[BUG] claudeVSCodeSidebarSecondary fails to render in VS Code Remote SSH with ["ui"] extensionKind

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?

The Claude Code VS Code extension fails to render the sidebar view (claudeVSCodeSidebarSecondary) when connected to a Remote SSH host. The error "Ein Fehler ist aufgetreten beim Wiederherstellen der Ansicht: claudeVSCodeSidebarSecondary" (Error restoring view: claudeVSCodeSidebarSecondary) appears and the panel stays blank. This happens because the remote server CPU lacks AVX support, causing the native binary to crash (SIGILL) when running on the server — so the extension must run locally via extensionKind ["ui"]. Even with this workaround, the WebView cannot be rendered in the Remote SSH context.
<img width="427" height="274" alt="Image" src="https://github.com/user-attachments/assets/287ac677-4035-4a00-88ce-e13e27a6cefb" />

What Should Happen?

The Claude Code sidebar should render correctly when the extension is configured to run locally (extensionKind: ["ui"]) while connected to a Remote SSH workspace. Authentication works fine (OAuth tokens found in secure storage), and the extension works correctly in local workspaces — it should also work in Remote SSH workspaces.

Error Messages/Logs

VS Code Output panel (Claude VSCode):
[info] AuthManager initialized
[info] Claude code extension is now active?
[info] MCP Server running on port XXXXX (localhost only)
[info] Getting authentication status
[info] OAuth tokens found in secure storage

Error in sidebar:
"Ein Fehler ist aufgetreten beim Wiederherstellen der Ansicht: claudeVSCodeSidebarSecondary"
(Translation: "An error occurred while restoring the view: claudeVSCodeSidebarSecondary")
Root cause (when extension runs on server):
CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x5547C000000
Error: Claude Code process terminated by signal SIGILL

Steps to Reproduce

1. Connect to a remote Linux server via VS Code Remote SSH where the server CPU lacks AVX support
2. Install Claude Code extension — it crashes on the server (SIGILL / Bun AVX requirement)
3. To work around the crash, add to local settings.json:

{
"remote.extensionKind": { "anthropic.claude-code": ["ui"] },
"claudeCode.runLocally": true
}

1. Reload VS Code window
2. Open the Claude Code panel in the secondary sidebar
3. Result: blank panel with error "claudeVSCodeSidebarSecondary"

Note: Authentication works correctly (OAuth tokens found in secure storage).
Note: Claude Code works fine in local (non-SSH) VS Code windows.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.81

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Local machine: Mac Studio M4 Max, 36GB RAM, macOS Tahoe 26.3.1
Remote server: Linux x64, kernel 4.18.0, glibc 2.28
Server CPU: No AVX support (Bun v1.3.11 crashes with SIGILL on server)

The extension binary path when running locally:
/Users/urbanstudio/.vscode/extensions/anthropic.claude-code-2.1.81-darwin-arm64/resources/native-binary/claude

All remote development at urbanstudio is done via VS Code Remote SSH — local workspaces are not an option. The AVX limitation affects multiple servers/VMs, making this a blocking issue for the entire Remote SSH workflow.

Workaround attempted: setting extensionKind to ["ui"] forces the extension to run locally, which fixes the crash — but introduces the claudeVSCodeSidebarSecondary rendering failure.