sync: preserve local archive intent across reconcile

Author: myobie

CHANGELOG.md

@@ -28,6 +28,15 @@ EXPERIMENTAL, so on-disk formats and the CLI may change without notice.
 
 ### Fixed
 
+- **Bus archive/delete intent lost to an inbound reconcile.** An atomic local
+  rename could remove an inbox file while Fabric's filesystem watcher was still
+  inside its 150 ms debounce window; an inbound sync in that gap could
+  materialize the stale Present entry and undo the archive. Inbound sessions now
+  carry an explicit last-observed disk receipt across reconciliation, durably
+  record local changes before merging, and guard final materialization. This
+  preserves deletes in both pre-merge and post-scan races while still accepting
+  genuinely new remote files, without deadlocking simultaneous peer syncs.
+
 - **Peer-config split when the daemon runs with `--home <default-root>`.** The
   managed service always launches the daemon as
   `--home ~/.local/share/fabric`, which made it read `peers.toml` from under that

src/daemon.rs

@@ -2532,17 +2532,21 @@ async fn handle_sync(connection: Connection, state: Arc<DaemonState>) -> Result<
     let resolver_engine = engine.clone();
     let outcome = sync::wire::run_server(stream, move |name| {
         let engine = resolver_engine.clone();
-        async move { engine.node_for(&name).await }
+        async move {
+            let prepared = engine.prepare_inbound(&name).await?;
+            Ok(prepared.map(|prepared| (prepared.node(), prepared)))
+        }
     })
     .await;
     match outcome {
-        Ok((name, stats)) => {
+        Ok((name, stats, prepared)) => {
             if !stats.is_noop() {
                 debug!(sync = %name, ?stats, "served sync reconcile");
             }
-            // Persist and write what the peer pushed to disk.
-            if let Err(error) = engine.materialize_entry(&name).await {
-                debug!(sync = %name, %error, "sync materialize failed");
+            // Re-scan changes that landed during the session, then persist and
+            // materialize while the inbound operation guard is still held.
+            if let Err(error) = engine.complete_inbound(prepared).await {
+                debug!(sync = %name, %error, "sync completion failed");
             }
         }
         Err(error) => debug!(%error, "sync serve failed"),