feat(sdk): Add /run socket paths for compatibility

Add /run/dstack.sock and /run/tappd.sock to the socket path search list
in all SDKs (Rust, Python, JS, Go). This ensures compatibility with
systemd socket activation which uses /run instead of /var/run.

Search order:
1. /var/run/dstack/*.sock (namespaced path)
2. /run/*.sock (modern systemd path)
3. /var/run/*.sock (legacy path)

Author: kvinwang

sdk/go/dstack/client.go

@@ -240,9 +240,10 @@ func (c *DstackClient) getEndpoint() string {
 		c.logger.Info("using simulator endpoint", "endpoint", simEndpoint)
 		return simEndpoint
 	}
-	// Try new path first, fall back to old path for backward compatibility
+	// Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
 	socketPaths := []string{
 		"/var/run/dstack/dstack.sock",
+		"/run/dstack.sock",
 		"/var/run/dstack.sock",
 	}
 	for _, path := range socketPaths {

sdk/go/tappd/client.go

@@ -230,9 +230,10 @@ func (c *TappdClient) getEndpoint() string {
 		c.logger.Info("using simulator endpoint", "endpoint", simEndpoint)
 		return simEndpoint
 	}
-	// Try new path first, fall back to old path for backward compatibility
+	// Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
 	socketPaths := []string{
 		"/var/run/dstack/tappd.sock",
+		"/run/tappd.sock",
 		"/var/run/tappd.sock",
 	}
 	for _, path := range socketPaths {

sdk/js/src/index.ts

@@ -179,9 +179,10 @@ export class DstackClient<T extends TcbInfo = TcbInfoV05x> {
         console.warn(`Using simulator endpoint: ${process.env.DSTACK_SIMULATOR_ENDPOINT}`)
         endpoint = process.env.DSTACK_SIMULATOR_ENDPOINT
       } else {
-        // Try new path first, fall back to old path for backward compatibility
+        // Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
         const socketPaths = [
           '/var/run/dstack/dstack.sock',
+          '/run/dstack.sock',
           '/var/run/dstack.sock',
         ]
         endpoint = socketPaths.find(p => fs.existsSync(p)) ?? socketPaths[0]
@@ -407,9 +408,10 @@ export class TappdClient extends DstackClient<TcbInfoV03x> {
         console.warn(`Using tappd endpoint: ${process.env.TAPPD_SIMULATOR_ENDPOINT}`)
         endpoint = process.env.TAPPD_SIMULATOR_ENDPOINT
       } else {
-        // Try new path first, fall back to old path for backward compatibility
+        // Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
         const socketPaths = [
           '/var/run/dstack/tappd.sock',
+          '/run/tappd.sock',
           '/var/run/tappd.sock',
         ]
         endpoint = socketPaths.find(p => fs.existsSync(p)) ?? socketPaths[0]

sdk/python/src/dstack_sdk/dstack_client.py

@@ -51,9 +51,10 @@ def get_endpoint(endpoint: str | None = None) -> str:
             f"Using simulator endpoint: {os.environ['DSTACK_SIMULATOR_ENDPOINT']}"
         )
         return os.environ["DSTACK_SIMULATOR_ENDPOINT"]
-    # Try new path first, fall back to old path for backward compatibility
+    # Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
     socket_paths = [
         "/var/run/dstack/dstack.sock",
+        "/run/dstack.sock",
         "/var/run/dstack.sock",
     ]
     for path in socket_paths:
@@ -69,9 +70,10 @@ def get_tappd_endpoint(endpoint: str | None = None) -> str:
     if "TAPPD_SIMULATOR_ENDPOINT" in os.environ:
         logger.info(f"Using tappd endpoint: {os.environ['TAPPD_SIMULATOR_ENDPOINT']}")
         return os.environ["TAPPD_SIMULATOR_ENDPOINT"]
-    # Try new path first, fall back to old path for backward compatibility
+    # Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
     socket_paths = [
         "/var/run/dstack/tappd.sock",
+        "/run/tappd.sock",
         "/var/run/tappd.sock",
     ]
     for path in socket_paths:

sdk/rust/src/dstack_client.rs

@@ -36,8 +36,12 @@ fn get_endpoint(endpoint: Option<&str>) -> String {
     if let Ok(sim_endpoint) = env::var("DSTACK_SIMULATOR_ENDPOINT") {
         return sim_endpoint;
     }
-    // Try new path first, fall back to old path for backward compatibility
-    const SOCKET_PATHS: &[&str] = &["/var/run/dstack/dstack.sock", "/var/run/dstack.sock"];
+    // Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
+    const SOCKET_PATHS: &[&str] = &[
+        "/var/run/dstack/dstack.sock",
+        "/run/dstack.sock",
+        "/var/run/dstack.sock",
+    ];
     for path in SOCKET_PATHS {
         if std::path::Path::new(path).exists() {
             return path.to_string();

sdk/rust/src/tappd_client.rs

@@ -21,8 +21,12 @@ fn get_tappd_endpoint(endpoint: Option<&str>) -> String {
     if let Ok(sim_endpoint) = env::var("TAPPD_SIMULATOR_ENDPOINT") {
         return sim_endpoint;
     }
-    // Try new path first, fall back to old path for backward compatibility
-    const SOCKET_PATHS: &[&str] = &["/var/run/dstack/tappd.sock", "/var/run/tappd.sock"];
+    // Try paths in order of preference (new paths first, then legacy paths for backward compatibility)
+    const SOCKET_PATHS: &[&str] = &[
+        "/var/run/dstack/tappd.sock",
+        "/run/tappd.sock",
+        "/var/run/tappd.sock",
+    ];
     for path in SOCKET_PATHS {
         if std::path::Path::new(path).exists() {
             return path.to_string();