This is where the magic of having a virtualized filesystem inside the browser
really shines. We can use the VFS to dynamically write a temporary `.c` file
containing the math expression, tell the LPC VM to JIT-compile it using
`clone_object`, execute the code, and then clean up the fileall in
milliseconds!

Here are the two updated files to add the `eval` command and the "Copy
Terminal" UI button.

### 1. The REPL Logic (`tests/repl.c`)

Save this inside your `tests/` folder. Notice how the `eval` command uses
`random()` to generate a unique filename, ensuring that the JIT compiler
doesn't accidentally cache the evaluated blueprint!

```c
/ tests/repl.c
void create() {
    printf("Type 'help' for a list of commands.
");
}

void process_repl_command_line(string input) {
    string cmd, arg;
    
    // Parse command vs argument
    if (sscanf(input, "%s %s", cmd, arg) != 2) {
        cmd = input;
    }

    if (cmd == "help") {
        printf("Available commands:
");
        printf("  help          - Show this message
");
        printf("  time          - Display system time
");
        printf("  md5 <string>  - Hash a string
");
        printf("  eval <lpc>    - Evaluate LPC expression dynamically
");
        printf("  clear         - Clear the screen (handled by frontend)
");
    } 
    else if (cmd == "time") {
        printf("System uptime: %d seconds
", uptime());
        printf("Current time: %s
", ctime(time()));
    }
    else if (cmd == "md5" && arg) {
        printf("MD5('%s') = %s
", arg, md5(arg));
    }
    else if (cmd == "eval" && arg) {
        // Use a random filename to bypass the JIT blueprint cache
        string filename = "tmp_eval_" + random(9999999) + ".c";
        
        // Wrap the user's expression inside a valid LPC function
        string src = "mixed do_eval() { return (" + arg + "); }
";
        
        if (write_file(filename, src)) {
            object ob = clone_object(filename);
            if (ob) {
                mixed res = ob->do_eval();
                printf("Result: %s
", res);
                destruct(ob);
            } else {
                printf("Error: Failed to compile expression.
");
            }
            rm(filename); // Clean up the VFS
        } else {
            printf("Error: Failed to write temp file to VFS.
");
        }
    }
    else if (cmd == "") {
        // Do nothing on empty enter
    }
    else {
        printf("Unrecognized command: %s
", cmd);
    }
}

```

### 2. The Updated `template.html`

I've added the Copy button UI to the top right of the terminal block. I also
added a quick frontend intercept for the `clear` command so the DOM actually
empties the scrollback buffer when you type it.

```html

Rebuild using `node build_web.js` to compile the new `repl.c` and
`template.html`.

You can now use `eval 5 * 10` or `eval pow(2, 8)` directly in the browser!