diff --git a/tests/ocl/ocl-background-resilience.test.js b/tests/ocl/ocl-background-resilience.test.js
new file mode 100644
index 00000000..a709cfa9
--- /dev/null
+++ b/tests/ocl/ocl-background-resilience.test.js
@@ -0,0 +1,192 @@
+const nock = require('nock');
+const { OCLBackgroundJobQueue } = require('../../tx/ocl/cs-ocl');
+const path = require('path');
+
+function resetQueueState() {
+  OCLBackgroundJobQueue.pendingJobs = [];
+  OCLBackgroundJobQueue.activeCount = 0;
+  OCLBackgroundJobQueue.queuedOrRunningKeys = new Set();
+  OCLBackgroundJobQueue.activeJobs = new Map();
+  OCLBackgroundJobQueue.enqueueSequence = 0;
+  if (OCLBackgroundJobQueue.heartbeatTimer) {
+    clearInterval(OCLBackgroundJobQueue.heartbeatTimer);
+    OCLBackgroundJobQueue.heartbeatTimer = null;
+  }
+}
+
+describe('OCL Background Job Resilience', () => {
+  const baseUrl = 'https://ocl.resilience.test';
+  const conceptsUrl = '/orgs/org-a/sources/src1/concepts/';
+  const meta = {
+    id: 'src1',
+    canonicalUrl: 'http://example.org/cs/source-one',
+    version: '1.0.0',
+    name: 'Source One',
+    checksum: 'meta-1',
+    conceptsUrl: `${baseUrl}${conceptsUrl}`,
+    codeSystem: { jsonObj: { content: 'not-present' } }
+  };
+  // Instância real de I18nSupport para testes
+  const { I18nSupport } = require('../../library/i18nsupport');
+  const { LanguageDefinitions } = require('../../library/languages');
+  const translationsPath = path.resolve(__dirname, '../../translations');
+  const i18n = new I18nSupport(translationsPath, new LanguageDefinitions());
+
+  beforeEach(() => {
+    nock.cleanAll();
+    resetQueueState();
+  });
+
+  afterEach(() => {
+    nock.cleanAll();
+    jest.restoreAllMocks();
+  });
+
+  test('OCL API hard offline (connection refused) via job queue', async () => {
+    nock(baseUrl)
+      .get(conceptsUrl)
+      .query(true)
+      .replyWithError({ code: 'ECONNREFUSED', message: 'Connection refused' });
+
+    const factory = new (require('../../tx/ocl/cs-ocl').OCLSourceCodeSystemFactory)(i18n, require('axios').create({ baseURL: baseUrl }), meta);
+    let jobFailed = false;
+    await new Promise((resolve) => {
+      OCLBackgroundJobQueue.enqueue(
+        'test:offline',
+        'Test offline',
+        async () => {
+          await factory.httpClient.get(conceptsUrl);
+        }
+      );
+      setTimeout(() => resolve(), 1500);
+      const origError = console.error;
+      console.error = (...args) => {
+        if (String(args[0]).includes('Background job failed')) jobFailed = true;
+        origError(...args);
+      };
+    });
+    expect(jobFailed).toBe(true);
+    expect(OCLBackgroundJobQueue.activeCount).toBe(0);
+  });
+
+  test('OCL API hangs (timeout) via job queue', async () => {
+    nock(baseUrl)
+      .get(conceptsUrl)
+      .query(true)
+      .delayConnection(2000)
+      .reply(200, { results: [] });
+
+    const factory = new (require('../../tx/ocl/cs-ocl').OCLSourceCodeSystemFactory)(i18n, require('axios').create({ baseURL: baseUrl, timeout: 1000 }), meta);
+    let jobFailed = false;
+    await new Promise((resolve) => {
+      OCLBackgroundJobQueue.enqueue(
+        'test:hang',
+        'Test hang',
+        async () => {
+          await factory.httpClient.get(conceptsUrl);
+        }
+      );
+      setTimeout(() => resolve(), 2500);
+      const origError = console.error;
+      console.error = (...args) => {
+        if (String(args[0]).includes('Background job failed')) jobFailed = true;
+        origError(...args);
+      };
+    });
+    expect(jobFailed).toBe(true);
+    expect(OCLBackgroundJobQueue.activeCount).toBe(0);
+  });
+
+  test('OCL API returns 500 repeatedly via job queue', async () => {
+    nock(baseUrl)
+      .get(conceptsUrl)
+      .query(true)
+      .times(2)
+      .reply(500, 'Internal Server Error');
+
+    const factory = new (require('../../tx/ocl/cs-ocl').OCLSourceCodeSystemFactory)(i18n, require('axios').create({ baseURL: baseUrl }), meta);
+    let jobFailed = false;
+    await new Promise((resolve) => {
+      OCLBackgroundJobQueue.enqueue(
+        'test:500',
+        'Test 500',
+        async () => {
+          await factory.httpClient.get(conceptsUrl);
+        }
+      );
+      setTimeout(() => resolve(), 1500);
+      const origError = console.error;
+      console.error = (...args) => {
+        if (String(args[0]).includes('Background job failed')) jobFailed = true;
+        origError(...args);
+      };
+    });
+    expect(jobFailed).toBe(true);
+    expect(OCLBackgroundJobQueue.activeCount).toBe(0);
+  });
+
+  test('OCL API returns malformed payload via job queue', async () => {
+    nock(baseUrl)
+      .get(conceptsUrl)
+      .query(true)
+      .reply(200, 'not-json');
+
+    const factory = new (require('../../tx/ocl/cs-ocl').OCLSourceCodeSystemFactory)(i18n, require('axios').create({ baseURL: baseUrl }), meta);
+    let jobFailed = false;
+    await new Promise((resolve) => {
+      OCLBackgroundJobQueue.enqueue(
+        'test:malformed',
+        'Test malformed',
+        async () => {
+          // Aciona o fluxo real de parsing/validação
+          await factory.listCodeSystems('5.0', null);
+        }
+      );
+      setTimeout(() => resolve(), 1500);
+      const origError = console.error;
+      console.error = (...args) => {
+        if (String(args[0]).includes('Background job failed')) jobFailed = true;
+        origError(...args);
+      };
+    });
+    expect(jobFailed).toBe(true);
+    expect(OCLBackgroundJobQueue.activeCount).toBe(0);
+  });
+
+  test('Multiple failures in sequence do not block queue', async () => {
+    nock(baseUrl)
+      .get(conceptsUrl)
+      .query(true)
+      .times(2)
+      .reply(500, 'Internal Server Error');
+
+    const factory = new (require('../../tx/ocl/cs-ocl').OCLSourceCodeSystemFactory)(i18n, require('axios').create({ baseURL: baseUrl }), meta);
+    let jobFailedCount = 0;
+    await new Promise((resolve) => {
+      OCLBackgroundJobQueue.enqueue(
+        'test:fail1',
+        'Test fail1',
+        async () => {
+          await factory.httpClient.get(conceptsUrl);
+        }
+      );
+      OCLBackgroundJobQueue.enqueue(
+        'test:fail2',
+        'Test fail2',
+        async () => {
+          await factory.httpClient.get(conceptsUrl);
+        }
+      );
+      setTimeout(() => resolve(), 2000);
+      const origError = console.error;
+      console.error = (...args) => {
+        if (String(args[0]).includes('Background job failed')) jobFailedCount++;
+        origError(...args);
+      };
+    });
+    expect(jobFailedCount).toBe(2);
+    expect(OCLBackgroundJobQueue.activeCount).toBe(0);
+  });
+
+  // Add more tests for partial/truncated response, recovery after outage, etc.
+});
diff --git a/tx/ocl/cs-ocl.cjs b/tx/ocl/cs-ocl.cjs
index 75afab31..2fb88e12 100644
--- a/tx/ocl/cs-ocl.cjs
+++ b/tx/ocl/cs-ocl.cjs
@@ -531,12 +531,17 @@ class OCLCodeSystemProvider extends AbstractCodeSystemProvider {
 
   async #fetchAllPages(path) {
     try {
-      return await fetchAllPages(this.httpClient, path, {
+      const result = await fetchAllPages(this.httpClient, path, {
         pageSize: PAGE_SIZE,
         baseUrl: this.baseUrl,
         logger: console,
         loggerPrefix: '[OCL]'
       });
+      // Verificação extra: payload deve ser objeto ou array
+      if (!result || (typeof result !== 'object' && !Array.isArray(result))) {
+        throw new Error('[OCL] Invalid response format: expected object or array');
+      }
+      return result;
     } catch (error) {
       if (error.response) {
         console.error(`[OCL] HTTP ${error.response.status}: ${error.response.statusText}`);