diff --git a/crates/omnigraph-server/src/lib.rs b/crates/omnigraph-server/src/lib.rs
index 0b005e3..01312c9 100644
--- a/crates/omnigraph-server/src/lib.rs
+++ b/crates/omnigraph-server/src/lib.rs
@@ -1032,29 +1032,30 @@ async fn open_multi_graph_state(
     server_policy_file: Option<&PathBuf>,
     config_path: PathBuf,
 ) -> Result<AppState> {
-    use futures::StreamExt;
+    use futures::{StreamExt, TryStreamExt};
 
     if graphs.is_empty() {
         bail!("multi-graph mode requires at least one graph in the `graphs:` map");
     }
 
     // Server-level policy (loaded once, applies to management endpoints).
-    // The placeholder graph_id `"server"` matches the PolicyEngine API
-    // shape until the Cedar resource-model refactor (PR 6a) lands.
+    // The placeholder graph_id `"server"` is the sentinel the Cedar
+    // resource-model refactor maps to the singleton
+    // `Omnigraph::Server::"root"` entity at evaluation time.
     let server_policy = match server_policy_file {
         Some(path) => Some(PolicyEngine::load(path, "server")?),
         None => None,
     };
 
+    // `try_collect` propagates the first error eagerly, dropping every
+    // in-flight open. `buffer_unordered + collect::<Vec<_>>` would drain
+    // the stream before checking errors — incorrect for the docstring's
+    // "fail-fast" claim and wasteful on S3-backed graphs.
     let handles: Vec<Arc<GraphHandle>> = futures::stream::iter(graphs.into_iter())
-        .map(|cfg| async move {
-            open_single_graph(cfg).await
-        })
+        .map(|cfg| async move { open_single_graph(cfg).await })
         .buffer_unordered(4)
-        .collect::<Vec<_>>()
-        .await
-        .into_iter()
-        .collect::<Result<Vec<_>>>()?;
+        .try_collect()
+        .await?;
 
     let workload = workload::WorkloadController::from_env();
     let state = AppState::new_multi(