Fix #10436

docs/changelog.rst

@@ -308,6 +308,12 @@ Detailed list of changes
   files that no longer exist. The dropped files are now kept alive for
   ten minutes and removed when kitty quits (:iss:`10430`)
 
+- macOS: Fix all signal handling being permanently disabled after the first
+  window that used the graphics protocol is closed. This caused exited window
+  shells to accumulate as zombie processes and also broke reloading the config
+  with ``SIGUSR1`` and quitting on ``SIGINT``/``SIGTERM``/``SIGHUP``
+  (:iss:`10436`)
+
 
 0.48.2 [2026-07-30]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

glfw/backend_utils.c

@@ -329,6 +329,15 @@ finalizePollData(EventLoopData *eld) {
 #endif
 }
 
+static int
+display_fd_ready(EventLoopData *eld) {
+    // watches[0] is always the display fd. Errors count as ready: the display
+    // callback must complete the read rather than cancel it, so that a
+    // compositor disconnect is turned into a display error instead of a poll()
+    // that keeps returning immediately forever.
+    return eld->fds[0].revents & (POLLIN | POLLERR | POLLHUP | POLLNVAL);
+}
+
 int
 pollForEvents(EventLoopData *eld, monotonic_t timeout, watch_callback_func display_callback) {
     int read_ok = 0;
@@ -344,7 +353,7 @@ pollForEvents(EventLoopData *eld, monotonic_t timeout, watch_callback_func displ
             errno = 0;
             result = pollWithTimeout(eld->fds, eld->watches_count, timeout);
             int saved_errno = errno;
-            if (display_callback) display_callback(result, eld->fds[0].revents && eld->watches[0].events, NULL);
+            if (display_callback) display_callback(result, display_fd_ready(eld), NULL);
             dispatchTimers(eld);
             if (result > 0) {
                 dispatchEvents(eld);
@@ -359,7 +368,7 @@ pollForEvents(EventLoopData *eld, monotonic_t timeout, watch_callback_func displ
             errno = 0;
             result = poll(eld->fds, eld->watches_count, -1);
             int saved_errno = errno;
-            if (display_callback) display_callback(result, eld->fds[0].revents && eld->watches[0].events, NULL);
+            if (display_callback) display_callback(result, display_fd_ready(eld), NULL);
             dispatchTimers(eld);
             if (result > 0) {
                 dispatchEvents(eld);

kitty/child-monitor.c

@@ -1826,8 +1826,8 @@ io_loop(void *data) {
             ret = poll(children_fds, self->count + EXTRA_FDS, -1);
         }
         if (ret > 0) {
-            if (children_fds[0].revents && POLLIN) drain_fd(children_fds[0].fd); // wakeup
-            if (children_fds[1].revents && POLLIN) {
+            if (children_fds[0].revents & POLLIN) drain_fd(children_fds[0].fd); // wakeup
+            if (children_fds[1].revents & POLLIN) {
                 SignalSet ss = {0};
                 data_received = true;
                 read_signals(children_fds[1].fd, handle_signal, &ss);

kitty/loop-utils.c

@@ -88,7 +88,9 @@ init_loop_data(LoopData *ld, ...) {
 static void
 remove_signal_handlers(LoopData *ld) {
 #ifndef HAS_SIGNAL_FD
-    signal_write_fd = -1;
+    // Only clear the global write fd if it is owned by this loop. Loops that
+    // handle no signals must not disable signal delivery for the loop that does.
+    if (ld->signal_fds[1] > -1 && signal_write_fd == ld->signal_fds[1]) signal_write_fd = -1;
     CLOSE(signal_fds, 0);
     CLOSE(signal_fds, 1);
 #endif
@@ -97,7 +99,7 @@ remove_signal_handlers(LoopData *ld) {
         safe_close(ld->signal_read_fd, __FILE__, __LINE__);
         sigprocmask(SIG_UNBLOCK, &ld->signals, NULL);
 #endif
-        for (size_t i = 0; i < ld->num_handled_signals; i++) signal(ld->num_handled_signals, SIG_DFL);
+        for (size_t i = 0; i < ld->num_handled_signals; i++) signal(ld->handled_signals[i], SIG_DFL);
     }
     ld->signal_read_fd = -1;
     ld->num_handled_signals = 0;