An editor killed with SIGTERM or SIGHUP removes its 9P socket, and a start sweeps the pardes-9p-<pid>.sock files whose pid is gone

The runtime directory had gathered a hundred sockets of dead editors:
only a clean exit removed its own, and a signal or a crash left it. The
terminal's kill handler and, where nothing else handles the signals, a
handler of the listener's own now unlink the socket before the signal's
death. At listen, each pardes-9p-<pid>.sock whose pid kill(pid, 0)
answers ESRCH for, that is a socket of this user's and that nothing
answers on, is removed; a live pid's, a named session's and anything
else are never touched.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/tty/tty.zig b/src/tty/tty.zig
index eabbbe22..8d121b1f 100644
--- a/src/tty/tty.zig
+++ b/src/tty/tty.zig
@@ -1150,6 +1150,8 @@ const Killed = struct {
             _ = std.c.write(fd, reset, reset.len);
             _ = std.c.tcsetattr(fd, .FLUSH, &cooked);
         }
+        // The 9P socket goes too: a killed editor leaves none behind.
+        ninep_io.unlinkOwnSocket();
         // SA_RESETHAND put the default back: the same signal, now fatal.
         _ = std.c.raise(sig);
     }