diff --git a/app/src/main/java/com/m57/hermescontrol/HermesControlApp.kt b/app/src/main/java/com/m57/hermescontrol/HermesControlApp.kt
index 0acb0bb1..f573f230 100644
--- a/app/src/main/java/com/m57/hermescontrol/HermesControlApp.kt
+++ b/app/src/main/java/com/m57/hermescontrol/HermesControlApp.kt
@@ -9,6 +9,7 @@ import coil.decode.ImageDecoderDecoder
 import com.m57.hermescontrol.data.local.AuthManager
 import com.m57.hermescontrol.data.remote.NetworkMonitor
 import com.m57.hermescontrol.data.remote.OkHttpProvider
+import com.m57.hermescontrol.data.update.UpdateNoticeManager
 import com.m57.hermescontrol.ui.analytics.AnalyticsPreloader
 
 class HermesControlApp :
@@ -25,6 +26,9 @@ class HermesControlApp :
         // so the tab renders instantly when opened (the usage endpoint is slow on a
         // cold backend). Fire-and-forget; never blocks UI startup.
         AnalyticsPreloader.preload(this)
+        // Issue #890: silent once-per-version update check right after launch,
+        // so the chat screen can show an update banner without user interaction.
+        UpdateNoticeManager.checkOnLaunch()
     }
 
     override fun newImageLoader(): ImageLoader =
diff --git a/app/src/main/java/com/m57/hermescontrol/data/config/ServerStoreState.kt b/app/src/main/java/com/m57/hermescontrol/data/config/ServerStoreState.kt
index 8616b737..2fa0580b 100644
--- a/app/src/main/java/com/m57/hermescontrol/data/config/ServerStoreState.kt
+++ b/app/src/main/java/com/m57/hermescontrol/data/config/ServerStoreState.kt
@@ -28,4 +28,8 @@ data class ServerStoreState(
     // Null / mismatched with BuildConfig.VERSION_NAME → the About tab runs
     // its one-time check again (re-check on app version bump).
     val updateCheckDoneForVersion: String? = null,
+    // Latest release tag the silent check (issue #890) last saw. Persisted so
+    // a dismissed chat banner can return on a later launch without re-pinging
+    // GitHub (the once-per-version guard skips the check by then).
+    val lastKnownLatestTag: String? = null,
 )
diff --git a/app/src/main/java/com/m57/hermescontrol/data/local/AuthManager.kt b/app/src/main/java/com/m57/hermescontrol/data/local/AuthManager.kt
index b2865ac8..960d2710 100644
--- a/app/src/main/java/com/m57/hermescontrol/data/local/AuthManager.kt
+++ b/app/src/main/java/com/m57/hermescontrol/data/local/AuthManager.kt
@@ -648,4 +648,11 @@ object AuthManager {
     fun setUpdateCheckDoneForVersion(version: String) {
         serverStore.update { it.copy(updateCheckDoneForVersion = version) }
     }
+
+    /** Latest release tag the launch check (issue #890) persisted. */
+    fun getLastKnownLatestTag(): String? = serverStore.getLatestState().lastKnownLatestTag
+
+    fun setLastKnownLatestTag(tag: String) {
+        serverStore.update { it.copy(lastKnownLatestTag = tag) }
+    }
 }
diff --git a/app/src/main/java/com/m57/hermescontrol/data/update/AppUpdateCache.kt b/app/src/main/java/com/m57/hermescontrol/data/update/AppUpdateCache.kt
new file mode 100644
index 00000000..baf1fc6b
--- /dev/null
+++ b/app/src/main/java/com/m57/hermescontrol/data/update/AppUpdateCache.kt
@@ -0,0 +1,41 @@
+package com.m57.hermescontrol.data.update
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/**
+ * Process-wide holder of the latest update-check result (issue #890). The
+ * launch check ([UpdateNoticeManager]) writes here so the chat banner can
+ * appear without a second network call, and the About tab adopts the same
+ * result so both surfaces agree on what the last check found.
+ */
+object AppUpdateCache {
+    private val _state = MutableStateFlow<AppUpdateState>(AppUpdateState.Idle)
+    val state: StateFlow<AppUpdateState> = _state.asStateFlow()
+
+    /**
+     * Session-only dismissal of the chat banner. Snapshot-backed so the chat
+     * screen recomposes when it flips; dies with the process, so a dismissed
+     * banner returns on the next launch (the persisted latest tag drives it).
+     */
+    var dismissed by mutableStateOf(false)
+        private set
+
+    fun update(state: AppUpdateState) {
+        _state.value = state
+    }
+
+    fun dismiss() {
+        dismissed = true
+    }
+
+    /** Test hook: clear state and dismissal between tests. */
+    internal fun reset() {
+        dismissed = false
+        _state.value = AppUpdateState.Idle
+    }
+}
diff --git a/app/src/main/java/com/m57/hermescontrol/data/update/AppUpdateState.kt b/app/src/main/java/com/m57/hermescontrol/data/update/AppUpdateState.kt
new file mode 100644
index 00000000..fa2f806d
--- /dev/null
+++ b/app/src/main/java/com/m57/hermescontrol/data/update/AppUpdateState.kt
@@ -0,0 +1,44 @@
+package com.m57.hermescontrol.data.update
+
+/**
+ * State of the in-app updater (issue #867) — shared by the About tab's
+ * [com.m57.hermescontrol.ui.settings.AppUpdateViewModel] and the launch
+ * notice (issue #890) via [AppUpdateCache].
+ */
+sealed interface AppUpdateState {
+    /** Nothing shown yet (no check run in this session). */
+    data object Idle : AppUpdateState
+
+    /** A check is in flight. */
+    data object Checking : AppUpdateState
+
+    /** Latest release equals the installed version. */
+    data class UpToDate(val latestTag: String) : AppUpdateState
+
+    /** A newer release with an APK asset exists. */
+    data class UpdateAvailable(
+        val latestTag: String,
+        val apkUrl: String,
+        val sizeBytes: Long,
+    ) : AppUpdateState
+
+    /** APK download in progress; [progress] is 0..1. */
+    data class Downloading(val progress: Float) : AppUpdateState
+
+    /** Download finished and the system package installer was launched. */
+    data class Installing(val latestTag: String) : AppUpdateState
+
+    /** Install-from-unknown-sources not granted for this app yet. */
+    data object NeedsUnknownSourcesPermission : AppUpdateState
+
+    data class Error(val message: String) : AppUpdateState
+}
+
+/** The release tag a state carries, when it carries one. */
+fun AppUpdateState.releaseTag(): String? =
+    when (this) {
+        is AppUpdateState.UpToDate -> latestTag
+        is AppUpdateState.UpdateAvailable -> latestTag
+        is AppUpdateState.Installing -> latestTag
+        else -> null
+    }
diff --git a/app/src/main/java/com/m57/hermescontrol/data/update/UpdateNoticeManager.kt b/app/src/main/java/com/m57/hermescontrol/data/update/UpdateNoticeManager.kt
new file mode 100644
index 00000000..51b53e08
--- /dev/null
+++ b/app/src/main/java/com/m57/hermescontrol/data/update/UpdateNoticeManager.kt
@@ -0,0 +1,82 @@
+package com.m57.hermescontrol.data.update
+
+import com.m57.hermescontrol.BuildConfig
+import com.m57.hermescontrol.data.local.AuthManager
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.launch
+import java.io.IOException
+
+/**
+ * Startup update check (issue #890): one silent GitHub ping per installed
+ * version, fired right after launch, so the chat screen can show an update
+ * banner without the user ever opening the About tab.
+ *
+ * The result lands in [AppUpdateCache] (consumed by the chat banner and
+ * adopted by the About tab) and the latest tag is persisted via
+ * [AuthManager.setLastKnownLatestTag] so a dismissed banner can return on a
+ * later launch. Failures leave the cache Idle — the About tab still has its
+ * own manual retry path.
+ */
+object UpdateNoticeManager {
+    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
+
+    /**
+     * Release-only feature (issue #890): the launch check and chat banner are
+     * disabled in debug builds (BuildConfig.DEBUG) so daily dev builds never
+     * hit the GitHub API or nag about updates. Tests flip this to true.
+     */
+    var enabled: Boolean = !BuildConfig.DEBUG
+        internal set
+
+    /** Run from Application.onCreate, after AuthManager.init. No-op once per version. */
+    fun checkOnLaunch(
+        checker: AppUpdateChecker = AppUpdateChecker(),
+        currentVersion: String = BuildConfig.VERSION_NAME,
+        ioDispatcher: CoroutineDispatcher = Dispatchers.IO,
+    ) {
+        if (!enabled) return
+        if (AuthManager.getUpdateCheckDoneForVersion() == currentVersion) return
+        scope.launch(ioDispatcher) {
+            AuthManager.setUpdateCheckDoneForVersion(currentVersion)
+            val result =
+                try {
+                    checker.fetchLatestRelease()
+                } catch (e: IOException) {
+                    return@launch
+                } catch (e: Exception) {
+                    return@launch
+                }
+            val info = result ?: return@launch
+            val apk = info.apkAsset ?: return@launch
+            val state =
+                if (isNewerVersion(info.tagName, currentVersion)) {
+                    AppUpdateState.UpdateAvailable(
+                        latestTag = info.tagName,
+                        apkUrl = apk.browserDownloadUrl,
+                        sizeBytes = apk.size,
+                    )
+                } else {
+                    AppUpdateState.UpToDate(latestTag = info.tagName)
+                }
+            AppUpdateCache.update(state)
+            state.releaseTag()?.let { AuthManager.setLastKnownLatestTag(it) }
+        }
+    }
+
+    /**
+     * The tag the chat banner should advertise, or null when nothing newer is
+     * known. Prefers the in-process check result; falls back to the persisted
+     * latest tag (issue #890) so a banner dismissed on a previous launch — or
+     * a launch whose check was skipped by the once-per-version guard — still
+     * comes back.
+     */
+    fun noticeTag(currentVersion: String = BuildConfig.VERSION_NAME): String? {
+        if (!enabled) return null
+        (AppUpdateCache.state.value as? AppUpdateState.UpdateAvailable)?.let { return it.latestTag }
+        val persisted = AuthManager.getLastKnownLatestTag() ?: return null
+        return persisted.takeIf { isNewerVersion(it, currentVersion) }
+    }
+}
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt b/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt
index 2445f3ad..00eb34c0 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt
@@ -77,8 +77,12 @@ import androidx.lifecycle.viewmodel.compose.viewModel
 import com.m57.hermescontrol.HistoryScreen
 import com.m57.hermescontrol.NavigationController
 import com.m57.hermescontrol.R
+import com.m57.hermescontrol.SettingsAbout
 import com.m57.hermescontrol.data.model.Attachment
 import com.m57.hermescontrol.data.model.AttachmentSource
+import com.m57.hermescontrol.data.update.AppUpdateCache
+import com.m57.hermescontrol.data.update.AppUpdateState
+import com.m57.hermescontrol.data.update.UpdateNoticeManager
 import com.m57.hermescontrol.data.ws.ConnectionStatus
 import com.m57.hermescontrol.data.ws.HermesWsClient
 import com.m57.hermescontrol.theme.LocalHermesStatusColors
@@ -102,6 +106,7 @@ import com.m57.hermescontrol.ui.common.AutoScrollingTitleText
 import com.m57.hermescontrol.ui.common.CredentialWarningBanner
 import com.m57.hermescontrol.ui.common.HermesScaffold
 import com.m57.hermescontrol.ui.common.NavIcon
+import com.m57.hermescontrol.ui.common.UpdateNoticeBanner
 import com.m57.hermescontrol.ui.model.components.ModelPickerDialog
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.collectLatest
@@ -518,6 +523,25 @@ fun ChatScreen(
                 )
             }
 
+            // Issue #890: launch update check — non-blocking banner when a
+            // newer release exists. "Update" jumps to the About-tab install
+            // flow; "Later" dismisses for the session (it returns next launch
+            // via the persisted latest tag). Release-only builds
+            // (UpdateNoticeManager.enabled = !BuildConfig.DEBUG).
+            val updateNotice by AppUpdateCache.state.collectAsStateWithLifecycle()
+            if (UpdateNoticeManager.enabled && !AppUpdateCache.dismissed) {
+                val noticeTag =
+                    (updateNotice as? AppUpdateState.UpdateAvailable)?.latestTag
+                        ?: UpdateNoticeManager.noticeTag()
+                if (noticeTag != null) {
+                    UpdateNoticeBanner(
+                        latestTag = noticeTag,
+                        onUpdate = { NavigationController.navigateTo(SettingsAbout) },
+                        onDismiss = { AppUpdateCache.dismiss() },
+                    )
+                }
+            }
+
             AnimatedVisibility(
                 visible = searchState.isActive,
                 enter = expandVertically() + fadeIn(),
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/common/UpdateNoticeBanner.kt b/app/src/main/java/com/m57/hermescontrol/ui/common/UpdateNoticeBanner.kt
new file mode 100644
index 00000000..0f9b0524
--- /dev/null
+++ b/app/src/main/java/com/m57/hermescontrol/ui/common/UpdateNoticeBanner.kt
@@ -0,0 +1,64 @@
+package com.m57.hermescontrol.ui.common
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Update
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.m57.hermescontrol.R
+
+/**
+ * Chat-screen banner for the launch update check (issue #890): a newer
+ * Hermes Mobile release exists. "Update" jumps into the About-tab install
+ * flow; "Later" dismisses for the session (the banner returns next launch).
+ */
+@Composable
+fun UpdateNoticeBanner(
+    latestTag: String,
+    onUpdate: () -> Unit,
+    onDismiss: () -> Unit,
+) {
+    Row(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 12.dp, vertical = 6.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        Icon(
+            imageVector = Icons.Filled.Update,
+            contentDescription = null,
+            tint = MaterialTheme.colorScheme.primary,
+            modifier = Modifier.padding(top = 2.dp),
+        )
+        Text(
+            text = stringResource(R.string.update_notice_banner_text, latestTag),
+            style = MaterialTheme.typography.bodySmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.weight(1f),
+        )
+        TextButton(onClick = onUpdate) {
+            Text(
+                text = stringResource(R.string.update_notice_banner_action),
+                style = MaterialTheme.typography.labelSmall,
+            )
+        }
+        TextButton(onClick = onDismiss) {
+            Text(
+                text = stringResource(R.string.action_dismiss),
+                style = MaterialTheme.typography.labelSmall,
+            )
+        }
+    }
+}
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModel.kt b/app/src/main/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModel.kt
index bb915a9f..614ce011 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModel.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModel.kt
@@ -8,8 +8,11 @@ import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
 import com.m57.hermescontrol.BuildConfig
 import com.m57.hermescontrol.data.local.AuthManager
+import com.m57.hermescontrol.data.update.AppUpdateCache
 import com.m57.hermescontrol.data.update.AppUpdateChecker
+import com.m57.hermescontrol.data.update.AppUpdateState
 import com.m57.hermescontrol.data.update.isNewerVersion
+import com.m57.hermescontrol.data.update.releaseTag
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -19,36 +22,6 @@ import kotlinx.coroutines.launch
 import java.io.File
 import java.io.IOException
 
-/** UI state of the About-tab in-app updater (issue #867). */
-sealed interface AppUpdateState {
-    /** Nothing shown yet (no check run in this session). */
-    data object Idle : AppUpdateState
-
-    /** A check is in flight. */
-    data object Checking : AppUpdateState
-
-    /** Latest release equals the installed version. */
-    data class UpToDate(val latestTag: String) : AppUpdateState
-
-    /** A newer release with an APK asset exists. */
-    data class UpdateAvailable(
-        val latestTag: String,
-        val apkUrl: String,
-        val sizeBytes: Long,
-    ) : AppUpdateState
-
-    /** APK download in progress; [progress] is 0..1. */
-    data class Downloading(val progress: Float) : AppUpdateState
-
-    /** Download finished and the system package installer was launched. */
-    data class Installing(val latestTag: String) : AppUpdateState
-
-    /** Install-from-unknown-sources not granted for this app yet. */
-    data object NeedsUnknownSourcesPermission : AppUpdateState
-
-    data class Error(val message: String) : AppUpdateState
-}
-
 /**
  * Drives the in-app self-update flow (issue #867): check the GitHub
  * releases API, download the release APK, and hand it to the system package
@@ -76,6 +49,14 @@ class AppUpdateViewModel(
         // on every visit.
         if (AuthManager.getUpdateCheckDoneForVersion() != currentVersion) {
             checkForUpdate()
+        } else {
+            // Issue #890: the launch check (UpdateNoticeManager) already ran
+            // for this version — adopt its result instead of pinging GitHub
+            // again, so the About tab agrees with the chat banner.
+            val cached = AppUpdateCache.state.value
+            if (cached is AppUpdateState.UpdateAvailable || cached is AppUpdateState.UpToDate) {
+                _state.value = cached
+            }
         }
     }
 
@@ -115,6 +96,9 @@ class AppUpdateViewModel(
                 } else {
                     AppUpdateState.UpToDate(latestTag = info.tagName)
                 }
+            // Keep the launch notice (issue #890) in sync with manual checks.
+            AppUpdateCache.update(_state.value)
+            _state.value.releaseTag()?.let { AuthManager.setLastKnownLatestTag(it) }
         }
     }
 
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/settings/components/AboutSection.kt b/app/src/main/java/com/m57/hermescontrol/ui/settings/components/AboutSection.kt
index df85bc8a..e05eba67 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/settings/components/AboutSection.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/settings/components/AboutSection.kt
@@ -21,7 +21,7 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import com.m57.hermescontrol.BuildConfig
 import com.m57.hermescontrol.R
-import com.m57.hermescontrol.ui.settings.AppUpdateState
+import com.m57.hermescontrol.data.update.AppUpdateState
 import com.m57.hermescontrol.ui.settings.InfoRow
 import com.m57.hermescontrol.ui.settings.SectionCard
 
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 0cc9fde7..340ebfe2 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -983,6 +983,10 @@
     <string name="action_done">Done</string>
     <string name="action_close">Close</string>
 
+    <!-- Update notice banner (issue #890) -->
+    <string name="update_notice_banner_text">Hermes Mobile %1$s is available</string>
+    <string name="update_notice_banner_action">Update</string>
+
     <!-- Processes Screen (issue #532) -->
     <string name="processes_empty_title">No running processes</string>
     <string name="processes_empty_desc">Background processes for this session will appear here.</string>
diff --git a/app/src/test/java/com/m57/hermescontrol/data/local/AuthManagerTest.kt b/app/src/test/java/com/m57/hermescontrol/data/local/AuthManagerTest.kt
index 7b5ac117..1c29fed8 100644
--- a/app/src/test/java/com/m57/hermescontrol/data/local/AuthManagerTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/data/local/AuthManagerTest.kt
@@ -134,6 +134,14 @@ class AuthManagerTest {
         verify { mockEditor.apply() }
     }
 
+    @Test
+    fun testGetAndSetLastKnownLatestTag() {
+        AuthManager.ensureDefaultProfile()
+        assertNull(AuthManager.getLastKnownLatestTag())
+        AuthManager.setLastKnownLatestTag("v1.22.0")
+        assertEquals("v1.22.0", AuthManager.getLastKnownLatestTag())
+    }
+
     @Test
     fun testGetHostAndPortFromBaseUrl() {
         AuthManager.setBaseUrl("https://10.0.0.1:9090/")
diff --git a/app/src/test/java/com/m57/hermescontrol/data/update/UpdateNoticeManagerTest.kt b/app/src/test/java/com/m57/hermescontrol/data/update/UpdateNoticeManagerTest.kt
new file mode 100644
index 00000000..cd6b8338
--- /dev/null
+++ b/app/src/test/java/com/m57/hermescontrol/data/update/UpdateNoticeManagerTest.kt
@@ -0,0 +1,210 @@
+package com.m57.hermescontrol.data.update
+
+import com.m57.hermescontrol.data.local.AuthManager
+import io.mockk.coEvery
+import io.mockk.coVerify
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.mockkObject
+import io.mockk.unmockkAll
+import io.mockk.verify
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.test.setMain
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+import java.io.IOException
+
+/**
+ * Launch update check (issue #890): the once-per-version guard, the
+ * cache write, and the persisted latest tag.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class UpdateNoticeManagerTest {
+    private val testDispatcher = StandardTestDispatcher()
+    private val currentVersion = "1.21.0"
+
+    private fun updateInfo(tag: String = "v1.22.0"): UpdateInfo =
+        UpdateInfo(
+            tagName = tag,
+            assets =
+                listOf(
+                    UpdateInfo.Asset(
+                        name = "hermes-mobile-v1.22.0.apk",
+                        size = 12345678L,
+                        browserDownloadUrl = "https://example.com/hermes-mobile-v1.22.0.apk",
+                    ),
+                ),
+        )
+
+    @Before
+    fun setUp() {
+        Dispatchers.setMain(testDispatcher)
+        AppUpdateCache.reset()
+        // Unit tests run against the debug variant where the feature is
+        // disabled by default — flip the knob on so the behavior is testable.
+        UpdateNoticeManager.enabled = true
+        mockkObject(AuthManager)
+        every { AuthManager.getUpdateCheckDoneForVersion() } returns null
+        every { AuthManager.setUpdateCheckDoneForVersion(any()) } returns Unit
+        every { AuthManager.getLastKnownLatestTag() } returns null
+        every { AuthManager.setLastKnownLatestTag(any()) } returns Unit
+    }
+
+    @After
+    fun tearDown() {
+        UpdateNoticeManager.enabled = false
+        unmockkAll()
+        Dispatchers.resetMain()
+    }
+
+    @Test
+    fun checkOnLaunch_runsOnceWhenNeverChecked() =
+        runTest {
+            val checker = mockk<AppUpdateChecker>()
+            coEvery { checker.fetchLatestRelease() } returns updateInfo()
+
+            UpdateNoticeManager.checkOnLaunch(checker, currentVersion, testDispatcher)
+            advanceUntilIdle()
+
+            assertTrue(AppUpdateCache.state.value is AppUpdateState.UpdateAvailable)
+            assertEquals(
+                "v1.22.0",
+                (AppUpdateCache.state.value as AppUpdateState.UpdateAvailable).latestTag,
+            )
+            verify(exactly = 1) { AuthManager.setUpdateCheckDoneForVersion(currentVersion) }
+            verify(exactly = 1) { AuthManager.setLastKnownLatestTag("v1.22.0") }
+        }
+
+    @Test
+    fun checkOnLaunch_skipsWhenAlreadyCheckedForThisVersion() =
+        runTest {
+            every { AuthManager.getUpdateCheckDoneForVersion() } returns currentVersion
+            val checker = mockk<AppUpdateChecker>()
+            coEvery { checker.fetchLatestRelease() } returns updateInfo()
+
+            UpdateNoticeManager.checkOnLaunch(checker, currentVersion, testDispatcher)
+            advanceUntilIdle()
+
+            coVerify(exactly = 0) { checker.fetchLatestRelease() }
+            assertEquals(AppUpdateState.Idle, AppUpdateCache.state.value)
+            verify(exactly = 0) { AuthManager.setUpdateCheckDoneForVersion(currentVersion) }
+        }
+
+    @Test
+    fun checkOnLaunch_upToDateWhenSameVersion() =
+        runTest {
+            val checker = mockk<AppUpdateChecker>()
+            coEvery { checker.fetchLatestRelease() } returns updateInfo(tag = "v1.21.0")
+
+            UpdateNoticeManager.checkOnLaunch(checker, currentVersion, testDispatcher)
+            advanceUntilIdle()
+
+            assertEquals(AppUpdateState.UpToDate("v1.21.0"), AppUpdateCache.state.value)
+            verify(exactly = 1) { AuthManager.setLastKnownLatestTag("v1.21.0") }
+        }
+
+    @Test
+    fun checkOnLaunch_networkFailure_leavesCacheIdle() =
+        runTest {
+            val checker = mockk<AppUpdateChecker>()
+            coEvery { checker.fetchLatestRelease() } throws IOException("boom")
+
+            UpdateNoticeManager.checkOnLaunch(checker, currentVersion, testDispatcher)
+            advanceUntilIdle()
+
+            assertEquals(AppUpdateState.Idle, AppUpdateCache.state.value)
+            // Still marked done so a dead network can't spam the API per launch.
+            verify(exactly = 1) { AuthManager.setUpdateCheckDoneForVersion(currentVersion) }
+        }
+
+    @Test
+    fun checkOnLaunch_noRelease_leavesCacheIdle() =
+        runTest {
+            val checker = mockk<AppUpdateChecker>()
+            coEvery { checker.fetchLatestRelease() } returns null
+
+            UpdateNoticeManager.checkOnLaunch(checker, currentVersion, testDispatcher)
+            advanceUntilIdle()
+
+            assertEquals(AppUpdateState.Idle, AppUpdateCache.state.value)
+            assertFalse(AppUpdateCache.dismissed)
+        }
+
+    // ── noticeTag (dismissed/restart banner return) ─────────────────────
+
+    @Test
+    fun noticeTag_prefersFreshCacheResult() {
+        AppUpdateCache.update(
+            AppUpdateState.UpdateAvailable(
+                latestTag = "v1.22.0",
+                apkUrl = "https://example.com/apk",
+                sizeBytes = 1L,
+            ),
+        )
+        every { AuthManager.getLastKnownLatestTag() } returns "v0.9.0"
+
+        assertEquals("v1.22.0", UpdateNoticeManager.noticeTag(currentVersion))
+    }
+
+    @Test
+    fun noticeTag_returnsPersistedNewerTagWhenCacheIdle() {
+        every { AuthManager.getLastKnownLatestTag() } returns "v1.22.0"
+
+        assertEquals("v1.22.0", UpdateNoticeManager.noticeTag(currentVersion))
+    }
+
+    @Test
+    fun noticeTag_nullWhenPersistedTagNotNewer() {
+        every { AuthManager.getLastKnownLatestTag() } returns "v1.21.0"
+
+        assertNull(UpdateNoticeManager.noticeTag(currentVersion))
+    }
+
+    @Test
+    fun noticeTag_nullWhenNothingKnown() {
+        assertNull(UpdateNoticeManager.noticeTag(currentVersion))
+    }
+
+    // ── debug builds: feature disabled by default (BuildConfig.DEBUG) ───
+
+    @Test
+    fun checkOnLaunch_disabled_makesNoNetworkCallAndLeavesCacheIdle() =
+        runTest {
+            UpdateNoticeManager.enabled = false
+            val checker = mockk<AppUpdateChecker>()
+            coEvery { checker.fetchLatestRelease() } returns updateInfo()
+
+            UpdateNoticeManager.checkOnLaunch(checker, currentVersion, testDispatcher)
+            advanceUntilIdle()
+
+            coVerify(exactly = 0) { checker.fetchLatestRelease() }
+            verify(exactly = 0) { AuthManager.setUpdateCheckDoneForVersion(any()) }
+            verify(exactly = 0) { AuthManager.setLastKnownLatestTag(any()) }
+            assertEquals(AppUpdateState.Idle, AppUpdateCache.state.value)
+        }
+
+    @Test
+    fun noticeTag_disabled_returnsNullEvenWhenNewerTagPersisted() {
+        UpdateNoticeManager.enabled = false
+        AppUpdateCache.update(
+            AppUpdateState.UpdateAvailable(
+                latestTag = "v1.22.0",
+                apkUrl = "https://example.com/apk",
+                sizeBytes = 1L,
+            ),
+        )
+        every { AuthManager.getLastKnownLatestTag() } returns "v1.22.0"
+
+        assertNull(UpdateNoticeManager.noticeTag(currentVersion))
+    }
+}
diff --git a/app/src/test/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModelTest.kt b/app/src/test/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModelTest.kt
index 05b855b4..8557a0e1 100644
--- a/app/src/test/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModelTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/ui/settings/AppUpdateViewModelTest.kt
@@ -6,7 +6,9 @@ import android.content.pm.PackageManager
 import android.net.Uri
 import androidx.core.content.FileProvider
 import com.m57.hermescontrol.data.local.AuthManager
+import com.m57.hermescontrol.data.update.AppUpdateCache
 import com.m57.hermescontrol.data.update.AppUpdateChecker
+import com.m57.hermescontrol.data.update.AppUpdateState
 import com.m57.hermescontrol.data.update.UpdateInfo
 import io.mockk.coEvery
 import io.mockk.coVerify
@@ -63,9 +65,11 @@ class AppUpdateViewModelTest {
     @Before
     fun setUp() {
         Dispatchers.setMain(testDispatcher)
+        AppUpdateCache.reset()
         mockkObject(AuthManager)
         every { AuthManager.getUpdateCheckDoneForVersion() } returns null
         every { AuthManager.setUpdateCheckDoneForVersion(any()) } returns Unit
+        every { AuthManager.setLastKnownLatestTag(any()) } returns Unit
 
         app = mockk(relaxed = true)
         every { app.cacheDir } returns File(System.getProperty("java.io.tmpdir"))
@@ -126,6 +130,30 @@ class AppUpdateViewModelTest {
             coVerify(exactly = 1) { checker.fetchLatestRelease() }
         }
 
+    @Test
+    fun init_adoptsLaunchCheckResultWithoutNetwork() =
+        runTest {
+            // Issue #890: the launch check already ran for this version and
+            // found an update — the About tab must adopt it, not ping GitHub.
+            every { AuthManager.getUpdateCheckDoneForVersion() } returns currentVersion
+            AppUpdateCache.update(
+                AppUpdateState.UpdateAvailable(
+                    latestTag = "v1.22.0",
+                    apkUrl = "https://example.com/hermes-mobile-v1.22.0.apk",
+                    sizeBytes = 12345678L,
+                ),
+            )
+
+            val vm = createViewModel()
+            advanceUntilIdle()
+
+            coVerify(exactly = 0) { checker.fetchLatestRelease() }
+            assertEquals(
+                AppUpdateState.UpdateAvailable("v1.22.0", "https://example.com/hermes-mobile-v1.22.0.apk", 12345678L),
+                vm.state.value,
+            )
+        }
+
     // ── Manual check ────────────────────────────────────────────────────
 
     @Test