test(agent-core-v2): strengthen recovery tests per review findings

Assert exact token_budget trigger values in the mixed-delta continuation
test, and cover the current-step abort guard separately from the
loop-signal abort case.

Author: elkaix

packages/agent-core-v2/test/agent/turnBudget/turnBudget.test.ts

@@ -130,7 +130,12 @@ describe('turnBudget plugin', () => {
 
     expect(result).toMatchObject({ type: 'completed' });
     expect(calls).toBe(5);
-    expect(retryOriginTriggers()).toHaveLength(4);
+    expect(retryOriginTriggers()).toEqual([
+      'token_budget',
+      'token_budget',
+      'token_budget',
+      'token_budget',
+    ]);
   });
 
   it('does not continue when the flag is off even with a budget configured', async () => {

packages/agent-core-v2/test/agent/turnRecovery/modelFallback.test.ts

@@ -172,7 +172,7 @@ describe('modelFallback plugin', () => {
     expect(ctx.get(IAgentProfileService).getModel()).toBe('mock-model');
   });
 
-  it('refuses to switch when the step is already aborted', async () => {
+  it('refuses to switch when the turn signal is already aborted', async () => {
     ctx = createTestAgent(
       fallbackFlags(),
       llmGenerateServices(async () => ({
@@ -214,4 +214,49 @@ describe('modelFallback plugin', () => {
     expect(switched).toBe(false);
     expect(ctx.get(IAgentProfileService).getModel()).toBe('mock-model');
   });
+
+  it('refuses to switch when only the current step is aborted', async () => {
+    ctx = createTestAgent(
+      fallbackFlags(),
+      llmGenerateServices(async () => ({
+        id: 'step-aborted',
+        message: {
+          role: 'assistant' as const,
+          content: [{ type: 'text' as const, text: 'ok' }],
+          toolCalls: [],
+        },
+        usage: emptyUsage(),
+        finishReason: 'completed' as const,
+        rawFinishReason: 'stop',
+      })),
+      { initialConfig: fallbackTestConfig() },
+    );
+
+    const stepController = new AbortController();
+    stepController.abort();
+    const stepStub: Step = {
+      id: 'step-1',
+      turnId: 1,
+      state: 'running',
+      signal: stepController.signal,
+      result: Promise.resolve({ type: 'cancelled', reason: new Error('cancelled') }),
+      cancel: () => false,
+    };
+    const context: LoopErrorContext = {
+      turnId: 1,
+      step: 1,
+      signal: new AbortController().signal,
+      currentStep: stepStub,
+      error: new APIConnectionError('terminated'),
+      failedDriver: new ContinuationStepRequest(),
+      retry: () => stepStub,
+    };
+
+    const switched = await ctx
+      .get(IAgentModelFallbackService)
+      .tryFallbackSwitch(context);
+
+    expect(switched).toBe(false);
+    expect(ctx.get(IAgentProfileService).getModel()).toBe('mock-model');
+  });
 });