[Bug] Windows workspace picker rejects home folders and falls through to drive root

[hellocybernetics]

Description

On native Windows, the New Chat workspace picker cannot open a folder that lives directly under the user profile. Clicking a home-directory child (for example Documents or work) is treated as an invalid path, and the picker jumps to the drive root (C:\). Sessions started from that state use C:\ as the workspace.

Expected: choosing C:\Users\alice\work lists that directory and can be selected as the session workspace.

Actual: every home-child path is rejected. The picker's current directory becomes /, which on Windows is the drive root.

This is not harness- or auth-specific. Session create already accepts Windows drive-letter paths; the picker and host filesystem browse API never deliver one.

Likely cause (0.10.0 and current main):

1. host.list_dir returns native paths such as C:\Users\alice\work.
2. The picker finds parents with lastIndexOf("/") only, so a backslash path has parent /.
3. GET /v1/hosts/{id}/filesystem/{path:path} always prefixes / after FastAPI strips the URL slash, so C:/Users/alice/work becomes /C:/Users/alice/work and 404s.
4. Create-directory rejects C:\... because it only allows paths starting with / or ~.

Steps to reproduce

1. On native Windows, run Omnigent 0.10.0 (or current main) with a connected host.
2. Open New Chat and open the workspace folder picker (it starts at home / ~).
3. Click any folder listed under the home directory.
4. The listing jumps to C:\ instead of entering the folder.
5. Starting a session from that state uses workspace C:\.

Version

0.10.0 (also reproduced on current main)

OS

Windows 11 (10.0.26200)

Harness

Not applicable

Harness mode

Not applicable

Platform or device

Windows

Observed impact

All users or sessions — anyone using the workspace picker on native Windows

Authentication type

Not authentication-related

[github-actions]

🤖 Automated triage

• Bot assessment: High impact
• Priority: P1-high
• Why: Native Windows users are blocked from selecting home-directory workspaces in the picker and sessions fall back to C:, with no practical workaround through the affected UI.

This automated assessment uses the issue content and repository signals. Maintainers can override the priority label.

[hellocybernetics]

The implementation for this issue is #5375. #5369 was opened earlier and then closed; please ignore it.