feat: add Responses API compatibility

apps/api/internal/httpapi/responses_streaming_test.go

@@ -0,0 +1,36 @@
+package httpapi
+
+import (
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/easyai/easyai-ai-gateway/apps/api/internal/clients"
+)
+
+func TestResponsesStreamWriterForwardsStandardEventsAndNeverWritesDoneMarker(t *testing.T) {
+	recorder := httptest.NewRecorder()
+	writer := newCompatibleStreamWriter("responses", "demo", true)
+	writer.writeDelta(recorder, clients.StreamDeltaEvent{Event: map[string]any{
+		"type": "response.created", "response": map[string]any{"id": "resp_123", "status": "in_progress"},
+	}})
+	writer.writeDelta(recorder, clients.StreamDeltaEvent{Event: map[string]any{
+		"type": "response.function_call_arguments.delta", "item_id": "fc_1", "delta": "{\"x\":",
+	}})
+	writer.writeDelta(recorder, clients.StreamDeltaEvent{Event: map[string]any{
+		"type": "response.completed", "sequence_number": 2, "response": map[string]any{"id": "resp_123", "status": "completed", "output": []any{}},
+	}})
+	writer.writeDone(recorder, map[string]any{"id": "resp_123", "object": "response", "status": "completed", "output": []any{}})
+	body := recorder.Body.String()
+	for _, expected := range []string{"event: response.created", "event: response.function_call_arguments.delta", "event: response.completed"} {
+		if !strings.Contains(body, expected) {
+			t.Fatalf("missing %q in stream: %s", expected, body)
+		}
+	}
+	if strings.Contains(body, "[DONE]") || strings.Contains(body, "chat.completion") {
+		t.Fatalf("Responses stream leaked Chat framing: %s", body)
+	}
+	if strings.Count(body, "event: response.completed") != 1 {
+		t.Fatalf("Responses stream duplicated response.completed: %s", body)
+	}
+}