Straw phase K: subscriptions store + Subscribe button + Home section

New SubscriptionsStore (SharedPrefs-lite, same pattern as History/Settings).
Holds Set<ChannelRef> { url, name, avatar }.

ChannelScreen header now has a "Subscribe / Subscribed" button on the
right. Button toggles membership; UI updates immediately via StateFlow.

StrawHome: new "Subscriptions" section above "Recently watched", a
LazyRow of subscribed channels (avatar + name, 80dp chips). Tap a
subscription chip → opens that channel.

StrawApp.onCreate: Subscriptions.init(this).

Day-4 ideas: auto-aggregate latest videos from subs on Home (no more
"hit search to see videos"), sub-feed-only screen, channel notifications.

strawApp/src/main/kotlin/com/sulkta/straw/StrawActivity.kt

@@ -63,6 +63,9 @@ class StrawActivity : ComponentActivity() {
                             onOpenVideo = { url, title ->
                                 nav.push(Screen.VideoDetail(url, title))
                             },
+                            onOpenChannel = { url, name ->
+                                nav.push(Screen.Channel(url, name))
+                            },
                         )
                         is Screen.Settings -> SettingsScreen()
                         is Screen.Search -> SearchScreen(

strawApp/src/main/kotlin/com/sulkta/straw/StrawApp.kt

@@ -8,6 +8,7 @@ package com.sulkta.straw
 import android.app.Application
 import com.sulkta.straw.data.History
 import com.sulkta.straw.data.Settings
+import com.sulkta.straw.data.Subscriptions
 import com.sulkta.straw.extractor.NewPipeDownloader
 import org.schabi.newpipe.extractor.NewPipe
 import org.schabi.newpipe.extractor.localization.ContentCountry
@@ -23,5 +24,6 @@ class StrawApp : Application() {
         )
         History.init(this)
         Settings.init(this)
+        Subscriptions.init(this)
     }
 }

strawApp/src/main/kotlin/com/sulkta/straw/StrawHome.kt

@@ -17,7 +17,9 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.LazyRow
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.Button
 import androidx.compose.material3.HorizontalDivider
@@ -37,7 +39,9 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import coil3.compose.AsyncImage
+import com.sulkta.straw.data.ChannelRef
 import com.sulkta.straw.data.History
+import com.sulkta.straw.data.Subscriptions
 import com.sulkta.straw.data.WatchHistoryItem
 
 @Composable
@@ -45,8 +49,10 @@ fun StrawHome(
     onOpenSearch: () -> Unit,
     onOpenSettings: () -> Unit,
     onOpenVideo: (url: String, title: String) -> Unit,
+    onOpenChannel: (channelUrl: String, name: String) -> Unit,
 ) {
     val watches by History.get().watches.collectAsState()
+    val subs by Subscriptions.get().subs.collectAsState()
 
     Column(
         modifier = Modifier.fillMaxSize().padding(horizontal = 20.dp, vertical = 12.dp),
@@ -81,6 +87,19 @@ fun StrawHome(
 
         Spacer(modifier = Modifier.height(20.dp))
 
+        if (subs.isNotEmpty()) {
+            Text(
+                "Subscriptions",
+                style = MaterialTheme.typography.titleMedium,
+                fontWeight = FontWeight.SemiBold,
+            )
+            Spacer(modifier = Modifier.height(8.dp))
+            LazyRow(horizontalArrangement = Arrangement.spacedBy(12.dp)) {
+                items(subs) { ch -> SubChip(ch, onOpenChannel) }
+            }
+            Spacer(modifier = Modifier.height(20.dp))
+        }
+
         if (watches.isEmpty()) {
             Text(
                 text = "Recently watched videos appear here.",
@@ -104,6 +123,32 @@ fun StrawHome(
     }
 }
 
+@Composable
+private fun SubChip(
+    ch: ChannelRef,
+    onOpenChannel: (url: String, name: String) -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .width(80.dp)
+            .clickable { onOpenChannel(ch.url, ch.name) },
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        AsyncImage(
+            model = ch.avatar,
+            contentDescription = null,
+            modifier = Modifier.size(56.dp).clip(CircleShape),
+        )
+        Spacer(modifier = Modifier.height(4.dp))
+        Text(
+            text = ch.name,
+            style = MaterialTheme.typography.labelSmall,
+            maxLines = 2,
+            overflow = TextOverflow.Ellipsis,
+        )
+    }
+}
+
 @Composable
 private fun RecentRow(item: WatchHistoryItem, onClick: () -> Unit) {
     Row(

strawApp/src/main/kotlin/com/sulkta/straw/data/SubscriptionsStore.kt

@@ -0,0 +1,78 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Sulkta
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * SharedPreferences-lite subscription list. Day-4 graduates to Room when
+ * we want background feed fetching for new uploads.
+ */
+
+package com.sulkta.straw.data
+
+import android.content.Context
+import android.content.SharedPreferences
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+
+@Serializable
+data class ChannelRef(
+    val url: String,
+    val name: String,
+    val avatar: String? = null,
+)
+
+private const val PREFS = "straw_subs"
+private const val KEY = "subs_v1"
+
+class SubscriptionsStore(context: Context) {
+    private val sp: SharedPreferences = context.getSharedPreferences(PREFS, Context.MODE_PRIVATE)
+    private val json = Json { ignoreUnknownKeys = true; isLenient = true }
+
+    private val _subs = MutableStateFlow(load())
+    val subs: StateFlow<List<ChannelRef>> = _subs.asStateFlow()
+
+    fun isSubscribed(channelUrl: String): Boolean =
+        _subs.value.any { it.url == channelUrl }
+
+    fun toggle(ref: ChannelRef) {
+        val cur = _subs.value
+        val next = if (cur.any { it.url == ref.url }) {
+            cur.filterNot { it.url == ref.url }
+        } else {
+            cur + ref
+        }
+        _subs.value = next
+        persist(next)
+    }
+
+    fun clear() {
+        _subs.value = emptyList()
+        sp.edit().remove(KEY).apply()
+    }
+
+    private fun persist(list: List<ChannelRef>) {
+        sp.edit().putString(KEY, json.encodeToString(list)).apply()
+    }
+
+    private fun load(): List<ChannelRef> = runCatching {
+        val s = sp.getString(KEY, null) ?: return emptyList()
+        json.decodeFromString<List<ChannelRef>>(s)
+    }.getOrDefault(emptyList())
+}
+
+object Subscriptions {
+    @Volatile private var instance: SubscriptionsStore? = null
+
+    fun init(context: Context) {
+        if (instance == null) {
+            synchronized(this) {
+                if (instance == null) instance = SubscriptionsStore(context.applicationContext)
+            }
+        }
+    }
+
+    fun get(): SubscriptionsStore = instance
+        ?: error("SubscriptionsStore not initialized — call Subscriptions.init(context)")
+}

strawApp/src/main/kotlin/com/sulkta/straw/feature/channel/ChannelScreen.kt

@@ -22,9 +22,13 @@ import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.FilterChip
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
@@ -35,9 +39,12 @@ import androidx.compose.ui.draw.clip
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
+import androidx.compose.runtime.collectAsState
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import coil3.compose.AsyncImage
+import com.sulkta.straw.data.ChannelRef
+import com.sulkta.straw.data.Subscriptions
 import com.sulkta.straw.feature.search.StreamItem
 
 @Composable
@@ -49,6 +56,8 @@ fun ChannelScreen(
 ) {
     val state by vm.ui.collectAsStateWithLifecycle()
     LaunchedEffect(channelUrl) { vm.load(channelUrl) }
+    val subs by Subscriptions.get().subs.collectAsState()
+    val subscribed = subs.any { it.url == channelUrl }
 
     when {
         state.loading -> Box(
@@ -86,7 +95,7 @@ fun ChannelScreen(
                         modifier = Modifier.size(56.dp).clip(CircleShape),
                     )
                     Spacer(modifier = Modifier.width(12.dp))
-                    Column {
+                    Column(modifier = Modifier.weight(1f)) {
                         Text(
                             text = state.name.ifBlank { initialName },
                             style = MaterialTheme.typography.titleLarge,
@@ -100,6 +109,20 @@ fun ChannelScreen(
                             )
                         }
                     }
+                    val onClick = {
+                        Subscriptions.get().toggle(
+                            ChannelRef(
+                                url = channelUrl,
+                                name = state.name.ifBlank { initialName },
+                                avatar = state.avatar,
+                            ),
+                        )
+                    }
+                    if (subscribed) {
+                        OutlinedButton(onClick = onClick) { Text("Subscribed") }
+                    } else {
+                        Button(onClick = onClick) { Text("Subscribe") }
+                    }
                 }
                 HorizontalDivider()
             }