security: default Studio host to 127.0.0.1 and prompt before auto-start

README.md

@@ -64,8 +64,9 @@ irm https://unsloth.ai/install.ps1 | iex
 
 #### Launch
 ```bash
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
+> For cloud VMs or LAN access, add `-H 0.0.0.0` to bind on all interfaces.
 
 #### Update
 To update, use the same install commands as above. Or run (does not work on Windows):
@@ -151,7 +152,7 @@ The below advanced instructions are for Unsloth Studio. For Unsloth Core advance
 git clone https://github.com/unslothai/unsloth
 cd unsloth
 ./install.sh --local
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
 Then to update :
 ```bash
@@ -164,7 +165,7 @@ git clone https://github.com/unslothai/unsloth.git
 cd unsloth
 Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
 .\install.ps1 --local
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
 Then to update :
 ```bash
@@ -177,11 +178,11 @@ git clone https://github.com/unslothai/unsloth
 cd unsloth
 git checkout nightly
 ./install.sh --local
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
 Then to launch every time:
 ```bash
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
 
 #### Nightly: Windows:
@@ -192,11 +193,11 @@ cd unsloth
 git checkout nightly
 Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
 .\install.ps1 --local
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
 Then to launch every time:
 ```bash
-unsloth studio -H 0.0.0.0 -p 8888
+unsloth studio
 ```
 
 #### Uninstall

install.ps1

@@ -958,15 +958,25 @@ shell.Run cmd, 0, False
         step "path" "added unsloth to PATH"
     }
 
-    # Launch studio automatically in interactive terminals;
-    # in non-interactive environments (CI, Docker) just print instructions.
+    # In interactive terminals, ask the user before starting Studio.
+    # In non-interactive environments (CI, Docker) just print instructions.
     $IsInteractive = [Environment]::UserInteractive -and (-not [Console]::IsInputRedirected)
     if ($IsInteractive) {
-        & $UnslothExe studio -H 0.0.0.0 -p 8888
+        Write-Host ""
+        $reply = Read-Host "  Start Unsloth Studio now? [Y/n]"
+        if ([string]::IsNullOrWhiteSpace($reply) -or $reply -match '^[Yy]') {
+            & $UnslothExe studio -p 8888
+        } else {
+            step "launch" "to start later, run:"
+            substep "unsloth studio"
+            substep "(add -H 0.0.0.0 to allow network / cloud access)"
+            Write-Host ""
+        }
     } else {
         step "launch" "manual commands:"
         substep "& `"$VenvDir\Scripts\Activate.ps1`""
-        substep "unsloth studio -H 0.0.0.0 -p 8888"
+        substep "unsloth studio"
+        substep "(add -H 0.0.0.0 to allow network / cloud access)"
         Write-Host ""
     }
 }

install.sh

@@ -447,11 +447,11 @@ if [ -t 1 ]; then
     ) &
     # Clear traps so exec does not trigger _release_lock (the subshell owns it)
     trap - EXIT INT TERM
-    exec "$UNSLOTH_EXE" studio -H 0.0.0.0 -p "$_launch_port"
+    exec "$UNSLOTH_EXE" studio -p "$_launch_port"
 else
     # ── Background mode (no TTY) ──
     # Used by macOS .app and headless invocations.
-    _launch_cmd=$(printf '%q ' "$UNSLOTH_EXE" studio -H 0.0.0.0 -p "$_launch_port")
+    _launch_cmd=$(printf '%q ' "$UNSLOTH_EXE" studio -p "$_launch_port")
     _launch_cmd=${_launch_cmd% }
     _spawn_terminal "$_launch_cmd"
 
@@ -1211,28 +1211,42 @@ printf "  ${C_TITLE}%s${C_RST}\n" "Unsloth Studio installed!"
 printf "  ${C_DIM}%s${C_RST}\n" "$RULE"
 echo ""
 
-# Launch studio automatically in interactive terminals;
-# in non-interactive environments (Docker, CI, cloud-init) just print instructions.
+# In interactive terminals, ask the user before starting Studio.
+# In non-interactive environments (Docker, CI, cloud-init) just print instructions.
 if [ -t 1 ]; then
-    step "launch" "starting Unsloth Studio..."
-    "$VENV_DIR/bin/unsloth" studio -H 0.0.0.0 -p 8888
-    _LAUNCH_EXIT=$?
-    if [ "$_LAUNCH_EXIT" -ne 0 ] && [ "$_MIGRATED" = true ]; then
-        echo ""
-        echo "⚠️  Unsloth Studio failed to start after migration."
-        echo "   Your migrated environment may be incompatible."
-        echo "   To fix, remove the environment and reinstall:"
-        echo ""
-        echo "   rm -rf $VENV_DIR"
-        echo "   curl -fsSL https://unsloth.ai/install.sh | sh"
-        echo ""
-    fi
-    exit "$_LAUNCH_EXIT"
+    echo ""
+    printf "  Start Unsloth Studio now? [Y/n] "
+    read -r _reply </dev/tty || _reply="y"
+    case "${_reply:-y}" in
+        [Yy]*|"")
+            step "launch" "starting Unsloth Studio..."
+            "$VENV_DIR/bin/unsloth" studio -p 8888
+            _LAUNCH_EXIT=$?
+            if [ "$_LAUNCH_EXIT" -ne 0 ] && [ "$_MIGRATED" = true ]; then
+                echo ""
+                echo "⚠️  Unsloth Studio failed to start after migration."
+                echo "   Your migrated environment may be incompatible."
+                echo "   To fix, remove the environment and reinstall:"
+                echo ""
+                echo "   rm -rf $VENV_DIR"
+                echo "   curl -fsSL https://unsloth.ai/install.sh | sh"
+                echo ""
+            fi
+            exit "$_LAUNCH_EXIT"
+            ;;
+        *)
+            step "launch" "to start later, run:"
+            substep "unsloth studio"
+            substep "(add -H 0.0.0.0 to allow network / cloud access)"
+            echo ""
+            ;;
+    esac
 else
     step "launch" "manual commands:"
-    substep "unsloth studio -H 0.0.0.0 -p 8888"
+    substep "unsloth studio"
     substep "or activate env first:"
     substep "source ${VENV_DIR}/bin/activate"
-    substep "unsloth studio -H 0.0.0.0 -p 8888"
+    substep "unsloth studio"
+    substep "(add -H 0.0.0.0 to allow network / cloud access)"
     echo ""
 fi

studio/backend/run.py

@@ -244,7 +244,7 @@ def _graceful_shutdown(server = None):
 
 
 def run_server(
-    host: str = "0.0.0.0",
+    host: str = "127.0.0.1",
     port: int = 8888,
     frontend_path: Path = Path(__file__).resolve().parent.parent / "frontend" / "dist",
     silent: bool = False,
@@ -357,21 +357,20 @@ def _trigger_shutdown():
     return app
 
 
-# For direct execution (also invoked by CLI via os.execvp / subprocess)
-if __name__ == "__main__":
-    import argparse
-    import signal
-    import traceback
+def _make_argument_parser() -> "argparse.ArgumentParser":
+    """Build and return the ArgumentParser for standalone run.py execution.
 
-    # Ensure stderr can handle Unicode on Windows (tracebacks with non-ASCII paths)
-    if sys.platform == "win32" and hasattr(sys.stderr, "reconfigure"):
-        try:
-            sys.stderr.reconfigure(encoding = "utf-8", errors = "replace")
-        except Exception:
-            pass
+    Extracted from ``__main__`` so it can be imported and tested without
+    executing the full startup sequence.
+    """
+    import argparse
 
     parser = argparse.ArgumentParser(description = "Run Unsloth UI Backend server")
-    parser.add_argument("--host", default = "0.0.0.0", help = "Host to bind to")
+    parser.add_argument(
+        "--host",
+        default = "127.0.0.1",
+        help = "Host to bind to (default: 127.0.0.1; use 0.0.0.0 for network/cloud access)",
+    )
     parser.add_argument("--port", type = int, default = 8888, help = "Port to bind to")
     parser.add_argument(
         "--frontend",
@@ -380,8 +379,22 @@ def _trigger_shutdown():
         help = "Path to frontend build",
     )
     parser.add_argument("--silent", action = "store_true", help = "Suppress output")
+    return parser
+
+
+# For direct execution (also invoked by CLI via os.execvp / subprocess)
+if __name__ == "__main__":
+    import signal
+    import traceback
+
+    # Ensure stderr can handle Unicode on Windows (tracebacks with non-ASCII paths)
+    if sys.platform == "win32" and hasattr(sys.stderr, "reconfigure"):
+        try:
+            sys.stderr.reconfigure(encoding = "utf-8", errors = "replace")
+        except Exception:
+            pass
 
-    args = parser.parse_args()
+    args = _make_argument_parser().parse_args()
 
     kwargs = dict(host = args.host, port = args.port, silent = args.silent)
     if args.frontend is not None:

unsloth_cli/commands/studio.py

@@ -76,7 +76,7 @@ def _find_setup_script() -> Optional[Path]:
 def studio_default(
     ctx: typer.Context,
     port: int = typer.Option(8888, "--port", "-p"),
-    host: str = typer.Option("0.0.0.0", "--host", "-H"),
+    host: str = typer.Option("127.0.0.1", "--host", "-H"),
     frontend: Optional[Path] = typer.Option(None, "--frontend", "-f"),
     silent: bool = typer.Option(False, "--silent", "-q"),
 ):