batch annotation offset to seek atomically and throttle slider drag

web/src/components/overlay/detail/AnnotationOffsetSlider.tsx

@@ -1,4 +1,6 @@
-import { useCallback, useState } from "react";
+import { useCallback, useEffect, useMemo, useState } from "react";
+import { flushSync } from "react-dom";
+import { throttle } from "lodash";
 import { Slider } from "@/components/ui/slider";
 import { Button } from "@/components/ui/button";
 import { Popover, PopoverContent, PopoverTrigger } from "../../ui/popover";
@@ -19,11 +21,21 @@ import { useIsAdmin } from "@/hooks/use-is-admin";
 import { useDocDomain } from "@/hooks/use-doc-domain";
 import { Link } from "react-router-dom";
 
+const SLIDER_DRAG_THROTTLE_MS = 80;
+
 type Props = {
   className?: string;
+  // Optional side-effect invoked atomically with setAnnotationOffset (inside
+  // flushSync) so callers like the timeline panel can re-seek the video in the
+  // same React commit as the offset state update — preventing a one-frame
+  // overlay mismatch where annotationOffset has changed but currentTime has not.
+  onApplyOffset?: (newOffset: number) => void;
 };
 
-export default function AnnotationOffsetSlider({ className }: Props) {
+export default function AnnotationOffsetSlider({
+  className,
+  onApplyOffset,
+}: Props) {
   const { annotationOffset, setAnnotationOffset, camera } = useDetailStream();
   const isAdmin = useIsAdmin();
   const { getLocaleDocUrl } = useDocDomain();
@@ -31,31 +43,62 @@ export default function AnnotationOffsetSlider({ className }: Props) {
   const { t } = useTranslation(["views/explore"]);
   const [isSaving, setIsSaving] = useState(false);
 
+  const applyOffset = useCallback(
+    (newOffset: number) => {
+      flushSync(() => {
+        setAnnotationOffset(newOffset);
+        onApplyOffset?.(newOffset);
+      });
+    },
+    [setAnnotationOffset, onApplyOffset],
+  );
+
+  const throttledApplyOffset = useMemo(
+    () =>
+      throttle(applyOffset, SLIDER_DRAG_THROTTLE_MS, {
+        leading: true,
+        trailing: true,
+      }),
+    [applyOffset],
+  );
+
+  useEffect(() => () => throttledApplyOffset.cancel(), [throttledApplyOffset]);
+
   const handleChange = useCallback(
     (values: number[]) => {
       if (!values || values.length === 0) return;
-      const valueMs = values[0];
-      setAnnotationOffset(valueMs);
+      throttledApplyOffset(values[0]);
     },
-    [setAnnotationOffset],
+    [throttledApplyOffset],
+  );
+
+  const handleCommit = useCallback(
+    (values: number[]) => {
+      if (!values || values.length === 0) return;
+      // Ensure the final value lands even if it would otherwise be discarded
+      // by the trailing edge of the throttle window.
+      throttledApplyOffset.cancel();
+      applyOffset(values[0]);
+    },
+    [throttledApplyOffset, applyOffset],
   );
 
   const stepOffset = useCallback(
     (delta: number) => {
-      setAnnotationOffset((prev) => {
-        const next = prev + delta;
-        return Math.max(
-          ANNOTATION_OFFSET_MIN,
-          Math.min(ANNOTATION_OFFSET_MAX, next),
-        );
-      });
+      const next = Math.max(
+        ANNOTATION_OFFSET_MIN,
+        Math.min(ANNOTATION_OFFSET_MAX, annotationOffset + delta),
+      );
+      throttledApplyOffset.cancel();
+      applyOffset(next);
     },
-    [setAnnotationOffset],
+    [annotationOffset, applyOffset, throttledApplyOffset],
   );
 
   const reset = useCallback(() => {
-    setAnnotationOffset(0);
-  }, [setAnnotationOffset]);
+    throttledApplyOffset.cancel();
+    applyOffset(0);
+  }, [applyOffset, throttledApplyOffset]);
 
   const save = useCallback(async () => {
     setIsSaving(true);
@@ -130,6 +173,7 @@ export default function AnnotationOffsetSlider({ className }: Props) {
             max={ANNOTATION_OFFSET_MAX}
             step={ANNOTATION_OFFSET_STEP}
             onValueChange={handleChange}
+            onValueCommit={handleCommit}
           />
         </div>
         <Button

web/src/components/overlay/detail/AnnotationSettingsPane.tsx

@@ -1,7 +1,9 @@
 import { Event } from "@/types/event";
 import { FrigateConfig } from "@/types/frigateConfig";
 import axios from "axios";
-import { useCallback, useState } from "react";
+import { useCallback, useEffect, useMemo, useState } from "react";
+import { flushSync } from "react-dom";
+import { throttle } from "lodash";
 import { LuExternalLink, LuMinus, LuPlus } from "react-icons/lu";
 import { Link } from "react-router-dom";
 import { toast } from "sonner";
@@ -19,6 +21,8 @@ import {
   ANNOTATION_OFFSET_STEP,
 } from "@/lib/const";
 
+const SLIDER_DRAG_THROTTLE_MS = 80;
+
 type AnnotationSettingsPaneProps = {
   event: Event;
   annotationOffset: number;
@@ -38,30 +42,64 @@ export function AnnotationSettingsPane({
 
   const [isLoading, setIsLoading] = useState(false);
 
-  const handleSliderChange = useCallback(
-    (values: number[]) => {
-      if (!values || values.length === 0) return;
-      setAnnotationOffset(values[0]);
-    },
-    [setAnnotationOffset],
-  );
-
-  const stepOffset = useCallback(
-    (delta: number) => {
-      setAnnotationOffset((prev) => {
-        const next = prev + delta;
-        return Math.max(
-          ANNOTATION_OFFSET_MIN,
-          Math.min(ANNOTATION_OFFSET_MAX, next),
-        );
+  // flushSync ensures setAnnotationOffset commits synchronously so the
+  // useLayoutEffect in TrackingDetails (which seeks the video and sets
+  // currentTime in response) runs before the browser paints — preventing a
+  // one-frame overlay mismatch where annotationOffset has changed but
+  // currentTime has not.
+  const applyOffset = useCallback(
+    (newOffset: number) => {
+      flushSync(() => {
+        setAnnotationOffset(newOffset);
       });
     },
     [setAnnotationOffset],
   );
 
+  const throttledApplyOffset = useMemo(
+    () =>
+      throttle(applyOffset, SLIDER_DRAG_THROTTLE_MS, {
+        leading: true,
+        trailing: true,
+      }),
+    [applyOffset],
+  );
+
+  useEffect(() => () => throttledApplyOffset.cancel(), [throttledApplyOffset]);
+
+  const handleSliderChange = useCallback(
+    (values: number[]) => {
+      if (!values || values.length === 0) return;
+      throttledApplyOffset(values[0]);
+    },
+    [throttledApplyOffset],
+  );
+
+  const handleSliderCommit = useCallback(
+    (values: number[]) => {
+      if (!values || values.length === 0) return;
+      throttledApplyOffset.cancel();
+      applyOffset(values[0]);
+    },
+    [throttledApplyOffset, applyOffset],
+  );
+
+  const stepOffset = useCallback(
+    (delta: number) => {
+      const next = Math.max(
+        ANNOTATION_OFFSET_MIN,
+        Math.min(ANNOTATION_OFFSET_MAX, annotationOffset + delta),
+      );
+      throttledApplyOffset.cancel();
+      applyOffset(next);
+    },
+    [annotationOffset, applyOffset, throttledApplyOffset],
+  );
+
   const reset = useCallback(() => {
-    setAnnotationOffset(0);
-  }, [setAnnotationOffset]);
+    throttledApplyOffset.cancel();
+    applyOffset(0);
+  }, [applyOffset, throttledApplyOffset]);
 
   const saveToConfig = useCallback(async () => {
     if (!config || !event) return;
@@ -143,6 +181,7 @@ export function AnnotationSettingsPane({
             max={ANNOTATION_OFFSET_MAX}
             step={ANNOTATION_OFFSET_STEP}
             onValueChange={handleSliderChange}
+            onValueCommit={handleSliderCommit}
             className="flex-1"
           />
           <Button

web/src/components/overlay/detail/TrackingDetails.tsx

@@ -1,5 +1,13 @@
 import useSWR from "swr";
-import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import {
+  useCallback,
+  useEffect,
+  useLayoutEffect,
+  useMemo,
+  useRef,
+  useState,
+} from "react";
+import { flushSync } from "react-dom";
 import { useResizeObserver } from "@/hooks/resize-observer";
 import { useFullscreen } from "@/hooks/use-fullscreen";
 import { Event } from "@/types/event";
@@ -389,7 +397,12 @@ export function TrackingDetails({
 
   // When the pinned timestamp or offset changes, re-seek the video and
   // explicitly update currentTime so the overlay shows the pinned event's box.
-  useEffect(() => {
+  // useLayoutEffect + flushSync force the setCurrentTime commit to land before
+  // the browser paints, so the overlay never shows a frame where
+  // annotationOffset has changed but currentTime has not — that mismatch would
+  // resolve effectiveCurrentTime away from the pinned detect timestamp and
+  // make the bounding box disappear or jump for one frame.
+  useLayoutEffect(() => {
     const pinned = pinnedDetectTimestampRef.current;
     if (!isAnnotationSettingsOpen || pinned == null) return;
     if (!videoRef.current || displaySource !== "video") return;
@@ -398,10 +411,9 @@ export function TrackingDetails({
     const relativeTime = timestampToVideoTime(targetTimeRecord);
     videoRef.current.currentTime = relativeTime;
 
-    // Explicitly update currentTime state so the overlay's effectiveCurrentTime
-    // resolves back to the pinned detect timestamp:
-    //   effectiveCurrentTime = targetTimeRecord - annotationOffset/1000 = pinned
-    setCurrentTime(targetTimeRecord);
+    flushSync(() => {
+      setCurrentTime(targetTimeRecord);
+    });
   }, [
     isAnnotationSettingsOpen,
     annotationOffset,

web/src/components/timeline/DetailStream.tsx

@@ -126,13 +126,20 @@ export default function DetailStream({
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [controlsExpanded]);
 
-  // Re-seek on annotation offset change while settings panel is open
-  useEffect(() => {
-    const pinned = pinnedDetectTimestampRef.current;
-    if (!controlsExpanded || pinned == null) return;
-    const recordTime = pinned + annotationOffset / 1000;
-    onSeek(recordTime, false);
-  }, [controlsExpanded, annotationOffset, onSeek]);
+  // The slider invokes this atomically with setAnnotationOffset (inside the
+  // same flushSync) so currentTime advances in the same React commit as the
+  // offset. Without this, the overlay would render one frame with the new
+  // offset but the old currentTime, briefly resolving effectiveCurrentTime to
+  // the wrong detect-stream timestamp and making the bounding box vanish or
+  // jump.
+  const handleApplyOffset = useCallback(
+    (newOffset: number) => {
+      const pinned = pinnedDetectTimestampRef.current;
+      if (!controlsExpanded || pinned == null) return;
+      onSeek(pinned + newOffset / 1000, false);
+    },
+    [controlsExpanded, onSeek],
+  );
 
   // Ensure we initialize the active review when reviewItems first arrive.
   // This helps when the component mounts while the video is already
@@ -337,7 +344,7 @@ export default function DetailStream({
           </button>
           {controlsExpanded && (
             <div className="space-y-4 px-3 pb-5 pt-2">
-              <AnnotationOffsetSlider />
+              <AnnotationOffsetSlider onApplyOffset={handleApplyOffset} />
               <Separator />
               <div className="flex flex-col gap-1">
                 <div className="flex items-center justify-between">