fix(agent): stop tool preflight after extension abort

closes #4276

packages/coding-agent/src/core/agent-session.ts

@@ -185,6 +185,7 @@ export interface AgentSessionConfig {
 export interface ExtensionBindings {
 	uiContext?: ExtensionUIContext;
 	commandContextActions?: ExtensionCommandContextActions;
+	abortHandler?: () => void;
 	shutdownHandler?: ShutdownHandler;
 	onError?: ExtensionErrorListener;
 }
@@ -296,6 +297,7 @@ export class AgentSession {
 	private _sessionStartEvent: SessionStartEvent;
 	private _extensionUIContext?: ExtensionUIContext;
 	private _extensionCommandContextActions?: ExtensionCommandContextActions;
+	private _extensionAbortHandler?: () => void;
 	private _extensionShutdownHandler?: ShutdownHandler;
 	private _extensionErrorListener?: ExtensionErrorListener;
 	private _extensionErrorUnsubscriber?: () => void;
@@ -2042,6 +2044,9 @@ export class AgentSession {
 		if (bindings.commandContextActions !== undefined) {
 			this._extensionCommandContextActions = bindings.commandContextActions;
 		}
+		if (bindings.abortHandler !== undefined) {
+			this._extensionAbortHandler = bindings.abortHandler;
+		}
 		if (bindings.shutdownHandler !== undefined) {
 			this._extensionShutdownHandler = bindings.shutdownHandler;
 		}
@@ -2206,7 +2211,13 @@ export class AgentSession {
 				getModel: () => this.model,
 				isIdle: () => !this.isStreaming,
 				getSignal: () => this.agent.signal,
-				abort: () => this.abort(),
+				abort: () => {
+					if (this._extensionAbortHandler) {
+						this._extensionAbortHandler();
+						return;
+					}
+					void this.abort();
+				},
 				hasPendingMessages: () => this.pendingMessageCount > 0,
 				shutdown: () => {
 					this._extensionShutdownHandler?.();