fix: surface playback errors and stabilize disk cache size

Playback errors in the global overlay (direct-start from Browse/Category/
StreamList screens) were silently discarded — the stream disappeared with
no user feedback. Now shows an error overlay with the streamlink message
and a dismiss hint; hls.js fatal errors use the same path.

Chromium computes disk-cache-size dynamically from free disk space, so
the value differs between runs. The cache index then contains a size that
no longer matches, producing "Invalid cache (current) size" on shutdown.
A fixed 500 MB cap keeps the value stable across restarts.

The cache classification thresholds (500 MB / 1 GB) were designed for an
uncapped cache. With a fixed 500 MB limit, the cache can never enter those
states, leaving dead UI states and unused logic behind.

src/main/index.ts

@@ -12,6 +12,9 @@ const isDev = !app.isPackaged
 // Erlaubt video.play() ohne vorangehende User-Geste (nötig, weil play() in hls.js-Callbacks
 // aufgerufen wird, die asynchron weit nach dem ursprünglichen Click-Event stattfinden).
 app.commandLine.appendSwitch('autoplay-policy', 'no-user-gesture-required')
+// Explizite Cache-Größe verhindert Chromiums dynamische Größenberechnung, die bei
+// wechselndem freiem Speicherplatz zu "Invalid cache (current) size"-Fehlern führt.
+app.commandLine.appendSwitch('disk-cache-size', String(500 * 1024 * 1024))
 
 function createWindow(): BrowserWindow {
   const isLinux = process.platform === 'linux'

src/renderer/src/screens/AppShell.tsx

@@ -14,7 +14,7 @@ import type { FollowedChannelInfo, GameInfo, HlsUrlPayload } from '../types/t4sd
 
 type Region = 'sidebar' | 'main'
 type QuitChoice = 'yes' | 'no'
-type GlobalPlayState = 'idle' | 'starting' | 'playing' | 'paused'
+type GlobalPlayState = 'idle' | 'starting' | 'playing' | 'paused' | 'error'
 
 interface Props {
   onLogout: () => void
@@ -42,6 +42,7 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
   const [liveCurrentQuality, setLiveCurrentQuality] = useState('best')
   const [liveQualityPanelOpen, setLiveQualityPanelOpen] = useState(false)
   const [liveQualityFocusedIndex, setLiveQualityFocusedIndex] = useState(0)
+  const [liveErrorMsg, setLiveErrorMsg] = useState('')
 
   const isGlobalPlaying = livePlayState !== 'idle'
 
@@ -56,7 +57,7 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
       if (!isGlobalPlaybackInitiated.current) return
       if (ev.kind === 'started') {
         setLivePlayState('playing')
-      } else if (ev.kind === 'stopped' || ev.kind === 'error') {
+      } else if (ev.kind === 'stopped') {
         isGlobalPlaybackInitiated.current = false
         setLiveHlsPayload(null)
         setLivePlayState('idle')
@@ -65,6 +66,14 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
         setLiveAvailableQualities(undefined)
         setLiveCurrentQuality('best')
         setLiveQualityPanelOpen(false)
+        setLiveErrorMsg('')
+      } else if (ev.kind === 'error') {
+        isGlobalPlaybackInitiated.current = false
+        setLiveHlsPayload(null)
+        setLivePlayState('error')
+        setLiveErrorMsg(ev.message ?? 'Stream konnte nicht gestartet werden.')
+        setLiveAvailableQualities(undefined)
+        setLiveQualityPanelOpen(false)
       }
     })
     return () => { unsubHls(); unsubEvent() }
@@ -106,6 +115,7 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
     setLiveAvailableQualities(undefined)
     setLiveCurrentQuality('best')
     setLiveQualityPanelOpen(false)
+    setLiveErrorMsg('')
     void window.t4sd.playback.startLive(ch.broadcasterLogin).then(() => {
       window.t4sd.playback.getQualities(`twitch.tv/${ch.broadcasterLogin}`)
         .then((qs) => setLiveAvailableQualities(qs.length > 0 ? qs : []))
@@ -114,10 +124,15 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
   }, [])
 
   const handleStopLive = useCallback(() => {
+    isGlobalPlaybackInitiated.current = false
     liveVideoRef.current?.stop()
+    setLiveHlsPayload(null)
+    setLivePlayState('idle')
+    setLiveChannel(null)
     setLiveAvailableQualities(undefined)
     setLiveCurrentQuality('best')
     setLiveQualityPanelOpen(false)
+    setLiveErrorMsg('')
     void window.t4sd.playback.stop()
   }, [])
 
@@ -352,6 +367,21 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
               Starte Wiedergabe…
             </div>
           )}
+          {/* Fehler-Overlay */}
+          {livePlayState === 'error' && (
+            <div style={{
+              position: 'fixed', inset: 0, zIndex: 100,
+              background: '#000', display: 'flex', flexDirection: 'column',
+              alignItems: 'center', justifyContent: 'center', gap: '1rem'
+            }}>
+              <p style={{ color: '#ff6868', fontSize: '1.1rem', maxWidth: '60ch', textAlign: 'center', margin: 0 }}>
+                {liveErrorMsg}
+              </p>
+              <p style={{ color: '#888', fontSize: '0.9rem', margin: 0 }}>
+                B / Esc — Schließen
+              </p>
+            </div>
+          )}
           {/* VideoPlayer + Overlay sobald HLS-URL da ist */}
           {liveHlsPayload && (
             <>
@@ -366,8 +396,8 @@ export default function AppShell({ onLogout }: Props): JSX.Element {
                 onError={() => {
                   isGlobalPlaybackInitiated.current = false
                   setLiveHlsPayload(null)
-                  setLivePlayState('idle')
+                  setLivePlayState('error')
-                  setLiveChannel(null)
+                  setLiveErrorMsg('Wiedergabefehler — Stream konnte nicht geladen werden.')
                 }}
                 onTimeUpdate={(s) => setLivePosition(s)}
               />

src/renderer/src/screens/SettingsScreen.tsx

@@ -34,10 +34,6 @@ const SIDEBAR_STEP = 10
 const BADGE_GAP_STEP = 2
 
 const MB = 1024 * 1024
-const CACHE_THRESHOLD_UNUSUAL = 500 * MB
-const CACHE_THRESHOLD_HIGH = 1024 * MB
-
-type CacheStatus = 'normal' | 'unusual' | 'high'
 
 function formatCacheSize(bytes: number): string {
   if (bytes < MB) return `${(bytes / 1024).toFixed(0)} KB`
@@ -46,12 +42,6 @@ function formatCacheSize(bytes: number): string {
   return `${(mb / 1024).toFixed(2)} GB`
 }
 
-function classifyCache(bytes: number): { status: CacheStatus; label: string } {
-  if (bytes >= CACHE_THRESHOLD_HIGH) return { status: 'high', label: 'Leeren empfohlen' }
-  if (bytes >= CACHE_THRESHOLD_UNUSUAL) return { status: 'unusual', label: 'Ungewöhnlich groß' }
-  return { status: 'normal', label: 'Normal' }
-}
-
 /** Total focusable rows: badge options + sidebar slider + badge gap slider + hls toggle + cache action */
 const SIDEBAR_SLIDER_ROW = OPTIONS.length
 const BADGE_GAP_SLIDER_ROW = OPTIONS.length + 1
@@ -162,8 +152,6 @@ export default function SettingsScreen({ hasFocus, onRequestSidebar }: Props): J
   const hlsCacheToggleFocused = hasFocus && focusedIndex === HLS_CACHE_TOGGLE_ROW
   const cacheActionFocused = hasFocus && focusedIndex === CACHE_ACTION_ROW
 
-  const cacheClassification = cacheSize !== null ? classifyCache(cacheSize) : null
-
   return (
     <div className="screen settings-screen">
       <header className="screen__header">
@@ -288,7 +276,7 @@ export default function SettingsScreen({ hasFocus, onRequestSidebar }: Props): J
           HLS-Segmente (Live &amp; VODs) sind Single-Use — sie werden nach dem Abspielen nie
           wieder abgerufen. Caching erzeugt auf dem Steam Deck unnötiges Disk-Wachstum und
           Akku-Belastung. Thumbnails und API-Antworten bleiben immer gecacht.
-          Cache-Größe: Normal unter 500 MB · ungewöhnlich ab 500 MB · Leeren empfohlen ab 1 GB.
+          Maximale Cache-Größe: 500 MB.
         </p>
 
         <button
@@ -332,11 +320,6 @@ export default function SettingsScreen({ hasFocus, onRequestSidebar }: Props): J
             <span className="settings-cache__size">
               {cacheSize === null ? '…' : formatCacheSize(cacheSize)}
             </span>
-            {cacheClassification && (
-              <span className={`settings-cache__pill settings-cache__pill--${cacheClassification.status}`}>
-                {cacheClassification.label}
-              </span>
-            )}
           </span>
           <span className="settings-cache__action">
             {clearing ? 'Wird geleert …' : 'Cache leeren'}

src/renderer/src/styles/global.css

@@ -1351,28 +1351,6 @@ body,
   min-width: 90px;
 }
 
-.settings-cache__pill {
-  font-size: 14px;
-  font-weight: 600;
-  padding: 4px 10px;
-  border-radius: 999px;
-  letter-spacing: 0.01em;
-}
-
-.settings-cache__pill--normal {
-  background: rgba(255, 255, 255, 0.08);
-  color: var(--color-fg-dim);
-}
-
-.settings-cache__pill--unusual {
-  background: rgba(255, 184, 60, 0.18);
-  color: #ffc56b;
-}
-
-.settings-cache__pill--high {
-  background: rgba(255, 95, 95, 0.18);
-  color: #ff8585;
-}
 
 .settings-cache__action {
   font-size: 16px;