fix: stabilize API key Codex manifest refreshes

backend/internal/handler/openai_codex_models_handler_test.go

@@ -0,0 +1,26 @@
+package handler
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+)
+
+func TestCodexModelsCanceledRequestDoesNotWriteResponse(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	c.Request = httptest.NewRequest(http.MethodGet, "/v1/models", nil).WithContext(ctx)
+
+	h := &OpenAIGatewayHandler{}
+	h.CodexModels(c)
+
+	if c.Writer.Written() {
+		t.Fatalf("canceled request wrote an HTTP response: status=%d body=%q", recorder.Code, recorder.Body.String())
+	}
+}