diff --git a/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.test.ts b/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.test.ts
index abc7b15e56..ae79cd9918 100644
--- a/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.test.ts
+++ b/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.test.ts
@@ -1,10 +1,27 @@
 import { getAiSdkProvider } from '../model-settings';
+import type { GatewayRequest } from '../openrouter/types';
+import type { Provider, TransformRequestContext } from '../types';
 import openCodeGo from './opencode-go';
 
 test('allows the Responses API for OpenCode Go', () => {
   expect(openCodeGo.supported_chat_apis).toContain('responses');
 });
 
+test.each([
+  ['messages', 'x-api-key'],
+  ['chat_completions', null],
+  ['responses', null],
+] as const)('uses the expected API key header for %s requests', (kind, apiKeyHeader) => {
+  const provider = { apiKeyHeader: null } as Provider;
+  const request = { kind, body: {} } as GatewayRequest;
+  const extraHeaders = {};
+
+  openCodeGo.transformRequest({ provider, request, extraHeaders } as TransformRequestContext);
+
+  expect(provider.apiKeyHeader).toBe(apiKeyHeader);
+  expect(extraHeaders).toEqual({});
+});
+
 describe('getAiSdkProvider', () => {
   test.each(['opencode-go/minimax-m3', 'opencode-go/qwen3.7-plus'])(
     'uses the Anthropic Messages API for OpenCode Go model %s',
diff --git a/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.ts b/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.ts
index 9b114f1027..401d058be9 100644
--- a/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.ts
+++ b/apps/web/src/lib/ai-gateway/providers/direct-byok/opencode-go.ts
@@ -8,9 +8,7 @@ export default {
   supported_chat_apis: ['chat_completions', 'messages', 'responses'],
   default_ai_sdk_provider: 'openai-compatible',
   transformRequest(context) {
-    if (context.request.kind === 'messages') {
-      context.extraHeaders['x-api-key'] = context.provider.apiKey;
-    }
+    context.provider.apiKeyHeader = context.request.kind === 'messages' ? 'x-api-key' : null;
   },
   models: cachedEnhancedDirectByokModelList({
     providerId: 'opencode-go',