feat: filter candidates by request resolution

apps/api/internal/httpapi/handlers.go

@@ -805,7 +805,7 @@ func (s *Server) estimatePricing(w http.ResponseWriter, r *http.Request) {
 	estimate, err := s.runner.Estimate(r.Context(), kind, model, body, user)
 	if err != nil {
 		if errors.Is(err, store.ErrNoModelCandidate) {
-			writeError(w, statusFromRunError(err), err.Error(), store.ModelCandidateErrorCode(err))
+			writeErrorWithDetails(w, statusFromRunError(err), runErrorMessage(err), runErrorDetails(err), store.ModelCandidateErrorCode(err))
 			return
 		}
 		s.logger.Error("estimate pricing failed", "error", err)
@@ -1168,6 +1168,9 @@ func runErrorDetails(err error) map[string]any {
 	if detail := rateLimitErrorDetail(err); len(detail) > 0 {
 		return map[string]any{"rateLimit": detail}
 	}
+	if detail := store.ModelCandidateErrorDetails(err); len(detail) > 0 {
+		return map[string]any{"modelCandidate": detail}
+	}
 	return nil
 }