diff --git a/web/package-lock.json b/web/package-lock.json
index cd09b79811..7e76155eb6 100644
--- a/web/package-lock.json
+++ b/web/package-lock.json
@@ -73,7 +73,7 @@
         "react-markdown": "^9.0.1",
         "react-router-dom": "^6.30.3",
         "react-swipeable": "^7.0.2",
-        "react-zoom-pan-pinch": "^3.7.0",
+        "react-zoom-pan-pinch": "3.6.1",
         "remark-gfm": "^4.0.0",
         "scroll-into-view-if-needed": "^3.1.0",
         "sonner": "^2.0.7",
@@ -12354,9 +12354,9 @@
       }
     },
     "node_modules/react-zoom-pan-pinch": {
-      "version": "3.7.0",
-      "resolved": "https://registry.npmjs.org/react-zoom-pan-pinch/-/react-zoom-pan-pinch-3.7.0.tgz",
-      "integrity": "sha512-UmReVZ0TxlKzxSbYiAj+LeGRW8s8LraAFTXRAxzMYnNRgGPsxCudwZKVkjvGmjtx7SW/hZamt69NUmGf4xrkXA==",
+      "version": "3.6.1",
+      "resolved": "https://registry.npmjs.org/react-zoom-pan-pinch/-/react-zoom-pan-pinch-3.6.1.tgz",
+      "integrity": "sha512-SdPqdk7QDSV7u/WulkFOi+cnza8rEZ0XX4ZpeH7vx3UZEg7DoyuAy3MCmm+BWv/idPQL2Oe73VoC0EhfCN+sZQ==",
       "license": "MIT",
       "engines": {
         "node": ">=8",
diff --git a/web/package.json b/web/package.json
index 7d22dc7183..08d167150d 100644
--- a/web/package.json
+++ b/web/package.json
@@ -87,7 +87,7 @@
     "react-markdown": "^9.0.1",
     "react-router-dom": "^6.30.3",
     "react-swipeable": "^7.0.2",
-    "react-zoom-pan-pinch": "^3.7.0",
+    "react-zoom-pan-pinch": "3.6.1",
     "remark-gfm": "^4.0.0",
     "scroll-into-view-if-needed": "^3.1.0",
     "sonner": "^2.0.7",
diff --git a/web/src/components/overlay/ReviewActivityCalendar.tsx b/web/src/components/overlay/ReviewActivityCalendar.tsx
index e925467db9..434d6a4759 100644
--- a/web/src/components/overlay/ReviewActivityCalendar.tsx
+++ b/web/src/components/overlay/ReviewActivityCalendar.tsx
@@ -20,6 +20,26 @@ function formatCalendarDay(day: Date): string {
   return `${y}-${m}-${d}`;
 }
 
+function getTodayInTimezone(timezone?: string): {
+  year: number;
+  month: number;
+  day: number;
+  offset: number;
+} {
+  const now = new Date();
+  const offset = Math.round(getUTCOffset(now, timezone));
+
+  // shifting by the offset makes the UTC getters read the timezone's wall clock
+  const wallClock = new Date(now.getTime() + offset * 60000);
+
+  return {
+    year: wallClock.getUTCFullYear(),
+    month: wallClock.getUTCMonth(),
+    day: wallClock.getUTCDate(),
+    offset,
+  };
+}
+
 type ReviewActivityCalendarProps = {
   reviewSummary?: ReviewSummary;
   recordingsSummary?: RecordingsSummary;
@@ -37,12 +57,14 @@ export default function ReviewActivityCalendar({
   const [weekStartsOn] = useUserPersistence("weekStartsOn", 0);
 
   const disabledDates = useMemo(() => {
-    const tomorrow = new Date();
-    tomorrow.setHours(tomorrow.getHours() + 24, -1, 0, 0);
-    const future = new Date();
-    future.setFullYear(tomorrow.getFullYear() + 10);
-    return { from: tomorrow, to: future };
-  }, []);
+    // day cells are TZDate in `timezone`, so the cutoff must be a real instant
+    const { year, month, day, offset } = getTodayInTimezone(timezone);
+    // midday: ranges match by calendar day, so this dodges DST edges
+    const from = new Date(Date.UTC(year, month, day + 1, 12) - offset * 60000);
+    const to = new Date(from);
+    to.setFullYear(from.getFullYear() + 10);
+    return { from, to };
+  }, [timezone]);
 
   const modifiers = useMemo(() => {
     const recordingsSet = new Set<string>();
@@ -182,48 +204,25 @@ export function TimezoneAwareCalendar({
     };
   }, [recordingsSummary]);
 
-  const timezoneOffset = useMemo(
-    () =>
-      timezone ? Math.round(getUTCOffset(new Date(), timezone)) : undefined,
+  // callers pre-shift dates so the local clock reads `timezone`, so boundaries
+  // are built in local time rather than as instants
+  const { year, month, day } = useMemo(
+    () => getTodayInTimezone(timezone),
     [timezone],
   );
+
   const disabledDates = useMemo(() => {
-    const tomorrow = new Date();
+    // midday: ranges match by calendar day, so this dodges DST edges
+    const from = new Date(year, month, day + 1, 12);
+    const to = new Date(from);
+    to.setFullYear(from.getFullYear() + 10);
+    return { from, to };
+  }, [year, month, day]);
 
-    if (timezoneOffset) {
-      tomorrow.setHours(
-        tomorrow.getHours() + 24,
-        tomorrow.getMinutes() + timezoneOffset,
-        0,
-        0,
-      );
-    } else {
-      tomorrow.setHours(tomorrow.getHours() + 24, -1, 0, 0);
-    }
-
-    const future = new Date();
-    future.setFullYear(tomorrow.getFullYear() + 10);
-    return { from: tomorrow, to: future };
-  }, [timezoneOffset]);
-
-  const today = useMemo(() => {
-    if (!timezoneOffset) {
-      return undefined;
-    }
-
-    const date = new Date();
-    const utc = Date.UTC(
-      date.getUTCFullYear(),
-      date.getUTCMonth(),
-      date.getUTCDate(),
-      date.getUTCHours(),
-      date.getUTCMinutes(),
-      date.getUTCSeconds(),
-    );
-    const todayUtc = new Date(utc);
-    todayUtc.setMinutes(todayUtc.getMinutes() + timezoneOffset, 0, 0);
-    return todayUtc;
-  }, [timezoneOffset]);
+  const today = useMemo(
+    () => new Date(year, month, day, 12),
+    [year, month, day],
+  );
 
   return (
     <Calendar