test: tighten core test mock fixtures

src/config/sessions/transcript-append-redact.test.ts

@@ -467,6 +467,7 @@ describe("appendExactAssistantMessageToSessionTranscript - redaction", () => {
           cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
         },
         stopReason: "stop",
+        timestamp: Date.now(),
       },
     });
     const deduped = await appendAssistantMessageToSessionTranscript({

src/flows/provider-flow.test.ts

@@ -49,7 +49,7 @@ let resolveProviderSetupFlowContributions: ResolveProviderSetupFlowContributions
 let resolveProviderModelPickerFlowContributions: ResolveProviderModelPickerFlowContributions;
 
 function requireFirstMockCall(mock: { mock: { calls: unknown[][] } }, label: string): unknown[] {
-  const call = mock.mock.calls.at(0);
+  const call = mock.mock.calls[0];
   if (!call) {
     throw new Error(`expected ${label} call`);
   }