diff --git a/packages/cloud-agents/src/server/__tests__/task-helper-subscription-transport.test.ts b/packages/cloud-agents/src/server/__tests__/task-helper-subscription-transport.test.ts
index 30a295846..4e5cb542f 100644
--- a/packages/cloud-agents/src/server/__tests__/task-helper-subscription-transport.test.ts
+++ b/packages/cloud-agents/src/server/__tests__/task-helper-subscription-transport.test.ts
@@ -143,8 +143,10 @@ describe.skipIf(process.env.ROOMOTE_TEST_OPENCODE_SUBSCRIPTIONS !== '1')(
           expect(requests[0]).toMatchObject({
             authorization: 'Bearer synthetic-run-token',
           });
-          expect(requests[0]?.url).toContain(
-            `/api/inference/${provider === 'openai' ? 'openai-chatgpt' : provider}/`,
+          expect(requests[0]?.url).toBe(
+            provider === 'openai'
+              ? '/api/inference/openai-chatgpt/v1/responses'
+              : '/api/inference/github-copilot/responses',
           );
           expect(
             isAgentSafetyStop(result.error ?? result.data?.info.error),
diff --git a/packages/cloud-agents/src/server/opencode-runtime.ts b/packages/cloud-agents/src/server/opencode-runtime.ts
index 224606be7..6a0489810 100644
--- a/packages/cloud-agents/src/server/opencode-runtime.ts
+++ b/packages/cloud-agents/src/server/opencode-runtime.ts
@@ -751,6 +751,11 @@ export function rebaseTaskHelperInference(
     const existing = asRecord(providers[id]) ?? {};
     providers[id] = {
       ...existing,
+      // As in the sandbox provider config, activate Copilot before OpenCode's
+      // custom-loader pass so GPT-5+ models use /responses, not /chat/completions.
+      ...(id === 'github-copilot'
+        ? { env: ['ROOMOTE_TASK_INFERENCE_TOKEN'] }
+        : {}),
       options: {
         ...asRecord(existing.options),
         baseURL: buildInferenceGatewayOpenCodeBaseUrl(