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, 49 insertions, 33 deletions

diff --git a/src/platform/wayland/backend.c b/src/platform/wayland/backend.c
index 02aae59..b3337cc 100644
--- a/src/platform/wayland/backend.c
+++ b/src/platform/wayland/backend.c
@@ -125,42 +125,36 @@ static bool egl_configure(struct wayland_display *d, const struct yasl_private_g
     return eglBindAPI(api) == EGL_TRUE;
 }
 
-static struct yasl_surface *impl_surface_create_gl(struct yasl_private_display *display,
-        const struct yasl_private_window_spec *spec, const int *attributes, struct yasl_surface *share)
-{
-    struct wayland_display *d = (struct wayland_display *)display;
-    struct yasl_private_gl_options o;
-    if (!spec || !yasl_private_gl_parse_options(attributes, &o) || !d || !d->egl_initialized)
-        return NULL;
-    struct yasl_private_window_spec gl_spec = *spec;
-    gl_spec.external_gpu = true;
-    gl_spec.flags &= ~YASL_PRIVATE_SURFACE_CPU;
-    struct wayland_surface *w = wayland_surface_create_toplevel(d, &gl_spec, NULL);
-    if (!w) return NULL;
-    if (!egl_configure(d, &o, &w->egl_config)) goto fail;
-    EGLContext share_context = share && share->display == display
-        ? ((struct wayland_surface *)share)->egl_context : EGL_NO_CONTEXT;
-    if (share && share_context == EGL_NO_CONTEXT) goto fail;
+bool surface_build_gl(struct wayland_surface *w)
+{
+    struct wayland_display *d = w->conn;
+    const struct yasl_private_gl_options *o = &w->gl_options;
+    if (!egl_configure(d, o, &w->egl_config)) return false;
+    EGLContext share_context = EGL_NO_CONTEXT;
+    if (w->gl_share) {
+        if (!w->gl_share->gl_built && !surface_build_gl(w->gl_share)) return false;
+        share_context = w->gl_share->egl_context;
+    }
     w->egl_window = wl_egl_window_create(w->surface, w->width, w->height);
-    if (!w->egl_window) goto fail;
+    if (!w->egl_window) return false;
     EGLint context_attrs[12];
     int n = 0;
-    if (o.api == YASL_PRIVATE_GL_OPENGL_ES) {
+    if (o->api == YASL_PRIVATE_GL_OPENGL_ES) {
         context_attrs[n++] = EGL_CONTEXT_CLIENT_VERSION;
-        context_attrs[n++] = o.major;
+        context_attrs[n++] = o->major;
     } else {
         context_attrs[n++] = EGL_CONTEXT_MAJOR_VERSION_KHR;
-        context_attrs[n++] = o.major;
+        context_attrs[n++] = o->major;
         context_attrs[n++] = EGL_CONTEXT_MINOR_VERSION_KHR;
-        context_attrs[n++] = o.minor;
-        if (o.profile != YASL_PRIVATE_GL_ANY) {
+        context_attrs[n++] = o->minor;
+        if (o->profile != YASL_PRIVATE_GL_ANY) {
             context_attrs[n++] = EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR;
-            context_attrs[n++] = o.profile == YASL_PRIVATE_GL_CORE
+            context_attrs[n++] = o->profile == YASL_PRIVATE_GL_CORE
                 ? EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR
                 : EGL_CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT_KHR;
         }
-        EGLint flags = (o.debug ? EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR : 0) |
-            (o.forward_compat ? EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR : 0);
+        EGLint flags = (o->debug ? EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR : 0) |
+            (o->forward_compat ? EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR : 0);
         if (flags) {
             context_attrs[n++] = EGL_CONTEXT_FLAGS_KHR;
             context_attrs[n++] = flags;
@@ -168,21 +162,42 @@ static struct yasl_surface *impl_surface_create_gl(struct yasl_private_display *
     }
     context_attrs[n] = EGL_NONE;
     w->egl_context = eglCreateContext(d->egl_display, w->egl_config, share_context, context_attrs);
-    if (w->egl_context == EGL_NO_CONTEXT) goto fail;
+    if (w->egl_context == EGL_NO_CONTEXT) { w->egl_context = 0; return false; }
     EGLint surface_attrs[] = {
 #ifdef EGL_GL_COLORSPACE_KHR
-        EGL_GL_COLORSPACE_KHR, o.srgb ? EGL_GL_COLORSPACE_SRGB_KHR : EGL_GL_COLORSPACE_LINEAR_KHR,
+        EGL_GL_COLORSPACE_KHR, o->srgb ? EGL_GL_COLORSPACE_SRGB_KHR : EGL_GL_COLORSPACE_LINEAR_KHR,
 #endif
         EGL_NONE,
     };
     w->egl_surface = eglCreateWindowSurface(d->egl_display, w->egl_config,
             (EGLNativeWindowType)w->egl_window, surface_attrs);
-    if (w->egl_surface == EGL_NO_SURFACE) { w->egl_surface = 0; goto fail; }
+    if (w->egl_surface == EGL_NO_SURFACE) { w->egl_surface = 0; return false; }
+    w->gl_built = true;
+    return true;
+}
+
+static struct yasl_surface *impl_surface_create_gl(struct yasl_private_display *display,
+        const struct yasl_private_window_spec *spec, const int *attributes, struct yasl_surface *share)
+{
+    struct wayland_display *d = (struct wayland_display *)display;
+    struct yasl_private_gl_options o;
+    if (!spec || !yasl_private_gl_parse_options(attributes, &o) || !d || !d->egl_initialized)
+        return NULL;
+    if (share && (share->display != display || !((struct wayland_surface *)share)->egl_context))
+        return NULL;
+    struct yasl_private_window_spec gl_spec = *spec;
+    gl_spec.external_gpu = true;
+    gl_spec.flags &= ~YASL_PRIVATE_SURFACE_CPU;
+    struct wayland_surface *w = wayland_surface_create_toplevel(d, &gl_spec, NULL);
+    if (!w) return NULL;
+    w->gl_options = o;
+    w->gl_share = (struct wayland_surface *)share;
+    if (!surface_build_gl(w)) {
+        wayland_surface_destroy(w);
+        return NULL;
+    }
     w->base.presenter = YASL_PRIVATE_PRESENTER_GL;
     return &w->base;
-fail:
-    wayland_surface_destroy(w);
-    return NULL;
 }
 
 static bool impl_gl_make_current(struct yasl_private_display *display, struct yasl_surface *surface)
@@ -250,7 +265,7 @@ static struct input_queue *impl_surface_input_queue(struct yasl_surface *s)
 static bool impl_surface_set_size(struct yasl_surface *s, struct yasl_private_vector2i size)
 {
     struct wayland_surface *w = (struct wayland_surface *)s;
-    if (!w || w->closed || w->destroyed || !w->toplevel ||
+    if (!w || w->closed || w->destroyed || (!w->toplevel && !w->conn->lost) ||
         size.x <= 0 || size.y <= 0) {
         errno = EINVAL;
         return false;
@@ -258,7 +273,8 @@ static bool impl_surface_set_size(struct yasl_surface *s, struct yasl_private_ve
     /* Floating windows choose their own size; constrained states keep it for later. */
     w->floating_width = size.x;
     w->floating_height = size.y;
-    if (w->base.state & (YASL_PRIVATE_STATE_MAXIMIZED | YASL_PRIVATE_STATE_FULLSCREEN | YASL_PRIVATE_STATE_TILED))
+    if (w->conn->lost ||
+        (w->base.state & (YASL_PRIVATE_STATE_MAXIMIZED | YASL_PRIVATE_STATE_FULLSCREEN | YASL_PRIVATE_STATE_TILED)))
         return true;
     w->req_width = w->req_height = 0;
     w->size_pending = true;