Function format_model_blob 

pub(crate) fn format_model_blob(
    buf: &[u8],
    exit_code: i32,
    elapsed: Duration,
) -> String

Build the aggregated, model-visible blob from the captured bytes. Truncates with head/tail markers if it exceeds 100KB.

UTF-8 safety: head/tail slice boundaries are snapped to the nearest UTF-8 character boundary so non-ASCII output (emoji, accented characters, CJK) doesn’t get corrupted into � replacement characters at the cut point — naive fixed-byte slicing splits multi-byte sequences and the lossy decode emits replacement chars.