Debug Protocol: support for launching debuggee in VS Code terminal

[weinand]

[daviwil]

Ohhhh, nice! This might be interesting for PowerShell.

[weinand]

I've added the first 'reverse request' to the protocol. A debug adapter can now launch a runtime or debug target in VS Code's integrated terminal.

This is the runInTerminalRequest in the protocol:

    /** runInTerminal request; value of command field is "runInTerminal".
        With this request a debug adapter can run a command in a terminal.
    */
    export interface RunInTerminalRequest extends Request {
        arguments: RunInTerminalRequestArguments;
    }
    /** Arguments for "runInTerminal" request. */
    export interface RunInTerminalRequestArguments {
        /** What kind of terminal to launch. */
        kind?: 'integrated' | 'external';
        /** Optional title of the terminal. */
        title?: string;
        /** Working directory of the command. */
        cwd: string;
        /** List of arguments. The first argument is the command to run. */
        args: string[];
        /** Environment key-value pairs that are added to the default environment. */
        env?: { [key: string]: string; }
    }
    /** Response to Initialize request. */
    export interface RunInTerminalResponse extends Response {
        body: {
            /** The process ID */
            processId?: number;
        };
    }

The debug adapter should only use the runInTerminalRequest if the attribute supportsRunInTerminalRequest is true in the initializeRequest:

    /** Client supports the runInTerminal request. */
    supportsRunInTerminalRequest?: boolean;

[daviwil]

This is really interesting, might have an application for the long-running debug session idea we talked about some time ago. Scenario:

1. PowerShell extension uses the new debug launcher API to launch the long-running debug configuration
2. My TypeScript-based debug adapter code immediately sends the RunInTerminalRequest so that my language/debug server process gets launched in the integrated terminal
3. The PowerShell extension connects to the language server running in that application
4. User now has a fully integrated development/debugging session and can run debug commands, etc directly through the integrated terminal using the native PowerShell console host

What do you think?

One question: if we did manage to start this long-running debug session, is there any way we could get a flag to make the status bar not be orange all the time? I know that sort of breaks the original UX of running in the debugger, but I think it might be a little annoying to the user if it looks like they're perpetually in the debug state.

/cc @rkeithhill