pub(crate) fn snapshot_preview(bytes: &[u8]) -> (String, usize)Expand description
(preview, node_count) from an output.state.json snapshot’s bytes, or
("", 0) when they don’t parse or have no nodes array. The preview is
the first user_message, skipping a leading “# Session Context” bootstrap
message when a later one exists, collapsed to one line of at most 240 chars.