feat(#2392): group boot sweep + reconciles under one boot dag

frontend/packages/dashboard/src/builds.js

@@ -215,11 +215,21 @@ function renderRebuildQueue(s) {
     }
     orderedLis.push(li);
   }
-  for (const top of tops) {
-    addEntry(top, false);
-    for (const child of childrenOf.get(top.id) || []) addEntry(child, true);
+  // Render each root followed by its whole subtree, depth-first. Recursion
+  // (rather than a single level of children) handles nested fan-outs such as
+  // the boot DAG: a `boot` root anchors the `startup_sweep` child, which itself
+  // fans out `rebuild` grandchildren — all of which must appear under the one
+  // boot tree. `visited` guards against re-rendering a node reached twice and
+  // any malformed parent cycle.
+  const visited = new Set();
+  function addTree(entry, isChild) {
+    if (visited.has(entry.id)) return;
+    visited.add(entry.id);
+    addEntry(entry, isChild);
+    for (const child of childrenOf.get(entry.id) || []) addTree(child, true);
   }
-  for (const o of orphans) addEntry(o, true);
+  for (const top of tops) addTree(top, false);
+  for (const o of orphans) addTree(o, true);
 
   const liveIds = new Set(queue.map((e) => e.id));
   for (const [id, entry] of rebuildQueueRowCache) {

hive-c0re/src/job_queue/exec.rs

@@ -94,6 +94,9 @@ pub(super) async fn run_node(coord: &Arc<Coordinator>, claim: &Claim) -> Result<
         NodeKind::WriteDropin => run_write_dropin(coord, claim).await,
         NodeKind::WritePermFile => run_write_perm_file(coord, claim, &ctx).await,
         NodeKind::ApprovalDeploy => run_approval_deploy(coord, claim).await,
+        // A pure grouping anchor (boot root): no work, completes immediately so
+        // its child DAGs settle it and the boot tree resolves.
+        NodeKind::Noop => Ok(NodeOutput::default()),
     }
 }
 

hive-c0re/src/job_queue/model.rs

@@ -125,6 +125,12 @@ pub enum NodeKind {
     /// deploy stays inside `actions.rs` in v1 — deliberately not
     /// modeled as scheduler nodes (see the design doc §9).
     ApprovalDeploy,
+    /// No-op anchor that completes immediately with no work. It exists so a
+    /// boot's `StartupSweep` + per-agent `Reconcile` child DAGs can hang off
+    /// one root (`parent_id`) and render as a single boot tree on the
+    /// dashboard. Holds no lease and no build slot; the child DAGs it anchors
+    /// still run concurrently — the grouping is a display link, not a dep edge.
+    Noop,
 }
 
 impl NodeKind {
@@ -144,6 +150,7 @@ impl NodeKind {
             NodeKind::WriteDropin => "write_dropin",
             NodeKind::WritePermFile => "write_perm_file",
             NodeKind::ApprovalDeploy => "approval_deploy",
+            NodeKind::Noop => "noop",
         }
     }
 

hive-c0re/src/job_queue/templates.rs

@@ -281,6 +281,30 @@ pub fn meta_update(
 /// Boot-time sweep parent: bump meta's hyperhive input (non-fatal),
 /// then fan out `Rebuild` children for the precomputed stale agent
 /// list (topology-sorted by the caller).
+/// Boot-time root anchor DAG: a single [`NodeKind::Noop`] node that groups
+/// this boot's `StartupSweep` + per-agent `Reconcile` child DAGs (linked via
+/// `parent_id`) into one tree so the dashboard renders the boot as one entry.
+/// Holds no lease and does no work — the children it anchors still run
+/// concurrently. `auto_update::run` submits it first (when there's any boot
+/// work), then parents the sweep + reconciles onto its id.
+pub fn boot_root(reason: String) -> DagSpec {
+    DagSpec {
+        template: Template::Boot,
+        agent: "hyperhive".to_owned(),
+        source: Source::AutoUpdate,
+        reason,
+        parent_id: None,
+        approval_id: None,
+        inputs: Vec::new(),
+        perm_payload: None,
+        transient: None,
+        nodes: vec![NodeSpec {
+            kind: NodeKind::Noop,
+            deps: Vec::new(),
+        }],
+    }
+}
+
 pub fn startup_sweep(reason: String, stale_agents: Vec<String>) -> DagSpec {
     DagSpec {
         template: Template::StartupSweep,

hive-c0re/src/workers/auto_update.rs

@@ -273,10 +273,52 @@ pub async fn run(coord: Arc<Coordinator>) -> Result<()> {
         "boot reconcile"
     );
 
-    // Sweep parent whenever ANY marker is stale — even when every
-    // stale agent is wanted-offline: the hyperhive lock bump must land
-    // now so their later start-upgrade rebuilds build against it.
-    // No stale agents ⇒ no sweep ⇒ no meta commit on a no-change boot.
+    submit_boot_tree(&coord, any_stale, fanout, drifted, n_deferred, n_skipped);
+    Ok(())
+}
+
+/// Submit this boot's DAGs under one `Boot` root: a `Noop` anchor with the
+/// startup sweep + per-agent reconciles hung off it via `parent_id`, so the
+/// dashboard renders the boot as a single tree instead of N+1 rows. No-op when
+/// there's nothing to do. The `parent_id` link is a display grouping, not a
+/// dependency edge — the children run concurrently, so the reconciles never
+/// wait behind the lock bump.
+fn submit_boot_tree(
+    coord: &Arc<Coordinator>,
+    any_stale: bool,
+    fanout: Vec<String>,
+    drifted: Vec<String>,
+    n_deferred: usize,
+    n_skipped: usize,
+) {
+    // Only emit a boot root when there's actually boot work — a fully-quiet
+    // boot (nothing stale, nothing drifted) submits nothing, exactly as before.
+    let boot_root_id = if any_stale || !drifted.is_empty() {
+        let reason = format!(
+            "boot: {} rebuild(s), {} reconcile(s), {} deferred (offline), {} up-to-date",
+            fanout.len(),
+            drifted.len(),
+            n_deferred,
+            n_skipped,
+        );
+        match coord
+            .job_queue
+            .submit(crate::job_queue::templates::boot_root(reason))
+        {
+            Ok(id) => Some(id),
+            Err(e) => {
+                tracing::warn!(error = ?e, "boot reconcile: boot-root submit failed");
+                None
+            }
+        }
+    } else {
+        None
+    };
+
+    // Sweep whenever ANY marker is stale — even when every stale agent is
+    // wanted-offline: the hyperhive lock bump must land now so their later
+    // start-upgrade rebuilds build against it. No stale agents ⇒ no sweep ⇒ no
+    // meta commit on a no-change boot.
     if any_stale {
         let reason = format!(
             "startup sweep: {} rebuild(s), {} deferred (offline), {} up-to-date",
@@ -284,27 +326,24 @@ pub async fn run(coord: Arc<Coordinator>) -> Result<()> {
             n_deferred,
             n_skipped,
         );
-        if let Err(e) = coord
-            .job_queue
-            .submit(crate::job_queue::templates::startup_sweep(reason, fanout))
-        {
+        let mut spec = crate::job_queue::templates::startup_sweep(reason, fanout);
+        spec.parent_id = boot_root_id;
+        if let Err(e) = coord.job_queue.submit(spec) {
             tracing::warn!(error = ?e, "boot reconcile: sweep submit failed");
         }
     }
     for name in drifted {
-        if let Err(e) = coord
-            .job_queue
-            .submit(crate::job_queue::templates::reconcile_only(
-                crate::job_queue::Template::Reconcile,
-                &name,
-                crate::job_queue::Source::AutoUpdate,
-                "boot reconcile".to_owned(),
-                None,
-            ))
-        {
+        let mut spec = crate::job_queue::templates::reconcile_only(
+            crate::job_queue::Template::Reconcile,
+            &name,
+            crate::job_queue::Source::AutoUpdate,
+            "boot reconcile".to_owned(),
+            None,
+        );
+        spec.parent_id = boot_root_id;
+        if let Err(e) = coord.job_queue.submit(spec) {
             tracing::warn!(%name, error = ?e, "boot reconcile: submit failed");
         }
     }
     coord.emit_rebuild_queue_snapshot();
-    Ok(())
 }

hive-sh4re/src/jobs.rs

@@ -40,6 +40,10 @@ pub enum Template {
     /// Bare converge of observed power state to the persisted intent
     /// (boot reconcile).
     Reconcile,
+    /// Boot-time root anchor: a single no-op node that groups this boot's
+    /// `StartupSweep` + per-agent `Reconcile` child DAGs under one tree, so the
+    /// dashboard renders the whole boot as one entry instead of N+1 rows.
+    Boot,
 }
 
 impl Template {
@@ -57,6 +61,7 @@ impl Template {
             Template::Start => "start",
             Template::Stop => "stop",
             Template::Reconcile => "reconcile",
+            Template::Boot => "boot",
         }
     }
 }