Exit promptly after parent death

src/main.c

@@ -50,6 +50,9 @@ enum {
 #include <string.h>
 #include <signal.h>
 #include <stdatomic.h>
+#ifndef _WIN32
+#include <unistd.h>
+#endif
 
 #ifndef CBM_VERSION
 #define CBM_VERSION "dev"
@@ -120,9 +123,9 @@ static void *parent_watchdog_thread(void *arg) {
         /* initial_ppid > 1 guards against an already-orphaned start (ppid==1),
          * where a changing ppid carries no signal. */
         if (initial_ppid > 1 && getppid() != initial_ppid) {
-            cbm_log_warn("parent.exited", "reason", "ppid_changed");
-            request_shutdown();
-            exit(0);
+            static const char msg[] = "level=warn msg=parent.exited reason=ppid_changed\n";
+            (void)write(STDERR_FILENO, msg, sizeof(msg) - 1);
+            _exit(0);
         }
     }
     return NULL;

tests/test_parent_watchdog.sh

@@ -73,16 +73,39 @@ if ! kill -0 "${child_pid}" 2>/dev/null; then
   exit 3
 fi
 
+# Wait until the child has reached startup far enough to have installed the
+# parent watchdog. The PID file is written immediately after fork; killing the
+# wrapper before the child runs main() is an untestable early-reparent race where
+# the child never observed the original parent PID.
+for _ in {1..50}; do
+  if [[ -s "${tmpdir}/child.err" ]] && grep -q "mem.init" "${tmpdir}/child.err"; then
+    break
+  fi
+  sleep 0.1
+done
+if ! grep -q "mem.init" "${tmpdir}/child.err" 2>/dev/null; then
+  echo "child did not reach watchdog-ready startup point" >&2
+  [[ -s "${tmpdir}/child.err" ]] && cat "${tmpdir}/child.err" >&2
+  exit 3
+fi
+
 # Kill the wrapper parent: the orphaned child must now self-exit.
 kill -9 "${wrapper_pid}"
 wait "${wrapper_pid}" 2>/dev/null || true
 
-deadline=$((SECONDS + 6))
+deadline=$((SECONDS + 15))
 while (( SECONDS < deadline )); do
   if ! kill -0 "${child_pid}" 2>/dev/null; then
     echo "ok: child ${child_pid} exited after parent death"
     exit 0
   fi
+  # A zombie no longer holds stdin or runs the MCP loop; kill -0 still reports
+  # it until launchd/test parent reaps it, so treat that as a successful exit.
+  child_state="$(ps -p "${child_pid}" -o stat= 2>/dev/null | tr -d '[:space:]' || true)"
+  if [[ "${child_state}" == Z* ]]; then
+    echo "ok: child ${child_pid} exited after parent death (zombie awaiting reap)"
+    exit 0
+  fi
   sleep 0.2
 done