From 667287c09b20e4f7b7f5d328d36e9567de780224 Mon Sep 17 00:00:00 2001
From: clockwork-labs-bot <clockwork-labs-bot@users.noreply.github.com>
Date: Mon, 15 Jun 2026 15:35:02 -0400
Subject: [PATCH] Track outgoing queue disconnects

---
 crates/core/src/client/client_connection.rs | 8 ++++++++
 crates/core/src/worker_metrics/mod.rs       | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/crates/core/src/client/client_connection.rs b/crates/core/src/client/client_connection.rs
index 8f19156d6bb..85c7d97a620 100644
--- a/crates/core/src/client/client_connection.rs
+++ b/crates/core/src/client/client_connection.rs
@@ -313,6 +313,7 @@ pub struct ClientConnectionSender {
 pub struct ClientConnectionMetrics {
     pub websocket_request_msg_size: Histogram,
     pub websocket_requests: IntCounter,
+    pub outgoing_queue_disconnects: IntCounter,
 
     /// The `total_outgoing_queue_length` metric labeled with this database's `Identity`,
     /// which we'll increment whenever sending a message.
@@ -333,6 +334,9 @@ impl ClientConnectionMetrics {
         let websocket_requests = WORKER_METRICS
             .websocket_requests
             .with_label_values(&database_identity, message_kind);
+        let outgoing_queue_disconnects = WORKER_METRICS
+            .client_outgoing_queue_disconnects
+            .with_label_values(&database_identity);
         let sendtx_queue_size = WORKER_METRICS
             .total_outgoing_queue_length
             .with_label_values(&database_identity);
@@ -340,6 +344,7 @@ impl ClientConnectionMetrics {
         Self {
             websocket_request_msg_size,
             websocket_requests,
+            outgoing_queue_disconnects,
             sendtx_queue_size,
         }
     }
@@ -442,6 +447,9 @@ impl ClientConnectionSender {
                     self.id,
                     self.sendtx.capacity(),
                 );
+                if let Some(metrics) = &self.metrics {
+                    metrics.outgoing_queue_disconnects.inc();
+                }
                 self.abort_handle.abort();
                 self.cancelled.store(true, Ordering::Relaxed);
                 return Err(ClientSendError::Cancelled);
diff --git a/crates/core/src/worker_metrics/mod.rs b/crates/core/src/worker_metrics/mod.rs
index 690afdd8c94..b485af4e2aa 100644
--- a/crates/core/src/worker_metrics/mod.rs
+++ b/crates/core/src/worker_metrics/mod.rs
@@ -375,6 +375,11 @@ metrics_group!(
         #[labels(db: Identity)]
         pub total_outgoing_queue_length: IntGaugeVec,
 
+        #[name = spacetime_client_outgoing_queue_disconnects_total]
+        #[help = "The number of clients disconnected because their outgoing WebSocket message queue filled up"]
+        #[labels(db: Identity)]
+        pub client_outgoing_queue_disconnects: IntCounterVec,
+
         #[name = spacetime_replay_total_time_seconds]
         #[help = "Total time spent replaying a database upon restart, including snapshot read, snapshot restore and commitlog replay"]
         #[labels(db: Identity)]