@@ -14,6 +14,7 @@ import {
     type ChildProcess,
     spawn,
 } from "node:child_process";
+import { randomBytes } from "node:crypto";
 import {
     closeSync,
     openSync,
@@ -86,6 +87,10 @@ process.on("exit", () => {
     liveChildren.clear();
 });
 
+export function createPipePath(): string {
+    return `\\\\.\\pipe\\tsgo-sync-${process.pid}-${randomBytes(16).toString("hex")}`;
+}
+
 /**
  * SyncRpcChannel – drop-in replacement for the native libsyncrpc class.
  *
@@ -147,7 +152,7 @@ export class SyncRpcChannel {
             // we create a Windows named pipe path, pass it to the child
             // via --pipe, and open it with fs.openSync which returns a
             // real C-runtime fd backed by a proper HANDLE.
-            const pipePath = `\\\\.\\pipe\\tsgo-sync-${process.pid}-${Date.now()}`;
+            const pipePath = createPipePath();
             this.child = spawn(exe, [...args, "--pipe", pipePath], {
                 stdio: ["ignore", "ignore", "inherit"],
             });
 
@@ -407,7 +407,7 @@ const customStructures: Structure[] = [
                 name: "pipe",
                 type: { kind: "base", name: "string" },
                 optional: true,
-                documentation: "Optional path to use for the named pipe or Unix domain socket. If not provided, a unique path will be generated.",
+                documentation: "Optional named pipe path on Windows. On Unix, the path must not exist and will be created as a private directory containing a socket named 'socket'. If not provided, a unique path will be generated.",
             },
         ],
         documentation: "Parameters for the initializeAPISession request.",
 
@@ -30,7 +30,7 @@ func parseAPIFlags(args []string) (apiFlags, error) {
 	flags := flag.NewFlagSet("api", flag.ContinueOnError)
 	result := apiFlags{}
 	flags.StringVar(&result.cwd, "cwd", core.Must(os.Getwd()), "current working directory")
-	flags.StringVar(&result.pipePath, "pipe", "", "use named pipe or Unix domain socket for communication instead of stdio")
+	flags.StringVar(&result.pipePath, "pipe", "", "use a named pipe (Windows) or create a private Unix socket at <path>/socket, where <path> must not exist")
 	flags.StringVar(&result.callbacks, "callbacks", "", "comma-separated list of FS callbacks and defaults to enable")
 	flags.BoolVar(&result.caseSensitive, "useCaseSensitiveFileNames", osvfs.FS().CaseSensitivity().IsCaseSensitive(), "treat filesystem paths as case-sensitive")
 	flags.BoolVar(&result.async, "async", false, "use JSON-RPC protocol instead of MessagePack (for async API)")
 
@@ -21,8 +21,8 @@ type StdioServerOptions struct {
 	Err                io.Writer
 	Cwd                tspath.RootedDirectoryPath
 	DefaultLibraryPath tspath.RootedDirectoryPath
-	// PipePath, if set, listens on a named pipe (Windows) or Unix domain
-	// socket instead of using In/Out for communication.
+	// PipePath, if set, is the named pipe path on Windows. On Unix, it must
+	// not exist and is created as a private directory containing "socket".
 	PipePath string
 	// Callbacks specifies which filesystem operations should be delegated
 	// to the client (e.g., "readFile", "fileExists"). Empty means no callbacks.
 
@@ -1,6 +1,7 @@
 package ipc
 
 import (
+	"errors"
 	"io"
 	"net"
 )
@@ -16,16 +17,33 @@ type Transport interface {
 // PipeTransport accepts connections on a Unix domain socket or Windows named pipe.
 type PipeTransport struct {
 	listener net.Listener
+	cleanup  func() error
 }
 
-// NewPipeTransport creates a new transport listening on the given path.
-// On Unix, this creates a Unix domain socket. On Windows, this creates a named pipe.
+// NewPipeTransport creates a new pipe transport.
+// On Unix, path must not exist and is created as a private directory containing "socket".
+// On Windows, path is the named pipe path.
 func NewPipeTransport(path string) (*PipeTransport, error) {
-	listener, err := newPipeListener(path)
+	listener, cleanup, err := newPipeListener(path)
 	if err != nil {
 		return nil, err
 	}
-	return &PipeTransport{listener: listener}, nil
+	return &PipeTransport{
+		listener: listener,
+		cleanup:  cleanup,
+	}, nil
+}
+
+// NewPrivatePipeTransport creates a transport at a private, generated path.
+func NewPrivatePipeTransport(name string) (*PipeTransport, error) {
+	listener, cleanup, err := newPrivatePipeListener(name)
+	if err != nil {
+		return nil, err
+	}
+	return &PipeTransport{
+		listener: listener,
+		cleanup:  cleanup,
+	}, nil
 }
 
 // Accept implements Transport.
@@ -35,7 +53,11 @@ func (t *PipeTransport) Accept() (io.ReadWriteCloser, error) {
 
 // Close implements Transport.
 func (t *PipeTransport) Close() error {
-	return t.listener.Close()
+	closeErr := t.listener.Close()
+	if t.cleanup == nil || errors.Is(closeErr, net.ErrClosed) {
+		return closeErr
+	}
+	return errors.Join(closeErr, t.cleanup())
 }
 
 // Path returns the path of the pipe/socket.
 
@@ -3,20 +3,59 @@
 package ipc
 
 import (
+	"errors"
+	"fmt"
+	"io/fs"
 	"net"
 	"os"
-	"path"
+	"path/filepath"
 )
 
-// newPipeListener creates a Unix domain socket listener.
-func newPipeListener(path string) (net.Listener, error) {
-	// Remove any existing socket file
-	_ = os.Remove(path) //nolint:forbidigo
-	return net.Listen("unix", path)
+func newPipeListener(dir string) (net.Listener, func() error, error) {
+	if err := os.Mkdir(dir, 0o700); err != nil { //nolint:forbidigo
+		return nil, nil, fmt.Errorf("create private socket directory: %w", err)
+	}
+	return listenInPrivatePipeDirectory(dir)
+}
+
+func newPrivatePipeListener(_ string) (net.Listener, func() error, error) {
+	dir, err := os.MkdirTemp("", "tsgo-api-") //nolint:forbidigo
+	if err != nil {
+		return nil, nil, fmt.Errorf("create private socket directory: %w", err)
+	}
+	return listenInPrivatePipeDirectory(dir)
+}
+
+func listenInPrivatePipeDirectory(dir string) (net.Listener, func() error, error) {
+	socketPath := filepath.Join(dir, "socket") //nolint:forbidigo
+	cleanup := func() error {
+		socketErr := os.Remove(socketPath) //nolint:forbidigo
+		if errors.Is(socketErr, fs.ErrNotExist) {
+			socketErr = nil
+		}
+		dirErr := os.Remove(dir) //nolint:forbidigo
+		if errors.Is(dirErr, fs.ErrNotExist) {
+			dirErr = nil
+		}
+		return errors.Join(socketErr, dirErr)
+	}
+
+	if err := os.Chmod(dir, 0o700); err != nil { //nolint:forbidigo
+		return nil, nil, errors.Join(fmt.Errorf("set private socket directory permissions: %w", err), cleanup())
+	}
+
+	listener, err := net.Listen("unix", socketPath)
+	if err != nil {
+		return nil, nil, errors.Join(fmt.Errorf("listen on private socket: %w", err), cleanup())
+	}
+	if err := os.Chmod(socketPath, 0o600); err != nil { //nolint:forbidigo
+		return nil, nil, errors.Join(fmt.Errorf("set private socket permissions: %w", err), listener.Close(), cleanup())
+	}
+	return listener, cleanup, nil
 }
 
 // GeneratePipePath returns a platform-appropriate pipe path for the given name.
 func GeneratePipePath(name string) string {
 	//nolint:forbidigo
-	return path.Join(os.TempDir(), name)
+	return filepath.Join(os.TempDir(), name)
 }
@@ -0,0 +1,103 @@
+//go:build !windows
+
+package ipc
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"syscall"
+	"testing"
+	"time"
+)
+
+const privatePipeHelperEnv = "TSGO_PRIVATE_PIPE_HELPER"
+
+func TestPipeTransportClosePreservesReplacement(t *testing.T) {
+	t.Parallel()
+
+	transport, err := NewPrivatePipeTransport("tsgo-api-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	socketPath := transport.Path()
+	if closeErr := transport.Close(); closeErr != nil {
+		t.Fatal(closeErr)
+	}
+
+	replacement, err := NewPipeTransport(filepath.Dir(socketPath))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer replacement.Close()
+
+	if closeErr := transport.Close(); !errors.Is(closeErr, net.ErrClosed) {
+		t.Fatalf("second Close returned %v, want net.ErrClosed", closeErr)
+	}
+	conn, err := net.DialTimeout("unix", socketPath, time.Second)
+	if err != nil {
+		t.Fatalf("replacement socket is unreachable: %v", err)
+	}
+	defer conn.Close()
+}
+
+func TestPipeTransportPermissions(t *testing.T) {
+	t.Parallel()
+
+	if os.Getenv(privatePipeHelperEnv) == "1" {
+		testPipeTransportPermissions(t)
+		return
+	}
+
+	cmd := exec.Command(os.Args[0], "-test.run=^TestPipeTransportPermissions$")
+	cmd.Env = append(os.Environ(), privatePipeHelperEnv+"=1")
+	if output, err := cmd.CombinedOutput(); err != nil {
+		t.Fatalf("helper process failed: %v\n%s", err, output)
+	}
+}
+
+func testPipeTransportPermissions(t *testing.T) {
+	syscall.Umask(0o002)
+
+	transport, err := NewPrivatePipeTransport("tsgo-api-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer transport.Close()
+
+	socketPath := transport.Path()
+	assertMode(t, filepath.Dir(socketPath), 0o700)
+	assertMode(t, socketPath, 0o600)
+
+	explicitDir := filepath.Join(os.TempDir(), fmt.Sprintf("tsgo-api-%d", os.Getpid()))
+	explicitTransport, err := NewPipeTransport(explicitDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertMode(t, explicitDir, 0o700)
+	assertMode(t, filepath.Join(explicitDir, "socket"), 0o600)
+
+	if _, err := NewPipeTransport(explicitDir); err == nil {
+		t.Fatal("NewPipeTransport succeeded with an existing directory")
+	}
+	if err := explicitTransport.Close(); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(explicitDir); !os.IsNotExist(err) {
+		t.Fatalf("socket directory still exists after close: %v", err)
+	}
+}
+
+func assertMode(t *testing.T, path string, want os.FileMode) {
+	t.Helper()
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := info.Mode().Perm(); got != want {
+		t.Fatalf("%s mode = %04o, want %04o", path, got, want)
+	}
+}
@@ -3,14 +3,27 @@
 package ipc
 
 import (
+	"fmt"
 	"net"
 
 	"github.com/Microsoft/go-winio"
+	"golang.org/x/sys/windows"
 )
 
 // newPipeListener creates a Windows named pipe listener.
-func newPipeListener(path string) (net.Listener, error) {
-	return winio.ListenPipe(path, nil)
+func newPipeListener(path string) (net.Listener, func() error, error) {
+	user, err := windows.GetCurrentProcessToken().GetTokenUser()
+	if err != nil {
+		return nil, nil, fmt.Errorf("get pipe owner SID: %w", err)
+	}
+	listener, err := winio.ListenPipe(path, &winio.PipeConfig{
+		SecurityDescriptor: "D:P(A;;GA;;;" + user.User.Sid.String() + ")",
+	})
+	return listener, nil, err
+}
+
+func newPrivatePipeListener(name string) (net.Listener, func() error, error) {
+	return newPipeListener(GeneratePipePath(name))
 }
 
 // GeneratePipePath returns a platform-appropriate pipe path for the given name.
 
@@ -0,0 +1,76 @@
+//go:build windows
+
+package ipc
+
+import (
+	"fmt"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/Microsoft/go-winio"
+	"golang.org/x/sys/windows"
+)
+
+func TestPipeTransportPermissions(t *testing.T) {
+	t.Parallel()
+
+	transport, err := NewPrivatePipeTransport(fmt.Sprintf("tsgo-api-test-%d", os.Getpid()))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer transport.Close()
+
+	accepted := make(chan error, 1)
+	done := make(chan struct{})
+	defer close(done)
+	go func() {
+		server, acceptErr := transport.Accept()
+		if acceptErr == nil {
+			defer server.Close()
+		}
+		accepted <- acceptErr
+		<-done
+	}()
+
+	timeout := time.Second
+	conn, err := winio.DialPipe(transport.Path(), &timeout)
+	if err != nil {
+		t.Fatalf("current user cannot connect: %v", err)
+	}
+	defer conn.Close()
+
+	select {
+	case acceptErr := <-accepted:
+		if acceptErr != nil {
+			t.Fatalf("failed to accept current user connection: %v", acceptErr)
+		}
+	case <-time.After(timeout):
+		t.Fatal("timed out accepting current user connection")
+	}
+
+	handle := windows.Handle(conn.(interface{ Fd() uintptr }).Fd())
+	sd, err := windows.GetSecurityInfo(handle, windows.SE_FILE_OBJECT, windows.DACL_SECURITY_INFORMATION)
+	if err != nil {
+		t.Fatal(err)
+	}
+	dacl, _, err := sd.DACL()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if dacl == nil || dacl.AceCount != 1 {
+		t.Fatalf("expected exactly one access-control entry: %s", sd.String())
+	}
+	user, err := windows.GetCurrentProcessToken().GetTokenUser()
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Windows maps generic all access to file all access and may abbreviate well-known SIDs.
+	expected, err := windows.SecurityDescriptorFromString("D:P(A;;FA;;;" + user.User.Sid.String() + ")")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := sd.String(), expected.String(); got != want {
+		t.Fatalf("pipe security descriptor = %s, want %s", got, want)
+	}
+}