Debug API

[isidorn]

We are looking into adding debug API to our vscode.d.ts. In order to design this as best as possible let's first look at the use cases and the current use of commands.

Use Cases

• Debug session end event Introduce a debugSessionEnds event  #28234
• Node internal modules navigator

Commands

Extension --> VS Code

• vscode.startDebug - extension can start a debug session by calling this command
• customDebugRequest - extension can send any DAP request to the currently active debug adapter
• debug.logToDebugConsole - extension can log a string to the debug console

VS Code --> Extension

• startSessionCommand - if contributed vscode calls this command instead of starting a debug session on its own
• initialConfigurations - if contributed vscode calls this command to get the initial content of the launch.json

Proposal

Minimal API proposal by @weinand and me. If name and type should be a part of DebugSession is very coraleted to the question @weinand raises below.

export namespace debug {
  export const onDidEndDebugSession: Event<DebugSession>;
}

export interface DebugSession {
   readonly name: string;
   readonly type: string;
   customRequest(requestName: string, args: any): Thenable<DebugRequestResult>;
}

[weinand]

One interesting question is: can a debugger extension only see the debug sessions that have the type introduced by the debugger extension or can it see all debug sessions of all types?

[DanTup]

I'd like to be able to report status messages from the debug adapter back to the extension so that I can show text in the status bar. There are some things that would be really spammy to log to the debug output window (for example, I think in full-VS it shows in the status bar every DLL symbols are being loaded for during debugging?).

If status messages is a common requirement, maybe something like an additional channel for OutputEvent (eg. status) would work, though being able to send complete custom messages (similar to customDebugRequest but in the opposite direction) would be ideal, since an extension/debugger than have complete two-way communication (something some debug adapters have apparently implemented themselves by hosting endpoints and connecting back).

[isidorn]

@DanTup thanks for the suggestion however we are taking this one step at a time, currently we are looking into what is the minimal set of APIs to make this good.
We will probably be focusing more on feature requests from next milestone onward

[DanTup]

@isidorn No worries; I figured it was worth you having the info even if you don't do anything with it for now (never hurts to have an idea of what people might want). My request is pretty minor tbh, the debugger just provides this info so I thought I'd look whether I could surface it anywhere.

[isidorn]

We have introduced an initial API, more details #28234 (comment)
@weinand should we close this issue, or leave it open as an umbrella item for future discussion regarding the debug API?

[weinand]

We leave this open as the umbrella item for future discussions.