actions::destroy syncs meta after lifecycle

once nixos-container destroy lands + per-agent state cleanup is
done, rerender the meta flake from the remaining containers so
the destroyed agent's input + nixosConfiguration drop off and
its flake.lock entry vanishes. log + keep going on meta-sync
failure — the destroy already succeeded at the lifecycle level,
so meta drift here is just bookkeeping. new public
lifecycle::agents_for_meta_listing exposes the agent
enumeration for callers outside the module.

hive-c0re/src/actions.rs

@@ -261,6 +261,14 @@ pub async fn destroy(coord: &Coordinator, name: &str, purge: bool) -> Result<()>
             }
         }
     }
+    // Meta flake: drop the agent's input + nixosConfiguration so a
+    // future spawn under the same name re-seeds cleanly, and so the
+    // meta lock doesn't reference a vanished applied repo. Log + keep
+    // going on failure — destroy already succeeded at the
+    // nixos-container level, the meta repo is just bookkeeping.
+    if let Err(e) = sync_meta_after_lifecycle(coord).await {
+        tracing::warn!(error = ?e, %name, "meta sync after destroy failed");
+    }
     let _ = coord.approvals.fail_pending_for_agent(
         name,
         if purge {
@@ -276,6 +284,14 @@ pub async fn destroy(coord: &Coordinator, name: &str, purge: bool) -> Result<()>
     Ok(())
 }
 
+/// Rerender the meta flake from whatever containers still exist on
+/// disk. Called after lifecycle ops that change the agent set (today:
+/// destroy). Idempotent — a no-op when nothing changed.
+async fn sync_meta_after_lifecycle(coord: &Coordinator) -> Result<()> {
+    let agents = lifecycle::agents_for_meta_listing().await?;
+    crate::meta::sync_agents(&coord.hyperhive_flake, coord.dashboard_port, &agents).await
+}
+
 pub async fn deny(coord: &Coordinator, id: i64, note: Option<&str>) -> Result<()> {
     let approval = coord.approvals.get(id)?;
     coord.approvals.mark_denied(id, note)?;