Today we seem to collect the launch.json from the single root workspace here: https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/parts/debug/electron-browser/debugConfigurationManager.ts#L345

In a multi root environment we need to change this assumption. There are a couple of options:

• just take the first folders configuration and show the others from a picker (e.g. add a "More..." command to the debug dropdown which opens a picker)
• track the active file and then use that files workspace as default when checking for the config file (there is IHistoryService.getLastActiveWorkspaceRoot() to help out)
• just treat all folders the same and collect configs from all folders and merge them into one list