diff --git a/go.mod b/go.mod
index b67187b73f1c7144d452364fa90578a7bb7337da..19df7e97ece12a2d1a1f0243e3513d2563e94cca 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,7 @@ require (
 	charm.land/bubbletea/v2 v2.0.6
 	charm.land/catwalk v0.40.0
 	charm.land/fang/v2 v2.0.1
-	charm.land/fantasy v0.23.2
+	charm.land/fantasy v0.24.0
 	charm.land/glamour/v2 v2.0.0
 	charm.land/lipgloss/v2 v2.0.3
 	charm.land/log/v2 v2.0.0
diff --git a/go.sum b/go.sum
index 2f9bbc3608391ad3c74c59dc3e6b22464cfb858f..c6878a43aba265a3c9a5a19e2bdb6c59c8525597 100644
--- a/go.sum
+++ b/go.sum
@@ -6,8 +6,8 @@ charm.land/catwalk v0.40.0 h1:Ldqr2YzTqk2QdXAFFa5W/EiFoxNGMQc7KXekze5Z+Cw=
 charm.land/catwalk v0.40.0/go.mod h1:LmMFJdRqF5F7qKa+xqD9SBq7tph7L98GU3ZFa1TxftA=
 charm.land/fang/v2 v2.0.1 h1:zQCM8JQJ1JnQX/66B5jlCYBUxL2as5JXQZ2KJ6EL0mY=
 charm.land/fang/v2 v2.0.1/go.mod h1:S1GmkpcvK+OB5w9caywUnJcsMew45Ot8FXqoz8ALrII=
-charm.land/fantasy v0.23.2 h1:9gUknrENwv0lV379Hs7m/GK2c/9m+gWXyfbox1tVHrg=
-charm.land/fantasy v0.23.2/go.mod h1:8QrWUzIcKwZQP+aAnC9vLu3iID6hu9/Jt+rPMiieBkc=
+charm.land/fantasy v0.24.0 h1:/q35T2TvrqTYqMnFOBHEqp8IWoKMxh05Y7r5wsF/6F4=
+charm.land/fantasy v0.24.0/go.mod h1:8QrWUzIcKwZQP+aAnC9vLu3iID6hu9/Jt+rPMiieBkc=
 charm.land/glamour/v2 v2.0.0 h1:IDBoqLEy7Hdpb9VOXN+khLP/XSxtJy1VsHuW/yF87+U=
 charm.land/glamour/v2 v2.0.0/go.mod h1:kjq9WB0s8vuUYZNYey2jp4Lgd9f4cKdzAw88FZtpj/w=
 charm.land/lipgloss/v2 v2.0.3 h1:yM2zJ4Cf5Y51b7RHIwioil4ApI/aypFXXVHSwlM6RzU=
diff --git a/internal/agent/coordinator.go b/internal/agent/coordinator.go
index 68e83b1a63f05b20dea567fefeb41e1519a19ce7..749db4572775e646e6ebb318e13f84b48be1fd6f 100644
--- a/internal/agent/coordinator.go
+++ b/internal/agent/coordinator.go
@@ -62,6 +62,15 @@ var (
 	errSmallModelNotFound              = errors.New("small model not found in provider config")
 )
 
+// Copilot models that use the Responses API instead of Chat Completions.
+var copilotResponsesModels = map[string]bool{
+	"gpt-5.2":       true,
+	"gpt-5.2-codex": true,
+	"gpt-5.3-codex": true,
+	"gpt-5.4-mini":  true,
+	"gpt-5-mini":    true,
+}
+
 type Coordinator interface {
 	// INFO: (kujtim) this is not used yet we will use this when we have multiple agents
 	// SetMainAgent(string)
@@ -731,7 +740,12 @@ 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())
+		opts = append(opts,
+			openaicompat.WithUseResponsesAPI(),
+			openaicompat.WithResponsesAPIFunc(func(modelID string) bool {
+				return copilotResponsesModels[modelID]
+			}),
+		)
 		httpClient = copilot.NewClient(isSubAgent, c.cfg.Config().Options.Debug)
 	} else if c.cfg.Config().Options.Debug {
 		httpClient = log.NewHTTPClient()