fix: inherit the compound root for all children of debug sessions

Fixes https://github.com/microsoft/vscode/issues/103705

src/vs/workbench/api/browser/mainThreadDebugService.ts

@@ -228,11 +228,13 @@ export class MainThreadDebugService implements MainThreadDebugServiceShape, IDeb
 	public $startDebugging(folder: UriComponents | undefined, nameOrConfig: string | IDebugConfiguration, options: IStartDebuggingOptions): Promise<boolean> {
 		const folderUri = folder ? uri.revive(folder) : undefined;
 		const launch = this.debugService.getConfigurationManager().getLaunch(folderUri);
+		const parentSession = this.getSession(options.parentSessionID);
 		const debugOptions: IDebugSessionOptions = {
 			noDebug: options.noDebug,
-			parentSession: this.getSession(options.parentSessionID),
+			parentSession,
 			repl: options.repl,
-			compact: options.compact
+			compact: options.compact,
+			compoundRoot: parentSession?.compoundRoot
 		};
 		return this.debugService.startDebugging(launch, nameOrConfig, debugOptions).then(success => {
 			return success;

src/vs/workbench/contrib/debug/browser/debugSession.ts

@@ -36,6 +36,7 @@ import { ILifecycleService } from 'vs/platform/lifecycle/common/lifecycle';
 import { localize } from 'vs/nls';
 import { canceled } from 'vs/base/common/errors';
 import { filterExceptionsFromTelemetry } from 'vs/workbench/contrib/debug/common/debugUtils';
+import { DebugCompoundRoot } from 'vs/workbench/contrib/debug/common/debugCompoundRoot';
 
 export class DebugSession implements IDebugSession {
 
@@ -133,6 +134,10 @@ export class DebugSession implements IDebugSession {
 		return !!this._options.compact;
 	}
 
+	get compoundRoot(): DebugCompoundRoot | undefined {
+		return this._options.compoundRoot;
+	}
+
 	setConfiguration(configuration: { resolved: IConfig, unresolved: IConfig | undefined }) {
 		this._configuration = configuration;
 	}

src/vs/workbench/contrib/debug/common/debug.ts

@@ -169,6 +169,7 @@ export interface IDebugSession extends ITreeElement {
 	readonly parentSession: IDebugSession | undefined;
 	readonly subId: string | undefined;
 	readonly compact: boolean;
+	readonly compoundRoot: DebugCompoundRoot | undefined;
 
 	setSubId(subId: string | undefined): void;
 

src/vs/workbench/contrib/debug/test/common/mockDebug.ts

@@ -13,6 +13,7 @@ import Severity from 'vs/base/common/severity';
 import { AbstractDebugAdapter } from 'vs/workbench/contrib/debug/common/abstractDebugAdapter';
 import { DebugStorage } from 'vs/workbench/contrib/debug/common/debugStorage';
 import { ExceptionBreakpoint, Expression, DataBreakpoint, FunctionBreakpoint, Breakpoint, DebugModel } from 'vs/workbench/contrib/debug/common/debugModel';
+import { DebugCompoundRoot } from 'vs/workbench/contrib/debug/common/debugCompoundRoot';
 
 export class MockDebugService implements IDebugService {
 
@@ -135,6 +136,10 @@ export class MockDebugService implements IDebugService {
 }
 
 export class MockSession implements IDebugSession {
+	get compoundRoot(): DebugCompoundRoot | undefined {
+		return undefined;
+	}
+
 	stepInTargets(frameId: number): Promise<{ id: number; label: string; }[]> {
 		throw new Error('Method not implemented.');
 	}