diff --git a/src/config.rs b/src/config.rs
index 0d400c2..84da369 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -17,7 +17,10 @@ impl AppConfig {
             .unwrap_or_else(|_| "60309".to_string())
             .parse::<u16>()
             .map_err(|_| "PORT must be a number")?;
-        let write_api_key = env::var("WRITE_KEY").ok();
+        // Prefer WRITE_API_KEY, keep WRITE_KEY as backward-compatible fallback.
+        let write_api_key = env::var("WRITE_API_KEY")
+            .ok()
+            .or_else(|| env::var("WRITE_KEY").ok());
 
         Ok(Self {
             database_url,
diff --git a/src/event.rs b/src/event.rs
index 4cd9f79..b8bc298 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -1,6 +1,8 @@
 use tokio::sync::mpsc;
 use uuid::Uuid;
 
+const EVENT_CHANNEL_CAPACITY: usize = 4096;
+
 #[derive(Debug, Clone)]
 pub enum ReloadEvent {
     SourceCreate {
@@ -24,7 +26,7 @@ pub enum ReloadEvent {
 }
 
 pub struct EventManager {
-    sender: mpsc::UnboundedSender<ReloadEvent>,
+    sender: mpsc::Sender<ReloadEvent>,
 }
 
 impl EventManager {
@@ -33,7 +35,7 @@ impl EventManager {
         connection_manager: std::sync::Arc<crate::connection::ConnectionManager>,
         ws_manager: Option<std::sync::Arc<crate::websocket::WebSocketManager>>,
     ) -> Self {
-        let (sender, mut receiver) = mpsc::unbounded_channel::<ReloadEvent>();
+        let (sender, mut receiver) = mpsc::channel::<ReloadEvent>(EVENT_CHANNEL_CAPACITY);
         let ws_manager_clone = ws_manager.clone();
 
         tokio::spawn(async move {
@@ -138,34 +140,27 @@ impl EventManager {
                                 value_changed,
                             };
 
-                            // 克隆 monitor，用于并行执行
-                            let monitor_for_ws = monitor.clone();
-                            let monitor_for_db = monitor.clone();
+                            // Process in event worker directly to avoid per-point spawn overhead.
+                            if let Err(e) = connection_manager_clone
+                                .update_point_monitor_data(monitor.clone())
+                                .await
+                            {
+                                tracing::error!(
+                                    "Failed to update point monitor data for point {}: {}",
+                                    point_id,
+                                    e
+                                );
+                            }
 
-                            // 并行执行 update_point_monitor_data 和 send_to_public，不等待完成
-                            let cm_clone = connection_manager_clone.clone();
-                            tokio::spawn(async move {
-                                // 更新监控数据
-                                if let Err(e) = cm_clone.update_point_monitor_data(monitor_for_db).await {
-                                    tracing::error!("Failed to update point monitor data for point {}: {}", point_id, e);
+                            if let Some(ws_manager) = &ws_manager_clone {
+                                let ws_message = crate::websocket::WsMessage::PointNewValue(monitor);
+                                if let Err(e) = ws_manager.send_to_public(ws_message).await {
+                                    tracing::error!(
+                                        "Failed to send WebSocket message to public room: {}",
+                                        e
+                                    );
                                 }
-                            });
-
-                            let ws_clone = ws_manager_clone.clone();
-                            tokio::spawn(async move {
-                                // 发送WebSocket消息
-                                if let Some(ws_manager) = ws_clone {
-                                    let ws_message = crate::websocket::WsMessage::PointNewValue(monitor_for_ws);
-                                    if let Err(e) = ws_manager.send_to_public(ws_message).await {
-                                        tracing::error!("Failed to send WebSocket message to public room: {}", e);
-                                    }
-
-                                    // 暂时注释掉 send_to_client，因为现在信息只需发送到 public
-                                    // if let Err(e) = ws_manager.send_to_client(point_id, ws_message).await {
-                                    //     tracing::error!("Failed to send WebSocket message to client room {}: {}", point_id, e);
-                                    // }
-                                }
-                            }); 
+                            }
                         } else {
                             tracing::warn!("Point not found for source {} client_handle {}", source_id, client_handle);
                         }
@@ -178,8 +173,23 @@ impl EventManager {
     }
 
     pub fn send(&self, event: ReloadEvent) -> Result<(), String> {
-        self.sender
-            .send(event)
-            .map_err(|e| format!("Failed to send event: {}", e))
+        match self.sender.try_send(event) {
+            Ok(()) => Ok(()),
+            Err(tokio::sync::mpsc::error::TrySendError::Closed(e)) => {
+                Err(format!("Failed to send event: channel closed ({e:?})"))
+            }
+            Err(tokio::sync::mpsc::error::TrySendError::Full(ReloadEvent::PointNewValue(payload))) => {
+                // High-frequency telemetry is lossy by design under sustained pressure.
+                tracing::warn!(
+                    "Dropping PointNewValue due to full event queue: source={}, client_handle={}",
+                    payload.source_id,
+                    payload.client_handle
+                );
+                Ok(())
+            }
+            Err(tokio::sync::mpsc::error::TrySendError::Full(e)) => {
+                Err(format!("Failed to send event: queue full ({e:?})"))
+            }
+        }
     }
 }
diff --git a/src/handler/point.rs b/src/handler/point.rs
index 2900217..51e6899 100644
--- a/src/handler/point.rs
+++ b/src/handler/point.rs
@@ -2,7 +2,7 @@ use axum::{Json, extract::{Path, Query, State}, http::HeaderMap, response::IntoR
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
 use validator::Validate;
-use sqlx::Row;
+use sqlx::{Row, QueryBuilder};
 
 use crate::util::{response::ApiErr, pagination::{PaginatedResponse, PaginationParams}};
 
@@ -69,12 +69,7 @@ pub async fn get_point(
     Path(point_id): Path<Uuid>,
 ) -> Result<impl IntoResponse, ApiErr> {
     let pool = &state.pool;
-    let point = sqlx::query_as::<_, Point>(
-        r#"SELECT * FROM point WHERE id = $1"#,
-    )
-    .bind(point_id)
-    .fetch_optional(pool)
-    .await?;
+    let point = crate::service::get_point_by_id(pool, point_id).await?;
 
     Ok(Json(point))
 }
@@ -136,51 +131,26 @@ pub async fn update_point(
         return Err(ApiErr::NotFound("Point not found".to_string(), None));
     }
 
-    // Build dynamic UPDATE SQL for provided fields.
-    let mut updates = Vec::new();
-    let mut values: Vec<String> = Vec::new();
-    let mut param_count = 1;
+    let mut qb = QueryBuilder::new("UPDATE point SET ");
+    let mut sep = qb.separated(", ");
 
     if let Some(name) = &payload.name {
-        updates.push(format!("name = ${}", param_count));
-        values.push(name.clone());
-        param_count += 1;
+        sep.push("name = ").push_bind(name);
     }
-
     if let Some(description) = &payload.description {
-        updates.push(format!("description = ${}", param_count));
-        values.push(description.clone());
-        param_count += 1;
+        sep.push("description = ").push_bind(description);
     }
-
     if let Some(unit) = &payload.unit {
-        updates.push(format!("unit = ${}", param_count));
-        values.push(unit.clone());
-        param_count += 1;
+        sep.push("unit = ").push_bind(unit);
     }
-
     if let Some(tag_id) = &payload.tag_id {
-        updates.push(format!("tag_id = ${}", param_count));
-        values.push(tag_id.to_string());
-        param_count += 1;
+        sep.push("tag_id = ").push_bind(tag_id);
     }
 
-    // Always update timestamp.
-    updates.push("updated_at = NOW()".to_string());
+    sep.push("updated_at = NOW()");
 
-    let sql = format!(
-        "UPDATE point SET {} WHERE id = ${}",
-        updates.join(", "),
-        param_count
-    );
-    values.push(point_id.to_string());
-
-    let mut query = sqlx::query(&sql);
-    for value in &values {
-        query = query.bind(value);
-    }
-
-    query.execute(pool).await?;
+    qb.push(" WHERE id = ").push_bind(point_id);
+    qb.build().execute(pool).await?;
 
     Ok(Json(serde_json::json!({"ok_msg": "Point updated successfully"})))
 }
@@ -489,7 +459,7 @@ pub async fn batch_set_point_value(
         return Err(ApiErr::Forbidden(
             "write permission denied".to_string(),
             Some(serde_json::json!({
-                "hint": "set WRITE_API_KEY and pass header X-Write-Key"
+                "hint": "set WRITE_API_KEY (or legacy WRITE_KEY) and pass header X-Write-Key"
             })),
         ));
     }
diff --git a/src/handler/source.rs b/src/handler/source.rs
index 843b015..effa3fd 100644
--- a/src/handler/source.rs
+++ b/src/handler/source.rs
@@ -58,18 +58,47 @@ impl TreeNode {
 #[derive(Debug, Serialize, Clone)]
 pub struct SourceWithStatus {
     #[serde(flatten)]
-    pub source: Source,
+    pub source: SourcePublic,
     pub is_connected: bool,
     pub last_error: Option<String>,
     #[serde(serialize_with = "crate::util::datetime::option_utc_to_local_str")]
     pub last_time: Option<DateTime<Utc>>,
 }
 
+#[derive(Debug, Serialize, Clone)]
+pub struct SourcePublic {
+    pub id: Uuid,
+    pub name: String,
+    pub protocol: String,
+    pub endpoint: String,
+    pub security_policy: Option<String>,
+    pub security_mode: Option<String>,
+    pub enabled: bool,
+    #[serde(serialize_with = "crate::util::datetime::utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+    #[serde(serialize_with = "crate::util::datetime::utc_to_local_str")]
+    pub updated_at: DateTime<Utc>,
+}
+
+impl From<Source> for SourcePublic {
+    fn from(source: Source) -> Self {
+        Self {
+            id: source.id,
+            name: source.name,
+            protocol: source.protocol,
+            endpoint: source.endpoint,
+            security_policy: source.security_policy,
+            security_mode: source.security_mode,
+            enabled: source.enabled,
+            created_at: source.created_at,
+            updated_at: source.updated_at,
+        }
+    }
+}
+
 pub async fn get_source_list(State(state): State<AppState>) -> Result<impl IntoResponse, ApiErr> {
     let pool = &state.pool;
-    let sources: Vec<Source> = sqlx::query_as(
-        r#"SELECT * FROM source where enabled is true"#,
-    ).fetch_all(pool).await?;
+    let sources: Vec<Source> = crate::service::get_all_enabled_sources(pool).await?;
 
     // 获取所有连接状态
     let status_map: std::collections::HashMap<Uuid, (bool, Option<String>, Option<DateTime<Utc>>)> = 
@@ -87,7 +116,7 @@ pub async fn get_source_list(State(state): State<AppState>) -> Result<impl IntoR
                 .map(|(connected, error, time)| (*connected, error.clone(), *time))
                 .unwrap_or((false, None, None));
             SourceWithStatus {
-                source,
+                source: source.into(),
                 is_connected,
                 last_error,
                 last_time,
@@ -444,159 +473,67 @@ async fn process_reference(
     let display_name = ref_desc.display_name.text.to_string();
     let node_class = format!("{:?}", ref_desc.node_class);
 
-    let now = Utc::now();
-    let node_uuid = Uuid::new_v4();
-
-    // ?? 关键优化：直接 UPSERT（避免 SELECT）
-    // 注意：如果 parent_id 存在，则必须确保该父节点已存在于数据库中
-    // 否则会触发外键约束失败
-    if parent_id.is_some() {
-        // 检查父节点是否已存在于数据库中
-        let parent_exists = sqlx::query(
-            r#"SELECT 1 FROM node WHERE id = $1"#,
-        )
-        .bind(parent_id.unwrap())
-        .fetch_optional(tx.as_mut())
-        .await?;
-        
-        if parent_exists.is_none() {
-            // 如果父节点不存在，则暂时不设置 parent_id
-            // 这样可以避免外键约束失败
-            sqlx::query(
-                r#"
-                INSERT INTO node (
-                    id,
-                    source_id,
-                    external_id,
-                    namespace_uri,
-                    namespace_index,
-                    identifier_type,
-                    identifier,
-                    browse_name,
-                    display_name,
-                    node_class,
-                    parent_id,
-                )
-                VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,NULL)
-                ON CONFLICT(source_id, external_id) DO UPDATE SET
-                    namespace_uri = excluded.namespace_uri,
-                    namespace_index = excluded.namespace_index,
-                    identifier_type = excluded.identifier_type,
-                    identifier = excluded.identifier,
-                    browse_name = excluded.browse_name,
-                    display_name = excluded.display_name,
-                    node_class = excluded.node_class,
-                    updated_at = NOW()
-                "#
-            )
-            .bind(node_uuid)
-            .bind(source_id)
-            .bind(&node_id_str)
-            .bind(&namespace_uri)
-            .bind(namespace_index.map(|v| v as i32))
-            .bind(&identifier_type)
-            .bind(&identifier)
-            .bind(&browse_name)
-            .bind(&display_name)
-            .bind(&node_class)
-            .execute(tx.as_mut())
-            .await
-            .context("Failed to execute UPSERT query")?;
+    let effective_parent_id = if let Some(pid) = parent_id {
+        let parent_exists = sqlx::query(r#"SELECT 1 FROM node WHERE id = $1"#)
+            .bind(pid)
+            .fetch_optional(tx.as_mut())
+            .await?;
+        if parent_exists.is_some() {
+            Some(pid)
         } else {
-            // 如果父节点存在，则正常设置 parent_id
-            sqlx::query(
-                r#"
-                INSERT INTO node (
-                    id,
-                    source_id,
-                    external_id,
-                    namespace_uri,
-                    namespace_index,
-                    identifier_type,
-                    identifier,
-                    browse_name,
-                    display_name,
-                    node_class,
-                    parent_id,
-                    created_at,
-                    updated_at
-                )
-                VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,NOW(),NOW())
-                ON CONFLICT(source_id, external_id) DO UPDATE SET
-                    namespace_uri = excluded.namespace_uri,
-                    namespace_index = excluded.namespace_index,
-                    identifier_type = excluded.identifier_type,
-                    identifier = excluded.identifier,
-                    browse_name = excluded.browse_name,
-                    display_name = excluded.display_name,
-                    node_class = excluded.node_class,
-                    parent_id = excluded.parent_id,
-                    updated_at = NOW()
-                "#
-            )
-            .bind(node_uuid)
-            .bind(source_id)
-            .bind(&node_id_str)
-            .bind(&namespace_uri)
-            .bind(namespace_index.map(|v| v as i32))
-            .bind(&identifier_type)
-            .bind(&identifier)
-            .bind(&browse_name)
-            .bind(&display_name)
-            .bind(&node_class)
-            .bind(parent_id)
-            .bind(now)
-            .bind(now)
-            .execute(tx.as_mut())
-            .await
-            .context("Failed to execute UPSERT query")?;
+            None
         }
     } else {
-        // 如果没有 parent_id，则正常插入
-        sqlx::query(
-            r#"
-            INSERT INTO node (
-                id,
-                source_id,
-                external_id,
-                namespace_uri,
-                namespace_index,
-                identifier_type,
-                identifier,
-                browse_name,
-                display_name,
-                node_class,
-                parent_id
-            )
-            VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,NULL)
-            ON CONFLICT(source_id, external_id) DO UPDATE SET
-                namespace_uri = excluded.namespace_uri,
-                namespace_index = excluded.namespace_index,
-                identifier_type = excluded.identifier_type,
-                identifier = excluded.identifier,
-                browse_name = excluded.browse_name,
-                display_name = excluded.display_name,
-                node_class = excluded.node_class,
-                updated_at = NOW()
-            "#
+        None
+    };
+
+    // Use RETURNING id so queue always carries the actual DB node id.
+    let persisted_node_id = sqlx::query_scalar::<_, Uuid>(
+        r#"
+        INSERT INTO node (
+            id,
+            source_id,
+            external_id,
+            namespace_uri,
+            namespace_index,
+            identifier_type,
+            identifier,
+            browse_name,
+            display_name,
+            node_class,
+            parent_id
         )
-        .bind(node_uuid)
-        .bind(source_id)
-        .bind(&node_id_str)
-        .bind(&namespace_uri)
-        .bind(namespace_index.map(|v| v as i32))
-        .bind(&identifier_type)
-        .bind(&identifier)
-        .bind(&browse_name)
-        .bind(&display_name)
-        .bind(&node_class)
-        .execute(tx.as_mut())
-        .await
-        .context("Failed to execute UPSERT query")?;
-    }
+        VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11)
+        ON CONFLICT(source_id, external_id) DO UPDATE SET
+            namespace_uri = excluded.namespace_uri,
+            namespace_index = excluded.namespace_index,
+            identifier_type = excluded.identifier_type,
+            identifier = excluded.identifier,
+            browse_name = excluded.browse_name,
+            display_name = excluded.display_name,
+            node_class = excluded.node_class,
+            parent_id = COALESCE(excluded.parent_id, node.parent_id),
+            updated_at = NOW()
+        RETURNING id
+        "#,
+    )
+    .bind(Uuid::new_v4())
+    .bind(source_id)
+    .bind(&node_id_str)
+    .bind(&namespace_uri)
+    .bind(namespace_index.map(|v| v as i32))
+    .bind(&identifier_type)
+    .bind(&identifier)
+    .bind(&browse_name)
+    .bind(&display_name)
+    .bind(&node_class)
+    .bind(effective_parent_id)
+    .fetch_one(tx.as_mut())
+    .await
+    .context("Failed to execute UPSERT query")?;
 
     processed_nodes.insert(node_id_str.clone(), ());
-    queue.push_back((node_id_obj.clone(), Some(node_uuid)));
+    queue.push_back((node_id_obj.clone(), Some(persisted_node_id)));
 
     Ok(())
 }
diff --git a/src/service.rs b/src/service.rs
index f5bcdc9..70e3997 100644
--- a/src/service.rs
+++ b/src/service.rs
@@ -17,6 +17,18 @@ pub async fn get_all_enabled_sources(pool: &PgPool) -> Result<Vec<Source>, sqlx:
         .await
 }
 
+pub async fn get_point_by_id(
+    pool: &PgPool,
+    point_id: uuid::Uuid,
+) -> Result<Option<crate::model::Point>, sqlx::Error> {
+    query_as::<_, crate::model::Point>(
+        r#"SELECT * FROM point WHERE id = $1"#,
+    )
+    .bind(point_id)
+    .fetch_optional(pool)
+    .await
+}
+
 pub async fn get_points_grouped_by_source(
     pool: &PgPool,
     point_ids: &[uuid::Uuid],
diff --git a/src/util/response.rs b/src/util/response.rs
index 6c41484..ab59fe8 100644
--- a/src/util/response.rs
+++ b/src/util/response.rs
@@ -68,13 +68,7 @@ impl IntoResponse for ApiErr {
 impl From<Error> for ApiErr {
     fn from(err: Error) -> Self {
         tracing::error!("Error: {:?}; root_cause: {}", err, err.root_cause());
-        ApiErr::Internal(
-            err.to_string(),
-            Some(serde_json::json!({
-                "root_cause": err.root_cause().to_string(),
-                "chain": err.chain().map(|e| e.to_string()).collect::<Vec<_>>()
-            })),
-        )
+        ApiErr::Internal("internal server error".to_string(), None)
     }
 }