feat: notification polling 30s->10s, video thumbnails, @-mentions

- NotificationBell: refetchInterval 30000->10000, refetchOnWindowFocus, i18n label
- ProfileTabs: Mux thumbnail for VIDEO posts in grid, play icon overlay
- parse-caption: add mention segment type for @word parsing
- MentionTextarea: new component with @-autocomplete via search.pets
- PostCard: render @mentions as blue links to /search
- CommentSheet: parse comment bodies for mentions, use MentionTextarea
- PhotoPostForm: use MentionTextarea for caption input

src/components/feed/CommentSheet.tsx

@@ -5,8 +5,9 @@ import { Trash2, Loader2 } from "lucide-react";
 import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
 import { toast } from "sonner";
 import { useTRPC } from "@/trpc/client";
+import Link from "next/link";
 import { Avatar, AvatarFallback } from "@/components/ui/avatar";
-import { Textarea } from "@/components/ui/textarea";
+import { MentionTextarea } from "@/components/ui/mention-textarea";
 import { Button } from "@/components/ui/button";
 import { ScrollArea } from "@/components/ui/scroll-area";
 import { Separator } from "@/components/ui/separator";
@@ -17,6 +18,7 @@ import {
   SheetTitle,
 } from "@/components/ui/sheet";
 import { getAvatarUrl } from "@/lib/avatar-url";
+import { parseCaption } from "@/lib/parse-caption";
 import { useTranslations } from "next-intl";
 
 interface CommentSheetProps {
@@ -144,7 +146,17 @@ export function CommentSheet({ postId, petId, open, onOpenChange }: CommentSheet
                           {formatRelativeTime(comment.createdAt)}
                         </span>
                       </div>
-                      <p className="text-sm mt-0.5 break-words">{comment.body}</p>
+                      <p className="text-sm mt-0.5 break-words">
+                        {parseCaption(comment.body).map((seg, i) =>
+                          seg.type === "hashtag" ? (
+                            <Link key={i} href={`/hashtag/${seg.tag}`} className="text-orange-500 hover:underline">#{seg.tag}</Link>
+                          ) : seg.type === "mention" ? (
+                            <Link key={i} href={`/search?q=${seg.name}`} className="text-blue-500 hover:underline">@{seg.name}</Link>
+                          ) : (
+                            <span key={i}>{seg.text}</span>
+                          )
+                        )}
+                      </p>
                     </div>
                     {isOwn && (
                       <button
@@ -170,13 +182,13 @@ export function CommentSheet({ postId, petId, open, onOpenChange }: CommentSheet
 
         {/* Comment input — sticky at bottom */}
         <div className="flex gap-2 px-4 py-3 bg-background">
-          <Textarea
+          <MentionTextarea
             ref={textareaRef}
             rows={1}
             maxLength={500}
             placeholder={t("placeholder")}
             value={body}
-            onChange={(e) => setBody(e.target.value)}
+            onChange={(val) => setBody(val)}
             onKeyDown={handleKeyDown}
             className="flex-1 resize-none min-h-[40px] max-h-[120px] text-sm"
           />

src/components/feed/PostCard.tsx

@@ -436,6 +436,14 @@ export function PostCard({ post, onDeleted, variant = "feed" }: PostCardProps) {
                     >
                       #{seg.tag}
                     </Link>
+                  ) : seg.type === "mention" ? (
+                    <Link
+                      key={i}
+                      href={`/search?q=${seg.name}`}
+                      className="text-blue-500 hover:underline"
+                    >
+                      @{seg.name}
+                    </Link>
                   ) : (
                     <span key={i}>{seg.text}</span>
                   )

src/components/notifications/NotificationBell.tsx

@@ -5,6 +5,7 @@ import { Bell } from "lucide-react";
 import { useQuery } from "@tanstack/react-query";
 import { useTRPC } from "@/trpc/client";
 import { useActivePet } from "@/context/ActivePetContext";
+import { useTranslations } from "next-intl";
 
 interface NotificationBellProps {
   /** "sidebar" = full row with label; "mobile" = icon + label stacked */
@@ -15,11 +16,13 @@ interface NotificationBellProps {
 export function NotificationBell({ variant, isActive }: NotificationBellProps) {
   const trpc = useTRPC();
   const { activePetId } = useActivePet();
+  const t = useTranslations("Nav");
 
   const { data } = useQuery({
     ...trpc.notifications.unreadCount.queryOptions({ petId: activePetId ?? "" }),
     enabled: !!activePetId,
-    refetchInterval: 30_000,
+    refetchInterval: 10_000,
+    refetchOnWindowFocus: true,
   });
 
   const count = data?.count ?? 0;
@@ -43,12 +46,11 @@ export function NotificationBell({ variant, isActive }: NotificationBellProps) {
             </span>
           )}
         </span>
-        <span>Notifications</span>
+        <span>{t("notifications")}</span>
       </Link>
     );
   }
 
-  // Mobile variant — icon stacked above label
   return (
     <Link
       href="/notifications"
@@ -64,7 +66,7 @@ export function NotificationBell({ variant, isActive }: NotificationBellProps) {
           </span>
         )}
       </span>
-      <span>Alerts</span>
+      <span>{t("notifications")}</span>
     </Link>
   );
 }

src/components/post-creation/PhotoPostForm.tsx

@@ -7,7 +7,7 @@ import { useMutation, useQueryClient } from "@tanstack/react-query";
 import { useTRPC } from "@/trpc/client";
 import { useActivePet } from "@/context/ActivePetContext";
 import { Button } from "@/components/ui/button";
-import { Textarea } from "@/components/ui/textarea";
+import { MentionTextarea } from "@/components/ui/mention-textarea";
 import { MultiImageUpload } from "@/components/post-creation/MultiImageUpload";
 
 /**
@@ -62,19 +62,6 @@ export function PhotoPostForm({ onClose }: PhotoPostFormProps) {
     })
   );
 
-  const handleCaptionChange = useCallback(
-    (e: React.ChangeEvent<HTMLTextAreaElement>) => {
-      const value = e.target.value;
-      setCaption(value);
-      if (value.length > 500) {
-        setCaptionError("Caption must be 500 characters or fewer.");
-      } else {
-        setCaptionError(null);
-      }
-    },
-    []
-  );
-
   const handleSubmit = useCallback(() => {
     if (!activePetId) {
       toast.error("No active pet selected.");
@@ -116,11 +103,18 @@ export function PhotoPostForm({ onClose }: PhotoPostFormProps) {
 
       {/* Caption textarea */}
       <div className="space-y-1">
-        <Textarea
+        <MentionTextarea
           placeholder="Write a caption…"
           value={caption}
-          onChange={handleCaptionChange}
-          maxLength={510} // let Zod catch exact limit; UI shows error at 500
+          onChange={(val) => {
+            setCaption(val);
+            if (val.length > 500) {
+              setCaptionError("Caption must be 500 characters or fewer.");
+            } else {
+              setCaptionError(null);
+            }
+          }}
+          maxLength={510}
           rows={3}
           className="text-sm resize-none"
         />

src/components/profile/ProfileTabs.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { useState, useCallback } from "react";
-import { Layers2 } from "lucide-react";
+import { Layers2, Play } from "lucide-react";
 import { useQuery } from "@tanstack/react-query";
 import { useTRPC } from "@/trpc/client";
 import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
@@ -71,7 +71,13 @@ export function ProfileTabs({ petId }: ProfileTabsProps) {
               {posts.map((post) => {
                 const firstImage = post.images?.[0];
                 const isCarousel = (post.images?.length ?? 0) > 1;
-                const mediaUrl = firstImage ? getMediaUrl(firstImage.storageKey) : null;
+                const isVideo = post.type === "VIDEO";
+                const muxPlaybackId = post.videoPost?.muxPlaybackId;
+                const mediaUrl = firstImage
+                  ? getMediaUrl(firstImage.storageKey)
+                  : isVideo && muxPlaybackId
+                    ? `https://image.mux.com/${muxPlaybackId}/thumbnail.jpg?width=320&time=0`
+                    : null;
 
                 return (
                   <button
@@ -91,7 +97,12 @@ export function ProfileTabs({ petId }: ProfileTabsProps) {
                     ) : (
                       <div className="w-full h-full bg-muted" />
                     )}
-                    {isCarousel && (
+                    {isVideo && (
+                      <div className="absolute top-1.5 right-1.5">
+                        <Play className="h-4 w-4 text-white drop-shadow fill-white" aria-hidden="true" />
+                      </div>
+                    )}
+                    {isCarousel && !isVideo && (
                       <div className="absolute top-1.5 right-1.5">
                         <Layers2 className="h-4 w-4 text-white drop-shadow" aria-hidden="true" />
                       </div>

src/components/ui/mention-textarea.tsx

@@ -0,0 +1,152 @@
+"use client";
+
+import { useState, useRef, useCallback } from "react";
+import { useQuery } from "@tanstack/react-query";
+import { useTRPC } from "@/trpc/client";
+import { Textarea } from "@/components/ui/textarea";
+import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar";
+import { getAvatarUrl } from "@/lib/avatar-url";
+
+interface MentionTextareaProps {
+  value: string;
+  onChange: (value: string) => void;
+  placeholder?: string;
+  maxLength?: number;
+  rows?: number;
+  className?: string;
+  onKeyDown?: React.KeyboardEventHandler<HTMLTextAreaElement>;
+  ref?: React.Ref<HTMLTextAreaElement>;
+}
+
+interface MentionState {
+  query: string;
+  start: number;
+}
+
+export function MentionTextarea({
+  value,
+  onChange,
+  placeholder,
+  maxLength,
+  rows,
+  className,
+  onKeyDown,
+  ref: externalRef,
+}: MentionTextareaProps) {
+  const trpc = useTRPC();
+  const [mention, setMention] = useState<MentionState | null>(null);
+  const internalRef = useRef<HTMLTextAreaElement>(null);
+
+  // Merged ref: keeps internal ref in sync and forwards to caller
+  const mergedRef = useCallback(
+    (el: HTMLTextAreaElement | null) => {
+      (internalRef as React.MutableRefObject<HTMLTextAreaElement | null>).current = el;
+      if (typeof externalRef === "function") {
+        externalRef(el);
+      } else if (externalRef) {
+        (externalRef as React.MutableRefObject<HTMLTextAreaElement | null>).current = el;
+      }
+    },
+    [externalRef]
+  );
+
+  const textareaRef = internalRef;
+
+  const { data } = useQuery({
+    ...trpc.search.pets.queryOptions({ query: mention?.query ?? ".", limit: 6 }),
+    enabled: !!mention && mention.query.length >= 1,
+  });
+
+  const detectMention = useCallback((text: string, cursorPos: number) => {
+    const textBeforeCursor = text.slice(0, cursorPos);
+    const match = textBeforeCursor.match(/@(\w+)$/);
+    if (match) {
+      setMention({ query: match[1], start: cursorPos - match[0].length });
+    } else {
+      setMention(null);
+    }
+  }, []);
+
+  const handleChange = useCallback(
+    (e: React.ChangeEvent<HTMLTextAreaElement>) => {
+      const newValue = e.target.value;
+      onChange(newValue);
+      detectMention(newValue, e.target.selectionStart ?? newValue.length);
+    },
+    [onChange, detectMention]
+  );
+
+  const handleKeyUp = useCallback(
+    (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
+      if (e.key === "Escape") {
+        setMention(null);
+        return;
+      }
+      detectMention(value, (e.target as HTMLTextAreaElement).selectionStart ?? value.length);
+    },
+    [value, detectMention]
+  );
+
+  const handleSelect = useCallback(
+    (petName: string) => {
+      if (!mention) return;
+      const before = value.slice(0, mention.start);
+      const after = value.slice(mention.start + 1 + mention.query.length);
+      const inserted = `${before}@${petName} ${after}`;
+      onChange(inserted);
+      setMention(null);
+      setTimeout(() => {
+        if (textareaRef.current) {
+          const pos = before.length + petName.length + 2;
+          textareaRef.current.focus();
+          textareaRef.current.setSelectionRange(pos, pos);
+        }
+      }, 0);
+    },
+    [mention, value, onChange]
+  );
+
+  const pets = data?.pets ?? [];
+
+  return (
+    <div className="relative">
+      <Textarea
+        ref={mergedRef}
+        value={value}
+        onChange={handleChange}
+        onKeyUp={handleKeyUp}
+        onKeyDown={onKeyDown}
+        placeholder={placeholder}
+        maxLength={maxLength}
+        rows={rows}
+        className={className}
+      />
+      {mention && pets.length > 0 && (
+        <div className="absolute z-50 bottom-full mb-1 left-0 right-0 bg-card border rounded-md shadow-lg overflow-hidden max-h-48 overflow-y-auto">
+          {pets.map((pet) => (
+            <button
+              key={pet.id}
+              type="button"
+              className="w-full flex items-center gap-2 px-3 py-2 hover:bg-muted text-sm text-left"
+              onMouseDown={(e) => {
+                e.preventDefault();
+                handleSelect(pet.name);
+              }}
+            >
+              <Avatar className="h-6 w-6 shrink-0">
+                {pet.avatarKey && (
+                  <AvatarImage src={getAvatarUrl(pet.avatarKey)!} alt={pet.name} />
+                )}
+                <AvatarFallback className="text-xs bg-muted">
+                  {pet.name.slice(0, 2).toUpperCase()}
+                </AvatarFallback>
+              </Avatar>
+              <span className="font-medium flex-1 truncate">{pet.name}</span>
+              <span className="text-muted-foreground text-xs shrink-0">{pet.species.name}</span>
+            </button>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}

src/lib/parse-caption.ts

@@ -1,13 +1,16 @@
 export type CaptionSegment =
   | { type: "text"; text: string }
-  | { type: "hashtag"; tag: string };
+  | { type: "hashtag"; tag: string }
+  | { type: "mention"; name: string };
 
 export function parseCaption(caption: string): CaptionSegment[] {
   const segments: CaptionSegment[] = [];
-  const parts = caption.split(/(#\w{1,50})/g);
+  const parts = caption.split(/(#\w{1,50}|@\w{1,50})/g);
   for (const part of parts) {
     if (part.startsWith("#")) {
       segments.push({ type: "hashtag", tag: part.slice(1).toLowerCase() });
+    } else if (part.startsWith("@")) {
+      segments.push({ type: "mention", name: part.slice(1) });
     } else if (part) {
       segments.push({ type: "text", text: part });
     }