refactor(#3): topology-based rebuild ordering — parents before children

hive-c0re/src/auto_update.rs

@@ -200,6 +200,41 @@ pub async fn ensure_manager(coord: &Arc<Coordinator>) -> Result<()> {
     Ok(())
 }
 
+/// Sort `names` in-place so parents precede their children in the topology.
+/// Uses BFS from root agents (depth 0). Agents absent from `topo` sort last,
+/// alphabetically within their tier. Stable within each depth tier.
+fn topology_sort(names: &mut Vec<String>, topo: &std::collections::BTreeMap<String, Option<String>>) {
+    use std::collections::{HashMap, VecDeque};
+    // Build depth map using owned clones so the borrow on `names` is released
+    // before the sort_by mutable borrow.
+    let name_set: Vec<String> = names.clone();
+    let mut depth: HashMap<String, usize> = HashMap::new();
+    let mut queue: VecDeque<String> = VecDeque::new();
+    // Seed roots: entries with no parent, or names not present in topo at all.
+    for name in &name_set {
+        if topo.get(name).map_or(true, |p| p.is_none()) {
+            depth.insert(name.clone(), 0);
+            queue.push_back(name.clone());
+        }
+    }
+    // BFS to assign depths to children.
+    while let Some(parent) = queue.pop_front() {
+        let d = depth[&parent] + 1;
+        for name in &name_set {
+            let is_child = topo.get(name).and_then(|p| p.as_deref()) == Some(parent.as_str());
+            if is_child && !depth.contains_key(name) {
+                depth.insert(name.clone(), d);
+                queue.push_back(name.clone());
+            }
+        }
+    }
+    names.sort_by(|a, b| {
+        let da = depth.get(a).copied().unwrap_or(usize::MAX);
+        let db = depth.get(b).copied().unwrap_or(usize::MAX);
+        da.cmp(&db).then(a.cmp(b))
+    });
+}
+
 /// Rebuild every container on startup. Enqueues a `StartupSweep` parent
 /// entry (agent = `"hyperhive"`) followed by per-agent `Rebuild` children
 /// linked via `parent_id`. The dashboard renders them nested so the operator
@@ -231,13 +266,23 @@ pub async fn run(coord: Arc<Coordinator>) -> Result<()> {
         "auto-update: queueing all on startup"
     );
 
-    for container in &containers {
-        let logical = if container == MANAGER_NAME {
-            Some(MANAGER_NAME.to_owned())
-        } else {
-            container.strip_prefix(AGENT_PREFIX).map(str::to_owned)
-        };
-        let Some(name) = logical else { continue };
+    // Resolve container names to logical agent names, then sort by
+    // topology depth so parents are always rebuilt before their
+    // children. Root agents (depth 0) go first; agents absent from
+    // the topology file sort last (stable, alphabetical within tier).
+    let mut logical_names: Vec<String> = containers
+        .iter()
+        .filter_map(|c| {
+            if c == MANAGER_NAME {
+                Some(MANAGER_NAME.to_owned())
+            } else {
+                c.strip_prefix(AGENT_PREFIX).map(str::to_owned)
+            }
+        })
+        .collect();
+    let topo = crate::topology::read();
+    topology_sort(&mut logical_names, &topo);
+    for name in logical_names {
         coord.rebuild_queue.enqueue(
             crate::rebuild_queue::QueueKind::Rebuild,
             name,