Claude Desktop MSIX updates on Windows Server cause session data loss + EXDEV save errors

Environment

• OS: Windows Server 2025 Standard 10.0.26100
• Claude Desktop: MSIX package, current version Claude_1.569.0.0_x64__pzs8sxrjxfjjc
• Update URL: https://api.anthropic.com/api/desktop/win32/x64/msix/update

Bug Description

Two related issues causing complete loss of conversation history on Windows Server:

1. MSIX Update removes all session data

Each Claude Desktop MSIX update follows a Remove+Add pattern (visible in AppX deployment logs). This wipes the .claude directory contents including sessions/ and projects/ session files. The %APPDATA%\Claude\ directory is also reset (creation date matches last update: March 31).

Update history from deployment logs:

• Mar 29: Register 1.1.9493.0
• Mar 31: Add 1.1.9669.0 → Remove 1.1.9669.0 → Stage+Add 1.1.9669.0
• Apr 01: Add 1.2.234.0
• Apr 03: Add 1.569.0.0

2. EXDEV: cross-device link not permitted - Session save continuously fails

Even between updates, session saving fails with EXDEV error. The app writes a .tmp file and tries to rename() it to the final location, but the MSIX virtualized filesystem causes a cross-device link error.

From main.log:

Failed to save session local_xxx: EXDEV: cross-device link not permitted, rename 
'C:\Users\...\AppData\Roaming\Claude\claude-code-sessions\...\local_xxx.json.tmp' 
-> 'C:\Users\...\AppData\Roaming\Claude\claude-code-sessions\...\local_xxx.json'

This error repeats for every session save attempt, and also affects SkillsPlugin downloads (pdf, docx, xlsx, pptx, skill-creator all fail to download).

3. Additional issues

• CoworkVMService fails with "signature verification initialization failed: failed to get service executable path" after updates
• Stale WindowsApps\Deleted\Claude_1.1.9669.0* folder fails to clean up repeatedly
• MoAppHang events frequent (crash reports reference old version 1.1.8629.0 vs installed 1.569.0.0)

Expected Behavior

• Session data should survive MSIX updates
• rename() should use copyFile+unlink fallback when EXDEV is detected (common Node.js pattern)
• The .claude user data directory should not be tied to the MSIX package lifecycle

Workaround

Using the Claude Code memory system (~/.claude/projects/.../memory/) to persist important context, as this directory survives better than session files.

Suggested Fix

For the EXDEV issue: replace fs.rename() with a cross-device-safe wrapper that catches EXDEV and falls back to fs.copyFile() + fs.unlink(). This is a well-known Node.js issue when source and destination are on different filesystems/volumes.