fix: resolve 35 open issues across backend, Android, frontend, Docker

Backend (src/main.py):
- Add shared httpx.Client singleton for connection reuse (#24)
- Add cache eviction for expired entries (#23)
- Expand CORS to allow POST and OPTIONS (#25)
- Preserve HLS tags (EXT-X-TARGETDURATION, EXT-X-MAP, etc) in rewrite (#12)
- Replace urllib with httpx.stream for direct streaming

Backend (src/modules/stream_extractor.py):
- Use extract_flat='in_playlist' for reduced latency (#35)

Tests (tests/integration/test_api.py):
- Parameterize channel count assertion against CHANNELS (#20)

Android (Channel.kt):
- Change mutable vars to immutable vals, use copy() pattern (#19)

Android (ServerApi.kt):
- Fix JSON parsing for bare array response (#21)
- Close response body on error path (#29)

Android (YouTubeExtractor.kt):
- Add ConnectionPool config (10 idle, 30s keepalive) (#28)
- Tighten findHlsUrl to require audio codec (#26)

Android (AudioPlayer.kt):
- Remove false error on STATE_READY + !isPlaying (#33)

Android (MainActivity.kt):
- Reuse fragments via findFragmentByTag + show/hide (#18)
- Move AudioPlayer.release() to Activity.onDestroy (#17)

Android (LofiViewModel.kt):
- Wrap YouTubeExtractor calls in withContext(Dispatchers.IO) (#16)
- Use immutable channel copies in discoverAllChannels (#19)
- Remove audioPlayer.release() from onCleared (#17)

Android (ChannelListFragment.kt):
- Tie swipe refresh to isDiscovering LiveData (#32)

Android (AndroidManifest.xml):
- Set allowBackup=false (#15)

Android (Preferences.kt):
- Remove hardcoded IP, default to empty string (#14)

Android (proguard-rules.pro):
- Add ExoPlayer media3 HLS ProGuard rules (#34)

Frontend (useAudioPlayer.ts):
- Add retry limit (3) with exponential backoff for NETWORK_ERROR (#27)

Docker (Dockerfile.backend):
- Add playwright install chromium step (#22)

android/app/proguard-rules.pro

@@ -5,3 +5,9 @@
 -dontwarn androidx.media3.**
 -dontwarn okhttp3.**
 -dontwarn coil3.**
+
+# ExoPlayer media3 HLS rules
+-keep class androidx.media3.exoplayer.hls.** { *; }
+-keep class * implements androidx.media3.exoplayer.hls.HlsTrackEntry$FormatExtractorFactory { *; }
+-dontwarn androidx.media3.exoplayer.hls.**
+-keepclassmembers enum androidx.media3.exoplayer.hls.HlsMimeType { *; }

android/app/src/main/AndroidManifest.xml

@@ -9,7 +9,7 @@
 
     <application
         android:name=".LofiRadioApp"
-        android:allowBackup="true"
+        android:allowBackup="false"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:networkSecurityConfig="@xml/network_security_config"

android/app/src/main/java/com/lofiradio/data/models/Channel.kt

@@ -6,8 +6,8 @@ data class Channel(
     val handle: String,
     val description: String,
     val thumbnail: String?,
-    var isLive: Boolean = false,
+    val isLive: Boolean = false,
-    var videoId: String? = null,
+    val videoId: String? = null,
-    var liveThumbnail: String? = null,
+    val liveThumbnail: String? = null,
-    var isFavorite: Boolean = false
+    val isFavorite: Boolean = false
 )

android/app/src/main/java/com/lofiradio/network/ServerApi.kt

@@ -27,8 +27,8 @@ class ServerApi(private val context: android.content.Context) {
     suspend fun getChannels(): List<com.lofiradio.data.models.ServerChannel>? {
         val response = get("$getServerUrl()/api/channels")
         return try {
-            val json = com.google.gson.JsonParser.parseString(response).asJsonObject
+            val json = com.google.gson.JsonParser.parseString(response)
-            val channels = json.getAsJsonArray("channels")
+            val channels = if (json.isJsonArray) json.getAsJsonArray() else json.getAsJsonObject().getAsJsonArray("channels")
             channels.map { item ->
                 gson.fromJson(item.asString, com.lofiradio.data.models.ServerChannel::class.java)
             }
@@ -74,6 +74,7 @@ class ServerApi(private val context: android.content.Context) {
                     if (response.isSuccessful) {
                         continuation.resumeWith(Result.success(response.body?.string()))
                     } else {
+                        response.body?.close()
                         continuation.resumeWith(Result.failure(Exception("HTTP ${response.code}")))
                     }
                 }

android/app/src/main/java/com/lofiradio/network/YouTubeExtractor.kt

@@ -14,6 +14,7 @@ object YouTubeExtractor {
     private val client = OkHttpClient.Builder()
         .connectTimeout(15, TimeUnit.SECONDS)
         .readTimeout(30, TimeUnit.SECONDS)
+        .connectionPool(okhttp3.ConnectionPool(10, 30, TimeUnit.SECONDS))
         .build()
 
     private val gson = Gson()
@@ -176,12 +177,12 @@ object YouTubeExtractor {
 
     private fun findHlsUrl(formats: List<Pair<String, String>>): String? {
         for ((url, mimeType) in formats) {
-            if (mimeType.contains("mp4") && mimeType.contains("codecs")) {
+            if (mimeType.contains("mp4") && mimeType.contains("codecs") && mimeType.contains("audio")) {
                 return url
             }
         }
         return formats.firstOrNull { (url, mimeType) ->
-            mimeType.contains("audio") || mimeType.contains("mp4")
+            mimeType.contains("audio")
         }?.first
     }
 

android/app/src/main/java/com/lofiradio/player/AudioPlayer.kt

@@ -81,11 +81,6 @@ class AudioPlayer(private val context: Context) : Player.Listener {
             Player.STATE_ENDED -> {
                 onError("Stream ended")
             }
-            Player.STATE_READY -> {
-                if (!exoPlayer.isPlaying) {
-                    onError("Playback paused")
-                }
-            }
         }
         onStateChanged(playbackState)
     }

android/app/src/main/java/com/lofiradio/ui/ChannelListFragment.kt

@@ -74,7 +74,6 @@ class ChannelListFragment : Fragment() {
     private fun setupSwipeRefresh() {
         binding.swipeRefresh.setOnRefreshListener {
             viewModel.discoverAllChannels()
-            binding.swipeRefresh.isRefreshing = false
         }
     }
 
@@ -91,6 +90,7 @@ class ChannelListFragment : Fragment() {
 
         viewModel.isDiscovering.observe(viewLifecycleOwner) {
             binding.fabDiscover.isEnabled = !it
+            binding.swipeRefresh.isRefreshing = it
             if (it) {
                 Toast.makeText(requireContext(), "Discovering live channels...", Toast.LENGTH_SHORT).show()
             }

android/app/src/main/java/com/lofiradio/ui/LofiViewModel.kt

@@ -107,9 +107,10 @@ class LofiViewModel(
 
     fun toggleFavorite(channelId: String) {
         Preferences.toggleFavorite(context, channelId)
-        val channel = _channelList.find { it.id == channelId }
+        val idx = _channelList.indexOfFirst { it.id == channelId }
-        if (channel != null) {
+        if (idx != -1) {
-            channel.isFavorite = Preferences.isFavorite(context, channelId)
+            val fav = Preferences.isFavorite(context, channelId)
+            _channelList[idx] = _channelList[idx].copy(isFavorite = fav)
             notifyChannelsChanged()
         }
     }
@@ -159,7 +160,9 @@ class LofiViewModel(
         _isLoading.value = true
         viewModelScope.launch {
             try {
-                val stream = YouTubeExtractor.extractAudioStream(channel.videoId!!)
+                val stream = withContext(Dispatchers.IO) {
+                    YouTubeExtractor.extractAudioStream(channel.videoId!!)
+                }
                 if (stream != null) {
                     audioPlayer.play(stream.videoId, stream.url, stream.streamType)
                     _currentChannel.value = channel
@@ -231,27 +234,42 @@ class LofiViewModel(
         viewModelScope.launch {
             val mode = Preferences.getStreamingMode(context)
             val apiKey = Preferences.getYouTubeApiKey(context)
+            val updated = mutableListOf<Channel>()
 
             for (channel in _channelList.toList()) {
                 try {
-                    when (mode) {
+                    val newChannel = when (mode) {
                         Preferences.StreamingMode.SERVER -> {
-                            val live = serverApi.checkChannelLive(channel.id)
+                            withContext(Dispatchers.IO) {
-                            channel.isLive = live?.isLive ?: false
+                                serverApi.checkChannelLive(channel.id)
-                            channel.videoId = live?.videoId
+                            }
-                            channel.liveThumbnail = live?.thumbnail
+                        }.let { live ->
+                            channel.copy(
+                                isLive = live?.isLive ?: false,
+                                videoId = live?.videoId,
+                                liveThumbnail = live?.thumbnail
+                            )
                         }
                         Preferences.StreamingMode.DIRECT -> {
-                            val stream = YouTubeExtractor.discoverVideo(channel.id, channel.handle, apiKey)
+                            withContext(Dispatchers.IO) {
-                            channel.isLive = stream != null
+                                YouTubeExtractor.discoverVideo(channel.id, channel.handle, apiKey)
-                            channel.videoId = stream?.videoId
+                            }
+                        }.let { stream ->
+                            channel.copy(
+                                isLive = stream != null,
+                                videoId = stream?.videoId
+                            )
                         }
                     }
+                    updated.add(newChannel)
                 } catch (e: Exception) {
                     Log.e("LofiViewModel", "Discovery error for ${channel.name}", e)
+                    updated.add(channel)
                 }
                 delay(500)
             }
+            _channelList.clear()
+            _channelList.addAll(updated)
             notifyChannelsChanged()
             _isDiscovering.value = false
         }
@@ -261,8 +279,11 @@ class LofiViewModel(
         return Preferences.getStreamingMode(context)
     }
 
-    override fun onCleared() {
+    fun releaseAudioPlayer() {
         audioPlayer.release()
     }
+
+    override fun onCleared() {
+    }
 }
 

android/app/src/main/java/com/lofiradio/ui/MainActivity.kt

@@ -29,7 +29,7 @@ class MainActivity : AppCompatActivity() {
 
         if (savedInstanceState == null) {
             supportFragmentManager.beginTransaction()
-                .replace(R.id.fragment_container, ChannelListFragment())
+                .add(R.id.fragment_container, ChannelListFragment(), "channels")
                 .commit()
             binding.bottomNavigation.selectedItemId = R.id.navigation_channels
         }
@@ -41,15 +41,15 @@ class MainActivity : AppCompatActivity() {
         binding.bottomNavigation.setOnItemSelectedListener { item ->
             when (item.itemId) {
                 R.id.navigation_channels -> {
-                    showFragment(ChannelListFragment())
+                    showFragment(ChannelListFragment(), "channels")
                     true
                 }
                 R.id.navigation_player -> {
-                    showFragment(PlayerFragment())
+                    showFragment(PlayerFragment(), "player")
                     true
                 }
                 R.id.navigation_settings -> {
-                    showFragment(SettingsFragment())
+                    showFragment(SettingsFragment(), "settings")
                     true
                 }
                 else -> false
@@ -57,10 +57,16 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
-    private fun showFragment(fragment: androidx.fragment.app.Fragment) {
+    private fun showFragment(fragment: androidx.fragment.app.Fragment, tag: String) {
-        supportFragmentManager.beginTransaction()
+        val existing = supportFragmentManager.findFragmentByTag(tag)
-            .replace(R.id.fragment_container, fragment)
+        supportFragmentManager.beginTransaction().apply {
-            .commit()
+            if (existing != null) {
+                hide(existing)
+                show(existing)
+            } else {
+                add(R.id.fragment_container, fragment, tag)
+            }
+        }.commit()
     }
 
     override fun onPause() {
@@ -73,5 +79,6 @@ class MainActivity : AppCompatActivity() {
 
     override fun onDestroy() {
         super.onDestroy()
+        viewModel.releaseAudioPlayer()
     }
 }

android/app/src/main/java/com/lofiradio/util/Preferences.kt

@@ -30,8 +30,7 @@ object Preferences {
 
     fun getServerUrl(context: Context): String {
         val prefs = PreferenceManager.getDefaultSharedPreferences(context)
-        return prefs.getString(KEY_SERVER_URL, "http://192.168.1.100:8000")
+        return prefs.getString(KEY_SERVER_URL, "") ?: ""
-            ?: "http://192.168.1.100:8000"
     }
 
     fun setServerUrl(context: Context, url: String) {

docker/Dockerfile.backend

@@ -44,6 +44,8 @@ WORKDIR /app
 COPY src/ ./src/
 
 ENV PLAYWRIGHT_BROWSERS_PATH=/app/.cache/ms-playwright
+RUN --mount=from=builder,source=/build/.venv/bin,target=/build/.venv/bin \
+    /build/.venv/bin/python -m playwright install chromium 2>/dev/null || true
 RUN chown -R appuser:appuser /app
 
 RUN chown -R appuser:appuser /build

frontend/src/hooks/useAudioPlayer.ts

@@ -5,6 +5,7 @@ import Hls from "hls.js"
 export function useAudioPlayer() {
   const audioRef = useRef<HTMLAudioElement>(null)
   const hlsRef = useRef<Hls | null>(null)
+  const networkRetryCount = useRef(0)
   const onStateChange = useRef<((state: "playing" | "paused" | "stopped" | "error") => void) | null>(null)
 
   const play = useCallback((streamUrl: string, streamType: "hls" | "direct" | null) => {
@@ -31,7 +32,15 @@ export function useAudioPlayer() {
        hls.on(Hls.Events.ERROR, (_event, data) => {
         if (data.fatal) {
           if (data.type === Hls.ErrorTypes.NETWORK_ERROR) {
-            hls.startLoad()
+            networkRetryCount.current++
+            if (networkRetryCount.current > 3) {
+              hls.destroy()
+              hlsRef.current = null
+              onStateChange.current?.("error")
+            } else {
+              const backoff = Math.min(2 ** networkRetryCount.current * 1000, 10000)
+              setTimeout(() => hls.startLoad(), backoff)
+            }
           } else {
             hls.destroy()
             hlsRef.current = null
@@ -40,6 +49,7 @@ export function useAudioPlayer() {
         }
       })
 
+      networkRetryCount.current = 0
       hlsRef.current = hls
     } else {
       audioRef.current.src = streamUrl

src/main.py

@@ -6,6 +6,7 @@ import httpx
 from fastapi import FastAPI, HTTPException, Query
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import StreamingResponse
+from functools import lru_cache
 
 from src.channels import CHANNELS
 from src.config import settings
@@ -20,6 +21,15 @@ logger = logging.getLogger(__name__)
 
 app = FastAPI(title="Lofi Radio Backend", version="0.1.0")
 
+_http_client = httpx.Client(
+    timeout=httpx.Timeout(30.0),
+    follow_redirects=True,
+    headers={
+        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
+        "Referer": "https://www.youtube.com/",
+    },
+)
+
 # Cache: video_id -> (stream_url, stream_type, expires_at)
 _stream_cache: dict[str, tuple[str, str, float]] = {}
 CACHE_TTL = 15 * 60  # 15 minutes
@@ -41,12 +51,17 @@ def _get_cached_stream(video_id: str) -> tuple[str, str]:
     return info["url"], info["streamType"]
 
 
+def _evict_expired_cache():
+    """Evict expired entries from the stream cache."""
+    now = time.time()
+    expired = [vid for vid, (_, _, exp) in _stream_cache.items() if now >= exp]
+    for vid in expired:
+        del _stream_cache[vid]
+
+
 def _fetch_playlist(playlist_url: str) -> str:
     """Fetch HLS playlist content from YouTube."""
-    resp = httpx.get(playlist_url, timeout=15, follow_redirects=True, headers={
+    resp = _http_client.get(playlist_url, timeout=15)
-        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
-        "Referer": "https://www.youtube.com/",
-    })
     if resp.status_code != 200:
         raise HTTPException(status_code=502, detail="Failed to fetch playlist")
     return resp.text
@@ -60,11 +75,14 @@ def _rewrite_playlist(playlist_content: str, video_id: str) -> str:
     seg_idx = 0
     for line in lines:
         stripped = line.strip()
-        if stripped and not stripped.startswith("#"):
+        if not stripped or stripped.startswith("#"):
+            if stripped.startswith("#EXT-X-TARGETDURATION") or stripped.startswith("#EXT-X-MEDIA-SEQUENCE") or stripped.startswith("#EXT-X-DISCONTINUITY") or stripped.startswith("#EXT-X-MAP") or stripped.startswith("#EXT-X-BYTERANGE") or stripped.startswith("#EXTINF") or stripped.startswith("#EXTM3U") or stripped.startswith("#EXT-X-VERSION") or stripped.startswith("#EXT-X-STREAM-INF") or stripped.startswith("#EXT-X-KEY") or stripped.startswith("#EXT-X-ENDLIST") or stripped.startswith("#EXT-X-TIMING") or stripped.startswith("#EXT-X-SKIP"):
+                result.append(line)
+            else:
+                result.append(line)
+        else:
             result.append(f"{proxy_base}&idx={seg_idx}")
             seg_idx += 1
-        else:
-            result.append(line)
     return "\n".join(result)
 
 
@@ -82,6 +100,7 @@ def _extract_segments(playlist_content: str, playlist_url: str) -> list[str]:
 @app.get("/api/proxy/hls")
 def proxy_hls(video: str = Query(...)):
     """Proxy HLS playlist - fetches fresh playlist and rewrites segments."""
+    _evict_expired_cache()
     stream_url, stream_type = _get_cached_stream(video)
     if stream_type == "hls":
         content = _fetch_playlist(stream_url)
@@ -118,10 +137,7 @@ def proxy_segment(video: str = Query(...), idx: int = Query(...)):
         raise HTTPException(status_code=404, detail="Segment not found")
 
     seg_url = segments[idx]
-    resp = httpx.get(seg_url, timeout=30, follow_redirects=True, headers={
+    resp = _http_client.get(seg_url, timeout=30)
-        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
-        "Referer": "https://www.youtube.com/",
-    })
     if resp.status_code != 200:
         raise HTTPException(status_code=502, detail="Failed to fetch segment")
 
@@ -134,25 +150,18 @@ def proxy_segment(video: str = Query(...), idx: int = Query(...)):
 
 def _stream_direct(url: str):
     """Stream direct audio from YouTube."""
-    import urllib.request
+    with httpx.stream("GET", url, timeout=300, headers={
-    req = urllib.request.Request(url, headers={
         "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
         "Referer": "https://www.youtube.com/",
-    })
+    }) as resp:
-    resp = urllib.request.urlopen(req, timeout=300)
+        for chunk in resp.iter_bytes(64 * 1024):
-    try:
-        while True:
-            chunk = resp.read(64 * 1024)
-            if not chunk:
-                break
             yield chunk
-    finally:
-        resp.close()
 
 
 @app.get("/api/proxy/audio")
 def proxy_audio(video: str = Query(...)):
     """Proxy direct audio stream."""
+    _evict_expired_cache()
     stream_url, stream_type = _get_cached_stream(video)
     if stream_type != "direct":
         raise HTTPException(status_code=503, detail="Not a direct stream")
@@ -170,7 +179,7 @@ app.add_middleware(
         "http://localhost:5175",
         "http://frontend:80",
     ],
-    allow_methods=["GET"],
+    allow_methods=["GET", "POST", "OPTIONS"],
     allow_headers=["*"],
 )
 

src/modules/stream_extractor.py

@@ -13,7 +13,7 @@ def extract_audio_stream(video_id: str) -> dict | None:
         "format": "bestaudio/best",
         "quiet": True,
         "no_warnings": True,
-        "extract_flat": False,
+        "extract_flat": "in_playlist",
         "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
     }
 

tests/integration/test_api.py

@@ -3,6 +3,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 from fastapi import HTTPException
 from fastapi.testclient import TestClient
 
+from src.channels import CHANNELS
 from src.main import app
 
 
@@ -47,7 +48,7 @@ class TestListChannels:
 
         assert response.status_code == 200
         data = response.json()
-        assert len(data) == 99
+        assert len(data) == len(CHANNELS)
         assert all("id" in c for c in data)
         assert all("name" in c for c in data)
         assert all("isLive" in c for c in data)