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//! Resuming an attempt a killed process left behind.
//!
//! Before an attempt, a marker records its admission key, the checkpoint it
//! started from and the acceptance tests it is judged by. A run that ends in
//! any ordinary way removes it ([`Guard`]); a killed process cannot, so a
//! marker on disk means an attempt was interrupted. The next run then keeps
//! the worktree as the attempt left it and admits the attempt under the same
//! key: agentplane finds the interrupted run and resumes it from its journal
//! — model calls and tool calls that finished are read back, not repeated —
//! and a run that had already finished is read back whole and judged again
//! (a task that passed just before the kill is ticked now).
use std::path::{Path, PathBuf};
use serde::{Deserialize, Serialize};
use sha2::{Digest as _, Sha256};
/// An attempt in progress.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct Marker {
/// The agentplane admission key.
pub key: String,
/// The checkpoint the attempt started from.
pub before: String,
/// The worktree's HEAD then; a different HEAD means the marker is stale.
pub head: String,
/// Which attempt of the task run.
pub attempt: u32,
/// Which best-of-n sample (0-based).
pub sample: usize,
/// The acceptance tests prepared for the task run.
pub acceptance: Option<serde_json::Value>,
}
/// Where the marker of `feature/task` lives.
#[must_use]
pub fn path(plane_dir: &Path, feature: &str, task: &str) -> PathBuf {
plane_dir
.join("resume")
.join(feature)
.join(format!("{task}.json"))
}
/// The marker, if an attempt was interrupted.
#[must_use]
pub fn load(path: &Path) -> Option<Marker> {
serde_json::from_str(&std::fs::read_to_string(path).ok()?).ok()
}
/// Records `marker` (written whole, then renamed: never half a marker).
pub fn save(path: &Path, marker: &Marker) -> std::io::Result<()> {
if let Some(dir) = path.parent() {
std::fs::create_dir_all(dir)?;
}
let tmp = path.with_extension("json.tmp");
std::fs::write(
&tmp,
serde_json::to_vec(marker).map_err(std::io::Error::other)?,
)?;
std::fs::rename(tmp, path)
}
/// A fresh admission key: unique per attempt, so an ordinary rerun never
/// meets an old attempt's run.
#[must_use]
pub fn new_key(feature: &str, task: &str) -> String {
static COUNTER: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
let nanos = std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.map_or(0, |d| d.as_nanos());
let n = COUNTER.fetch_add(1, std::sync::atomic::Ordering::SeqCst);
let digest = Sha256::digest(format!(
"{feature}/{task}/{nanos}/{}/{n}",
std::process::id()
));
let hex: String = digest.iter().take(16).map(|b| format!("{b:02x}")).collect();
format!("attempt-{hex}")
}
/// Removes the marker when a task run that started an attempt ends in any
/// ordinary way. A run refused before its attempt starts (a session check,
/// a worktree held by a waiting call) leaves an interrupted or waiting
/// attempt's marker alone: that attempt still resumes.
#[derive(Debug)]
pub struct Guard {
path: PathBuf,
armed: std::cell::Cell<bool>,
}
impl Guard {
/// A guard for the marker at `path`, not yet armed.
#[must_use]
pub fn new(path: PathBuf) -> Self {
Self {
path,
armed: std::cell::Cell::new(false),
}
}
/// An attempt is starting: the marker goes when the run ends.
pub fn arm(&self) {
self.armed.set(true);
}
/// Leaves the marker in place: the attempt waits for a person and the
/// next run resumes it.
pub fn keep(self) {
self.armed.set(false);
}
}
impl Drop for Guard {
fn drop(&mut self) {
if self.armed.get() {
let _ = std::fs::remove_file(&self.path);
}
}
}