diff --git a/internal/agent/coordinator.go b/internal/agent/coordinator.go
index ff9e746220e1b2e4acc481259343f30ca39e030b..b1be1be93b4b428011bfc360e548da560e087f69 100644
--- a/internal/agent/coordinator.go
+++ b/internal/agent/coordinator.go
@@ -592,6 +592,7 @@ func (c *coordinator) buildOpenaiCompatProvider(baseURL, apiKey string, headers
 	// Set HTTP client based on provider and debug mode.
 	var httpClient *http.Client
 	if providerID == string(catwalk.InferenceProviderCopilot) {
+		opts = append(opts, openaicompat.WithUseResponsesAPI())
 		httpClient = copilot.NewClient(isSubAgent, c.cfg.Options.Debug)
 	} else if c.cfg.Options.Debug {
 		httpClient = log.NewHTTPClient()