[BUG] Filesystem extension install crashes Extensions.getInstalledExtensionsWithState (TypeError: u._parse is not a function) — macOS

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Installing the official Filesystem desktop extension in Claude Desktop (macOS) triggers a TypeError in the app's internal state parser and permanently breaks the Settings > Extensions dialog until the local extension settings folder is manually cleared.

This happens even starting from a completely clean/empty extension state — it is not caused by pre-existing corrupted data.

What Should Happen?

The Filesystem extension should install and appear in Settings > Extensions, and the Extensions dialog should keep working normally afterward.

Error Messages/Logs

Error invoking remote method '$eipc_message$_7e1d0999-1d7f-4b41-a6c4-a0f6f7b779d2_$_claude.settings_$_Extensions_$_getInstalledExtensionsWithState': TypeError: u._parse is not a function

Steps to Reproduce

1. Extension state was previously stuck on "Loading extensions..." indefinitely (pre-existing corruption of unknown origin).
2. 2. Quit Claude Desktop. Renamed ~/Library/Application Support/Claude/Claude Extensions Settings and ~/Library/Application Support/Claude/Claude Extensions to back up the old state.
3. 3. Restarted Claude Desktop — Settings > Extensions now loads correctly with a clean, empty extension list.
4. 4. Installed the official Filesystem extension via Settings > Extensions > Browse extensions.
5. 5. Installation immediately fails with the TypeError shown above (see Error Messages/Logs).
6. 6. After this error, Settings > Extensions no longer opens at all — it hangs on "Loading extensions..." again. The only way to restore it is to rename the Claude Extensions Settings folder again, which removes the Filesystem install along with it.

This was reproduced twice: once from the original corrupted state, and again from a freshly cleared/empty state, with the same result both times.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.21459.0 (f7518f)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_