diff --git a/src/offerings/distributionsRoute.test.ts b/src/offerings/distributionsRoute.test.ts
index e1fbd046..03d8e741 100644
--- a/src/offerings/distributionsRoute.test.ts
+++ b/src/offerings/distributionsRoute.test.ts
@@ -32,7 +32,7 @@ const createNext = (): NextFunction => jest.fn();
 
 const createRequest = (overrides: {
   params?: Record<string, string>;
-  query?: Record<string, string | undefined>;
+  query?: Record<string, string | string[] | undefined>;
   userId?: string;
 }): Request => {
   return {
@@ -269,6 +269,28 @@ describe('createListDistributionsByOfferingHandler', () => {
     expect(mockDistributionRepository.listByOffering).not.toHaveBeenCalled();
   });
 
+  it.each([
+    { description: 'page is repeated', query: { page: ['1', '2'] } },
+    { description: 'pageSize is repeated', query: { pageSize: ['10', '20'] } },
+    { description: 'page is zero', query: { page: '0' } },
+    { description: 'pageSize is fractional', query: { pageSize: '1.5' } },
+  ])('returns 400 when $description', async ({ query }) => {
+    const handler = createListDistributionsByOfferingHandler({
+      distributionRepository: mockDistributionRepository,
+      offeringOwnershipRepository: mockOfferingOwnershipRepository,
+    });
+
+    const req = createRequest({ userId: 'user-1', query });
+    const res = createResponse();
+
+    await handler(req, res, createNext());
+
+    expect(res.status).toHaveBeenCalledWith(400);
+    expect(res.json).toHaveBeenCalledWith({ error: 'Invalid pagination parameters' });
+    expect(mockOfferingOwnershipRepository.isOwnedByUser).not.toHaveBeenCalled();
+    expect(mockDistributionRepository.listByOffering).not.toHaveBeenCalled();
+  });
+
   // 10. pageSize is capped at MAX_PAGE_SIZE (100)
   it('caps pageSize at 100', async () => {
     mockOfferingOwnershipRepository.isOwnedByUser.mockResolvedValueOnce(true);
diff --git a/src/routes/apiDocs.test.ts b/src/routes/apiDocs.test.ts
new file mode 100644
index 00000000..c5183101
--- /dev/null
+++ b/src/routes/apiDocs.test.ts
@@ -0,0 +1,56 @@
+import express, { Express, NextFunction, Request, Response } from 'express';
+import path from 'path';
+import request from 'supertest';
+import { createApiDocsRouter } from './apiDocs';
+
+describe('createApiDocsRouter', () => {
+  let app: Express;
+
+  beforeEach(() => {
+    app = express();
+    app.use(createApiDocsRouter());
+  });
+
+  it('serves the OpenAPI specification', async () => {
+    const response = await request(app).get('/openapi.yaml');
+
+    expect(response.status).toBe(200);
+    expect(response.text).toContain('openapi: 3.0.0');
+    expect(response.text).toContain('title: Revora Backend API');
+  });
+
+  it('serves Swagger UI configured to load the OpenAPI specification', async () => {
+    const response = await request(app).get('/api-docs/');
+
+    expect(response.status).toBe(200);
+    expect(response.headers['content-type']).toMatch(/text\/html/);
+    expect(response.text).toContain('Swagger UI');
+    expect(response.text).toContain('/openapi.yaml');
+  });
+
+  it('returns not found for unsupported paths and methods', async () => {
+    const unknownPath = await request(app).get('/not-api-docs');
+    const unsupportedMethod = await request(app).post('/openapi.yaml');
+
+    expect(unknownPath.status).toBe(404);
+    expect(unsupportedMethod.status).toBe(404);
+  });
+
+  it('passes OpenAPI file errors to Express error middleware', async () => {
+    const resolveSpy = jest.spyOn(path, 'resolve').mockReturnValue('/missing/openapi.yaml');
+    try {
+      app = express();
+      app.use(createApiDocsRouter());
+    } finally {
+      resolveSpy.mockRestore();
+    }
+    app.use((error: NodeJS.ErrnoException, _req: Request, res: Response, _next: NextFunction) => {
+      res.status(500).json({ code: error.code });
+    });
+
+    const response = await request(app).get('/openapi.yaml');
+
+    expect(response.status).toBe(500);
+    expect(response.body).toEqual({ code: 'ENOENT' });
+  });
+});
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