feat: fit full-view media to the viewport and play with sound

Media in the post modal used w-full/h-auto, so a portrait video or image grew
taller than the screen (a 720x1280 reel rendered 768x1365 in a 786px viewport)
and forced the modal to scroll. Full view now caps height to the viewport minus
the modal's own padding. Video sizes to its own aspect within the cap so a
portrait clip isn't letterboxed edge to edge; images keep filling the modal
width and only gain a height ceiling.

Opening the modal or a story reel is a user gesture, so playback now starts
unmuted and only falls back to muted if the browser actually refuses the
play() promise — previously it always started muted, and the earlier
muted-by-default fix meant a blocked video could stall the story progress bar.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011uBWhwV3wFQ5MBCcMHHem7

src/components/MediaRenderer.tsx

@@ -1,12 +1,45 @@
-import React, { useState } from 'react';
+import React, { useState, useEffect, useRef } from 'react';
 import { Play, Volume2, VolumeX } from 'lucide-react';
 import { MediaFile } from '../types';
 import { cn } from '../lib/utils';
 
 export const MediaRenderer = ({ file, className, isFullView }: { file: MediaFile; className?: string; isFullView?: boolean }) => {
-  // Start muted so autoplay is not blocked by Safari/Firefox policy.
-  const [isMuted, setIsMuted] = useState(true);
-  const sizingClass = isFullView ? "w-full h-auto block" : "w-full h-full object-cover";
+  // Try to play with sound: opening the modal is a user gesture, so browsers
+  // generally allow it. If this particular browser still refuses, the effect
+  // below falls back to muted playback rather than leaving a stalled video.
+  const [isMuted, setIsMuted] = useState(false);
+  const videoRef = useRef<HTMLVideoElement>(null);
+
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video || file.type !== 'video') return;
+
+    let cancelled = false;
+    video.muted = false;
+    video.play().catch(() => {
+      if (cancelled) return;
+      setIsMuted(true);
+      video.muted = true;
+      video.play().catch(() => { /* user can start it from the controls */ });
+    });
+
+    return () => { cancelled = true; };
+  }, [file.url, file.type]);
+  /**
+   * In full view the media must never outgrow the viewport.
+   *
+   * Video is sized to its own aspect within the cap (`w-auto`) so a portrait
+   * clip doesn't sit in a wide letterbox, while images keep filling the modal
+   * width and only gain a height ceiling — `object-contain` stops the cap from
+   * distorting anything that hits it.
+   *
+   * The desktop cap subtracts the modal's own padding (md:p-10 = 2.5rem each
+   * side); mobile leaves room for the caption panel stacked underneath.
+   */
+  const fullViewCap = "max-h-[70vh] md:max-h-[calc(100vh-5rem)] object-contain";
+  const videoSizing = isFullView ? `block w-auto max-w-full ${fullViewCap}` : "w-full h-full object-cover";
+  const imageSizing = isFullView ? `block w-full h-auto ${fullViewCap}` : "w-full h-full object-cover";
+  const sizingClass = file.type === 'video' ? videoSizing : imageSizing;
   const mediaStyle = { transform: 'translateZ(0)' };
 
   if (!file.url) return <div className={cn("bg-gray-100 flex items-center justify-center text-black", sizingClass)}><Play size={24} className="text-gray-300" /></div>;
@@ -14,7 +47,7 @@ export const MediaRenderer = ({ file, className, isFullView }: { file: MediaFile
   if (file.type === 'video') {
     return (
       <div className="relative w-full h-full flex items-center justify-center group/video text-black">
-        <video src={file.url} className={cn("transition-all duration-300", sizingClass, className)} style={mediaStyle} playsInline autoPlay muted={isMuted} loop controls />
+        <video ref={videoRef} src={file.url} className={cn("transition-all duration-300", sizingClass, className)} style={mediaStyle} playsInline autoPlay muted={isMuted} loop controls />
         <button onClick={(e) => { e.stopPropagation(); setIsMuted(!isMuted); }} className="absolute bottom-16 right-4 z-30 bg-black/40 hover:bg-black/60 text-white p-2 rounded-full backdrop-blur-md transition-all md:opacity-0 md:group-hover/video:opacity-100">
           {isMuted ? <VolumeX size={20} /> : <Volume2 size={20} />}
         </button>

src/components/StoryViewer.tsx

@@ -26,9 +26,10 @@ export const StoryViewer: React.FC<StoryViewerProps> = ({
 }) => {
   const [currentStoryIndex, setCurrentStoryIndex] = useState(0);
   const [progress, setProgress] = useState(0);
-  // Start muted: Safari and Firefox refuse to autoplay audible media, which
-  // would stall the reel on its first video.
-  const [isMuted, setIsMuted] = useState(true);
+  // Opening the reel is a user gesture, so try for sound; the effect below
+  // falls back to muted if the browser refuses, which would otherwise stall
+  // the progress bar on the first video.
+  const [isMuted, setIsMuted] = useState(false);
   const videoRef = useRef<HTMLVideoElement>(null);
   const story = stories[currentStoryIndex];
   const primary = story?.media?.[0];
@@ -61,6 +62,22 @@ export const StoryViewer: React.FC<StoryViewerProps> = ({
     return () => clearInterval(timer);
   }, [currentStoryIndex, primary]);
 
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video || primary?.type !== 'video') return;
+
+    let cancelled = false;
+    video.muted = false;
+    video.play().catch(() => {
+      if (cancelled) return;
+      setIsMuted(true);
+      video.muted = true;
+      video.play().catch(() => { /* leave it to the controls */ });
+    });
+
+    return () => { cancelled = true; };
+  }, [primary]);
+
   useEffect(() => {
     if (progress >= 100) {
       if (currentStoryIndex < stories.length - 1) {