diff --git a/autobot-frontend/tests/e2e/kb-librarian-api.spec.ts b/autobot-frontend/tests/e2e/kb-librarian-api.spec.ts
new file mode 100644
index 000000000..3179b70cc
--- /dev/null
+++ b/autobot-frontend/tests/e2e/kb-librarian-api.spec.ts
@@ -0,0 +1,182 @@
+// AutoBot - AI-Powered Automation Platform
+// Copyright (c) 2025 mrveiss
+// Author: mrveiss
+/**
+ * E2E tests for the KB Librarian HTTP surface.
+ *
+ * Covers the three endpoints registered at /api/kb-librarian (issue #3402):
+ *   GET  /api/kb-librarian/status    — agent singleton runtime config
+ *   POST /api/kb-librarian/query     — intent-detect + similarity search + summarise
+ *   PUT  /api/kb-librarian/configure — update agent runtime parameters
+ *
+ * Auth: all three endpoints require a valid bearer token.  Tests that omit
+ * a token verify that the backend returns 401/403.
+ */
+
+import { test, expect } from '@playwright/test';
+import { TEST_CONFIG } from './config';
+
+test.describe('KB Librarian API', () => {
+  // ---------------------------------------------------------------------------
+  // GET /api/kb-librarian/status
+  // ---------------------------------------------------------------------------
+  test.describe('GET /api/kb-librarian/status', () => {
+    test('returns 401 when no auth token is provided', async ({ request }) => {
+      const response = await request.get(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/status'),
+      );
+      expect([401, 403]).toContain(response.status());
+    });
+
+    test('returns agent runtime config when authenticated', async ({ request }) => {
+      // Skip if no test token is configured — auth smoke test above is sufficient
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set — skipping authenticated status test');
+
+      const response = await request.get(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/status'),
+        { headers: { Authorization: `Bearer ${token}` } },
+      );
+      expect(response.status()).toBe(200);
+
+      const body = await response.json();
+      expect(typeof body.enabled).toBe('boolean');
+      expect(typeof body.similarity_threshold).toBe('number');
+      expect(typeof body.max_results).toBe('number');
+      expect(typeof body.auto_summarize).toBe('boolean');
+      expect(typeof body.knowledge_base_active).toBe('boolean');
+    });
+  });
+
+  // ---------------------------------------------------------------------------
+  // POST /api/kb-librarian/query
+  // ---------------------------------------------------------------------------
+  test.describe('POST /api/kb-librarian/query', () => {
+    test('returns 401 when no auth token is provided', async ({ request }) => {
+      const response = await request.post(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/query'),
+        { data: { query: 'What is machine learning?' } },
+      );
+      expect([401, 403]).toContain(response.status());
+    });
+
+    test('returns 422 when query field is missing', async ({ request }) => {
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set');
+
+      const response = await request.post(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/query'),
+        {
+          headers: { Authorization: `Bearer ${token}` },
+          data: {},
+        },
+      );
+      expect(response.status()).toBe(422);
+    });
+
+    test('returns structured response for a valid query', async ({ request }) => {
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set');
+
+      const response = await request.post(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/query'),
+        {
+          headers: { Authorization: `Bearer ${token}` },
+          data: { query: 'What is AutoBot?' },
+        },
+      );
+      expect(response.status()).toBe(200);
+
+      const body = await response.json();
+      expect(typeof body.enabled).toBe('boolean');
+      expect(typeof body.is_question).toBe('boolean');
+      expect(typeof body.query).toBe('string');
+      expect(typeof body.documents_found).toBe('number');
+      expect(Array.isArray(body.documents)).toBe(true);
+    });
+
+    test('accepts per-request parameter overrides', async ({ request }) => {
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set');
+
+      const response = await request.post(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/query'),
+        {
+          headers: { Authorization: `Bearer ${token}` },
+          data: {
+            query: 'How does the knowledge base work?',
+            max_results: 3,
+            similarity_threshold: 0.8,
+            auto_summarize: false,
+          },
+        },
+      );
+      expect(response.status()).toBe(200);
+
+      const body = await response.json();
+      // auto_summarize was false so summary should be absent or null
+      expect(body.summary == null || body.summary === undefined).toBeTruthy();
+    });
+  });
+
+  // ---------------------------------------------------------------------------
+  // PUT /api/kb-librarian/configure
+  // ---------------------------------------------------------------------------
+  test.describe('PUT /api/kb-librarian/configure', () => {
+    test('returns 401 when no auth token is provided', async ({ request }) => {
+      const response = await request.put(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/configure'),
+        { data: { enabled: true } },
+      );
+      expect([401, 403]).toContain(response.status());
+    });
+
+    test('returns 400 when similarity_threshold is out of range', async ({ request }) => {
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set');
+
+      const response = await request.put(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/configure'),
+        {
+          headers: { Authorization: `Bearer ${token}` },
+          // similarity_threshold must be 0.0–1.0; 1.5 is invalid
+          params: { similarity_threshold: '1.5' },
+        },
+      );
+      expect(response.status()).toBe(400);
+    });
+
+    test('returns 400 when max_results is less than 1', async ({ request }) => {
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set');
+
+      const response = await request.put(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/configure'),
+        {
+          headers: { Authorization: `Bearer ${token}` },
+          params: { max_results: '0' },
+        },
+      );
+      expect(response.status()).toBe(400);
+    });
+
+    test('updates agent config and echoes new values', async ({ request }) => {
+      const token = process.env.E2E_AUTH_TOKEN;
+      test.skip(!token, 'E2E_AUTH_TOKEN not set');
+
+      const response = await request.put(
+        TEST_CONFIG.getApiUrl('/api/kb-librarian/configure'),
+        {
+          headers: { Authorization: `Bearer ${token}` },
+          params: { max_results: '7', similarity_threshold: '0.65' },
+        },
+      );
+      expect(response.status()).toBe(200);
+
+      const body = await response.json();
+      expect(body.message).toBe('KB Librarian configuration updated');
+      expect(body.max_results).toBe(7);
+      expect(body.similarity_threshold).toBeCloseTo(0.65);
+    });
+  });
+});