[BUG] [claude.ai Projects] Slash in knowledge item title creates folders in the knowledge panel

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?

This is a claude.ai Projects bug (web/desktop app), not a Claude Code CLI bug.

A forward slash in the title of a project knowledge item creates folders in the project knowledge panel. Each / starts a new folder level. Nothing in the UI or the docs mentions folder support for project knowledge, so this looks unintended.

It also happens with chat artifacts that have a slash in the title and get added to a project. An artifact titled "Server setup for 24/7 operation" shows up as a folder Server setup for 24 with one item 7 operation inside. Any natural title with a slash, like dates, version ranges or "24/7", runs into this.

What Should Happen?

One knowledge item with the full title, slash included. Or the UI sanitizes the slash, or rejects it with a message. If folders are a planned feature, they need to be visible and manageable on purpose, not triggered by a character in the title.

Error Messages/Logs

No error. The panel shows the folder silently.

Steps to Reproduce

1. Open any claude.ai Project.
2. In the project knowledge panel, click + and choose "Add text content".
3. Enter the title TEST Level-1/Level-2/File-2 and any content.
4. Save.
5. The panel shows a folder TEST Level-1 with a subfolder Level-2 containing one item File-2. The folder card says "1 item".

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.9939.2 (Desktop App Version)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• File uploads don't trigger this. macOS stores / from Finder names as :, so an uploaded file shows a colon instead. That part is expected OS behavior.
• The model sees a flat file list. Inside a chat, the same item appears as TEST_Level-1_Level-2_File-2, slashes replaced by underscores. Only the panel renders folders.
• Folders can't be renamed or removed directly. The only fix is deleting the item and re-adding it with a new title.
• Items added via "Add text content" show no extension. Items from markdown artifacts keep .md. Both paths create folders.
• Plan: Max
• Client: Claude Desktop for macOS, version 2.9939.2