Reconnect to a restarted Wayland compositor

Windows now outlive the compositor. On connection loss YASL sends
DISPLAY_LOST instead of closing every window, retries the connection on
a loop timer, rebuilds each toplevel with its title, size, state and GL
context, and sends DISPLAY_RESTORED. CPU windows keep their pixels;
GPU renderers drop Vulkan surfaces and GL objects on loss and rebuild
them on restore.

- Free the dead connection's objects on the next wait, after the
  application has released GPU objects built on them.
- Report a lost connection as an event rather than a failed wait.
- Refuse window and Vulkan surface creation while offline with the new
  YASL_ERROR_DISCONNECTED.
- Close popups, cancel drags and fail pending clipboard requests on loss.
- Print only protocol errors, not ordinary disconnects.
- Examples survive a restart; game.c rebinds its GL context.
- Add an end-to-end test that kills Weston under CPU, GL and Vulkan
  windows and requires them to recover.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/common/backend.h b/src/common/backend.h
index e3dc6de..bf6815a 100644
--- a/src/common/backend.h
+++ b/src/common/backend.h
@@ -16,6 +16,7 @@ struct yasl_private_event_state;
 struct yasl_private_display {
     const struct yasl_private_backend_ops *ops;
     void *native_handle;
+    bool offline; /* Connection lost; native handles are unusable until it is restored. */
     struct yasl_private_display_cbs callbacks;
     struct yasl_private_loop *loop;
     /* Backend's copy of yasl_private_display_spec.app_id, or NULL; for desktop services. */