fix(coding-agent): refresh thinking border from extensions

closes #3888

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

@@ -120,6 +120,7 @@ export type AgentSessionEvent =
 	  }
 	| { type: "compaction_start"; reason: "manual" | "threshold" | "overflow" }
 	| { type: "session_info_changed"; name: string | undefined }
+	| { type: "thinking_level_changed"; level: ThinkingLevel }
 	| {
 			type: "compaction_end";
 			reason: "manual" | "threshold" | "overflow";
@@ -1505,7 +1506,8 @@ export class AgentSession {
 		const effectiveLevel = availableLevels.includes(level) ? level : this._clampThinkingLevel(level, availableLevels);
 
 		// Only persist if actually changing
-		const isChanging = effectiveLevel !== this.agent.state.thinkingLevel;
+		const previousLevel = this.agent.state.thinkingLevel;
+		const isChanging = effectiveLevel !== previousLevel;
 
 		this.agent.state.thinkingLevel = effectiveLevel;
 
@@ -1514,6 +1516,12 @@ export class AgentSession {
 			if (this.supportsThinking() || effectiveLevel !== "off") {
 				this.settingsManager.setDefaultThinkingLevel(effectiveLevel);
 			}
+			this._emit({ type: "thinking_level_changed", level: effectiveLevel });
+			void this._extensionRunner.emit({
+				type: "thinking_level_select",
+				level: effectiveLevel,
+				previousLevel,
+			});
 		}
 	}
 

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

@@ -718,6 +718,13 @@ export interface ModelSelectEvent {
 	source: ModelSelectSource;
 }
 
+/** Fired when a new thinking level is selected */
+export interface ThinkingLevelSelectEvent {
+	type: "thinking_level_select";
+	level: ThinkingLevel;
+	previousLevel: ThinkingLevel;
+}
+
 // ============================================================================
 // User Bash Events
 // ============================================================================
@@ -958,6 +965,7 @@ export type ExtensionEvent =
 	| ToolExecutionUpdateEvent
 	| ToolExecutionEndEvent
 	| ModelSelectEvent
+	| ThinkingLevelSelectEvent
 	| UserBashEvent
 	| InputEvent
 	| ToolCallEvent
@@ -1111,6 +1119,7 @@ export interface ExtensionAPI {
 	on(event: "tool_execution_update", handler: ExtensionHandler<ToolExecutionUpdateEvent>): void;
 	on(event: "tool_execution_end", handler: ExtensionHandler<ToolExecutionEndEvent>): void;
 	on(event: "model_select", handler: ExtensionHandler<ModelSelectEvent>): void;
+	on(event: "thinking_level_select", handler: ExtensionHandler<ThinkingLevelSelectEvent>): void;
 	on(event: "tool_call", handler: ExtensionHandler<ToolCallEvent, ToolCallEventResult>): void;
 	on(event: "tool_result", handler: ExtensionHandler<ToolResultEvent, ToolResultEventResult>): void;
 	on(event: "user_bash", handler: ExtensionHandler<UserBashEvent, UserBashEventResult>): void;

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -2658,6 +2658,11 @@ export class InteractiveMode {
 				this.ui.requestRender();
 				break;
 
+			case "thinking_level_changed":
+				this.footer.invalidate();
+				this.updateEditorBorderColor();
+				break;
+
 			case "message_start":
 				if (event.message.role === "custom") {
 					this.addMessageToChat(event.message);