treat an entry as a scheme.
A single-letter prefix, such as the Windows drive letter in C:, is no longer filtered out.
Why
On Windows, a directory given as a bare drive such as C: is now kept as a real path instead of being silently thrown away.