Function classify

crates/flowtrace-cli/src/serve/classify.rs:8–86

Classify a filesystem event path into an SSE event body. `scope_root` MUST be canonicalized (see AppState::new). `path` MUST be the absolute path produced by notify.

(scope_root: &Path, path: &Path)

/// `scope_root` MUST be canonicalized (see AppState::new).
/// `path` MUST be the absolute path produced by notify.
pub fn classify(scope_root: &Path, path: &Path) -> SseEventBody {
    let rel = match path.strip_prefix(scope_root) {
        Ok(r) => r,
        Err(_) => {
            return SseEventBody::Other {
                path: path.display().to_string(),
            };
        }
    };
    let comps: Vec<&str> = rel
        .components()
        .filter_map(|c| match c {
            Component::Normal(s) => s.to_str(),
            _ => None,
        })
        .collect();
    if comps.is_empty() {
        return SseEventBody::Other {
            path: path.display().to_string(),
        };
    }
    // Layout under scope: <trace_id>/(trace.json | runs/<run>/...)
    let trace_id = comps[0].to_string();
    if comps.len() == 1 {
        return SseEventBody::Other {
            path: path.display().to_string(),
        };
    }
    match comps.as_slice() {
        [_, "trace.json"] => SseEventBody::TraceUpdated { trace_id },
        [_, "runs", run_id] => SseEventBody::RunCreated {
            trace_id,
            run_id: (*run_id).into(),
        },
        [_, "runs", run_id, "state.json"] => SseEventBody::RunUpdated {
            trace_id,
            run_id: (*run_id).into(),
        },
        [_, "runs", run_id, "replies", reply_file] => {
            // Skip writer tempfiles (`.tmp.<pid>.<nanos>.reply`) and any other
            // hidden / non-NNNN.json names. Otherwise a bad parse would emit
            // ReplyAppended{seq=0}, which the frontend dedupes — silently
            // dropping the real reply that follows.
            if reply_file.starts_with('.') {
                return SseEventBody::Other {
                    path: path.display().to_string(),
                };
            }
            let Some(stem) = reply_file.strip_suffix(".json") else {
                return SseEventBody::Other {
                    path: path.display().to_string(),
                };
            };
            let Ok(seq) = stem.parse::<u32>() else {
                eprintln!(
                    "[trace] warn: watcher saw non-numeric reply filename `{}` — \
                     ignoring; expected NNNN.json",
                    reply_file