feat(player): watched controls, compact layout, description popover

- Watched: an explicit toggle in the modal (Mark watched / Watched→unmark) plus
  auto-mark when playback reaches the end (within 10s, or on the ended event).
- Compact layout: drop the header bar and the redundant 'Open on YouTube' button
  (the embed's own YouTube logo already jumps out); Close moves to the title row,
  channel + meta share one line — fits without a scrollbar at higher zoom.
- Card actions reflect status: watched shows a double-check, saved a filled
  bookmark, with matching tooltips.
- Description: new GET /api/videos/{id} exposes the already-stored description,
  shown in a popover when hovering the modal title (fetched lazily).

frontend/src/components/Feed.tsx

@@ -139,7 +139,11 @@ export default function Feed({
         </div>
       )}
       {activeVideo && (
-        <PlayerModal video={activeVideo} onClose={() => setActiveVideo(null)} />
+        <PlayerModal
+          video={activeVideo}
+          onClose={() => setActiveVideo(null)}
+          onState={onState}
+        />
       )}
       <div ref={sentinel} className="h-10" />
       {isFetchingNextPage && (

frontend/src/components/PlayerModal.tsx

@@ -1,13 +1,17 @@
-import { useEffect, useRef } from "react";
-import { ExternalLink, X } from "lucide-react";
-import type { Video } from "../lib/api";
+import { useEffect, useRef, useState } from "react";
+import { useQuery } from "@tanstack/react-query";
+import { Check, CheckCheck, X } from "lucide-react";
+import { api, type Video } from "../lib/api";
 import { formatDuration, formatViews, relativeTime } from "../lib/format";
 
 // Experiment (branch experiment/inline-player): play the video in-app via the
 // YouTube IFrame Player API (not a bare embed) so we can read playback position
-// and resume where the user left off. The modal closes via the header X button,
-// the backdrop, or ESC (ESC only while focus is on our page, not inside the
-// cross-origin player iframe — a browser security boundary we can't cross).
+// and resume where the user left off. The modal closes via the in-card Close
+// button, the backdrop, or ESC (ESC only while focus is on our page, not inside
+// the cross-origin player iframe — a browser security boundary we can't cross).
+
+// How close to the end (seconds) counts as "finished" → auto-mark watched.
+const FINISH_MARGIN = 10;
 
 // --- IFrame Player API loader (singleton) ---
 let apiPromise: Promise<any> | null = null;
@@ -32,7 +36,7 @@ function loadYouTubeApi(): Promise<any> {
 const posKey = (id: string) => `subfeed:player-pos:${id}`;
 function savePos(id: string, seconds: number, duration: number): void {
   // Don't store trivially-early or near-finished positions (start fresh next time).
-  if (!Number.isFinite(seconds) || seconds < 5 || (duration > 0 && seconds > duration - 10)) {
+  if (!Number.isFinite(seconds) || seconds < 5 || (duration > 0 && seconds > duration - FINISH_MARGIN)) {
     localStorage.removeItem(posKey(id));
     return;
   }
@@ -47,12 +51,34 @@ function loadPos(id: string): number {
 export default function PlayerModal({
   video,
   onClose,
+  onState,
 }: {
   video: Video;
   onClose: () => void;
+  onState: (id: string, status: string) => void;
 }) {
   const mountRef = useRef<HTMLDivElement | null>(null);
   const playerRef = useRef<any>(null);
+  const autoMarkedRef = useRef(false);
+
+  // Local mirror of watch status so the toggle reacts instantly; changes are
+  // propagated to the feed (and server) via onState.
+  const [status, setStatus] = useState(video.status);
+  const watched = status === "watched";
+  const setWatched = (on: boolean) => {
+    const next = on ? "watched" : "new";
+    setStatus(next);
+    onState(video.id, next);
+  };
+
+  // Lazy description (fetched only when the title is hovered).
+  const [showDesc, setShowDesc] = useState(false);
+  const detail = useQuery({
+    queryKey: ["video-detail", video.id],
+    queryFn: () => api.videoDetail(video.id),
+    enabled: showDesc,
+    staleTime: 5 * 60_000,
+  });
 
   // ESC + background scroll lock.
   useEffect(() => {
@@ -68,15 +94,27 @@ export default function PlayerModal({
     };
   }, [onClose]);
 
-  // Create the player, resume from the saved position, and persist progress.
+  // Create the player, resume from the saved position, persist progress, and
+  // auto-mark watched once playback reaches the end.
   useEffect(() => {
     let cancelled = false;
     const id = video.id;
+
+    const maybeAutoWatch = (current: number, duration: number) => {
+      if (autoMarkedRef.current || duration <= 0) return;
+      if (current > duration - FINISH_MARGIN) {
+        autoMarkedRef.current = true;
+        setWatched(true);
+      }
+    };
     const persist = () => {
       const p = playerRef.current;
       if (!p || typeof p.getCurrentTime !== "function") return;
       try {
-        savePos(id, p.getCurrentTime(), typeof p.getDuration === "function" ? p.getDuration() : 0);
+        const cur = p.getCurrentTime();
+        const dur = typeof p.getDuration === "function" ? p.getDuration() : 0;
+        maybeAutoWatch(cur, dur);
+        savePos(id, cur, dur);
       } catch {
         /* player may be tearing down */
       }
@@ -96,10 +134,19 @@ export default function PlayerModal({
           origin: window.location.origin,
           playsinline: 1,
         },
+        events: {
+          onStateChange: (e: any) => {
+            // 0 === ended → mark watched even if the timer hasn't fired yet.
+            if (e?.data === 0 && !autoMarkedRef.current) {
+              autoMarkedRef.current = true;
+              setWatched(true);
+            }
+          },
+        },
       });
     });
 
-    // Periodic checkpoint so progress survives a crash/refresh, not just a clean close.
+    // Periodic checkpoint so progress (and auto-watch) survive a crash/refresh.
     const timer = window.setInterval(persist, 5000);
 
     return () => {
@@ -116,6 +163,7 @@ export default function PlayerModal({
       }
       playerRef.current = null;
     };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [video.id]);
 
   return (
@@ -129,71 +177,91 @@ export default function PlayerModal({
         className="glass-card relative w-full max-w-4xl max-h-full overflow-y-auto rounded-2xl shadow-2xl"
         onClick={(e) => e.stopPropagation()}
       >
-        {/* Header bar — keeps our close button off the player's own top-right controls. */}
-        <div className="flex items-center justify-between gap-3 px-4 h-12 border-b border-border">
-          <span className="truncate text-sm font-medium text-muted">{video.title}</span>
-          <button
-            onClick={onClose}
-            title="Close (Esc)"
-            aria-label="Close"
-            className="shrink-0 p-2 -mr-2 rounded-full text-muted hover:text-fg hover:bg-surface transition"
-          >
-            <X className="w-5 h-5" />
-          </button>
-        </div>
-
-        <div className="aspect-video w-full bg-black">
+        <div className="aspect-video w-full bg-black rounded-t-2xl overflow-hidden">
           <div ref={mountRef} className="w-full h-full" />
         </div>
 
         <div className="p-4 sm:p-5">
-          <h2 className="text-lg font-semibold leading-snug">{video.title}</h2>
+          {/* Title row — title (with hover description) on the left, Close on the right. */}
+          <div className="flex items-start gap-3">
+            <div
+              className="relative min-w-0 flex-1"
+              onMouseEnter={() => setShowDesc(true)}
+              onMouseLeave={() => setShowDesc(false)}
+            >
+              <h2 className="text-lg font-semibold leading-snug cursor-default">
+                {video.title}
+              </h2>
+              {showDesc && (
+                <div className="absolute left-0 top-full mt-2 z-10 w-full max-w-2xl glass-card rounded-xl shadow-2xl p-4">
+                  <div className="text-xs uppercase tracking-wide text-muted mb-2">
+                    Description
+                  </div>
+                  {detail.isLoading ? (
+                    <div className="text-sm text-muted">Loading…</div>
+                  ) : detail.data?.description ? (
+                    <div className="text-sm whitespace-pre-wrap max-h-64 overflow-y-auto leading-relaxed">
+                      {detail.data.description}
+                    </div>
+                  ) : (
+                    <div className="text-sm text-muted">No description.</div>
+                  )}
+                </div>
+              )}
+            </div>
+            <button
+              onClick={onClose}
+              title="Close (Esc)"
+              className="shrink-0 inline-flex items-center gap-1.5 text-sm px-3 py-1.5 rounded-lg text-muted hover:text-fg hover:bg-surface transition"
+            >
+              Close
+              <X className="w-4 h-4" />
+            </button>
+          </div>
 
+          {/* Channel + meta on one line, with the watched toggle pushed to the right. */}
           <div className="flex items-center gap-3 mt-3">
             {video.channel_thumbnail && (
               <img
                 src={video.channel_thumbnail}
                 alt=""
-                className="w-10 h-10 rounded-full shrink-0"
+                className="w-9 h-9 rounded-full shrink-0"
               />
             )}
             <a
               href={video.channel_url}
               target="_blank"
               rel="noreferrer"
-              className="font-medium hover:text-accent truncate"
+              className="font-medium hover:text-accent shrink-0"
             >
               {video.channel_title}
             </a>
-          </div>
+            <div className="flex flex-wrap items-center gap-x-2 gap-y-0.5 text-sm text-muted min-w-0">
+              {video.view_count != null && <span>· {formatViews(video.view_count)} views</span>}
+              <span>· {relativeTime(video.published_at)}</span>
+              {video.duration_seconds != null && (
+                <span>· {formatDuration(video.duration_seconds)}</span>
+              )}
+              {video.live_status === "was_live" && (
+                <span className="bg-accent text-accent-fg text-[10px] font-semibold uppercase tracking-wide px-1.5 py-0.5 rounded">
+                  stream
+                </span>
+              )}
+            </div>
 
-          <div className="flex flex-wrap items-center gap-x-2 gap-y-1 text-sm text-muted mt-3">
-            {video.view_count != null && <span>{formatViews(video.view_count)} views</span>}
-            {video.view_count != null && <span>·</span>}
-            <span>{relativeTime(video.published_at)}</span>
-            {video.duration_seconds != null && (
-              <>
-                <span>·</span>
-                <span>{formatDuration(video.duration_seconds)}</span>
-              </>
-            )}
-            {video.live_status === "was_live" && (
-              <span className="bg-accent text-accent-fg text-[10px] font-semibold uppercase tracking-wide px-1.5 py-0.5 rounded">
-                stream
-              </span>
-            )}
-          </div>
-
-          <div className="mt-4">
-            <a
-              href={video.watch_url}
-              target="_blank"
-              rel="noreferrer"
-              className="inline-flex items-center gap-2 text-sm px-3 py-2 rounded-lg bg-accent text-accent-fg shadow-sm hover:opacity-90 transition"
+            <button
+              onClick={() => setWatched(!watched)}
+              title={watched ? "Watched — click to unmark" : "Mark watched"}
+              className={
+                "ml-auto shrink-0 inline-flex items-center gap-1.5 text-sm px-3 py-1.5 rounded-lg transition " +
+                (watched
+                  ? "bg-accent text-accent-fg shadow-sm hover:opacity-90"
+                  : "text-muted hover:text-fg hover:bg-surface border border-border")
+              }
             >
-              <ExternalLink className="w-4 h-4" />
-              Open on YouTube
-            </a>
+              {watched ? <CheckCheck className="w-4 h-4" /> : <Check className="w-4 h-4" />}
+              {watched ? "Watched" : "Mark watched"}
+            </button>
           </div>
         </div>
       </div>

frontend/src/components/VideoCard.tsx

@@ -1,4 +1,4 @@
-import { Bookmark, Check, Eye, EyeOff, ListFilter } from "lucide-react";
+import { Bookmark, Check, CheckCheck, Eye, EyeOff, ListFilter } from "lucide-react";
 import clsx from "clsx";
 import type { Video } from "../lib/api";
 import { formatDuration, formatViews, relativeTime } from "../lib/format";
@@ -21,20 +21,24 @@ function Actions({
     <div className="flex gap-1 opacity-0 group-hover:opacity-100 transition">
       <button
         onClick={act("watched")}
-        title="Mark watched"
+        title={video.status === "watched" ? "Watched — click to unmark" : "Mark watched"}
         className={clsx(
           "p-1.5 rounded-md hover:bg-surface text-muted hover:text-fg",
           video.status === "watched" && "text-accent"
         )}
       >
-        <Check className="w-4 h-4" />
+        {video.status === "watched" ? (
+          <CheckCheck className="w-4 h-4" />
+        ) : (
+          <Check className="w-4 h-4" />
+        )}
       </button>
       <button
         onClick={act("saved")}
-        title="Save for later"
+        title={video.status === "saved" ? "Saved — click to remove" : "Save for later"}
         className={clsx(
           "p-1.5 rounded-md hover:bg-surface text-muted hover:text-fg",
-          video.status === "saved" && "text-accent"
+          video.status === "saved" && "fill-current text-accent"
         )}
       >
         <Bookmark className="w-4 h-4" />