MCP servers with workspace variables cannot be migrated to .mcp.json

Type of Bug

Bug

Description

The Migrate MCP Servers flow does not offer otherwise compatible workspace MCP servers when their .vscode/mcp.json configuration contains deterministic workspace or path variables.

Variables such as ${workspaceFolder}, ${workspaceFolderBasename}, ${cwd}, ${pathSeparator}, and their scoped or legacy aliases can be resolved without user interaction. The migration should replace them with concrete values before writing the workspace-root .mcp.json.

Steps to Reproduce

1. Enable chat.customizations.mcpServerMigration.enabled.

2. Open a trusted folder and create .vscode/mcp.json:

   {
     "servers": {
       "workspace-server": {
         "type": "stdio",
         "command": "${workspaceFolder}/server.js",
         "args": ["${workspaceFolderBasename}", "${pathSeparator}"]
       }
     }
   }
   

3. Start an Agent Host session for the folder.

4. Open Chat: Open Customizations and select Migrate MCP Servers.

Actual Behavior

workspace-server is excluded from migration because the source configuration contains variable interpolation.

Expected Behavior

The server is offered for migration. Migrating it removes the entry from .vscode/mcp.json and writes it to .mcp.json with the supported variables replaced by their concrete path, folder-name, or separator values. Variables requiring user interaction or potentially exposing secrets, such as ${input:...}, ${command:...}, and ${env:...}, remain excluded.

Simple Verification

1. Repeat the reproduction steps in a build containing #336822.
2. Verify workspace-server appears in Migrate MCP Servers.
3. Migrate it and confirm .mcp.json contains concrete values with no ${...} placeholders.
4. Confirm the original entry is removed from .vscode/mcp.json.
5. Add a server using ${env:NAME} and verify that server is not offered for migration.

Related

• Fix: #336822
• Test plan: #336823