diff --git a/apps/server/agent/lifecycle/controller.test.ts b/apps/server/agent/lifecycle/controller.test.ts
new file mode 100644
index 0000000..de7462b
--- /dev/null
+++ b/apps/server/agent/lifecycle/controller.test.ts
@@ -0,0 +1,154 @@
+/**
+ * AgentLifecycleController Tests — Regression coverage for event emissions.
+ */
+
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { AgentLifecycleController } from './controller.js';
+import type { AgentRepository } from '../../db/repositories/agent-repository.js';
+import type { AccountRepository } from '../../db/repositories/account-repository.js';
+import type { SignalManager } from './signal-manager.js';
+import type { RetryPolicy } from './retry-policy.js';
+import type { AgentErrorAnalyzer } from './error-analyzer.js';
+import type { ProcessManager } from '../process-manager.js';
+import type { CleanupManager } from '../cleanup-manager.js';
+import type { CleanupStrategy } from './cleanup-strategy.js';
+import type { EventBus, AgentAccountSwitchedEvent } from '../../events/types.js';
+
+function makeController(overrides: {
+  repository?: Partial<AgentRepository>;
+  accountRepository?: Partial<AccountRepository>;
+  eventBus?: EventBus;
+}): AgentLifecycleController {
+  const signalManager: SignalManager = {
+    clearSignal: vi.fn(),
+    checkSignalExists: vi.fn(),
+    readSignal: vi.fn(),
+    waitForSignal: vi.fn(),
+    validateSignalFile: vi.fn(),
+  };
+  const retryPolicy: RetryPolicy = {
+    maxAttempts: 3,
+    shouldRetry: vi.fn().mockReturnValue(false),
+    getRetryDelay: vi.fn().mockReturnValue(0),
+  };
+  const errorAnalyzer = { analyzeError: vi.fn() } as unknown as AgentErrorAnalyzer;
+  const processManager = { getAgentWorkdir: vi.fn() } as unknown as ProcessManager;
+  const cleanupManager = {} as unknown as CleanupManager;
+  const cleanupStrategy = {
+    shouldCleanup: vi.fn(),
+    executeCleanup: vi.fn(),
+  } as unknown as CleanupStrategy;
+
+  return new AgentLifecycleController(
+    signalManager,
+    retryPolicy,
+    errorAnalyzer,
+    processManager,
+    overrides.repository as AgentRepository,
+    cleanupManager,
+    cleanupStrategy,
+    overrides.accountRepository as AccountRepository | undefined,
+    false,
+    overrides.eventBus,
+  );
+}
+
+describe('AgentLifecycleController', () => {
+  describe('handleAccountExhaustion', () => {
+    it('emits agent:account_switched with correct payload when new account is available', async () => {
+      const emittedEvents: AgentAccountSwitchedEvent[] = [];
+      const eventBus: EventBus = {
+        emit: vi.fn((event) => { emittedEvents.push(event as AgentAccountSwitchedEvent); }),
+        on: vi.fn(),
+        off: vi.fn(),
+        once: vi.fn(),
+      };
+
+      const agentRecord = {
+        id: 'agent-1',
+        name: 'test-agent',
+        accountId: 'old-account-id',
+        provider: 'claude',
+      };
+      const newAccount = { id: 'new-account-id' };
+
+      const repository: Partial<AgentRepository> = {
+        findById: vi.fn().mockResolvedValue(agentRecord),
+      };
+      const accountRepository: Partial<AccountRepository> = {
+        markExhausted: vi.fn().mockResolvedValue(agentRecord),
+        findNextAvailable: vi.fn().mockResolvedValue(newAccount),
+      };
+
+      const controller = makeController({ repository, accountRepository, eventBus });
+
+      // Call private method via any-cast
+      await (controller as any).handleAccountExhaustion('agent-1');
+
+      const accountSwitchedEvents = emittedEvents.filter(
+        (e) => e.type === 'agent:account_switched'
+      );
+      expect(accountSwitchedEvents).toHaveLength(1);
+      const event = accountSwitchedEvents[0];
+      expect(event.type).toBe('agent:account_switched');
+      expect(event.payload.agentId).toBe('agent-1');
+      expect(event.payload.name).toBe('test-agent');
+      expect(event.payload.previousAccountId).toBe('old-account-id');
+      expect(event.payload.newAccountId).toBe('new-account-id');
+      expect(event.payload.reason).toBe('account_exhausted');
+    });
+
+    it('does not emit agent:account_switched when no new account is available', async () => {
+      const eventBus: EventBus = {
+        emit: vi.fn(),
+        on: vi.fn(),
+        off: vi.fn(),
+        once: vi.fn(),
+      };
+
+      const agentRecord = {
+        id: 'agent-2',
+        name: 'test-agent-2',
+        accountId: 'old-account-id',
+        provider: 'claude',
+      };
+
+      const repository: Partial<AgentRepository> = {
+        findById: vi.fn().mockResolvedValue(agentRecord),
+      };
+      const accountRepository: Partial<AccountRepository> = {
+        markExhausted: vi.fn().mockResolvedValue(agentRecord),
+        findNextAvailable: vi.fn().mockResolvedValue(null),
+      };
+
+      const controller = makeController({ repository, accountRepository, eventBus });
+
+      await (controller as any).handleAccountExhaustion('agent-2');
+
+      expect(eventBus.emit).not.toHaveBeenCalled();
+    });
+
+    it('does not emit when agent has no accountId', async () => {
+      const eventBus: EventBus = {
+        emit: vi.fn(),
+        on: vi.fn(),
+        off: vi.fn(),
+        once: vi.fn(),
+      };
+
+      const repository: Partial<AgentRepository> = {
+        findById: vi.fn().mockResolvedValue({ id: 'agent-3', name: 'x', accountId: null }),
+      };
+      const accountRepository: Partial<AccountRepository> = {
+        markExhausted: vi.fn(),
+        findNextAvailable: vi.fn(),
+      };
+
+      const controller = makeController({ repository, accountRepository, eventBus });
+
+      await (controller as any).handleAccountExhaustion('agent-3');
+
+      expect(eventBus.emit).not.toHaveBeenCalled();
+    });
+  });
+});