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, 7 insertions, 3 deletions

diff --git a/include/yasl/yasl.h b/include/yasl/yasl.h
index 350339b..38c5b88 100644
--- a/include/yasl/yasl.h
+++ b/include/yasl/yasl.h
@@ -20,7 +20,7 @@ typedef struct yasl_event yasl_event;
 enum yasl_backend { YASL_BACKEND_AUTO, YASL_BACKEND_WAYLAND, YASL_BACKEND_X11, YASL_BACKEND_COCOA };
 enum yasl_surface_flags { YASL_SURFACE_CPU=1u, YASL_SURFACE_HIDDEN=2u, YASL_SURFACE_UNDECORATED=4u, YASL_SURFACE_FIXED_SIZE=8u };
 enum yasl_error { YASL_ERROR_NONE, YASL_ERROR_INVALID, YASL_ERROR_UNSUPPORTED, YASL_ERROR_NO_MEMORY,
-    YASL_ERROR_NOT_INITIALIZED, YASL_ERROR_BUSY, YASL_ERROR_WRONG_THREAD, YASL_ERROR_CONTEXT_EXPIRED, YASL_ERROR_IO };
+    YASL_ERROR_NOT_INITIALIZED, YASL_ERROR_BUSY, YASL_ERROR_WRONG_THREAD, YASL_ERROR_CONTEXT_EXPIRED, YASL_ERROR_IO, YASL_ERROR_DISCONNECTED };
 enum yasl_selection { YASL_CLIPBOARD, YASL_PRIMARY };
 enum yasl_key_action { YASL_KEY_PRESS, YASL_KEY_RELEASE, YASL_KEY_REPEAT };
 enum yasl_mod { YASL_MOD_SHIFT=1u, YASL_MOD_ALT=2u, YASL_MOD_CTRL=4u, YASL_MOD_SUPER=8u, YASL_MOD_CAPS=16u };
@@ -52,7 +52,7 @@ enum yasl_resize_edge { YASL_EDGE_TOP=1, YASL_EDGE_BOTTOM=2, YASL_EDGE_LEFT=4, Y
 enum yasl_event_type { YASL_EVENT_NONE, YASL_EVENT_CLOSE, YASL_EVENT_QUIT, YASL_EVENT_REOPEN, YASL_EVENT_WINDOW,
     YASL_EVENT_REFRESH, YASL_EVENT_KEY, YASL_EVENT_TEXT, YASL_EVENT_POINTER, YASL_EVENT_SCROLL, YASL_EVENT_PEN,
     YASL_EVENT_INPUT_RESET, YASL_EVENT_COMPOSITION, YASL_EVENT_TEXT_EDIT, YASL_EVENT_CLIPBOARD, YASL_EVENT_DROP,
-    YASL_EVENT_DRAG, YASL_EVENT_DISPLAY_LOST };
+    YASL_EVENT_DRAG, YASL_EVENT_DISPLAY_LOST, YASL_EVENT_DISPLAY_RESTORED };
 enum yasl_drop_action { YASL_DROP_OVER, YASL_DROP_LEAVE, YASL_DROP_DATA };
 enum yasl_drag_action { YASL_DRAG_OVER, YASL_DRAG_LEAVE, YASL_DRAG_DROP };
 /** Read the union member named by type. Strings stay valid until the next wait.
@@ -60,7 +60,11 @@ enum yasl_drag_action { YASL_DRAG_OVER, YASL_DRAG_LEAVE, YASL_DRAG_DROP };
  * WINDOW: size, scale or state changed. REFRESH: draw now; sent once the window
  * has a size, after every resize and when the system needs the contents again.
  * INPUT_RESET: forget held keys, buttons and strokes. DROP: external data over
- * the window, delivered as DATA. DRAG: another YASL surface dragged over. */
+ * the window, delivered as DATA. DRAG: another YASL surface dragged over.
+ * DISPLAY_LOST: the display server went away. Destroy Vulkan surfaces and GL
+ * objects now; windows stay valid. Wayland reconnects, then sends DISPLAY_RESTORED:
+ * recreate them (GL contexts are new and must be bound again). Elsewhere loss is
+ * final and later waits fail. */
 struct yasl_event {
     enum yasl_event_type type;
     yasl_surface *surface;