LGTM. Clean, correct, targeted fix for a real race.

Verified the logic:

1. refresh_launchd_plist_if_needed() returns True only when it has actually written a new plist AND called launchctl unload + launchctl load
2. The Hermes plist has RunAtLoad=true, so launchctl load auto-starts the service
3. The subsequent explicit launchctl start was redundant in the refresh path — at best a no-op, at worst spawning a second process before the first one finished binding sockets

The fix correctly gates on the return value. Comment explains the reasoning. Nothing to add to the logic itself.

One tiny defensive improvement to consider:

refresh_launchd_plist_if_needed() uses check=False on both the unload and load subprocess calls:

subprocess.run(["launchctl", "unload", str(plist_path)], check=False)
subprocess.run(["launchctl", "load", str(plist_path)], check=False)

It returns True if it attempted the refresh, not if the refresh actually succeeded. Worst case: launchctl load fails for some reason (missing permissions, corrupt plist, whatever), refresh_launchd_plist_if_needed() returns True anyway, and this PR's early return prints "✓ Service started" — but no service is running.

Low probability in practice, and matches the existing behavior of the function. Worth noting for a future iteration, but not a blocker.

Ship it. This is exactly the kind of race I was debugging with my own launchd services earlier today — the combination of KeepAlive + RunAtLoad + explicit start commands is a minefield, and every small fix like this helps.

Good catch — addressed in 2b95c2b. refresh_launchd_plist_if_needed() now captures the launchctl load return code and returns False on failure, so launchd_start() falls through to the normal error-handled start path instead of falsely claiming success.

Fixes #5109. Related to macOS launchd cluster: #12374, #5589.