VSCode Extension v2.1.141: 'Unhandled case: [object Object]' notification with no actionable details

Bug

VSCode extension shows a persistent error notification reading Unhandled case: [object Object] with links to View output logs · Troubleshooting resources. The error object is not being stringified, leaving no diagnosable info in the UI.

Environment

• Extension: anthropic.claude-code v2.1.141 (darwin-arm64)
• VS Code: latest stable
• macOS: Darwin 25.4.0
• Node: v24.3.0

Suspected trigger (from extension output log)

On startup, the embedded claude-vscode MCP server (port 50612) returns JSON-RPC -32601 Method not found to tools/list:

13:18:55.776 [DEBUG] MCP server "claude-vscode": tools/list failed (MCP error -32601: Method not found); retrying once
13:18:55.777 [ERROR] MCP server "claude-vscode" Failed to fetch tools: MCP error -32601: Method not found

The error object appears to propagate to a webview render path that lacks a case for this shape, surfacing as the generic Unhandled case: [object Object] notification.

Reproduction

Open VS Code with Claude Code extension installed. Banner appears within seconds of launch and persists across sessions.

Suggested fix

1. Implement tools/list on the internal claude-vscode MCP server, OR
2. Handle -32601 silently if the server isn't expected to expose tools, OR
3. At minimum, stringify the error properly so the notification surfaces a real message.

Side observation (separate noise, not the trigger)

HTTP-typed MCP servers configured with X-API-KEY headers (no OAuth) still get an auth provider attached, producing once-per-second No token data found DEBUG entries. Cosmetic but log-noisy.