From 4a41de72ec9612368cc3145abb7b09ebaca0f647 Mon Sep 17 00:00:00 2001
From: CypherNaugh_0x <9931495+CypherNaught-0x@users.noreply.github.com>
Date: Sat, 10 Oct 2026 18:51:18 +0200
Subject: [PATCH] Autosave ids are unique within the process: an app restarted
 in the same second (the scenario harness crashes and restarts in one process)
 took the id `{seconds}-{pid}` of the crashed app, locked its entry again and
 so offered nothing to recover. The id now carries a per-process sequence
 number. Test: a restart in the same second still offers the crashed app's
 work

---
 crates/engine/src/recovery.rs | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/crates/engine/src/recovery.rs b/crates/engine/src/recovery.rs
index 2157d528..9f316c55 100644
--- a/crates/engine/src/recovery.rs
+++ b/crates/engine/src/recovery.rs
@@ -140,7 +140,11 @@ impl Autosaver {
                 let _ = fs::remove_file(&p);
             }
         }
-        let id = format!("{}-{}", unix_now(), std::process::id());
+        // Unique within the process too: an app started again in the same second (tests that
+        // "crash" and restart) must not take over the crashed app's entry.
+        static SEQ: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
+        let seq = SEQ.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+        let id = format!("{}-{}-{seq}", unix_now(), std::process::id());
         let lock = OpenOptions::new().create(true).truncate(false).write(true).open(file(dir, &id, "lock")).map_err(io)?;
         lock.lock().map_err(io)?;
         Ok(Autosaver { dir: dir.to_path_buf(), id, interval, lock: Some(lock), last: None, last_at: Instant::now(), has_entry: false })
@@ -225,6 +229,21 @@ mod tests {
         let _ = fs::remove_dir_all(&d);
     }
 
+    #[test]
+    fn an_app_restarted_in_the_same_second_still_offers_the_crashed_ones_work() {
+        let d = dir("restart");
+        let mut s = Session::default();
+        let mut a = Autosaver::new(&d, Duration::from_secs(3600)).unwrap();
+        s.execute("solid.box", &json!({"length": 10, "width": 10, "height": 10})).unwrap();
+        assert!(a.save(&s).unwrap());
+        drop(a);
+        let b = Autosaver::new(&d, Duration::from_secs(3600)).unwrap();
+        let found = orphans(&d);
+        assert_eq!(found.len(), 1, "the crashed app's entry is offered");
+        assert_ne!(found[0].id, b.id);
+        let _ = fs::remove_dir_all(&d);
+    }
+
     #[test]
     fn saving_drops_the_entry_and_a_clean_close_leaves_nothing() {
         let d = dir("clean");