[Bug]: mcp add/remove commands hang indefinitely when stdin is not a TTY and target client is running

[devadathanmb]

Description

When smithery mcp add or smithery mcp remove is run non-interactively (piped stdin — e.g. from CI, a script, or any tool that spawns the CLI via execFile/spawn), the process hangs forever if the target client app is currently open.

Steps to Reproduce

1. Have the target client app open (e.g. Opencode).
2. Run:

# Run smithery with stdin as a pipe (not a TTY) to simulate CI / automation.
# Because there is no interactive terminal, the restart prompt hangs forever.
node -e "const {spawn}=require('child_process'); spawn('smithery',['mcp','add','brightdata','--client','opencode'],{stdio:['pipe','inherit','inherit']}); setInterval(()=>console.error('still running...'),2000);"

Expected Behaviour

CLI detects non-TTY stdin and skips the prompt, exits cleanly.

Actual Behaviour

Process hangs indefinitely.

Additional Information

Root Cause

In src/utils/client.ts — promptForRestart() calls inquirer.prompt unconditionally when the client is running:

const isRunning = await isClientRunning(client)
if (!isRunning) return false

const { shouldRestart } = await inquirer.prompt([
  { type: "confirm", name: "shouldRestart", default: true, ... }
])

promptForRestart is called at the end of both install.ts and uninstall.ts with no TTY check. When stdin is a pipe, inquirer blocks forever waiting for input that never comes.

Environment

smithery CLI version: 4.4.0
Platform: macOS (darwin)

[devadathanmb]

A simple fix would be to check process.stdin.isTTY at the start of promptForRestart in src/utils/client.ts. If stdin isn’t a TTY, the CLI is running in a non-interactive environment, so it should just skip the prompt and return early instead of waiting for input.

Alternatively, adding a --no-restart (or --yes) flag to mcp add / mcp remove would make it easier to use the CLI safely in scripts and CI without getting stuck on the restart prompt.

[arjunkmrm]

@devadathanmb thanks for reporting, i'm looking into this