fix(coding-agent): add settled agent lifecycle event

closes #6363

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

@@ -22,6 +22,7 @@ export { ExtensionRunner } from "./runner.ts";
 export type {
 	AfterProviderResponseEvent,
 	AgentEndEvent,
+	AgentSettledEvent,
 	AgentStartEvent,
 	// Re-exports
 	AgentToolResult,

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

@@ -705,6 +705,11 @@ export interface AgentEndEvent {
 	messages: AgentMessage[];
 }
 
+/** Fired after an agent run has fully settled and no automatic retry, compaction, or queued continuation will run. */
+export interface AgentSettledEvent {
+	type: "agent_settled";
+}
+
 /** Fired at the start of each turn */
 export interface TurnStartEvent {
 	type: "turn_start";
@@ -1021,6 +1026,7 @@ export type ExtensionEvent =
 	| BeforeAgentStartEvent
 	| AgentStartEvent
 	| AgentEndEvent
+	| AgentSettledEvent
 	| TurnStartEvent
 	| TurnEndEvent
 	| MessageStartEvent
@@ -1188,6 +1194,7 @@ export interface ExtensionAPI {
 	on(event: "before_agent_start", handler: ExtensionHandler<BeforeAgentStartEvent, BeforeAgentStartEventResult>): void;
 	on(event: "agent_start", handler: ExtensionHandler<AgentStartEvent>): void;
 	on(event: "agent_end", handler: ExtensionHandler<AgentEndEvent>): void;
+	on(event: "agent_settled", handler: ExtensionHandler<AgentSettledEvent>): void;
 	on(event: "turn_start", handler: ExtensionHandler<TurnStartEvent>): void;
 	on(event: "turn_end", handler: ExtensionHandler<TurnEndEvent>): void;
 	on(event: "message_start", handler: ExtensionHandler<MessageStartEvent>): void;