TASK-069: bottom tabs glide past the tabs between

The four tab screens are pages of one pager that a tab press scrolls, so 홈
to 알림 passes 저장소 and 작업 instead of sliding straight there. Swiping is
off; entering and leaving other screens is unchanged.

Agent: main (opus)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/src/main/java/com/ubisam/ubgitea/MainActivity.kt

@@ -18,12 +18,10 @@ import androidx.activity.result.contract.ActivityResultContracts
 import androidx.activity.viewModels
 import androidx.browser.customtabs.CustomTabsIntent
 import androidx.compose.animation.AnimatedContent
-import androidx.compose.animation.core.FastOutSlowInEasing
 import androidx.compose.animation.core.tween
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
 import androidx.compose.animation.slideInHorizontally
-import androidx.compose.animation.slideOutHorizontally
 import androidx.compose.animation.togetherWith
 import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.foundation.layout.Arrangement
@@ -48,7 +46,6 @@ import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.dp
 import com.ubisam.ubgitea.core.auth.protocol.UBGiteaOAuthDefaults
 import com.ubisam.ubgitea.core.notifications.FavoritePushNotifier
@@ -95,6 +92,7 @@ import com.ubisam.ubgitea.feature.workitems.WorkItemsScreen
 import com.ubisam.ubgitea.feature.workitems.WorkItemsTarget
 import com.ubisam.ubgitea.feature.workitems.WorkItemsViewModel
 import com.ubisam.ubgitea.ui.components.SplashOverlay
+import com.ubisam.ubgitea.ui.components.TabPager
 import com.ubisam.ubgitea.ui.navigation.Route
 import com.ubisam.ubgitea.ui.navigation.RouteStackSaver
 import com.ubisam.ubgitea.ui.shell.AppShell
@@ -437,9 +435,9 @@ class MainActivity : ComponentActivity() {
                             onViewSettings = { push(Route.Settings) },
                         )
                     }
-                    // Entering a screen slides it in from the side it was opened towards, and a
-                    // tab switch from the side that tab sits on in the bar. Keyed by the kind of
-                    // screen, so moving between code tabs or pages of one screen does not replay it.
+                    // Entering a screen slides it in from the side it was opened towards. Keyed by
+                    // the kind of screen, so moving between code tabs or pages of one screen does
+                    // not replay it. The four tabs are one kind: between them the pager below glides.
                     val stackDepth = routeStack.size
                     val shownDepth = remember { intArrayOf(stackDepth) }
                     val shownReady = remember { booleanArrayOf(sessionReady) }
@@ -451,30 +449,21 @@ class MainActivity : ComponentActivity() {
                         targetState = currentRoute.takeIf { sessionReady } ?: Route.Repositories,
                         modifier = Modifier.fillMaxSize(),
                         transitionSpec = {
-                            val fromTab = initialState.tab
-                            val toTab = targetState.tab
-                            val tabSwitch = stackDepth == shownDepth[0] && fromTab != null && toTab != null
                             if (!shownReady[0]) {
                                 // The session has just been found: the first screen takes the
                                 // waiting one's place where it stands. Nothing was navigated, so
                                 // nothing slides.
                                 fadeIn(tween(200)).togetherWith(fadeOut(tween(90)))
-                            } else if (tabSwitch) {
-                                // Tabs sit side by side: the old one glides out as the new one
-                                // glides in, the whole width, like turning to the next page.
-                                val direction = (toTab.ordinal - fromTab.ordinal).coerceIn(-1, 1)
-                                val glide = tween<IntOffset>(320, easing = FastOutSlowInEasing)
-                                slideInHorizontally(glide) { it * direction }
-                                    .togetherWith(slideOutHorizontally(glide) { -it * direction })
                             } else {
                                 val direction = (stackDepth - shownDepth[0]).coerceIn(-1, 1)
                                 (fadeIn(tween(200, delayMillis = 50)) + slideInHorizontally(tween(260)) { it / 10 * direction })
                                     .togetherWith(fadeOut(tween(90)))
                             }
                         },
-                        contentKey = { it::class },
+                        contentKey = { if (it.isTab) AppTab::class else it::class },
                         label = "route",
-                    ) { route ->
+                    ) { shown ->
+                    val screen: @Composable (Route) -> Unit = { route ->
                     Box(Modifier.fillMaxSize()) {
                     when (route) {
                         Route.Home -> HomeScreen(
@@ -634,6 +623,14 @@ class MainActivity : ComponentActivity() {
                     }
                     }
                     }
+                    // Tabs sit side by side: going from one to another passes the ones between.
+                    val shownTab = shown.tab
+                    if (shownTab != null && sessionReady) {
+                        TabPager(AppTab.entries, shownTab) { screen(it.route) }
+                    } else {
+                        screen(shown)
+                    }
+                    }
                 }
               }
                 LaunchedEffect(viewModel) {

app/src/main/java/com/ubisam/ubgitea/ui/components/Motion.kt

@@ -28,6 +28,8 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.pager.HorizontalPager
+import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -67,6 +69,7 @@ import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.dp
 import com.ubisam.ubgitea.ui.theme.UBGiteaTheme
 import kotlin.math.PI
+import kotlin.math.abs
 import kotlin.math.sin
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.first
@@ -314,6 +317,31 @@ fun <S> TabGlide(
 
 const val TabGlideMillis = 320
 
+/**
+ * The bottom tabs' screens, laid side by side in the order of [tabs]. Changing [current] glides
+ * to it past whatever lies between, a little longer for each tab passed. Only a tab press moves
+ * it: swiping stays with what is inside the screens.
+ */
+@Composable
+fun <T> TabPager(tabs: List<T>, current: T, modifier: Modifier = Modifier, content: @Composable (T) -> Unit) {
+    val pager = rememberPagerState(initialPage = tabs.indexOf(current)) { tabs.size }
+    LaunchedEffect(current) {
+        val page = tabs.indexOf(current)
+        val passed = abs(page - pager.currentPage)
+        if (passed > 0 || pager.isScrollInProgress) {
+            pager.animateScrollToPage(
+                page,
+                animationSpec = tween(TabGlideMillis + TabGlideStepMillis * (passed - 1).coerceAtLeast(0), easing = FastOutSlowInEasing),
+            )
+        }
+    }
+    HorizontalPager(pager, modifier.fillMaxSize(), userScrollEnabled = false, key = { it }) { page ->
+        content(tabs[page])
+    }
+}
+
+const val TabGlideStepMillis = 50
+
 const val SplashLongestWaitMillis = 1500L
 
 private val SplashGradient = listOf(Color(0xFF4DB0FF), Color(0xFF2F98F9), Color(0xFF0A6FD8))

docs/development-log.md

@@ -1629,3 +1629,16 @@ This is the append-only implementation and handoff record shared by Codex and Cl
 - Checks and results: the five required checks pass.
 - Caution: diagnosed from the code, not seen on a device. If the stutter is still there, the
   remaining suspect is the cost of Home's first frames on that phone.
+
+## 2026-10-12 (continued) — TASK-069: bottom tabs pass the tabs between
+
+- Request: going from 홈 to 알림 went straight there; the product owner wants it to glide
+  quickly past 저장소 and 작업.
+- What changed: the four tab screens are pages of one `TabPager` (`Motion.kt`), which a tab
+  press scrolls with 320 ms plus 50 ms per extra tab passed; swiping is off, so gestures inside
+  the screens are unchanged. In `MainActivity` the tab routes share one `AnimatedContent` key,
+  and the two-screen tab glide there is removed. Entering and leaving other screens is as before.
+- Design decision: a tab that is only passed shows whatever its ViewModel last held (its list,
+  or its loading state if never opened); it is not loaded for the pass.
+- Checks and results: the five required checks pass.
+- Caution: not seen on a device.

tasks/069-in-app-motion.md

@@ -26,6 +26,9 @@ The app moves where it used to jump, and what moves is the launcher icon's tea c
     screen was gliding in sideways underneath, as if a tab had been switched, while the cover was
     fading. The first screen now fades in where it stands, and the cover waits for it (at most
     1.5 seconds longer) before it leaves.
+11. Asked by the product owner (2026-10-12): going from 홈 to 알림 should pass 저장소 and 작업
+    on the way, quickly, not jump straight there. The four tab screens now sit side by side in a
+    pager that only a tab press moves.
 
 ## Scope
 
@@ -50,7 +53,7 @@ The app moves where it used to jump, and what moves is the launcher icon's tea c
 
 ## Acceptance criteria
 
-- [x] Each of the ten items above is in the code and the app builds.
+- [x] Each of the eleven items above is in the code and the app builds.
 - [x] The splash covers the app without delaying it: sign-in, loading and the OAuth callback run
   underneath, and taps do not pass through the cover.
 - [x] Moving between code tabs, or between pages of one screen, does not replay the screen