Generate all halting Smallfuck programs of length n

Question

Your task is to write a program that, given a number n, returns a list of all valid, halting Smallfuck programs of length n, in any order.

Actually, we're using a variation of Smallfuck called F2, which is just Smallfuck with a right-unbounded tape. For the purposes of this challenge, a program that moves left from the start of the tape is considered invalid, as is one with unbalanced brackets.

Scoring

Since solving this for every n is impossible (as it would require you to solve the halting problem), your submission's score will be the lowest n for which it returns an incorrect answer.

Each submission must be, at most, 1000 bytes (though you are encouraged to provide an ungolfed version as well). In the event of a tie, the earlier answer wins.

Test Cases

n = 1:

+ >

n = 2:

++ +> >+ >< >> []

n = 3:

+++ ++> +>+ +>< +>> >++ >+< >+> ><+ ><> >>+ >>< >>> >[] [+] [<] [>] []+ []>

n = 4:

++++ +++> ++>+ ++>< ++>> +>++ +>+< +>+> +><+ +><> +>>+ +>>< +>>> >+++ >++< >++> >+<+ >+<> >+>+ >+>< >+>> ><++ ><+> ><>+ ><>< ><>> >>++ >>+< >>+> >><+ >><< >><> >>>+ >>>< >>>> [][] ++[] +>[] ><[] >>[] [++] [+<] [+>] [<+] [<<] [<>] [>+] [><] [>>] []++ []+> []>+ []>< []>> +[+] +[>] >[+] >[<] >[>] >[]+ >[]< >[]> [+]+ [+]> [<]+ [<]> [>]+ [>]> [[]]

Please inform me if there are any more that I have forgotten to add.

Answer 1

Java (OpenJDK 8), Score: ???

This clocks in at 980 bytes, since I had so much to work with I decided to make it a little more readable. Basically I'm generating all the possible programs for length n and iterating them n^x times for some x. x is currently 3 but it can be modified arbitrarily to any size, limited only by the limitation of the JVM's precission. This will work for arbitrarily large input values if x is increased, but I have it set to 3 for tio.

import java.util.*;
public class Main{
    public static void main(String[] args){
        int i = new Scanner(System.in).nextInt();
        int x = 3;
        l:for(int j=0;j<Math.pow(5, i);j++){
            try {
                String s="";
                for(int k=j;s.length()<i;k/=5)
                    s="+<>][".charAt(k%5)+s;
                Stack<Integer>y=new Stack<Integer>();
                Map<Integer,Integer>f=new HashMap<>(),b=new HashMap<>();
                for(int m=0; m<s.length();m++){
                    char c=s.charAt(m);
                    if(c=='[')y.push(m);
                    if(c==']'){int n=y.pop();f.put(n, m);b.put(m, n);}
                }
                if(y.size()>0)
                    continue;
                boolean[] t= new boolean[s.length()];
                int l=0,n=0;
                for(long m=0;l<s.length()&m<Math.pow(i,x);l++,m++){
                    switch(s.charAt(l)){
                    case'+':t[n]=!t[n];break;
                    case'>':n++;break;
                    case'<':n--; if(n < 0)continue l;break;
                    case'[':if(!t[n])l=f.get(l);break;
                    case']':l=b.get(l)-1;break;
                    }
                }
                if(l>=s.length()){
                    System.out.println(s);
                }
            } catch(Exception e){continue;}
        }
    }
}

Try it online!

Answer 2

Braingolf, Score: 3

1-?"++ +> >+ >< >> []":"+ >"|&@

Start things off nice and easy, hardcodes the correct answer for 1 and 2, outputs + > if n = 1, and ++ +> >+ >< >> [] otherwise