diff --git a/frontend/src/components/PlayerModal.tsx b/frontend/src/components/PlayerModal.tsx
index 88568a5..9d592f5 100644
--- a/frontend/src/components/PlayerModal.tsx
+++ b/frontend/src/components/PlayerModal.tsx
@@ -20,6 +20,14 @@ import { useBackToClose } from "../lib/history";
 // How close to the end (seconds) counts as "finished" → auto-mark watched.
 const FINISH_MARGIN = 10;
 
+// One-time HD-unlock (see attemptHdUnlock). YouTube hard-caps a windowed embed to ~360p and only a
+// real fullscreen lifts the cap; the lift then persists for the whole page session. So on the first
+// video opened we briefly flash the player to fullscreen and back to coax YouTube past the cap once.
+// Cap the flash at this many ms, but exit as soon as we see the quality actually rise.
+const HD_UNLOCK_MAX_MS = 2500;
+// Module-scoped so the flash happens only ONCE per page session (the unlock persists afterwards).
+let hdUnlockDone = false;
+
 // Persistent playback settings (stored in users.preferences). Auto-advance = what plays when a
 // video ends; loop = whether it repeats the current video ("one"), wraps the list at its ends
 // ("all"), or neither ("off"). Both apply to any queued player (feed or playlist).
@@ -124,6 +132,9 @@ export default function PlayerModal({
   // modal adjusts volume (not just the small player area).
   const dialogRef = useRef<HTMLDivElement | null>(null);
   const volTimerRef = useRef<number | undefined>(undefined);
+  // HD-unlock flash bookkeeping (see attemptHdUnlock / finishHdUnlock).
+  const unlockTimerRef = useRef<number | undefined>(undefined);
+  const unlockingRef = useRef(false);
   // Volume level to flash in the on-player overlay (null = hidden). Auto-fades after a moment.
   const [volumeUi, setVolumeUi] = useState<number | null>(null);
   // When the user interacts with YouTube's own controls (gear/seek/CC), focus moves into the
@@ -146,6 +157,32 @@ export default function PlayerModal({
     if (document.fullscreenElement) document.exitFullscreen?.();
     else el.requestFullscreen?.();
   };
+  // End the HD-unlock flash: exit fullscreen (if we're still in it) and mark the session unlocked so
+  // it never flashes again. Called either when YouTube's quality is seen to rise or on the max timeout.
+  const finishHdUnlock = () => {
+    if (!unlockingRef.current) return;
+    unlockingRef.current = false;
+    window.clearTimeout(unlockTimerRef.current);
+    hdUnlockDone = true;
+    if (document.fullscreenElement) document.exitFullscreen?.().catch(() => {});
+  };
+  // Coax YouTube past its windowed 360p cap: on the first opened video, briefly enter fullscreen so
+  // YouTube lifts the cap (which then persists for the session), then exit back to the small player.
+  // Needs live user activation (the modal-open click) — silently retried on the next click if it's
+  // already expired, and a no-op once the session is unlocked. Best-effort; can't be forced further.
+  const attemptHdUnlock = () => {
+    if (hdUnlockDone || unlockingRef.current) return;
+    const el = stageRef.current;
+    if (!el || !el.requestFullscreen || document.fullscreenElement) return;
+    el.requestFullscreen()
+      .then(() => {
+        unlockingRef.current = true;
+        unlockTimerRef.current = window.setTimeout(finishHdUnlock, HD_UNLOCK_MAX_MS);
+      })
+      .catch(() => {
+        /* no user activation yet / fullscreen blocked — leave hdUnlockDone false to retry on a click */
+      });
+  };
   const flashVolume = (level: number) => {
     setVolumeUi(level);
     window.clearTimeout(volTimerRef.current);
@@ -488,18 +525,24 @@ export default function PlayerModal({
           playsinline: 1,
           // Best-effort HD hint. The IFrame API's setPlaybackQuality/suggestedQuality are hard no-ops
           // now (YouTube removed them), and the undocumented `vq` URL param is only occasionally
-          // honoured — kept because it's harmless. NOTE: YouTube hard-caps an embed's max quality by
-          // the player's on-screen size; a windowed embed is stuck ~360p and only true fullscreen
-          // lifts the cap (after which the higher pick persists for the session). We can't beat that
-          // programmatically — a CSS transform-scale trick was tried and does NOT fool the cap.
+          // honoured — kept because it's harmless. YouTube hard-caps an embed's max quality by the
+          // player's on-screen size; a windowed embed is stuck ~360p and only true fullscreen lifts
+          // the cap (then it persists for the session). A CSS transform-scale trick does NOT fool it;
+          // we instead do a one-time fullscreen flash on open (see attemptHdUnlock) to lift the cap.
           vq: "hd1080",
         },
         events: {
-          // Keep keyboard focus on the modal, not the iframe, so shortcuts work right away.
-          onReady: () => focusModal(),
+          // Keep keyboard focus on the modal, not the iframe, so shortcuts work right away, and try
+          // the one-time HD-unlock flash while the modal-open click is still a live user activation.
+          onReady: () => {
+            focusModal();
+            attemptHdUnlock();
+          },
           onStateChange: (e: any) => {
-            // 1 === playing → sync the navigated-to video's title/author for display.
+            // 1 === playing → sync the navigated-to video's title/author for display, and retry the
+            // HD-unlock (a second chance at the flash right as playback begins).
             if (e?.data === 1) {
+              attemptHdUnlock();
               const p = playerRef.current;
               const d = p && typeof p.getVideoData === "function" ? p.getVideoData() : null;
               if (d) setLiveData({ title: d.title, author: d.author });
@@ -513,6 +556,15 @@ export default function PlayerModal({
               advanceOnEnd();
             }
           },
+          // While the HD-unlock flash is running, exit fullscreen as soon as YouTube's quality is
+          // seen to rise (no need to hold the flash the full timeout). onPlaybackQualityChange is one
+          // of the few still-live quality signals; e.data is a label ("hd1080"/"hd720"/"large"/…).
+          onPlaybackQualityChange: (e: any) => {
+            const q = String(e?.data || "");
+            if (unlockingRef.current && (q === "hd1080" || q === "hd720" || q === "large" || q === "highres")) {
+              finishHdUnlock();
+            }
+          },
           // The embed couldn't play this video (embedding disabled, removed, private…).
           // Surface our own message + an "Open on YouTube" escape hatch.
           onError: (e: any) => setPlayerError(typeof e?.data === "number" ? e.data : -1),
@@ -526,6 +578,12 @@ export default function PlayerModal({
     return () => {
       cancelled = true;
       window.clearInterval(timer);
+      // If the modal closes / advances mid-flash, don't leave the player stuck in fullscreen.
+      window.clearTimeout(unlockTimerRef.current);
+      if (unlockingRef.current) {
+        unlockingRef.current = false;
+        if (document.fullscreenElement) document.exitFullscreen?.().catch(() => {});
+      }
       // Final flush, then refresh the feed + playlists so resume bars reflect this session.
       Promise.resolve(persist()).finally(() => {
         qc.invalidateQueries({ queryKey: ["feed"] });
@@ -593,6 +651,7 @@ export default function PlayerModal({
             <div
               onClick={() => {
                 focusModal();
+                attemptHdUnlock(); // fallback: a real click is a fresh user activation for the flash
                 togglePlay();
               }}
               title={t("player.shortcutsHint")}