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fix(cua-driver-rs): TTY hint instead of silent stdin hang on bare invocation #1672

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Merged
f-trycua merged 1 commit into from
May 24, 2026
Merged

fix(cua-driver-rs): TTY hint instead of silent stdin hang on bare invocation #1672

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29 changes: 28 additions & 1 deletion libs/cua-driver-rs/crates/cua-driver/src/cli.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -172,7 +172,34 @@ pub fn parse_command() -> Command {

let mut pos = positionals.into_iter();
match pos.next() {
None | Some("mcp") => Command::Mcp {
None => {
// Bare `cua-driver` defaults to MCP, which reads JSON-RPC from
// stdin forever. From a terminal that looks like a hang. If
// stdin is a TTY (i.e. interactive shell, no client piping
// stdio), surface a hint and exit. Piped / redirected stdin —
// the normal MCP client case — falls through to MCP mode.
// Explicit `cua-driver mcp` bypasses the check entirely.
use std::io::IsTerminal as _;
if std::io::stdin().is_terminal() {
eprintln!("cua-driver: bare invocation defaults to the MCP server, which reads");
eprintln!("JSON-RPC from stdin. From a terminal that looks like a hang.");
eprintln!();
eprintln!("You probably meant one of:");
eprintln!(" cua-driver list-tools # available tools");
eprintln!(" cua-driver status # check the daemon");
eprintln!(" cua-driver mcp-config --client claude-code # wire into a client");
eprintln!(" cua-driver --help # everything else");
eprintln!();
eprintln!("To run the MCP server explicitly (and pipe JSON-RPC by hand):");
eprintln!(" cua-driver mcp");
std::process::exit(0);
}
Command::Mcp {
no_daemon_relaunch,
socket: socket.clone(),
}
}
Some("mcp") => Command::Mcp {
no_daemon_relaunch,
socket: socket.clone(),
},
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