修复模型猫过渡审查问题

- 过渡 Promise 失败时记录警告并清理 return ball transition 标记。\n- 抽取模型容器 transition CSS 变量，并补齐 VRM 缩放 transform-origin。\n- 补充 VRM goodbye 统一链路断言和 CSS helper 说明。

Author: yiyiyiyiGKY

static/avatar-ui-buttons.js

@@ -3883,7 +3883,10 @@ const AvatarButtonMixin = {
                         anchorRect: rect,
                         coverRect: window._savedGoodbyeRect || null,
                         container: returnButtonContainer
-                    }).catch(() => {});
+                    }).catch((error) => {
+                        console.warn('[AvatarButtonMixin] model/cat return transition failed:', error);
+                        returnButtonContainer.removeAttribute('data-neko-model-cat-transitioning');
+                    });
                     dispatchReturnEvent();
                     return;
                 }

static/css/index.css

@@ -1,5 +1,11 @@
 @import url('base.css');
 
+:root {
+    --neko-model-opacity-transition: opacity 280ms ease-in;
+    --neko-model-transform-transition: transform 400ms cubic-bezier(0.22, 1, 0.36, 1);
+    --neko-model-visibility-delay: 400ms;
+}
+
 html,
 body {
     height: 100%;
@@ -233,7 +239,7 @@ button * {
     opacity: 1;
     overflow: hidden;
     visibility: visible;
-    transition: opacity 280ms ease-in, transform 400ms cubic-bezier(0.22, 1, 0.36, 1), height 0ms 400ms, width 0ms 400ms, visibility 0ms 400ms;
+    transition: var(--neko-model-opacity-transition), var(--neko-model-transform-transition), height 0ms var(--neko-model-visibility-delay), width 0ms var(--neko-model-visibility-delay), visibility 0ms var(--neko-model-visibility-delay);
     /* GPU 合成层隔离：减少窗口级重绘对 canvas 的影响 */
     will-change: transform;
     transform: translateZ(0);
@@ -293,10 +299,11 @@ button * {
     /* 【修复】仅过渡 opacity 和 transform，排除 visibility 的过渡影响，
      * 避免 MMD 模式下隐藏 VRM 容器时因 transition: all 导致约 1s 的视觉
      * 残留窗口，使 VRM canvas 中缓存的旧模型（如 sister1.0）短暂可见。 */
-    transition: opacity 280ms ease-in, transform 400ms cubic-bezier(0.22, 1, 0.36, 1);
+    transition: var(--neko-model-opacity-transition), var(--neko-model-transform-transition);
     /* GPU 合成层隔离：减少窗口级重绘对 canvas 的影响 */
     will-change: transform;
     transform: translateZ(0);
+    transform-origin: var(--neko-model-exit-origin-x, 50%) var(--neko-model-exit-origin-y, 50%);
 }
 
 /* 看板娘MMD模型判定框-容器 */
@@ -314,7 +321,7 @@ button * {
     opacity: 1;
     overflow: hidden;
     visibility: visible;
-    transition: opacity 280ms ease-in, transform 400ms cubic-bezier(0.22, 1, 0.36, 1);
+    transition: var(--neko-model-opacity-transition), var(--neko-model-transform-transition);
     /* GPU 合成层隔离 */
     will-change: transform;
     transform: translateZ(0);

tests/unit/test_auto_goodbye_goodbye_return_contract.py

@@ -26,6 +26,7 @@ def test_auto_goodbye_reuses_existing_goodbye_base_chain():
     assert "function playModelGoodbyeExit(container, rect)" in ui_source
     assert "playModelGoodbyeExit(live2dContainerForGoodbye, savedGoodbyeRect)" in ui_source
     assert "playModelGoodbyeExit(mmdContainer, savedGoodbyeRect)" in ui_source
+    assert "playModelGoodbyeExit(vrmContainer, savedGoodbyeRect)" in ui_source
     assert "container.classList.add('minimized');" in ui_source
     assert "resetSessionButton.disabled = false;\n                    resetSessionButton.click();" in ui_source
 

tests/unit/test_avatar_return_button_idle_tiers_static.py

@@ -167,9 +167,13 @@ def test_model_goodbye_exit_shrinks_in_place_instead_of_sliding_right():
     assert "#vrm-container.minimized" in source
     assert "#mmd-container.minimized" in source
     assert "transform: scale(0.38) translateZ(0);" in source
-    assert "opacity 280ms ease-in, transform 400ms cubic-bezier(0.22, 1, 0.36, 1)" in source
-    assert "height 0ms 400ms" in source
+    assert "--neko-model-opacity-transition: opacity 280ms ease-in;" in source
+    assert "--neko-model-transform-transition: transform 400ms cubic-bezier(0.22, 1, 0.36, 1);" in source
+    assert "--neko-model-visibility-delay: 400ms;" in source
+    assert "transition: var(--neko-model-opacity-transition), var(--neko-model-transform-transition)" in source
+    assert "height 0ms var(--neko-model-visibility-delay)" in source
     assert "transform-origin: var(--neko-model-exit-origin-x, 50%) var(--neko-model-exit-origin-y, 50%);" in source
+    assert source.count("transform-origin: var(--neko-model-exit-origin-x, 50%) var(--neko-model-exit-origin-y, 50%);") >= 3
     assert "function setModelExitTransformOrigin(container, rect)" in app_ui_source
     assert "function playModelGoodbyeExit(container, rect)" in app_ui_source
     assert "function applyModelGoodbyeVisualFade(container, options = {})" in app_ui_source
@@ -521,6 +525,17 @@ def test_no_box_shadow_or_border_in_base_return_btn_css():
 
 
 def _extract_css_block(source, selector):
+    """Extract a selector's CSS block body from source.
+
+    Args:
+        source: CSS source string to search.
+        selector: Selector text whose following brace-delimited block is read.
+
+    Returns:
+        The string inside the matched braces, or '' when the selector/opening
+        brace/closing brace is not found. Nested braces are handled with
+        brace-depth tracking.
+    """
     start = source.find(selector)
     if start == -1:
         return ''