fix(coding-agent): emit session name changes to extensions

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

@@ -2683,7 +2683,9 @@ export class AgentSession {
 	 */
 	setSessionName(name: string): void {
 		this.sessionManager.appendSessionInfo(name);
-		this._emit({ type: "session_info_changed", name: this.sessionManager.getSessionName() });
+		const event = { type: "session_info_changed", name: this.sessionManager.getSessionName() } as const;
+		this._emit(event);
+		void this._extensionRunner.emit(event);
 	}
 
 	// =========================================================================

packages/coding-agent/src/core/extensions/index.ts

@@ -128,6 +128,7 @@ export type {
 	SessionBeforeTreeResult,
 	SessionCompactEvent,
 	SessionEvent,
+	SessionInfoChangedEvent,
 	SessionShutdownEvent,
 	// Events - Session
 	SessionStartEvent,

packages/coding-agent/src/core/extensions/types.ts

@@ -551,6 +551,13 @@ export interface SessionStartEvent {
 	previousSessionFile?: string;
 }
 
+/** Fired when the current session metadata changes. */
+export interface SessionInfoChangedEvent {
+	type: "session_info_changed";
+	/** Current normalized session name. Undefined when the name is cleared. */
+	name: string | undefined;
+}
+
 /** Fired before switching to another session (can be cancelled) */
 export interface SessionBeforeSwitchEvent {
 	type: "session_before_switch";
@@ -630,6 +637,7 @@ export interface SessionTreeEvent {
 
 export type SessionEvent =
 	| SessionStartEvent
+	| SessionInfoChangedEvent
 	| SessionBeforeSwitchEvent
 	| SessionBeforeForkEvent
 	| SessionBeforeCompactEvent
@@ -1133,6 +1141,7 @@ export interface ExtensionAPI {
 	on(event: "project_trust", handler: ProjectTrustHandler): void;
 	on(event: "resources_discover", handler: ExtensionHandler<ResourcesDiscoverEvent, ResourcesDiscoverResult>): void;
 	on(event: "session_start", handler: ExtensionHandler<SessionStartEvent>): void;
+	on(event: "session_info_changed", handler: ExtensionHandler<SessionInfoChangedEvent>): void;
 	on(
 		event: "session_before_switch",
 		handler: ExtensionHandler<SessionBeforeSwitchEvent, SessionBeforeSwitchResult>,

packages/coding-agent/src/index.ts

@@ -122,6 +122,7 @@ export type {
 	SessionBeforeSwitchEvent,
 	SessionBeforeTreeEvent,
 	SessionCompactEvent,
+	SessionInfoChangedEvent,
 	SessionShutdownEvent,
 	SessionStartEvent,
 	SessionTreeEvent,