Function truncate_utf8

core/src/llm/structured.rs:1095–1104

UTF-8-safe truncation to at most `max` bytes (never splits a multibyte char — repair prompts echo arbitrary model output, including CJK).

(s: &str, max: usize)

/// UTF-8-safe truncation to at most `max` bytes (never splits a multibyte char —
/// repair prompts echo arbitrary model output, including CJK).
fn truncate_utf8(s: &str, max: usize) -> &str {
    if s.len() <= max {
        return s;
    }
    let mut end = max;
    while end > 0 && !s.is_char_boundary(end) {
        end -= 1;
    }
    &s[..end]
}

/// Repair prompt for when nothing parseable was produced at all.
fn build_parse_failure_repair(raw_text: &str) -> String {