diff --git a/packages/ai/infermatic/src/index.test.ts b/packages/ai/infermatic/src/index.test.ts
index 87178cde..f077f5e9 100644
--- a/packages/ai/infermatic/src/index.test.ts
+++ b/packages/ai/infermatic/src/index.test.ts
@@ -87,22 +87,43 @@ describe('Infermatic chat completions generation', () => {
   });
 
   it('supports text-style choices from compatible responses', async () => {
-    vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
+    const fetchMock = vi.fn().mockResolvedValue({
       ok: true,
       json: async () => ({
         model: 'TheDrummer-UnslopNemo-12B-v4.1',
         choices: [{ text: 'legacy text response' }],
       }),
-    }));
+    });
+    vi.stubGlobal('fetch', fetchMock);
 
-    const result = await adapter.generate(ctx(), 'hello', {}, { baseUrl: 'https://infermatic.test' });
+    const result = await adapter.generate(ctx(), 'hello', {}, { baseUrl: 'https://infermatic.test/' });
 
+    expect(fetchMock).toHaveBeenCalledWith(
+      'https://infermatic.test/v1/chat/completions',
+      expect.any(Object),
+    );
     expect(result).toEqual({
       text: 'legacy text response',
       model: 'TheDrummer-UnslopNemo-12B-v4.1',
     });
   });
 
+  it.each([
+    ['missing scheme', 'infermatic.test'],
+    ['unsupported scheme', 'ftp://infermatic.test'],
+    ['credentials', 'https://user:pass@infermatic.test'],
+    ['query string', 'https://infermatic.test?debug=true'],
+    ['fragment', 'https://infermatic.test#v1'],
+  ])('rejects unclean custom baseUrl values: %s', async (_case, baseUrl) => {
+    const fetchMock = vi.fn();
+    vi.stubGlobal('fetch', fetchMock);
+
+    await expect(adapter.generate(ctx(), 'hello', {}, { baseUrl })).rejects.toThrow(
+      /Infermatic baseUrl/,
+    );
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+
   it('includes status and response body excerpt on errors', async () => {
     vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
       ok: false,
diff --git a/packages/ai/infermatic/src/index.ts b/packages/ai/infermatic/src/index.ts
index 74630a22..034f6077 100644
--- a/packages/ai/infermatic/src/index.ts
+++ b/packages/ai/infermatic/src/index.ts
@@ -27,8 +27,9 @@ export default defineAi<Config>({
     const messages: InfermaticMessage[] = [];
     if (opts.system) messages.push({ role: 'system', content: opts.system });
     messages.push({ role: 'user', content: prompt });
+    const baseUrl = cleanBaseUrl(config.baseUrl ?? DEFAULT_BASE);
 
-    const res = await fetch(`${config.baseUrl ?? DEFAULT_BASE}/v1/chat/completions`, {
+    const res = await fetch(`${baseUrl}/v1/chat/completions`, {
       method: 'POST',
       headers: {
         authorization: `Bearer ${apiKey}`,
@@ -66,6 +67,22 @@ export default defineAi<Config>({
   }),
 });
 
+function cleanBaseUrl(value: string): string {
+  let url: URL;
+  try {
+    url = new URL(value);
+  } catch {
+    throw new Error('Infermatic baseUrl must be a valid URL');
+  }
+  if (url.protocol !== 'https:' && url.protocol !== 'http:') {
+    throw new Error('Infermatic baseUrl must use http or https');
+  }
+  if (url.username || url.password || url.search || url.hash) {
+    throw new Error('Infermatic baseUrl must be a clean API base without credentials, query, or hash');
+  }
+  return url.toString().replace(/\/+$/, '');
+}
+
 type InfermaticRole = 'system' | 'user' | 'assistant' | 'tool';
 
 interface InfermaticMessage {