TASK-069: bottom tab switches glide the whole width

Agent: main (opus)

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

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

@@ -17,10 +17,12 @@ 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.Box
@@ -41,6 +43,7 @@ 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 com.ubisam.ubgitea.core.auth.protocol.UBGiteaOAuthDefaults
 import com.ubisam.ubgitea.core.notifications.FavoritePushNotifier
 import com.ubisam.ubgitea.core.notifications.FavoritePushScheduler
@@ -436,13 +439,19 @@ class MainActivity : ComponentActivity() {
                         transitionSpec = {
                             val fromTab = initialState.tab
                             val toTab = targetState.tab
-                            val direction = when {
-                                stackDepth != shownDepth[0] -> stackDepth - shownDepth[0]
-                                fromTab != null && toTab != null -> toTab.ordinal - fromTab.ordinal
-                                else -> 0
-                            }.coerceIn(-1, 1)
+                            val tabSwitch = stackDepth == shownDepth[0] && fromTab != null && toTab != null
+                            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 },
                         label = "route",

docs/development-log.md

@@ -1552,3 +1552,12 @@ This is the append-only implementation and handoff record shared by Codex and Cl
   superseded. Publishing is the three steps in `tasks/070-update-from-gitea.md`.
 - Caution: the page at `choimy0204.github.io/ubgitea/` still exists (password, 0.2.0). Copies of
   the app older than 0.2.2 keep reading it and see "up to date".
+
+## 2026-10-12 (continued) — TASK-069: tab switches glide
+
+- Request: the product owner wanted moving between bottom tabs to glide.
+- What changed: a tab switch now moves both screens the whole width, the old one out as the new
+  one comes in (320 ms), in place of the short nudge with a fade. Pushed and popped screens keep
+  the short slide.
+- Checks and results: the five required checks pass. Not seen on a device; not in the published
+  0.2.2.

tasks/069-in-app-motion.md

@@ -17,7 +17,8 @@ The app moves where it used to jump, and what moves is the launcher icon's tea c
 6. Pull to refresh brings the cup down with the finger; the steam appears near the release point.
 7. A file's diff arrives row by row the first time it is shown.
 8. Added while this was in progress (product owner, 2026-10-12): switching bottom tabs slides the
-   screen in from the side that tab sits on, and the tab's icon springs.
+   whole screen sideways, the old tab gliding out as the new one glides in, and the tab's icon
+   springs.
 
 ## Scope