feat: add app-owned Copilot and Grok subscription connections

src/agent/subagents/pi-run.ts

@@ -2,6 +2,7 @@ import { Agent, type AgentEvent, type AgentMessage, type AgentTool } from "@eare
 import type { AssistantMessage, ToolResultMessage, Usage } from "@earendil-works/pi-ai";
 import { randomUUID } from "node:crypto";
 import { APP_IDENTITY, piEngineFor, type PiEngine } from "../models.ts";
+import { usageWasAdmitted } from "../subscription-request-cycle.ts";
 import { providerEventObserver } from "../provider-events.ts";
 import type { ModelRole } from "../../../config.ts";
 
@@ -107,6 +108,7 @@ export async function runSubagent(tools: AgentTool<any, any>[], opts: SubagentRu
 								aborted = true;
 							break;
 						}
+						if (!usageWasAdmitted(m.usage)) { if (m.stopReason === "error") errorMessage = m.errorMessage; break; }
 						step++;
 						opts.onUsage?.(m.usage);
 						opts.onAssistantMessage?.(m, step);