diff --git a/src-tauri/src/commands/acp.rs b/src-tauri/src/commands/acp.rs
index 1e1549d..4756e5c 100644
--- a/src-tauri/src/commands/acp.rs
+++ b/src-tauri/src/commands/acp.rs
@@ -91,6 +91,25 @@ async fn detect_global_cmd_version(cmd: &str) -> Option<String> {
     normalize_version_candidate(&raw)
 }
 
+/// Check whether a command is available on the system PATH.
+/// Uses `which` on unix and `where` on windows — lightweight and does not
+/// invoke the target binary itself, avoiding side-effects or slow startups.
+async fn is_cmd_available(cmd: &str) -> bool {
+    #[cfg(unix)]
+    let check_cmd = "which";
+    #[cfg(windows)]
+    let check_cmd = "where";
+
+    crate::process::tokio_command(check_cmd)
+        .arg(cmd)
+        .stdout(std::process::Stdio::null())
+        .stderr(std::process::Stdio::null())
+        .status()
+        .await
+        .map(|s| s.success())
+        .unwrap_or(false)
+}
+
 async fn detect_local_version(agent_type: AgentType) -> Option<String> {
     let meta = registry::get_agent_meta(agent_type);
     match meta.distribution {
@@ -1036,9 +1055,12 @@ pub async fn acp_connect(
         runtime_env.insert("OPENCLAW_RESET_SESSION".into(), "1".into());
     }
 
-    if let registry::AgentDistribution::Npx { cmd, package, .. } = meta.distribution {
-        if detect_global_cmd_version(cmd).await.is_none() {
-            install_npm_global_package(package).await?;
+    if let registry::AgentDistribution::Npx { cmd, .. } = meta.distribution {
+        if !is_cmd_available(cmd).await {
+            return Err(AcpError::protocol(format!(
+                "{} SDK is not installed. Please install it in Agent Settings.",
+                meta.name
+            )));
         }
     }