Best Practices for Dynamically Generating Values in Literal Type Declaration

Thank you for your help.

I'd like to ask you about the best practices for dynamically generating values when using literal type in TypeScript.

typevalueType='foo_1'|'foo_2';

const prefix=(value:string):string=>{
    const prefix = 'foo';
    return`${prefix}_${value}`;
}

const process=():valueType=>{
    if(/* omitted*/){
        return prefix ('1');
    } else{
        return prefix ('2');
    }
}

For example, if there is a code like this, the prefix is dynamically generated because it could change in the future.
Naturally, the following error will be printed in the return statement:

 type 'string' cannot be assigned to type 'valueType'.ts(2322)

const process=():valueType=>{
    if(/* omitted*/){
        return prefix('1') as 'foo_1';
    } else{
        return prefix('2') as 'foo_2';
    }
}

It's obviously useless, and it's better to write return'foo_1' from the beginning as it needs to be fixed if the prefix changes anyway.
→ Is it still better to specify the type explicitly?

In the first place, stop the literal type and leave it to type reasoning.
→ However, the possibility of anything other than foo_1 and foo_2 being included is zero, and if possible, I would like to tie it in literal form instead of string type.

I was an amateur for about a week in TypeScript, and I could hardly think of the best way to do it.
Isn't it possible to do it with generic?I tried and tried, but I still don't know if this is possible at the basic level of TypeScript.

• Get rid of literal types and type inference is sufficient
• Dynamic generation (prefixing) should stop
• Can/Cannot do with generic type

I would appreciate it if I could ask my seniors about various knowledge.
I apologize for the inconvenience, but I appreciate your cooperation.