feat(core,cli): enforce mandatory MessageBus injection (Phase 3 Hard Migration) (#15776)

packages/core/src/agents/subagent-tool-wrapper.ts

@@ -38,7 +38,7 @@ export class SubagentToolWrapper extends BaseDeclarativeTool<
   constructor(
     private readonly definition: AgentDefinition,
     private readonly config: Config,
-    messageBus?: MessageBus,
+    messageBus: MessageBus,
   ) {
     const parameterSchema = convertInputConfigToJsonSchema(
       definition.inputConfig,
@@ -50,9 +50,9 @@ export class SubagentToolWrapper extends BaseDeclarativeTool<
       definition.description,
       Kind.Think,
       parameterSchema,
+      messageBus,
       /* isOutputMarkdown */ true,
       /* canUpdateOutput */ true,
-      messageBus,
     );
   }
 
@@ -67,12 +67,12 @@ export class SubagentToolWrapper extends BaseDeclarativeTool<
    */
   protected createInvocation(
     params: AgentInputs,
-    messageBus?: MessageBus,
+    messageBus: MessageBus,
     _toolName?: string,
     _toolDisplayName?: string,
   ): ToolInvocation<AgentInputs, ToolResult> {
     const definition = this.definition;
-    const effectiveMessageBus = messageBus ?? this.messageBus;
+    const effectiveMessageBus = messageBus;
 
     if (definition.kind === 'remote') {
       return new RemoteAgentInvocation(