fix(chat): release keyboard fallback on close

src/hooks/use-keyboard-height.ts

@@ -8,7 +8,8 @@
  *   1. 持续写入 --app-viewport-height，聊天页高度不再只依赖 100dvh。
  *   2. 优先使用 visualViewport 计算键盘高度。
  *   3. 输入框聚焦后测量目标元素是否越过可见底部，计算额外抬升。
- *   4. 小米系 Android + Facebook IAB 若 viewport 未可靠变化，启用保守 fallback 抬升。
+ *   4. 小米系 Android + Facebook IAB 若 viewport 未可靠变化，启用保守 fallback 抬升；
+ *      键盘收起后若焦点仍停留在 textarea，也要主动释放 fallback。
  */
 import { type RefObject, useEffect, useRef } from "react";
 
@@ -21,6 +22,7 @@ const FOCUS_GAP_PX = 14;
 const FALLBACK_KEYBOARD_RATIO = 0.42;
 const FALLBACK_KEYBOARD_MIN = 260;
 const FALLBACK_KEYBOARD_MAX = 380;
+const FALLBACK_CLOSE_GRACE_MS = 900;
 const RECHECK_DELAYS_MS = [0, 50, 120, 240, 420, 700];
 const RECHECK_EVENT = "cozsweet:keyboard-recheck";
 
@@ -36,9 +38,13 @@ export function useKeyboardHeight({
   active = false,
 }: UseKeyboardHeightOptions = {}): void {
   const activeRef = useRef(active);
+  const fallbackAllowedRef = useRef(false);
+  const focusedAtRef = useRef(0);
 
   useEffect(() => {
     activeRef.current = active;
+    fallbackAllowedRef.current = active;
+    focusedAtRef.current = active ? performance.now() : 0;
     window.dispatchEvent(new Event(RECHECK_EVENT));
   }, [active]);
 
@@ -50,14 +56,27 @@ export function useKeyboardHeight({
     let lastKeyboardHeight = -1;
     let lastViewportHeight = -1;
     let lastInputLift = -1;
+    let lastMayBeKeyboardClose = false;
 
     const apply = () => {
       rafId = null;
 
       const metrics = readViewportMetrics();
+      if (
+        activeRef.current &&
+        fallbackAllowedRef.current &&
+        lastMayBeKeyboardClose &&
+        shouldReleaseFallback(metrics, focusedAtRef.current)
+      ) {
+        fallbackAllowedRef.current = false;
+      }
+      lastMayBeKeyboardClose = false;
+
       const keyboardHeight = Math.round(metrics.keyboardHeight);
       const viewportHeight = Math.round(metrics.visibleHeight);
-      const fallbackLift = computeFallbackLift(metrics);
+      const fallbackLift = fallbackAllowedRef.current
+        ? computeFallbackLift(metrics)
+        : 0;
       const inputLift = Math.round(
         activeRef.current
           ? Math.max(
@@ -95,7 +114,9 @@ export function useKeyboardHeight({
           viewportHeight,
           inputLift,
           fallbackLift,
+          fallbackAllowed: fallbackAllowedRef.current,
           visualViewport: metrics.hasVisualViewport,
+          virtualKeyboard: metrics.hasVirtualKeyboard,
         });
       }
     };
@@ -105,7 +126,10 @@ export function useKeyboardHeight({
       rafId = window.requestAnimationFrame(apply);
     };
 
-    const scheduleRechecks = () => {
+    const scheduleRechecks = (event?: Event) => {
+      if (event && isPossibleKeyboardCloseEvent(event)) {
+        lastMayBeKeyboardClose = true;
+      }
       timeoutIds.forEach((id) => window.clearTimeout(id));
       timeoutIds = RECHECK_DELAYS_MS.map((delay) =>
         window.setTimeout(schedule, delay),
@@ -117,6 +141,8 @@ export function useKeyboardHeight({
       vv.addEventListener("resize", scheduleRechecks);
       vv.addEventListener("scroll", scheduleRechecks);
     }
+    const virtualKeyboard = getVirtualKeyboard();
+    virtualKeyboard?.addEventListener("geometrychange", scheduleRechecks);
     window.addEventListener("resize", scheduleRechecks);
     window.addEventListener("orientationchange", scheduleRechecks);
     window.addEventListener("focusin", scheduleRechecks);
@@ -132,6 +158,7 @@ export function useKeyboardHeight({
         vv.removeEventListener("resize", scheduleRechecks);
         vv.removeEventListener("scroll", scheduleRechecks);
       }
+      virtualKeyboard?.removeEventListener("geometrychange", scheduleRechecks);
       window.removeEventListener("resize", scheduleRechecks);
       window.removeEventListener("orientationchange", scheduleRechecks);
       window.removeEventListener("focusin", scheduleRechecks);
@@ -144,6 +171,7 @@ export function useKeyboardHeight({
 
 interface ViewportMetrics {
   hasVisualViewport: boolean;
+  hasVirtualKeyboard: boolean;
   layoutHeight: number;
   visibleHeight: number;
   visibleBottom: number;
@@ -153,24 +181,36 @@ interface ViewportMetrics {
 function readViewportMetrics(): ViewportMetrics {
   const layoutHeight = window.innerHeight;
   const vv = window.visualViewport;
+  const virtualKeyboard = getVirtualKeyboard();
+  const virtualKeyboardRect = virtualKeyboard?.boundingRect ?? null;
+  const virtualKeyboardHeight = virtualKeyboardRect?.height ?? 0;
   if (!vv) {
+    const visibleBottom =
+      virtualKeyboardHeight > 0 ? layoutHeight - virtualKeyboardHeight : layoutHeight;
     return {
       hasVisualViewport: false,
+      hasVirtualKeyboard: virtualKeyboard != null,
       layoutHeight,
-      visibleHeight: layoutHeight,
-      visibleBottom: layoutHeight,
-      keyboardHeight: 0,
+      visibleHeight: visibleBottom,
+      visibleBottom,
+      keyboardHeight: virtualKeyboardHeight,
     };
   }
 
-  const visibleHeight = vv.height;
-  const visibleBottom = vv.offsetTop + vv.height;
+  const visualBottom = vv.offsetTop + vv.height;
+  const keyboardTop =
+    virtualKeyboardHeight > 0
+      ? Math.min(virtualKeyboardRect?.y ?? layoutHeight, layoutHeight - virtualKeyboardHeight)
+      : layoutHeight;
+  const visibleBottom = Math.min(visualBottom, keyboardTop);
+  const visibleHeight = Math.min(vv.height, visibleBottom);
   return {
     hasVisualViewport: true,
+    hasVirtualKeyboard: virtualKeyboard != null,
     layoutHeight,
     visibleHeight,
     visibleBottom,
-    keyboardHeight: Math.max(0, layoutHeight - visibleBottom),
+    keyboardHeight: Math.max(0, layoutHeight - visibleBottom, virtualKeyboardHeight),
   };
 }
 
@@ -185,6 +225,7 @@ function computeTargetOverlap(
 
 function computeFallbackLift(metrics: ViewportMetrics): number {
   if (!shouldUseInAppKeyboardFallback()) return 0;
+  if (metrics.hasVirtualKeyboard && metrics.keyboardHeight <= 0) return 0;
 
   const viewportAlreadyShrank = metrics.visibleHeight < metrics.layoutHeight * 0.82;
   const keyboardAlreadyDetected = metrics.keyboardHeight > 80;
@@ -197,6 +238,26 @@ function computeFallbackLift(metrics: ViewportMetrics): number {
   );
 }
 
+function shouldReleaseFallback(
+  metrics: ViewportMetrics,
+  focusedAt: number,
+): boolean {
+  if (focusedAt <= 0) return false;
+  if (performance.now() - focusedAt < FALLBACK_CLOSE_GRACE_MS) return false;
+  return !hasDetectedKeyboard(metrics);
+}
+
+function hasDetectedKeyboard(metrics: ViewportMetrics): boolean {
+  return (
+    metrics.keyboardHeight > 80 ||
+    metrics.visibleHeight < metrics.layoutHeight * 0.82
+  );
+}
+
+function isPossibleKeyboardCloseEvent(event: Event): boolean {
+  return event.type === "resize" || event.type === "geometrychange";
+}
+
 function shouldUseInAppKeyboardFallback(): boolean {
   if (typeof navigator === "undefined") return false;
   const ua = navigator.userAgent;
@@ -216,3 +277,14 @@ function resetVars(): void {
   document.documentElement.style.setProperty(VIEWPORT_VAR, "100dvh");
   document.documentElement.style.setProperty(INPUT_LIFT_VAR, "0px");
 }
+
+interface VirtualKeyboardLike extends EventTarget {
+  readonly boundingRect: DOMRectReadOnly;
+}
+
+function getVirtualKeyboard(): VirtualKeyboardLike | null {
+  const nav = navigator as Navigator & {
+    virtualKeyboard?: VirtualKeyboardLike;
+  };
+  return nav.virtualKeyboard ?? null;
+}