Buf connect-go protoc-gen-validate interceptor by @akshayjshah

validator_interceptor.go

var validatorInterceptor = connect.UnaryInterceptorFunc(
	func(next connect.UnaryFunc) connect.UnaryFunc {
		return connect.UnaryFunc(func(ctx context.Context, request connect.AnyRequest) (connect.AnyResponse, error) {
			validator, ok := request.Any().(interface{ ValidateAll() error })
			if !ok {
				// Handle this however you'd like; maybe return an error with
				// CodeInternal if all your types should support validation?
				return next(ctx, request)
			}
			if err := validator.ValidateAll(); err != nil {
				// If the client needs very granular details about the error (maybe to
				// highlight invalid data in some UI?), you can attach
				// https://pkg.go.dev/google.golang.org/genproto/googleapis/rpc/errdetails#BadRequest
				// as an error detail. I'm not super-familiar with protoc-gen-validate,
				// so I'm not sure how to convert the ValidateAll error into a bunch of
				// errdetail.BadRequest_FieldViolation messages.
				return nil, connect.NewError(connect.CodeInvalidArgument, err)
			}
			return next(ctx, request)
		})
	}
)

Usage example here by @utamori