chore: consistently used the arc shared workers configs + CI flake fixes (#5707)

Signed-off-by: PeaBrane <yanrpei@gmail.com>

lib/llm/src/discovery.rs

@@ -2,7 +2,10 @@
 // SPDX-License-Identifier: Apache-2.0
 
 mod model_manager;
-pub use model_manager::{ModelManager, ModelManagerError, RuntimeConfigsWithNotify};
+pub use model_manager::{ModelManager, ModelManagerError};
+
+pub(crate) mod runtime_configs;
+pub use runtime_configs::{RuntimeConfigs, RuntimeConfigsSubscriber};
 
 mod watcher;
 pub use watcher::{ModelUpdate, ModelWatcher};

lib/llm/src/discovery/model_manager.rs

@@ -8,13 +8,14 @@ use std::{
 
 use dashmap::{DashMap, mapref::entry::Entry};
 use parking_lot::{Mutex, RwLock};
-use tokio::sync::{Notify, oneshot};
+use tokio::sync::oneshot;
 
 use crate::discovery::KvWorkerMonitor;
+use crate::discovery::runtime_configs::RuntimeConfigs;
 
 use dynamo_runtime::{
     component::{Client, Endpoint, build_transport_type},
-    discovery::{DiscoveryQuery, DiscoverySpec, watch_and_extract_field},
+    discovery::DiscoverySpec,
     prelude::DistributedRuntimeProvider,
     protocols::EndpointId,
 };
@@ -24,7 +25,7 @@ use crate::{
         KvRouter, KvRouterConfig, protocols::WorkerId, router_endpoint_id,
         scheduler::DefaultWorkerSelector,
     },
-    local_model::runtime_config::{DisaggregatedEndpoint, ModelRuntimeConfig},
+    local_model::runtime_config::DisaggregatedEndpoint,
     model_card::ModelDeploymentCard,
     model_type::ModelType,
     types::{
@@ -81,14 +82,8 @@ pub struct ModelManager {
 
     /// Runtime configs per endpoint using DashMap for lock-free access.
     /// Outer DashMap: keyed by EndpointId
-    /// Inner RuntimeConfigsWithNotify: shared with KvScheduler
-    runtime_configs: DashMap<EndpointId, Arc<RuntimeConfigsWithNotify>>,
-}
-
-/// Runtime configs for an endpoint with a notify for change notifications.
-pub struct RuntimeConfigsWithNotify {
-    pub configs: DashMap<WorkerId, Option<ModelRuntimeConfig>>,
-    pub notify: Notify,
+    /// Inner RuntimeConfigs: shared with KvScheduler
+    runtime_configs: DashMap<EndpointId, Arc<RuntimeConfigs>>,
 }
 
 impl Default for ModelManager {
@@ -621,12 +616,12 @@ impl ModelManager {
     }
 
     /// Get or create a runtime config watcher for an endpoint.
-    /// Spawns a background task to watch DiscoveryQuery::EndpointModels.
-    /// Returns a shared RuntimeConfigsWithNotify that KvScheduler can use directly.
+    /// Spawns a background task to watch for worker config changes.
+    /// Returns a shared RuntimeConfigs that KvScheduler can use directly.
     pub async fn get_or_create_runtime_config_watcher(
         &self,
         endpoint: &Endpoint,
-    ) -> anyhow::Result<Arc<RuntimeConfigsWithNotify>> {
+    ) -> anyhow::Result<Arc<RuntimeConfigs>> {
         let endpoint_id = endpoint.id();
 
         // Fast path: return existing if present
@@ -635,10 +630,7 @@ impl ModelManager {
         }
 
         // Atomic get-or-insert to avoid TOCTOU race
-        let inner = Arc::new(RuntimeConfigsWithNotify {
-            configs: DashMap::new(),
-            notify: Notify::new(),
-        });
+        let inner = Arc::new(RuntimeConfigs::new());
         let (result, is_new) = match self.runtime_configs.entry(endpoint_id) {
             Entry::Occupied(e) => (e.get().clone(), false),
             Entry::Vacant(e) => {
@@ -649,8 +641,7 @@ impl ModelManager {
 
         // Only spawn watcher if we were the one who inserted
         if is_new {
-            self.spawn_runtime_config_watcher(endpoint, result.clone())
-                .await?;
+            result.start_watcher(endpoint).await?;
         }
 
         Ok(result)
@@ -668,126 +659,6 @@ impl ModelManager {
         config_ref.as_ref()?.disaggregated_endpoint.clone()
     }
 
-    /// Spawn background task to watch runtime configs via discovery.
-    /// Blocks until at least one worker with a runtime config is available.
-    async fn spawn_runtime_config_watcher(
-        &self,
-        endpoint: &Endpoint,
-        inner: Arc<RuntimeConfigsWithNotify>,
-    ) -> anyhow::Result<()> {
-        let component = endpoint.component();
-        let cancellation_token = component.drt().primary_token();
-
-        // Set up discovery watch for EndpointModels
-        let discovery = component.drt().discovery();
-        let endpoint_id = endpoint.id();
-        let discovery_key = DiscoveryQuery::EndpointModels {
-            namespace: endpoint_id.namespace.clone(),
-            component: endpoint_id.component.clone(),
-            endpoint: endpoint_id.name.clone(),
-        };
-        let discovery_stream = discovery
-            .list_and_watch(discovery_key.clone(), Some(cancellation_token.clone()))
-            .await?;
-
-        // Extract runtime_config from ModelDeploymentCard
-        let mut runtime_configs_rx =
-            watch_and_extract_field(discovery_stream, |card: ModelDeploymentCard| {
-                card.runtime_config
-            });
-
-        // Also watch instance IDs
-        let client = endpoint.client().await?;
-        let mut instance_ids_rx = client.instance_avail_watcher();
-
-        // Wait for at least one worker with runtime config before proceeding.
-        // This ensures the DashMap is populated before KvScheduler starts.
-        tracing::info!("ModelManager: Waiting for at least one worker with runtime config...");
-        runtime_configs_rx
-            .changed()
-            .await
-            .map_err(|_| anyhow::anyhow!("runtime configs watch sender shutdown while waiting"))?;
-
-        // Populate initial state
-        {
-            let instance_ids = instance_ids_rx.borrow();
-            let configs = runtime_configs_rx.borrow();
-            for worker_id in instance_ids.iter() {
-                let config = configs.get(worker_id).cloned();
-                inner.configs.insert(*worker_id, config);
-            }
-            tracing::info!(
-                "ModelManager: Found {} workers, proceeding",
-                inner.configs.len()
-            );
-        }
-
-        // Spawn background task to update configs for future changes
-        let cancel_token = cancellation_token.clone();
-        tokio::spawn(async move {
-            tracing::trace!("ModelManager runtime config watcher started");
-            loop {
-                // Wait for either instances or configs to change
-                tokio::select! {
-                    _ = cancel_token.cancelled() => {
-                        tracing::trace!("ModelManager runtime config watcher shutting down");
-                        break;
-                    }
-                    result = instance_ids_rx.changed() => {
-                        if result.is_err() {
-                            tracing::warn!("instance IDs watch sender shutdown in ModelManager");
-                            break;
-                        }
-                    }
-                    result = runtime_configs_rx.changed() => {
-                        if result.is_err() {
-                            tracing::warn!("runtime configs watch sender shutdown in ModelManager");
-                            break;
-                        }
-                    }
-                }
-
-                // Get the latest values from both channels
-                let new_instance_ids = instance_ids_rx.borrow_and_update().clone();
-                let new_configs = runtime_configs_rx.borrow_and_update().clone();
-
-                // Update the DashMap
-                // First, remove workers that no longer exist
-                let current_workers: HashSet<WorkerId> =
-                    inner.configs.iter().map(|r| *r.key()).collect();
-                let new_workers: HashSet<WorkerId> = new_instance_ids.iter().copied().collect();
-                for removed_worker in current_workers.difference(&new_workers) {
-                    inner.configs.remove(removed_worker);
-                }
-
-                // Then, add/update workers
-                for worker_id in &new_instance_ids {
-                    let config = new_configs.get(worker_id).cloned();
-                    if config.is_some() {
-                        let prev_config = inner.configs.get(worker_id);
-                        if prev_config.as_ref().map(|r| r.value()) != Some(&config) {
-                            tracing::info!(
-                                "ModelManager: Runtime config found for worker_id: {worker_id}"
-                            );
-                        }
-                    }
-                    inner.configs.insert(*worker_id, config);
-                }
-
-                // Notify waiters that configs have changed
-                inner.notify.notify_waiters();
-
-                tracing::trace!(
-                    "ModelManager: Updated runtime_configs with {} workers",
-                    inner.configs.len()
-                );
-            }
-            tracing::trace!("ModelManager runtime config watcher shutting down");
-        });
-
-        Ok(())
-    }
-
     /// Lists all models that have worker monitors (and thus busy thresholds) configured.
     ///
     /// Returns a vector of (model_name, active_decode_blocks_threshold, active_prefill_tokens_threshold) tuples.

lib/llm/src/discovery/runtime_configs.rs

+// SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+use std::collections::{HashMap, HashSet};
+use std::sync::Arc;
+
+use dashmap::DashMap;
+use tokio::sync::watch;
+
+use dynamo_runtime::component::Endpoint;
+use dynamo_runtime::discovery::{DiscoveryQuery, watch_and_extract_field};
+use dynamo_runtime::prelude::DistributedRuntimeProvider;
+
+use crate::kv_router::protocols::WorkerId;
+use crate::local_model::runtime_config::ModelRuntimeConfig;
+use crate::model_card::ModelDeploymentCard;
+
+/// Runtime configs for an endpoint with watch-based change notifications.
+/// Call `subscribe()` to get a subscriber with its own watch receiver.
+pub struct RuntimeConfigs {
+    pub configs: Arc<DashMap<WorkerId, Option<ModelRuntimeConfig>>>,
+    change_tx: watch::Sender<u64>,
+}
+
+impl RuntimeConfigs {
+    pub(crate) fn new() -> Self {
+        let (change_tx, _) = watch::channel(0u64);
+        Self {
+            configs: Arc::new(DashMap::new()),
+            change_tx,
+        }
+    }
+
+    /// Create a subscriber that can wait for config changes.
+    /// Each subscriber has its own watch receiver, so notifications are not lost.
+    pub fn subscribe(&self) -> RuntimeConfigsSubscriber {
+        RuntimeConfigsSubscriber {
+            configs: self.configs.clone(),
+            change_rx: self.change_tx.subscribe(),
+        }
+    }
+
+    /// Notify all subscribers of a change (internal use only).
+    fn notify_change(&self) {
+        // Increment counter to notify subscribers
+        self.change_tx.send_modify(|v| *v = v.wrapping_add(1));
+    }
+
+    /// Returns the number of workers in the configs.
+    pub fn num_workers(&self) -> usize {
+        self.configs.len()
+    }
+
+    /// Update configs with new worker instances and their configs.
+    /// Notifies subscribers if a config with Some value is added or a worker is removed.
+    pub(crate) fn update(
+        &self,
+        new_instance_ids: &[WorkerId],
+        new_configs: &HashMap<WorkerId, ModelRuntimeConfig>,
+    ) {
+        // First, remove workers that no longer exist
+        let current_workers: HashSet<WorkerId> = self.configs.iter().map(|r| *r.key()).collect();
+        let new_workers: HashSet<WorkerId> = new_instance_ids.iter().copied().collect();
+        let mut worker_removed = false;
+        for removed_worker in current_workers.difference(&new_workers) {
+            self.configs.remove(removed_worker);
+            worker_removed = true;
+        }
+
+        // Then, add/update workers
+        // Track if any config became Some (for notify)
+        let mut config_added = false;
+        for worker_id in new_instance_ids {
+            let config = new_configs.get(worker_id).cloned();
+            if config.is_some() {
+                let prev_config = self.configs.get(worker_id);
+                let was_none = prev_config
+                    .as_ref()
+                    .map(|r| r.value().is_none())
+                    .unwrap_or(true);
+                if was_none {
+                    tracing::info!("RuntimeConfigs: config found for worker_id: {worker_id}");
+                    config_added = true;
+                }
+            }
+            self.configs.insert(*worker_id, config);
+        }
+
+        // Notify when a config with Some value is added OR a worker is removed
+        if config_added || worker_removed {
+            self.notify_change();
+        }
+    }
+
+    /// Spawn background task to watch runtime configs via discovery.
+    /// Does not block - consumers should use `subscribe().wait_for_some()` if they need workers.
+    pub(crate) async fn start_watcher(self: &Arc<Self>, endpoint: &Endpoint) -> anyhow::Result<()> {
+        let component = endpoint.component();
+        let cancellation_token = component.drt().primary_token();
+
+        // Set up discovery watch for EndpointModels
+        let discovery = component.drt().discovery();
+        let endpoint_id = endpoint.id();
+        let discovery_key = DiscoveryQuery::EndpointModels {
+            namespace: endpoint_id.namespace.clone(),
+            component: endpoint_id.component.clone(),
+            endpoint: endpoint_id.name.clone(),
+        };
+        let discovery_stream = discovery
+            .list_and_watch(discovery_key.clone(), Some(cancellation_token.clone()))
+            .await?;
+
+        // Extract runtime_config from ModelDeploymentCard
+        let mut runtime_configs_rx =
+            watch_and_extract_field(discovery_stream, |card: ModelDeploymentCard| {
+                card.runtime_config
+            });
+
+        // Also watch instance IDs
+        let client = endpoint.client().await?;
+        let mut instance_ids_rx = client.instance_avail_watcher();
+
+        // Spawn background task to watch for config changes
+        // Note: We don't block here - consumers should wait on notify for configs they need
+        let inner = self.clone();
+        let cancel_token = cancellation_token.clone();
+        tokio::spawn(async move {
+            tracing::trace!("RuntimeConfigs watcher started");
+            loop {
+                // Wait for either instances or configs to change
+                tokio::select! {
+                    _ = cancel_token.cancelled() => {
+                        tracing::trace!("RuntimeConfigs watcher shutting down");
+                        break;
+                    }
+                    result = instance_ids_rx.changed() => {
+                        if result.is_err() {
+                            tracing::warn!("instance IDs watch sender shutdown");
+                            break;
+                        }
+                    }
+                    result = runtime_configs_rx.changed() => {
+                        if result.is_err() {
+                            tracing::warn!("runtime configs watch sender shutdown");
+                            break;
+                        }
+                    }
+                }
+
+                // Get the latest values from both channels
+                let new_instance_ids = instance_ids_rx.borrow_and_update().clone();
+                let new_configs = runtime_configs_rx.borrow_and_update().clone();
+
+                inner.update(&new_instance_ids, &new_configs);
+
+                tracing::trace!(
+                    "RuntimeConfigs: Updated with {} workers",
+                    inner.configs.len()
+                );
+            }
+            tracing::trace!("RuntimeConfigs watcher stopped");
+        });
+
+        Ok(())
+    }
+}
+
+/// A subscriber to runtime config changes.
+/// Each subscriber has its own watch receiver, ensuring no notifications are lost.
+pub struct RuntimeConfigsSubscriber {
+    pub configs: Arc<DashMap<WorkerId, Option<ModelRuntimeConfig>>>,
+    pub change_rx: watch::Receiver<u64>,
+}
+
+impl RuntimeConfigsSubscriber {
+    /// Wait until at least one worker has a Some config.
+    /// Returns the list of worker IDs that have configs.
+    /// This is race-safe: checks the DashMap first, only waits if empty.
+    /// Returns empty vec if the sender is dropped (shutdown).
+    pub async fn wait_for_some(&mut self) -> Vec<WorkerId> {
+        loop {
+            let ready: Vec<WorkerId> = self
+                .configs
+                .iter()
+                .filter(|r| r.value().is_some())
+                .map(|r| *r.key())
+                .collect();
+
+            if !ready.is_empty() {
+                return ready;
+            }
+
+            // If sender dropped (shutdown), return empty rather than loop forever
+            if self.change_rx.changed().await.is_err() {
+                tracing::warn!("RuntimeConfigsSubscriber: sender dropped during wait_for_some");
+                return vec![];
+            }
+        }
+    }
+}

lib/llm/src/hub.rs

@@ -4,6 +4,7 @@
 use std::env;
 use std::path::{Path, PathBuf};
 
+use hf_hub::Cache;
 use modelexpress_client::{
     Client as MxClient, ClientConfig as MxClientConfig, ModelProvider as MxModelProvider,
 };
@@ -11,14 +12,77 @@ use modelexpress_common::download as mx;
 
 use dynamo_runtime::config::environment_names::model as env_model;
 
+/// Check if a model is already cached in the HuggingFace hub cache directory.
+/// Returns the path to the cached model directory if found, None otherwise.
+///
+/// Uses hf-hub's Cache API to check for cached files. For tokenizer-only downloads
+/// (ignore_weights=true), we check for config.json and tokenizer files.
+/// For full downloads, we also require weight files to be present.
+fn get_cached_model_path(model_name: &str, ignore_weights: bool) -> Option<PathBuf> {
+    let cache = Cache::new(get_model_express_cache_dir());
+    let repo = cache.model(model_name.to_string());
+
+    // Check for required config file
+    let config_path = repo.get("config.json")?;
+
+    // Check for tokenizer files (at least one must exist)
+    let has_tokenizer =
+        repo.get("tokenizer.json").is_some() || repo.get("tokenizer_config.json").is_some();
+
+    if !has_tokenizer {
+        return None;
+    }
+
+    // For full downloads, check for weight files
+    if !ignore_weights {
+        // Check common weight file patterns - at least one must exist
+        let has_weights = repo.get("model.safetensors").is_some()
+            || repo.get("pytorch_model.bin").is_some()
+            || repo.get("model.safetensors.index.json").is_some()
+            || repo.get("pytorch_model.bin.index.json").is_some();
+
+        if !has_weights {
+            return None;
+        }
+    }
+
+    // Return the parent directory (snapshot dir) containing the model files
+    let snapshot_path = config_path.parent()?.to_path_buf();
+    tracing::info!("Found cached model '{model_name}' at {snapshot_path:?}, skipping download");
+    Some(snapshot_path)
+}
+
+/// Check if offline mode is enabled via HF_HUB_OFFLINE environment variable.
+fn is_offline_mode() -> bool {
+    env::var(env_model::huggingface::HF_HUB_OFFLINE)
+        .map(|v| v == "1" || v.to_lowercase() == "true")
+        .unwrap_or(false)
+}
+
 /// Download a model using ModelExpress client. The client first requests for the model
 /// from the server and fallbacks to direct download in case of server failure.
 /// If ignore_weights is true, model weight files will be skipped
 /// Returns the path to the model files
+///
+/// If HF_HUB_OFFLINE=1 is set and the model is already cached, returns the cached
+/// path without making any API calls to HuggingFace.
 pub async fn from_hf(name: impl AsRef<Path>, ignore_weights: bool) -> anyhow::Result<PathBuf> {
     let name = name.as_ref();
     let model_name = name.display().to_string();
 
+    // In offline mode, check cache first and return immediately if found
+    if is_offline_mode() {
+        if let Some(cached_path) = get_cached_model_path(&model_name, ignore_weights) {
+            tracing::info!(
+                "Offline mode: using cached model '{model_name}' without API validation"
+            );
+            return Ok(cached_path);
+        }
+        tracing::warn!(
+            "Offline mode enabled but model '{model_name}' not found in cache, attempting download anyway"
+        );
+    }
+
     let mut config: MxClientConfig = MxClientConfig::default();
     if let Ok(endpoint) = env::var(env_model::model_express::MODEL_EXPRESS_URL) {
         config = config.with_endpoint(endpoint);

lib/llm/src/kv_router.rs

@@ -9,7 +9,7 @@ use anyhow::Result;
 use derive_builder::Builder;
 use dynamo_runtime::{
     component::{Client, Endpoint},
-    discovery::{DiscoveryQuery, EventTransportKind, watch_and_extract_field},
+    discovery::{DiscoveryQuery, EventTransportKind},
     pipeline::{
         AsyncEngine, AsyncEngineContextProvider, Error, ManyOut, PushRouter, ResponseStream,
         SingleIn, async_trait,
@@ -41,7 +41,7 @@ pub use prefill_router::PrefillRouter;
 use worker_query::WorkerQueryClient;
 
 use crate::{
-    discovery::RuntimeConfigsWithNotify,
+    discovery::RuntimeConfigs,
     kv_router::{
         approx::PruneConfig,
         indexer::{KvIndexer, KvIndexerInterface, KvRouterError},
@@ -55,7 +55,6 @@ use crate::{
         subscriber::{start_kv_router_background, start_kv_router_background_event_plane},
     },
     local_model::runtime_config::ModelRuntimeConfig,
-    model_card::ModelDeploymentCard,
     preprocessor::PreprocessedRequest,
     protocols::common::llm_backend::LLMEngineOutput,
     protocols::common::timing::RequestPhase,
@@ -332,7 +331,7 @@ impl KvRouter {
     pub async fn new(
         endpoint: Endpoint,
         client: Client,
-        workers_with_configs: Arc<RuntimeConfigsWithNotify>,
+        workers_with_configs: Arc<RuntimeConfigs>,
         block_size: u32,
         selector: Option<Box<dyn WorkerSelector + Send + Sync>>,
         kv_router_config: Option<KvRouterConfig>,
@@ -342,23 +341,6 @@ impl KvRouter {
         let component = endpoint.component();
         let cancellation_token = component.drt().primary_token();
 
-        // Watch for runtime config updates via discovery interface
-        // (still needed for WorkerQueryClient and background tasks)
-        let discovery = component.drt().discovery();
-        let endpoint_id = endpoint.id();
-        let discovery_key = DiscoveryQuery::EndpointModels {
-            namespace: endpoint_id.namespace.clone(),
-            component: endpoint_id.component.clone(),
-            endpoint: endpoint_id.name.clone(),
-        };
-        let discovery_stream = discovery
-            .list_and_watch(discovery_key.clone(), Some(cancellation_token.clone()))
-            .await?;
-        let runtime_configs_rx =
-            watch_and_extract_field(discovery_stream, |card: ModelDeploymentCard| {
-                card.runtime_config
-            });
-
         let indexer = if kv_router_config.overlap_score_weight == 0.0 {
             // When overlap_score_weight is zero, we don't need to track prefixes
             Indexer::None
@@ -385,6 +367,9 @@ impl KvRouter {
             ))
         };
 
+        // Wait for at least one worker with a known runtime config before starting scheduler
+        workers_with_configs.subscribe().wait_for_some().await;
+
         let scheduler = KvScheduler::start(
             component.clone(),
             block_size,
@@ -397,30 +382,27 @@ impl KvRouter {
 
         // Initialize worker query client using namespace abstraction
         // (created before background task so we can use it for startup recovery)
-        let worker_query_client =
-            worker_query::WorkerQueryClient::new(component.clone(), runtime_configs_rx.clone());
+        // Uses a subscriber from workers_with_configs
+        let worker_query_client = worker_query::WorkerQueryClient::new(
+            component.clone(),
+            workers_with_configs.subscribe(),
+        );
         tracing::info!("Worker query client initialized");
 
         // Start KV event subscriber background process (only when use_kv_events is enabled)
-        // model_manager.get_or_create_runtime_config_watcher() guarantees at least one worker exists.
         if kv_router_config.use_kv_events
             && let Indexer::KvIndexer(ref kv_indexer) = indexer
         {
-            // model_manager guarantees workers_with_configs is populated
-            // Wait for at least one worker before starting the subscriber
-            while workers_with_configs.configs.is_empty() {
-                tracing::info!("KV router waiting for at least one worker...");
-                workers_with_configs.notify.notified().await;
-            }
-
-            let count = workers_with_configs.configs.len();
             let all_local_indexer = workers_with_configs
                 .configs
                 .iter()
                 .filter_map(|r| r.value().as_ref().map(|c| c.enable_local_indexer))
                 .all(|b| b);
 
-            tracing::info!("Found {count} worker(s), starting KV event subscriber");
+            tracing::info!(
+                "Found {} worker(s), starting KV event subscriber",
+                workers_with_configs.num_workers()
+            );
 
             let transport_kind = EventTransportKind::from_env_or_default();
 
@@ -436,7 +418,8 @@ impl KvRouter {
                     }
                 } else {
                     tracing::info!(
-                        "All {count} workers have local_indexer enabled, using NATS Core subscription"
+                        "All {} workers have local_indexer enabled, using NATS Core subscription",
+                        workers_with_configs.num_workers()
                     );
                 }
 
@@ -447,7 +430,7 @@ impl KvRouter {
                     cancellation_token.clone(),
                     worker_query::WorkerQueryClient::new(
                         component.clone(),
-                        runtime_configs_rx.clone(),
+                        workers_with_configs.subscribe(),
                     ),
                     transport_kind,
                 )

lib/llm/src/kv_router/publisher.rs

@@ -921,7 +921,7 @@ impl<'de> Visitor<'de> for RawKvEventVisitor {
 // -------------------------------------------------------------------------
 
 /// Metrics data passed through the channel for NATS publishing
-#[derive(Debug, Clone, Default)]
+#[derive(Debug, Clone, Default, PartialEq)]
 struct WorkerMetrics {
     dp_rank: DpRank,
     active_decode_blocks: u64,
@@ -982,7 +982,7 @@ impl WorkerMetricsPublisher {
                 };
 
             let mut rx = nats_rx;
-            let mut last_active_decode_blocks: Option<u64> = Some(0);
+            let mut last_metrics: Option<WorkerMetrics> = None;
             let mut pending_publish: Option<WorkerMetrics> = None;
             let mut publish_timer =
                 Box::pin(tokio::time::sleep(tokio::time::Duration::from_secs(0)));
@@ -1001,16 +1001,13 @@ impl WorkerMetricsPublisher {
 
                         let metrics = rx.borrow_and_update().clone();
 
-                        // Check if active_decode_blocks has changed
-                        let has_changed = match last_active_decode_blocks {
-                            Some(last) => last != metrics.active_decode_blocks,
-                            None => true, // First time, consider it changed
-                        };
+                        // Check if metrics have changed
+                        let has_changed = last_metrics.as_ref() != Some(&metrics);
 
-                        // If load metrics changed, schedule a publish
+                        // If metrics changed, schedule a publish
                         if has_changed {
                             pending_publish = Some(metrics.clone());
-                            last_active_decode_blocks = Some(metrics.active_decode_blocks);
+                            last_metrics = Some(metrics);
 
                             // Start the 1ms timer
                             publish_timer.as_mut().reset(

lib/llm/src/kv_router/scheduler.rs

 // SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::discovery::RuntimeConfigsWithNotify;
+use crate::discovery::RuntimeConfigs;
 use crate::local_model::runtime_config::ModelRuntimeConfig;
 use anyhow::Result;
 use dynamo_runtime::component::Component;
@@ -98,7 +98,7 @@ impl KvScheduler {
     pub async fn start(
         component: Component,
         block_size: u32,
-        workers_with_configs: Arc<RuntimeConfigsWithNotify>,
+        workers_with_configs: Arc<RuntimeConfigs>,
         selector: Option<Box<dyn WorkerSelector + Send + Sync>>,
         replica_sync: bool,
         router_id: u64,
@@ -106,7 +106,7 @@ impl KvScheduler {
         let selector = selector.unwrap_or(Box::new(DefaultWorkerSelector::default()));
 
         // Get initial workers from DashMap for slot initialization.
-        // ModelManager guarantees at least one worker is present before KvRouter::new() is called.
+        // Caller must ensure at least one worker is present (via wait_for_some).
         let initial_workers: HashMap<WorkerId, Option<ModelRuntimeConfig>> = workers_with_configs
             .configs
             .iter()
@@ -126,9 +126,11 @@ impl KvScheduler {
         );
 
         // Spawn background task to sync slots with DashMap when notified of changes.
-        // ModelManager's watcher updates the DashMap and notifies; we wait on notify here.
+        // ModelManager's watcher updates the DashMap and notifies; we wait on watch receiver here.
         let slots_monitor = slots.clone();
-        let workers_monitor = workers_with_configs.clone();
+        let subscriber = workers_with_configs.subscribe();
+        let configs_monitor = subscriber.configs;
+        let mut change_rx = subscriber.change_rx;
         let monitor_cancel_token = component.drt().child_token();
         tokio::spawn(async move {
             tracing::trace!("KvScheduler workers monitoring task started");
@@ -141,13 +143,17 @@ impl KvScheduler {
                         tracing::trace!("KvScheduler workers monitoring task shutting down");
                         break;
                     }
-                    _ = workers_monitor.notify.notified() => {}
+                    result = change_rx.changed() => {
+                        if result.is_err() {
+                            tracing::warn!("KvScheduler: config watch sender dropped, shutting down");
+                            break;
+                        }
+                    }
                 }
 
                 // Get current workers from DashMap
                 let current_workers: HashMap<WorkerId, Option<ModelRuntimeConfig>> =
-                    workers_monitor
-                        .configs
+                    configs_monitor
                         .iter()
                         .map(|r| (*r.key(), r.value().clone()))
                         .collect();

lib/llm/src/kv_router/subscriber.rs

@@ -55,9 +55,9 @@ const WORKER_QUERY_INITIAL_BACKOFF_MS: u64 = 200;
 // Discovery Helpers
 // ============================================================================
 
-/// Wait for at least one worker instance to be discovered.
-/// Returns a peekable stream of discovery events for the generate endpoint.
-async fn wait_for_worker_instance(
+/// Get the instance discovery stream for monitoring worker add/remove events.
+/// Waits for at least one instance to be discovered before returning.
+async fn get_instance_discovery_stream(
     component: &Component,
     cancellation_token: &CancellationToken,
 ) -> Result<std::pin::Pin<Box<dyn futures::Stream<Item = Result<DiscoveryEvent>> + Send>>> {
@@ -524,7 +524,7 @@ pub async fn start_kv_router_background(
 
     // Wait for at least one worker instance before proceeding
     let mut instance_event_stream =
-        wait_for_worker_instance(&component, &cancellation_token).await?;
+        get_instance_discovery_stream(&component, &cancellation_token).await?;
 
     // Watch for router deletions to clean up orphaned consumers via discovery
     let generate_endpoint = component.endpoint("generate");
@@ -762,7 +762,7 @@ pub async fn start_kv_router_background_event_plane(
     kv_events_tx: mpsc::Sender<RouterEvent>,
     remove_worker_tx: mpsc::Sender<WorkerId>,
     cancellation_token: CancellationToken,
-    worker_query_client: WorkerQueryClient,
+    mut worker_query_client: WorkerQueryClient,
     transport_kind: EventTransportKind,
 ) -> Result<()> {
     // Subscribe to KV events using the selected event plane transport
@@ -792,44 +792,35 @@ pub async fn start_kv_router_background_event_plane(
         }
     }
 
-    // Wait for at least one worker instance before proceeding
-    let mut instance_event_stream =
-        wait_for_worker_instance(&component, &cancellation_token).await?;
-
-    // Drain and process all existing workers before spawning the background loop.
-    // list_and_watch returns existing instances first, so we poll with a short timeout
-    // to process all initial workers synchronously before the router becomes "ready".
-    loop {
-        // Use a short timeout to detect when initial discovery events are exhausted
-        let poll_result =
-            tokio::time::timeout(Duration::from_millis(100), instance_event_stream.next()).await;
+    // Wait for at least one worker with a known runtime config before proceeding.
+    // This ensures we have actual config data (including enable_local_indexer) available.
+    tracing::info!("KV subscriber waiting for at least one worker with runtime config...");
+    let ready_workers = worker_query_client.wait_for_ready().await;
+    tracing::info!(
+        "KV subscriber found {} worker(s) with runtime config, proceeding",
+        ready_workers.len()
+    );
 
-        match poll_result {
-            Ok(Some(Ok(event))) => {
-                handle_worker_discovery(
-                    event,
-                    &worker_query_client,
-                    &kv_events_tx,
-                    &remove_worker_tx,
-                )
-                .await;
-            }
-            Ok(Some(Err(e))) => {
-                tracing::warn!("Error receiving discovery event during initial sync: {e}");
+    // Recover initial state from all ready workers
+    for worker_id in &ready_workers {
+        if worker_query_client.has_local_indexer(*worker_id) {
+            match recover_from_worker(&worker_query_client, *worker_id, None, None, &kv_events_tx)
+                .await
+            {
+                Ok(count) => {
+                    tracing::info!("Successfully recovered {count} events from worker {worker_id}");
                 }
-            Ok(None) => {
-                // Stream ended
-                tracing::warn!("Discovery stream ended during initial sync");
-                break;
+                Err(e) => {
+                    tracing::warn!("Failed to recover from worker {worker_id}: {e}");
                 }
-            Err(_) => {
-                // Timeout - no more initial events
-                tracing::debug!("Initial worker discovery sync complete");
-                break;
             }
         }
     }
 
+    // Get instance discovery stream for ongoing monitoring of worker add/remove events
+    let mut instance_event_stream =
+        get_instance_discovery_stream(&component, &cancellation_token).await?;
+
     tokio::spawn(async move {
         // Track last received event ID per worker for gap detection
         let mut last_event_ids: HashMap<WorkerId, u64> = HashMap::new();

lib/llm/src/kv_router/worker_query.rs

 // SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-use std::collections::HashMap;
 use std::sync::Arc;
 
 use anyhow::{Context, Result};
@@ -11,46 +10,49 @@ use dynamo_runtime::pipeline::{
     SingleIn, async_trait, network::Ingress,
 };
 use dynamo_runtime::protocols::maybe_error::MaybeError;
-use tokio::sync::{OnceCell, watch};
+use tokio::sync::OnceCell;
 use tokio_stream::StreamExt;
 
+use crate::discovery::RuntimeConfigsSubscriber;
 use crate::kv_router::WORKER_KV_INDEXER_QUERY_ENDPOINT;
 use crate::kv_router::indexer::{LocalKvIndexer, WorkerKvQueryRequest, WorkerKvQueryResponse};
 use crate::kv_router::protocols::WorkerId;
-use crate::local_model::runtime_config::ModelRuntimeConfig;
 use dynamo_runtime::stream;
 
 /// Router-side client for querying worker local KV indexers
 ///
 /// Performs request/reply communication with workers via request plane endpoint routing.
 /// (Only queries workers that have `enable_local_indexer=true` in their MDC user_data)
-/// The client is spawned by KvRouter; it watches same discovery stream as the router.
+/// The client is spawned by KvRouter; it uses a subscriber from RuntimeConfigs.
 pub struct WorkerQueryClient {
     component: Component,
-    /// Watch receiver for enable_local_indexer state per worker
-    model_runtime_config_rx: watch::Receiver<HashMap<WorkerId, ModelRuntimeConfig>>,
+    /// Subscriber for runtime configs (includes shared configs DashMap)
+    subscriber: RuntimeConfigsSubscriber,
     router: OnceCell<Arc<PushRouter<WorkerKvQueryRequest, WorkerKvQueryResponse>>>,
 }
 
 impl WorkerQueryClient {
-    /// Create a new WorkerQueryClient with a watch receiver for local indexer states
-    pub fn new(
-        component: Component,
-        model_runtime_config_rx: watch::Receiver<HashMap<WorkerId, ModelRuntimeConfig>>,
-    ) -> Self {
+    /// Create a new WorkerQueryClient with a subscriber to runtime configs
+    pub fn new(component: Component, subscriber: RuntimeConfigsSubscriber) -> Self {
         Self {
             component,
-            model_runtime_config_rx,
+            subscriber,
             router: OnceCell::new(),
         }
     }
 
+    /// Wait until at least one worker has a known runtime config (Some).
+    /// Returns the list of worker IDs that have configs.
+    pub async fn wait_for_ready(&mut self) -> Vec<WorkerId> {
+        self.subscriber.wait_for_some().await
+    }
+
     /// Check if a worker has local indexer enabled
     pub fn has_local_indexer(&self, worker_id: WorkerId) -> bool {
-        self.model_runtime_config_rx
-            .borrow()
+        self.subscriber
+            .configs
             .get(&worker_id)
-            .map(|config| config.enable_local_indexer)
+            .and_then(|entry| entry.value().as_ref().map(|c| c.enable_local_indexer))
             .unwrap_or(false)
     }
 

lib/runtime/src/config/environment_names.rs

@@ -301,6 +301,10 @@ pub mod model {
 
         /// Hugging Face home directory
         pub const HF_HOME: &str = "HF_HOME";
+
+        /// Offline mode - skip API calls when model is cached
+        /// Set to "1" or "true" to enable
+        pub const HF_HUB_OFFLINE: &str = "HF_HUB_OFFLINE";
     }
 }
 
@@ -436,6 +440,7 @@ mod tests {
             model::huggingface::HF_TOKEN,
             model::huggingface::HF_HUB_CACHE,
             model::huggingface::HF_HOME,
+            model::huggingface::HF_HUB_OFFLINE,
             // Event Plane
             event_plane::DYN_EVENT_PLANE,
             event_plane::DYN_EVENT_PLANE_CODEC,

lib/runtime/src/transports/nats.rs

@@ -335,12 +335,6 @@ impl ClientOptions {
 
         let js_ctx = jetstream::new(client.clone());
 
-        // Validate JetStream is available
-        js_ctx
-            .query_account()
-            .await
-            .map_err(|e| anyhow::anyhow!("JetStream not available: {e}"))?;
-
         Ok(Client { client, js_ctx })
     }
 }

tests/conftest.py

@@ -298,7 +298,7 @@ class EtcdServer(ManagedProcess):
 
 
 class NatsServer(ManagedProcess):
-    def __init__(self, request, port=4222, timeout=300):
+    def __init__(self, request, port=4222, timeout=300, disable_jetstream=False):
         # Allocate a free port if port is 0
         use_random_port = port == 0
         if use_random_port:
@@ -309,16 +309,16 @@ class NatsServer(ManagedProcess):
         self.use_random_port = use_random_port  # Track if we allocated the port
         self._request = request  # Store for restart
         self._timeout = timeout
-        data_dir = tempfile.mkdtemp(prefix="nats_")
+        self._disable_jetstream = disable_jetstream
+        data_dir = tempfile.mkdtemp(prefix="nats_") if not disable_jetstream else None
         command = [
             "nats-server",
-            "-js",
             "--trace",
-            "--store_dir",
-            data_dir,
             "-p",
             str(port),
         ]
+        if not disable_jetstream and data_dir:
+            command.extend(["-js", "--store_dir", data_dir])
         super().__init__(
             command=command,
             timeout=timeout,
@@ -326,9 +326,45 @@ class NatsServer(ManagedProcess):
             terminate_existing=not use_random_port,  # Disabled for parallel test execution with random ports
             data_dir=data_dir,
             health_check_ports=[port],
+            health_check_funcs=[self._nats_ready],
             log_dir=request.node.name,
         )
 
+    def _nats_ready(self, timeout: float = 5) -> bool:
+        """Verify NATS server is ready by connecting and optionally checking JetStream."""
+        import asyncio
+
+        import nats
+
+        async def check():
+            try:
+                nc = await nats.connect(
+                    f"nats://localhost:{self.port}",
+                    connect_timeout=min(timeout, 2),
+                )
+                try:
+                    if not self._disable_jetstream:
+                        # Verify JetStream is initialized
+                        js = nc.jetstream()
+                        await js.account_info()
+                    return True
+                finally:
+                    await nc.close()
+            except Exception:
+                return False
+
+        # Handle both sync and async contexts
+        try:
+            asyncio.get_running_loop()  # Check if we're in async context
+            # Already in async context - run in a thread to avoid blocking
+            import concurrent.futures
+
+            with concurrent.futures.ThreadPoolExecutor() as pool:
+                return pool.submit(asyncio.run, check()).result(timeout=timeout)
+        except RuntimeError:
+            # No running loop - safe to use asyncio.run()
+            return asyncio.run(check())
+
     def __exit__(self, exc_type, exc_val, exc_tb):
         """Release allocated port when server exits."""
         try:
@@ -344,9 +380,10 @@ class NatsServer(ManagedProcess):
         """Stop the NATS server for restart. Does not release port or clean up fully."""
         _logger.info(f"Stopping NATS server on port {self.port}")
         self._terminate_process_group()
-        if self.proc:
+        proc = self.proc  # type: ignore[has-type]
+        if proc is not None:
             try:
-                self.proc.wait(timeout=10)
+                proc.wait(timeout=10)
             except Exception as e:
                 _logger.warning(f"Error waiting for NATS process to stop: {e}")
             self.proc = None
@@ -354,130 +391,130 @@ class NatsServer(ManagedProcess):
     def start(self):
         """Restart a stopped NATS server with fresh state."""
         _logger.info(f"Starting NATS server on port {self.port} with fresh state")
-        # Clean up old data directory and create fresh one
-        if self.data_dir:
-            shutil.rmtree(self.data_dir, ignore_errors=True)
+        # Clean up old data directory and create fresh one (only if JetStream enabled)
+        if not self._disable_jetstream:
+            old_data_dir = self.data_dir  # type: ignore[has-type]
+            if old_data_dir is not None:
+                shutil.rmtree(old_data_dir, ignore_errors=True)
             self.data_dir = tempfile.mkdtemp(prefix="nats_")
 
-        # Rebuild command with new data_dir
+        # Rebuild command
         self.command = [
             "nats-server",
-            "-js",
             "--trace",
-            "--store_dir",
-            self.data_dir,
             "-p",
             str(self.port),
         ]
+        if not self._disable_jetstream and self.data_dir:
+            self.command.extend(["-js", "--store_dir", self.data_dir])
 
         self._start_process()
-        self._check_ports(self._timeout)
+        elapsed = self._check_ports(self._timeout)
+        self._check_funcs(self._timeout - elapsed)
 
 
 class SharedManagedProcess:
-    """Base class for ManagedProcess with file-based reference counting for multi-process sharing."""
+    """Base class for persistent shared processes across pytest-xdist workers.
+
+    Simplified design: first worker starts the process on a dynamic port, it lives forever
+    (until the container dies). No ref counting, no teardown. Subsequent workers just
+    reuse via port check. This eliminates race conditions and simplifies the logic.
+    """
 
     def __init__(
         self,
         request,
         tmp_path_factory,
         resource_name: str,
-        port: int,
+        start_port: int,
         timeout: int = 300,
     ):
         self.request = request
-        self.port = port
+        self.start_port = start_port
+        self.port: Optional[int] = None  # Set when entering context
         self.timeout = timeout
         self.resource_name = resource_name
         self._server: Optional[ManagedProcess] = None
-        self._owns_process = False
 
-        root_tmp = Path(tempfile.gettempdir()) / "pytest_ref_counting"
+        root_tmp = Path(tempfile.gettempdir()) / "pytest_shared_services"
         root_tmp.mkdir(parents=True, exist_ok=True)
 
-        self.ref_file = root_tmp / f"pytest_{resource_name}_{port}_ref_count"
-        self.lock_file = str(self.ref_file) + ".lock"
+        self.port_file = root_tmp / f"{resource_name}_port"
+        self.lock_file = str(self.port_file) + ".lock"
 
-    def _create_server(self) -> ManagedProcess:
+    def _create_server(self, port: int) -> ManagedProcess:
         """Create the underlying server instance. Must be implemented by subclasses."""
         raise NotImplementedError
 
-    def _read_ref_count(self) -> int:
-        """Read current reference count."""
-        if self.ref_file.exists():
+    def _is_port_in_use(self, port: int) -> bool:
+        """Check if a port is in use (i.e., a process is listening on it)."""
+        import socket
+
+        try:
+            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            sock.settimeout(1)
+            result = sock.connect_ex(("localhost", port))
+            sock.close()
+            return result == 0  # 0 means connection succeeded (port in use)
+        except Exception:
+            return False
+
+    def _read_port(self) -> Optional[int]:
+        """Read stored port from file."""
+        if self.port_file.exists():
             try:
-                return int(self.ref_file.read_text().strip())
+                return int(self.port_file.read_text().strip())
             except (ValueError, IOError):
-                return 0
-        return 0
-
-    def _write_ref_count(self, count: int):
-        """Write reference count atomically."""
-        self.ref_file.write_text(str(count))
-
-    def _increment_ref_count(self) -> int:
-        """Increment reference count and return new count."""
-        count = self._read_ref_count()
-        count += 1
-        self._write_ref_count(count)
-        return count
-
-    def _decrement_ref_count(self) -> int:
-        """Decrement reference count and return new count."""
-        count = self._read_ref_count()
-        count = max(0, count - 1)
-        self._write_ref_count(count)
-        return count
+                return None
+        return None
+
+    def _write_port(self, port: int):
+        """Write port to file."""
+        self.port_file.write_text(str(port))
 
     def __enter__(self):
         with FileLock(self.lock_file):
-            ref_count = self._increment_ref_count()
-            if ref_count == 1:
-                # First reference - start the process
-                self._server = self._create_server()
-                self._server.__enter__()
-                self._owns_process = True
-                logging.info(f"[{self.resource_name}] Started process (ref_count=1)")
-            else:
-                # Process already running, just track reference
-                self._owns_process = False
+            stored_port = self._read_port()
+
+            # Check if a process is already running on the stored port
+            if stored_port is not None and self._is_port_in_use(stored_port):
+                # Reuse existing process
+                self.port = stored_port
                 logging.info(
-                    f"[{self.resource_name}] Reusing existing process (ref_count={ref_count})"
+                    f"[{self.resource_name}] Reusing existing process on port {self.port}"
                 )
-        return self
-
-    def __exit__(self, exc_type, exc_val, exc_tb):
-        with FileLock(self.lock_file):
-            ref_count = self._decrement_ref_count()
-            if ref_count == 0 and self._owns_process:
-                # Last reference - stop the process
-                if self._server:
-                    self._server.__exit__(exc_type, exc_val, exc_tb)
-                logging.info(f"[{self.resource_name}] Stopped process (ref_count=0)")
-            elif ref_count == 0:
-                # Last reference but we don't own it - shouldn't happen, but clean up ref file
-                if self.ref_file.exists():
-                    self.ref_file.unlink()
+            else:
+                # Start new process
+                if stored_port is not None:
                     logging.warning(
-                    f"[{self.resource_name}] Ref count reached 0 but we don't own process"
+                        f"[{self.resource_name}] Stale port file: port {stored_port} not in use, starting fresh"
                     )
-            else:
+                self.port = allocate_port(self.start_port)
+                self._write_port(self.port)
+                self._server = self._create_server(self.port)
+                self._server.__enter__()
                 logging.info(
-                    f"[{self.resource_name}] Released reference (ref_count={ref_count})"
+                    f"[{self.resource_name}] Started process on port {self.port}"
                 )
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        # Never tear down - let the process live until the container dies.
+        # This avoids race conditions and simplifies the logic.
+        pass
 
 
 class SharedEtcdServer(SharedManagedProcess):
     """EtcdServer with file-based reference counting for multi-process sharing."""
 
-    def __init__(self, request, tmp_path_factory, port=2379, timeout=300):
-        super().__init__(request, tmp_path_factory, "etcd", port, timeout)
+    def __init__(self, request, tmp_path_factory, start_port=2380, timeout=300):
+        super().__init__(request, tmp_path_factory, "etcd", start_port, timeout)
         # Create a log directory for session-scoped servers
         self._log_dir = tempfile.mkdtemp(prefix=f"pytest_{self.resource_name}_logs_")
 
-    def _create_server(self) -> ManagedProcess:
+    def _create_server(self, port: int) -> ManagedProcess:
         """Create EtcdServer instance."""
-        server = EtcdServer(self.request, port=self.port, timeout=self.timeout)
+        server = EtcdServer(self.request, port=port, timeout=self.timeout)
         # Override log_dir since request.node.name is empty in session scope
         server.log_dir = self._log_dir
         return server
@@ -486,14 +523,27 @@ class SharedEtcdServer(SharedManagedProcess):
 class SharedNatsServer(SharedManagedProcess):
     """NatsServer with file-based reference counting for multi-process sharing."""
 
-    def __init__(self, request, tmp_path_factory, port=4222, timeout=300):
-        super().__init__(request, tmp_path_factory, "nats", port, timeout)
+    def __init__(
+        self,
+        request,
+        tmp_path_factory,
+        start_port=4223,
+        timeout=300,
+        disable_jetstream=False,
+    ):
+        super().__init__(request, tmp_path_factory, "nats", start_port, timeout)
         # Create a log directory for session-scoped servers
         self._log_dir = tempfile.mkdtemp(prefix=f"pytest_{self.resource_name}_logs_")
+        self._disable_jetstream = disable_jetstream
 
-    def _create_server(self) -> ManagedProcess:
+    def _create_server(self, port: int) -> ManagedProcess:
         """Create NatsServer instance."""
-        server = NatsServer(self.request, port=self.port, timeout=self.timeout)
+        server = NatsServer(
+            self.request,
+            port=port,
+            timeout=self.timeout,
+            disable_jetstream=self._disable_jetstream,
+        )
         # Override log_dir since request.node.name is empty in session scope
         server.log_dir = self._log_dir
         return server
@@ -525,6 +575,27 @@ def request_plane(request):
     return getattr(request, "param", "nats")
 
 
+@pytest.fixture
+def use_nats_core(request):
+    """
+    Whether to use NATS Core mode (local indexer) instead of JetStream. Defaults to False.
+
+    When True:
+    - NATS server starts without JetStream (-js flag omitted) for faster startup
+    - Tests should use enable_local_indexer=True in mocker_args
+
+    When False (default):
+    - NATS server starts with JetStream for KV event distribution
+    - Tests use JetStream-based indexer synchronization
+
+    To use NATS Core mode:
+        @pytest.mark.parametrize("use_nats_core", [True], indirect=True)
+        def test_example(runtime_services_dynamic_ports):
+            ...
+    """
+    return getattr(request, "param", False)
+
+
 @pytest.fixture()
 def runtime_services(request, store_kv, request_plane):
     """
@@ -551,7 +622,7 @@ def runtime_services(request, store_kv, request_plane):
 
 
 @pytest.fixture()
-def runtime_services_dynamic_ports(request, store_kv, request_plane):
+def runtime_services_dynamic_ports(request, store_kv, request_plane, use_nats_core):
     """Provide NATS and Etcd servers with truly dynamic ports per test.
 
     This fixture actually allocates dynamic ports by passing port=0 to the servers.
@@ -566,6 +637,7 @@ def runtime_services_dynamic_ports(request, store_kv, request_plane):
     - If store_kv != "etcd", etcd is not started (returns None)
     - NATS is always started when etcd is used, because KV events require NATS
       regardless of the request_plane (tcp/nats only affects request transport)
+    - JetStream is enabled by default; disabled when use_nats_core=True for faster startup
 
     Returns a tuple of (nats_process, etcd_process) where each has a .port attribute.
     """
@@ -573,23 +645,41 @@ def runtime_services_dynamic_ports(request, store_kv, request_plane):
 
     # Port cleanup is now handled in NatsServer and EtcdServer __exit__ methods
     # Always start NATS when etcd is used - KV events require NATS regardless of request_plane
+    # When use_nats_core=True, disable JetStream for faster startup
     if store_kv == "etcd":
-        with NatsServer(request, port=0) as nats_process:
+        with NatsServer(
+            request, port=0, disable_jetstream=use_nats_core
+        ) as nats_process:
             with EtcdServer(request, port=0) as etcd_process:
-                # Set environment variables for Rust/Python runtime to use. Note that xdist (parallel execution)
-                # will launch isolated tests in a new process, so no need to worry about environment pollution.
+                # Save original env vars (may be set by session-scoped fixture)
+                orig_nats = os.environ.get("NATS_SERVER")
+                orig_etcd = os.environ.get("ETCD_ENDPOINTS")
+
+                # Set environment variables for this test's dynamic ports
                 os.environ["NATS_SERVER"] = f"nats://localhost:{nats_process.port}"
                 os.environ["ETCD_ENDPOINTS"] = f"http://localhost:{etcd_process.port}"
 
                 yield nats_process, etcd_process
 
-                # No test should rely on these variables after the test, but clean up just in case.
+                # Restore original env vars (or remove if they weren't set)
+                if orig_nats is not None:
+                    os.environ["NATS_SERVER"] = orig_nats
+                else:
                     os.environ.pop("NATS_SERVER", None)
+                if orig_etcd is not None:
+                    os.environ["ETCD_ENDPOINTS"] = orig_etcd
+                else:
                     os.environ.pop("ETCD_ENDPOINTS", None)
     elif request_plane == "nats":
-        with NatsServer(request, port=0) as nats_process:
+        with NatsServer(
+            request, port=0, disable_jetstream=use_nats_core
+        ) as nats_process:
+            orig_nats = os.environ.get("NATS_SERVER")
             os.environ["NATS_SERVER"] = f"nats://localhost:{nats_process.port}"
             yield nats_process, None
+            if orig_nats is not None:
+                os.environ["NATS_SERVER"] = orig_nats
+            else:
                 os.environ.pop("NATS_SERVER", None)
     else:
         yield None, None
@@ -599,22 +689,28 @@ def runtime_services_dynamic_ports(request, store_kv, request_plane):
 def runtime_services_session(request, tmp_path_factory):
     """Session-scoped fixture that provides shared NATS and etcd instances for all tests.
 
-    Uses file-based reference counting to coordinate between pytest-xdist worker processes.
-    Only the first worker starts services, and only the last worker tears them down.
+    Uses file locking to coordinate between pytest-xdist worker processes.
+    First worker starts services on dynamic ports, subsequent workers reuse them.
+    Services are never torn down (live until container dies) to avoid race conditions.
 
-    WARNING: may not be parallel/xdist safe.
-    - This fixture shares one NATS + one etcd across many tests (and across xdist workers).
-    - It is only safe if tests fully isolate state (e.g. unique namespaces) and do not
-      assume exclusive access to global streams/keys/ports.
-    - Prefer `runtime_services_dynamic_ports` for true per-test isolation in parallel runs.
+    This fixture is xdist-safe when tests use unique namespaces (e.g. random suffixes)
+    and do not assume exclusive access to global streams/keys.
 
-    TODO: once nothing uses `runtime_services_session`, make the per-test dynamic ports
-    behavior the default for router/frontend integration tests.
+    For tests that need to restart NATS (e.g. indexer sync), use `runtime_services_dynamic_ports`
+    which provides per-test isolated instances.
     """
     with SharedNatsServer(request, tmp_path_factory) as nats:
         with SharedEtcdServer(request, tmp_path_factory) as etcd:
+            # Set environment variables for Rust/Python runtime to use
+            os.environ["NATS_SERVER"] = f"nats://localhost:{nats.port}"
+            os.environ["ETCD_ENDPOINTS"] = f"http://localhost:{etcd.port}"
+
             yield nats, etcd
 
+            # Clean up environment variables
+            os.environ.pop("NATS_SERVER", None)
+            os.environ.pop("ETCD_ENDPOINTS", None)
+
 
 @pytest.fixture
 def file_storage_backend():

tests/router/common.py

@@ -525,10 +525,10 @@ async def send_request_via_python_kv_router(
             stream = await kv_python_router.generate(
                 token_ids=token_ids,
                 model=model_name,
-                stop_conditions=stop_conditions,
-                sampling_options=sampling_options,
-                output_options=output_options,
-                router_config_override=router_config_override,
+                stop_conditions=stop_conditions,  # type: ignore[arg-type]
+                sampling_options=sampling_options,  # type: ignore[arg-type]
+                output_options=output_options,  # type: ignore[arg-type]
+                router_config_override=router_config_override,  # type: ignore[arg-type]
                 worker_id=worker_id,
                 dp_rank=dp_rank,
             )
@@ -693,6 +693,7 @@ def _test_router_two_routers(
     test_payload: dict,
     num_requests: int,
     store_backend: str = "etcd",
+    skip_consumer_verification: bool = False,
 ):
     """Test two KV routers with alternating requests and consumer lifecycle verification.
 
@@ -701,8 +702,8 @@ def _test_router_two_routers(
     This test:
     1. Starts two KV routers on different ports
     2. Sends requests alternating between the two routers
-    3. Verifies that both routers create durable consumers
-    4. Verifies consumers are cleaned up when routers exit
+    3. Verifies that both routers create durable consumers (unless skipped)
+    4. Verifies consumers are cleaned up when routers exit (unless skipped)
 
     Args:
         engine_workers: Backend workers (mocker/vllm) already initialized with __enter__()
@@ -712,6 +713,7 @@ def _test_router_two_routers(
         test_payload: Test payload to send to /v1/chat/completions
         num_requests: Number of concurrent requests to send
         store_backend: Storage backend to use ("etcd" or "file"). Defaults to "etcd".
+        skip_consumer_verification: Skip JetStream consumer verification (for NATS Core mode).
 
     Raises:
         AssertionError: If consumer lifecycle verification fails
@@ -846,7 +848,13 @@ def _test_router_two_routers(
             finally:
                 await nc.close()
 
-        # Run consumer lifecycle verification
+        # Run consumer lifecycle verification (skip for NATS Core mode)
+        if skip_consumer_verification:
+            logger.info("Skipping JetStream consumer verification (NATS Core mode)")
+            # Clean up routers manually since we're not doing consumer verification
+            for kv_router in kv_routers:
+                kv_router.__exit__(None, None, None)
+        else:
             asyncio.run(verify_consumer_lifecycle())
 
         # Clear the kv_routers list since we've already cleaned them up

tests/router/test_router_e2e_with_mockers.py

@@ -323,8 +323,15 @@ class DisaggMockerProcess:
 
 @pytest.mark.timeout(42)  # ~3x average (~13.80s), rounded up
 @pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize(
+    "use_nats_core", [True], indirect=True
+)  # Use NATS Core (local indexer)
 def test_mocker_kv_router(
-    request, runtime_services_dynamic_ports, predownload_tokenizers, request_plane
+    request,
+    runtime_services_dynamic_ports,
+    predownload_tokenizers,
+    request_plane,
+    use_nats_core,
 ):
     """
     Test KV router with multiple mocker engine instances.
@@ -335,8 +342,12 @@ def test_mocker_kv_router(
     # runtime_services starts etcd and optionally nats based on request_plane
     logger.info(f"Starting mocker KV router test with request_plane={request_plane}")
 
-    # Create mocker args dictionary
-    mocker_args = {"speedup_ratio": SPEEDUP_RATIO, "block_size": BLOCK_SIZE}
+    # Create mocker args dictionary - use local indexer (NATS Core mode)
+    mocker_args = {
+        "speedup_ratio": SPEEDUP_RATIO,
+        "block_size": BLOCK_SIZE,
+        "enable_local_indexer": use_nats_core,
+    }
 
     try:
         # Start mocker instances with the new CLI interface
@@ -372,6 +383,9 @@ def test_mocker_kv_router(
 
 
 @pytest.mark.parametrize("store_backend", ["etcd", "file"])
+@pytest.mark.parametrize(
+    "use_nats_core", [True], indirect=True
+)  # Use NATS Core (local indexer)
 @pytest.mark.timeout(60)  # ~3x average (~19.86s), rounded up
 def test_mocker_two_kv_router(
     request,
@@ -379,6 +393,7 @@ def test_mocker_two_kv_router(
     predownload_tokenizers,
     file_storage_backend,
     store_backend,
+    use_nats_core,
 ):
     """
     Test with two KV routers and multiple mocker engine instances.
@@ -391,8 +406,12 @@ def test_mocker_two_kv_router(
         f"Starting mocker two KV router test with {store_backend} storage backend"
     )
 
-    # Create mocker args dictionary
-    mocker_args = {"speedup_ratio": SPEEDUP_RATIO, "block_size": BLOCK_SIZE}
+    # Create mocker args dictionary - use local indexer (NATS Core mode)
+    mocker_args = {
+        "speedup_ratio": SPEEDUP_RATIO,
+        "block_size": BLOCK_SIZE,
+        "enable_local_indexer": use_nats_core,
+    }
 
     try:
         # Start mocker instances with the new CLI interface
@@ -420,6 +439,7 @@ def test_mocker_two_kv_router(
             test_payload=TEST_PAYLOAD,
             num_requests=NUM_REQUESTS,
             store_backend=store_backend,
+            skip_consumer_verification=use_nats_core,  # Skip JetStream checks in NATS Core mode
         )
 
     finally:
@@ -428,17 +448,21 @@ def test_mocker_two_kv_router(
 
 
 @pytest.mark.skip(reason="Flaky, temporarily disabled")
+@pytest.mark.parametrize(
+    "use_nats_core", [True], indirect=True
+)  # Use NATS Core (local indexer)
 @pytest.mark.timeout(60)  # ~3x average (~19.86s), rounded up (when enabled)
 def test_mocker_kv_router_overload_503(
-    request, runtime_services_dynamic_ports, predownload_tokenizers
+    request, runtime_services_dynamic_ports, predownload_tokenizers, use_nats_core
 ):
     """Test that KV router returns 503 when mocker workers are overloaded."""
     logger.info("Starting mocker KV router overload test for 503 status")
-    # Create mocker args dictionary with limited resources
+    # Create mocker args dictionary with limited resources - use local indexer (NATS Core mode)
     mocker_args = {
         "speedup_ratio": 10,
         "block_size": 4,  # Smaller block size
         "num_gpu_blocks": 64,  # Limited GPU blocks to exhaust quickly
+        "enable_local_indexer": use_nats_core,
     }
 
     try:
@@ -468,12 +492,24 @@ def test_mocker_kv_router_overload_503(
 
 @pytest.mark.timeout(22)  # ~3x average (~7.10s), rounded up
 @pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize(
+    "use_nats_core", [True], indirect=True
+)  # Use NATS Core (local indexer)
 def test_kv_push_router_bindings(
-    request, runtime_services_dynamic_ports, predownload_tokenizers, request_plane
+    request,
+    runtime_services_dynamic_ports,
+    predownload_tokenizers,
+    request_plane,
+    use_nats_core,
 ):
     """Test KvPushRouter Python bindings with mocker engines."""
     logger.info("Starting KvPushRouter bindings test")
-    mocker_args = {"speedup_ratio": SPEEDUP_RATIO, "block_size": BLOCK_SIZE}
+    # Use local indexer (NATS Core mode)
+    mocker_args = {
+        "speedup_ratio": SPEEDUP_RATIO,
+        "block_size": BLOCK_SIZE,
+        "enable_local_indexer": use_nats_core,
+    }
 
     try:
         # Start mocker instances
@@ -507,19 +543,19 @@ def test_kv_push_router_bindings(
             mockers.__exit__(None, None, None)
 
 
-# NO @pytest.mark.parallel - nats_core variant stops/restarts NATS
 @pytest.mark.parametrize(
     "store_backend,use_nats_core,request_plane",
     [
-        ("etcd", False, "nats"),  # JetStream mode
-        ("etcd", True, "tcp"),  # NATS core mode (with gap detection)
-        ("file", False, "nats"),  # File backend
+        ("etcd", False, "nats"),  # JetStream mode - uses JetStream (default)
+        ("etcd", True, "tcp"),  # NATS core mode (with gap detection) - no JetStream
+        ("file", False, "nats"),  # File backend - uses JetStream (default)
     ],
     ids=[
         "jetstream",
         "nats_core",
         "file",
     ],
+    indirect=["request_plane", "use_nats_core"],
 )
 @pytest.mark.timeout(90)  # TODO: figure out a timeout
 def test_indexers_sync(
@@ -590,12 +626,20 @@ def test_indexers_sync(
 
 
 @pytest.mark.timeout(42)  # ~3x average (~13.80s), rounded up
+@pytest.mark.parametrize(
+    "use_nats_core", [True], indirect=True
+)  # Use NATS Core (local indexer)
 def test_query_instance_id_returns_worker_and_tokens(
-    request, runtime_services_dynamic_ports, predownload_tokenizers
+    request, runtime_services_dynamic_ports, predownload_tokenizers, use_nats_core
 ):
     """Test query_instance_id annotation with mocker engines."""
     logger.info("Starting KV router query_instance_id annotation test")
-    mocker_args = {"speedup_ratio": SPEEDUP_RATIO, "block_size": BLOCK_SIZE}
+    # Use local indexer (NATS Core mode)
+    mocker_args = {
+        "speedup_ratio": SPEEDUP_RATIO,
+        "block_size": BLOCK_SIZE,
+        "enable_local_indexer": use_nats_core,
+    }
     os.makedirs(request.node.name, exist_ok=True)
 
     try:
@@ -629,11 +673,12 @@ def test_query_instance_id_returns_worker_and_tokens(
 @pytest.mark.parametrize(
     "use_nats_core,use_kv_events",
     [
-        (False, True),  # JetStream mode (default)
-        (True, True),  # NATS Core + local indexer mode
-        (False, False),  # Approximate mode (--no-kv-events)
+        (False, True),  # JetStream mode (default) - uses JetStream
+        (True, True),  # NATS Core + local indexer mode - no JetStream
+        (False, False),  # Approximate mode (--no-kv-events) - uses JetStream
     ],
     ids=["jetstream", "nats_core", "no_kv_events"],
+    indirect=["use_nats_core"],
 )
 def test_router_decisions(
     request,
@@ -828,9 +873,16 @@ def test_router_decisions_disagg(
 
 
 @pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize(
+    "use_nats_core", [True], indirect=True
+)  # Use NATS Core (local indexer)
 @pytest.mark.timeout(39)  # ~3x average (~12.84s), rounded up
 def test_busy_threshold_endpoint(
-    request, runtime_services_dynamic_ports, predownload_tokenizers, request_plane
+    request,
+    runtime_services_dynamic_ports,
+    predownload_tokenizers,
+    request_plane,
+    use_nats_core,
 ):
     """Test that the /busy_threshold endpoint can be hit and responds correctly.
 
@@ -846,7 +898,12 @@ def test_busy_threshold_endpoint(
         f"Starting busy_threshold endpoint test with request_plane={request_plane}"
     )
 
-    mocker_args = {"speedup_ratio": SPEEDUP_RATIO, "block_size": BLOCK_SIZE}
+    # Use local indexer (NATS Core mode)
+    mocker_args = {
+        "speedup_ratio": SPEEDUP_RATIO,
+        "block_size": BLOCK_SIZE,
+        "enable_local_indexer": use_nats_core,
+    }
 
     try:
         logger.info(f"Starting {NUM_MOCKERS} mocker instances")

tests/router/test_router_e2e_with_sglang.py

@@ -87,6 +87,7 @@ class SGLangProcess:
         data_parallel_size: Optional[int] = None,
         request_plane: str = "tcp",
         store_backend: str = "etcd",
+        enable_local_indexer: bool = False,
     ):
         """Initialize SGLang workers with dynamo integration.
 
@@ -103,6 +104,7 @@ class SGLangProcess:
             data_parallel_size: If set, enables data parallelism with this many ranks (num_workers must equal data_parallel_size)
             request_plane: Request plane to use ("nats", "tcp", or "http"). Defaults to "tcp".
             store_backend: Storage backend to use ("etcd" or "file"). Defaults to "etcd".
+            enable_local_indexer: If True, enable worker-local KV indexer for NATS Core mode. Defaults to False.
         """
         # Generate unique namespace for isolation
         namespace_suffix = generate_random_suffix()
@@ -192,6 +194,10 @@ class SGLangProcess:
             if self.store_backend == "file" and "DYN_FILE_KV" in os.environ:
                 env_vars["DYN_FILE_KV"] = os.environ["DYN_FILE_KV"]
 
+            # Enable local indexer for NATS Core mode
+            if enable_local_indexer:
+                env_vars["DYN_LOCAL_INDEXER"] = "true"
+
             env.update(env_vars)
 
             # Create managed process for the worker
@@ -313,7 +319,7 @@ class SGLangProcess:
 
 @pytest.mark.pre_merge
 @pytest.mark.gpu_1
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 @pytest.mark.timeout(150)  # ~3x average (~46s/test), rounded up
 def test_sglang_kv_router_basic(
     request,
@@ -369,7 +375,7 @@ def test_sglang_kv_router_basic(
 @pytest.mark.gpu_1
 @pytest.mark.skip(reason="Broken by sglang changes")
 # TODO: Re-enable this test once https://github.com/sgl-project/sglang/pull/14934 is merged
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 def test_router_decisions_sglang_multiple_workers(
     request,
     runtime_services_dynamic_ports,
@@ -414,7 +420,7 @@ def test_router_decisions_sglang_multiple_workers(
 
 @pytest.mark.gpu_2
 @pytest.mark.post_merge
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 @pytest.mark.timeout(600)  # 10 min max (multi-GPU + DP startup variance)
 def test_router_decisions_sglang_dp(
     request,
@@ -469,10 +475,10 @@ def test_router_decisions_sglang_dp(
     "store_backend,use_nats_core,request_plane",
     [
         ("etcd", False, "nats"),  # JetStream mode
-        # ("etcd", True, "tcp"),  # ignored, needs unconditional nats_client
+        # ("etcd", True, "tcp"),  # nats_core mode - disabled for now
         # ("file", False, "nats"),  # File backend - TODO: investigate file backend support for SGLang
     ],
-    ids=["jetstream"],  # "nats_core" and "file" commented out
+    ids=["jetstream"],
 )
 @pytest.mark.timeout(150)  # ~3x average (~46s/test), rounded up
 def test_sglang_indexers_sync(
@@ -491,8 +497,11 @@ def test_sglang_indexers_sync(
 
     Tests with configuration:
     - jetstream: etcd backend, JetStream for KV events, NATS request plane
+    - tcp_nats_core: etcd backend, local indexer with NATS Core, TCP request plane
     """
     # runtime_services_dynamic_ports handles NATS and etcd startup
+    nats_process, _etcd_process = runtime_services_dynamic_ports
+
     logger.info(
         f"Starting SGLang indexers sync test: store_backend={store_backend}, "
         f"use_nats_core={use_nats_core}, request_plane={request_plane}"
@@ -510,6 +519,7 @@ def test_sglang_indexers_sync(
             single_gpu=True,  # fit workers into one GPU
             request_plane=request_plane,
             store_backend=store_backend,
+            enable_local_indexer=use_nats_core,
         )
         logger.info(f"All SGLang workers using namespace: {sglang_workers.namespace}")
         sglang_workers.__enter__()
@@ -523,6 +533,8 @@ def test_sglang_indexers_sync(
             num_workers=N_SGLANG_WORKERS,
             store_backend=store_backend,
             request_plane=request_plane,
+            test_nats_interruption=use_nats_core,
+            nats_server=nats_process if use_nats_core else None,
         )
 
         logger.info("SGLang indexers sync test completed successfully")

tests/router/test_router_e2e_with_trtllm.py

@@ -84,6 +84,7 @@ class TRTLLMProcess:
         single_gpu: bool = False,
         request_plane: str = "tcp",
         store_backend: str = "etcd",
+        enable_local_indexer: bool = False,
     ):
         """Initialize TRT-LLM workers with dynamo integration.
 
@@ -98,6 +99,7 @@ class TRTLLMProcess:
             single_gpu: If True, all workers share GPU 0
             request_plane: Request plane to use ("nats", "tcp", or "http"). Defaults to "tcp".
             store_backend: Storage backend to use ("etcd" or "file"). Defaults to "etcd".
+            enable_local_indexer: If True, enable worker-local KV indexer for NATS Core mode. Defaults to False.
 
         Note: TRT-LLM doesn't support data parallelism like vLLM (dp_rank is always 0).
               Tensor parallelism (TP) is supported but creates 1 worker spanning multiple GPUs,
@@ -172,6 +174,10 @@ class TRTLLMProcess:
             if self.store_backend == "file" and "DYN_FILE_KV" in os.environ:
                 env_vars["DYN_FILE_KV"] = os.environ["DYN_FILE_KV"]
 
+            # Enable local indexer for NATS Core mode
+            if enable_local_indexer:
+                env_vars["DYN_LOCAL_INDEXER"] = "true"
+
             env.update(env_vars)
 
             # Create managed process for the worker
@@ -286,7 +292,7 @@ class TRTLLMProcess:
 
 @pytest.mark.pre_merge
 @pytest.mark.gpu_1
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 @pytest.mark.timeout(150)  # ~3x average (~45s/test), rounded up
 def test_trtllm_kv_router_basic(
     request,
@@ -340,7 +346,7 @@ def test_trtllm_kv_router_basic(
 
 @pytest.mark.pre_merge
 @pytest.mark.gpu_1
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 @pytest.mark.timeout(150)  # ~3x average (~45s/test), rounded up
 def test_router_decisions_trtllm_multiple_workers(
     request,
@@ -398,10 +404,10 @@ def test_router_decisions_trtllm_multiple_workers(
     "store_backend,use_nats_core,request_plane",
     [
         ("etcd", False, "nats"),  # JetStream mode
-        # ("etcd", True, "tcp"),  # ignored, needs unconditional nats_client
+        # ("etcd", True, "tcp"),  # nats_core mode - disabled for now
         # ("file", False, "nats"),  # File backend - TODO: investigate file backend support for TRT-LLM
     ],
-    ids=["jetstream"],  # "nats_core" and "file" commented out
+    ids=["jetstream"],
 )
 def test_trtllm_indexers_sync(
     request,
@@ -419,8 +425,11 @@ def test_trtllm_indexers_sync(
 
     Tests with configuration:
     - jetstream: etcd backend, JetStream for KV events, NATS request plane
+    - tcp_nats_core: etcd backend, local indexer with NATS Core, TCP request plane
     """
     # runtime_services_dynamic_ports handles NATS and etcd startup
+    nats_process, _etcd_process = runtime_services_dynamic_ports
+
     logger.info(
         f"Starting TRT-LLM indexers sync test: store_backend={store_backend}, "
         f"use_nats_core={use_nats_core}, request_plane={request_plane}"
@@ -438,6 +447,7 @@ def test_trtllm_indexers_sync(
             single_gpu=True,  # fit workers into one GPU
             request_plane=request_plane,
             store_backend=store_backend,
+            enable_local_indexer=use_nats_core,
         )
         logger.info(f"All TRT-LLM workers using namespace: {trtllm_workers.namespace}")
         trtllm_workers.__enter__()
@@ -451,6 +461,8 @@ def test_trtllm_indexers_sync(
             num_workers=N_TRTLLM_WORKERS,
             store_backend=store_backend,
             request_plane=request_plane,
+            test_nats_interruption=use_nats_core,
+            nats_server=nats_process if use_nats_core else None,
         )
 
         logger.info("TRT-LLM indexers sync test completed successfully")

tests/router/test_router_e2e_with_vllm.py

@@ -87,6 +87,7 @@ class VLLMProcess:
         data_parallel_size: Optional[int] = None,
         request_plane: str = "tcp",
         store_backend: str = "etcd",
+        enable_local_indexer: bool = False,
     ):
         """Initialize vLLM workers with dynamo integration.
 
@@ -104,6 +105,7 @@ class VLLMProcess:
             data_parallel_size: If set, enables data parallelism with this many ranks (num_workers must equal data_parallel_size)
             request_plane: Request plane to use ("nats", "tcp", or "http"). Defaults to "tcp".
             store_backend: Storage backend to use ("etcd" or "file"). Defaults to "etcd".
+            enable_local_indexer: If True, enable worker-local KV indexer for NATS Core mode. Defaults to False.
         """
         # Generate unique namespace for isolation
         namespace_suffix = generate_random_suffix()
@@ -209,6 +211,10 @@ class VLLMProcess:
             if self.store_backend == "file" and "DYN_FILE_KV" in os.environ:
                 env_vars["DYN_FILE_KV"] = os.environ["DYN_FILE_KV"]
 
+            # Enable local indexer for NATS Core mode
+            if enable_local_indexer:
+                env_vars["DYN_LOCAL_INDEXER"] = "true"
+
             env.update(env_vars)
 
             # Create managed process for the worker
@@ -329,7 +335,7 @@ class VLLMProcess:
 @pytest.mark.pre_merge
 @pytest.mark.gpu_1
 @pytest.mark.timeout(150)  # ~3x average (~43s/test), rounded up
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 def test_vllm_kv_router_basic(
     request,
     runtime_services_dynamic_ports,
@@ -383,7 +389,7 @@ def test_vllm_kv_router_basic(
 @pytest.mark.pre_merge
 @pytest.mark.gpu_1
 @pytest.mark.timeout(150)  # ~3x average (~43s/test), rounded up
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 def test_router_decisions_vllm_multiple_workers(
     request,
     runtime_services_dynamic_ports,
@@ -428,7 +434,7 @@ def test_router_decisions_vllm_multiple_workers(
 
 @pytest.mark.gpu_2
 @pytest.mark.nightly
-@pytest.mark.parametrize("request_plane", ["nats", "tcp"], indirect=True)
+@pytest.mark.parametrize("request_plane", ["tcp"], indirect=True)
 @pytest.mark.timeout(600)  # 10 min max (multi-GPU + DP startup variance)
 def test_router_decisions_vllm_dp(
     request,
@@ -484,10 +490,10 @@ def test_router_decisions_vllm_dp(
     "store_backend,use_nats_core,request_plane",
     [
         ("etcd", False, "nats"),  # JetStream mode
-        ("etcd", True, "tcp"),  # nats_core mode
+        # ("etcd", True, "tcp"),  # nats_core mode - disabled for now
         # ("file", False, "nats"),  # File backend
     ],
-    ids=["jetstream", "tcp_nats_core"],
+    ids=["jetstream"],
 )
 def test_vllm_indexers_sync(
     request,
@@ -508,6 +514,8 @@ def test_vllm_indexers_sync(
     - tcp_nats_core: etcd backend, local indexer with NATS Core, TCP request plane
     """
     # runtime_services_dynamic_ports handles NATS and etcd startup
+    nats_process, _etcd_process = runtime_services_dynamic_ports
+
     logger.info(
         f"Starting vLLM indexers sync test: store_backend={store_backend}, "
         f"use_nats_core={use_nats_core}, request_plane={request_plane}"
@@ -525,6 +533,7 @@ def test_vllm_indexers_sync(
             single_gpu=True,  # fit workers into one GPU
             request_plane=request_plane,
             store_backend=store_backend,
+            enable_local_indexer=use_nats_core,
         )
         logger.info(f"All vLLM workers using namespace: {vllm_workers.namespace}")
         vllm_workers.__enter__()
@@ -538,6 +547,8 @@ def test_vllm_indexers_sync(
             num_workers=N_VLLM_WORKERS,
             store_backend=store_backend,
             request_plane=request_plane,
+            test_nats_interruption=use_nats_core,
+            nats_server=nats_process if use_nats_core else None,
         )
 
         logger.info("vLLM indexers sync test completed successfully")

tests/utils/managed_process.py

@@ -35,7 +35,7 @@ def terminate_process(process, logger=logging.getLogger(), immediate_kill=False)
 
 
 def terminate_process_tree(
-    pid, logger=logging.getLogger(), immediate_kill=False, timeout=10
+    pid, logger=logging.getLogger(), immediate_kill=False, timeout=2
 ):
     try:
         parent = psutil.Process(pid)
@@ -277,7 +277,7 @@ class ManagedProcess:
                 )
             self._tee_proc = None
 
-    def _terminate_process_group(self, timeout: float = 5.0):
+    def _terminate_process_group(self, timeout: float = 2.0):
         """Terminate the entire process group/session started for the child.
 
         This catches cases where the launcher shell exits and its children are reparented,
@@ -296,10 +296,23 @@ class ManagedProcess:
             )
             return
 
-        # Give processes a brief moment to exit gracefully
-        time.sleep(timeout)
+        # Poll for process exit instead of fixed sleep to minimize teardown time
+        poll_interval = 0.1
+        elapsed = 0.0
+        while elapsed < timeout:
+            try:
+                # Check if any process in the group is still alive
+                os.killpg(self._pgid, 0)  # Signal 0 = check existence
+            except ProcessLookupError:
+                # Process group no longer exists - done
+                return
+            except Exception:
+                # Other errors (e.g., permission) - assume done
+                return
+            time.sleep(poll_interval)
+            elapsed += poll_interval
 
-        # Force kill if anything remains
+        # Force kill if anything remains after timeout
         try:
             os.killpg(self._pgid, signal.SIGKILL)
         except ProcessLookupError: