From 9b3ec65476d79de0f2ed0412e4c2038ee1dd3d1b Mon Sep 17 00:00:00 2001
From: Bryan Van Deusen <bryan.vandeusen@fabledsword.com>
Date: Tue, 2 Jun 2026 10:04:38 -0400
Subject: [PATCH] feat(android): swipe to change Library tabs

Operator: tabs in the Library view should feel swipeable, not just
tappable. Replace the selectedTab Int state + when-block content
with HorizontalPager whose state drives the PrimaryScrollableTabRow.
Tap routes through animateScrollToPage so swipe + tap share one
source of truth.

Horizontal pager gestures don't conflict with the LazyVerticalGrid
inside each tab (different axes) or with PullToRefreshScaffold's
vertical pull (different axes). HorizontalPager renders only the
current page by default; adjacent tabs remain composed during the
swipe but not eager-mounted at start.
---
 .../minstrel/library/ui/LibraryScreen.kt      | 27 ++++++++++++-------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/android/app/src/main/java/com/fabledsword/minstrel/library/ui/LibraryScreen.kt b/android/app/src/main/java/com/fabledsword/minstrel/library/ui/LibraryScreen.kt
index d01236eb..c0971a5b 100644
--- a/android/app/src/main/java/com/fabledsword/minstrel/library/ui/LibraryScreen.kt
+++ b/android/app/src/main/java/com/fabledsword/minstrel/library/ui/LibraryScreen.kt
@@ -4,7 +4,6 @@ package com.fabledsword.minstrel.library.ui
 
 import androidx.compose.animation.Crossfade
 import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.fillMaxSize
@@ -12,6 +11,8 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.grid.GridCells
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.items
+import androidx.compose.foundation.pager.HorizontalPager
+import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -22,11 +23,10 @@ import androidx.compose.material3.Tab
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableIntStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.launch
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.navigation.NavHostController
@@ -69,8 +69,12 @@ fun LibraryScreen(
     navController: NavHostController,
     viewModel: LibraryViewModel = hiltViewModel(),
 ) {
-    var selectedTab by remember { mutableIntStateOf(0) }
     val tabs = LIBRARY_TABS
+    // HorizontalPager owns the active-tab state — the TabRow reads
+    // pagerState.currentPage and animateScrollToPage drives it on tap,
+    // so swipe and tap stay in sync.
+    val pagerState = rememberPagerState(pageCount = { tabs.size })
+    val scope = rememberCoroutineScope()
 
     Scaffold(
         modifier = Modifier.fillMaxSize(),
@@ -91,13 +95,13 @@ fun LibraryScreen(
                     },
                 )
                 PrimaryScrollableTabRow(
-                    selectedTabIndex = selectedTab,
+                    selectedTabIndex = pagerState.currentPage,
                     edgePadding = 16.dp,
                 ) {
                     tabs.forEachIndexed { index, label ->
                         Tab(
-                            selected = selectedTab == index,
-                            onClick = { selectedTab = index },
+                            selected = pagerState.currentPage == index,
+                            onClick = { scope.launch { pagerState.animateScrollToPage(index) } },
                             text = { Text(label) },
                         )
                     }
@@ -105,8 +109,11 @@ fun LibraryScreen(
             }
         },
     ) { inner ->
-        Box(modifier = Modifier.fillMaxSize().padding(inner)) {
-            when (selectedTab) {
+        HorizontalPager(
+            state = pagerState,
+            modifier = Modifier.fillMaxSize().padding(inner),
+        ) { page ->
+            when (page) {
                 TAB_ARTISTS -> ArtistsTab(viewModel = viewModel, navController = navController)
                 TAB_ALBUMS -> AlbumsTab(viewModel = viewModel, navController = navController)
                 TAB_HISTORY -> HistoryTab(