[EmbryoSpace]

Fixes #93.

Problem

npm/cli.js runs the binary with execFileSync. That call never forwards termination signals to the child, so when a supervisor stops the Node wrapper, the binary keeps running, gets reparented, and still holds the host's stdin and stdout. For xurl mcp this means an MCP host that restarts the command collects a stray bridge process each time.

Fix

• Start the binary with spawn (stdio: "inherit", same as before).
• Forward SIGINT, SIGTERM, SIGHUP and SIGQUIT to it. Signals the platform can't listen for are skipped.
• When the binary exits, exit with its code. If a signal killed it, the wrapper re-raises that signal, so callers see the same exit status as before.
• Print a clear message if the binary can't be started. The "binary not found" check is unchanged.
• Add a CHANGELOG entry under Unreleased.

Testing

On Linux (Docker, node:18-alpine and node:20-bookworm-slim), with a stand-in binary that records its pid and waits, I sent each signal to the wrapper and checked the binary 0.5 s later:

Signal to wrapper	Before	After	Wrapper exit status
SIGTERM	binary left running	binary stopped	143, unchanged
SIGINT	binary left running	binary stopped	130, unchanged
SIGHUP	binary left running	binary stopped	129, unchanged

Also checked, before and after:

• Arguments and exit codes still pass through (exit3 a "b c" exits 3 with the same arguments).
• Piped stdin still reaches the binary, which is how MCP hosts talk to xurl mcp.
• The missing-binary message and exit code 1 are unchanged.
• On Windows (Node 24), arguments and exit codes pass through.

One limit: SIGKILL can't be caught, so a wrapper killed with SIGKILL still can't stop its child. Hosts that want a hard guarantee can invoke the binary directly. That's the other option in the issue, and I left it alone because it changes how the package is installed.

[CLAassistant]

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