diff --git a/app/src/wolfskin/java/org/justinvisser/wolfskin/tv/update/FakeUpdateController.kt b/app/src/wolfskin/java/org/justinvisser/wolfskin/tv/update/FakeUpdateController.kt
new file mode 100644
index 00000000..3976489b
--- /dev/null
+++ b/app/src/wolfskin/java/org/justinvisser/wolfskin/tv/update/FakeUpdateController.kt
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-only
+package org.justinvisser.wolfskin.tv.update
+
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/** Deterministic capture/test controller; no network, storage or Android hand-off. */
+class FakeUpdateController(
+    initialState: UpdateUiState = UpdateUiState.Idle,
+    initialAutoCheck: Boolean = true,
+    initialVersion: InstalledVersion = InstalledVersion("1.1.1", 100001),
+) : UpdateController {
+    private val mutableState = MutableStateFlow(initialState)
+    private val mutableAutoCheck = MutableStateFlow(initialAutoCheck)
+    private val mutableVersion = MutableStateFlow(initialVersion)
+    override val state = mutableState.asStateFlow()
+    override val autoCheck = mutableAutoCheck.asStateFlow()
+    override val installedVersion = mutableVersion.asStateFlow()
+    val actions = mutableListOf<String>()
+
+    fun show(state: UpdateUiState) { mutableState.value = state }
+    fun showInstalled(version: InstalledVersion) { mutableVersion.value = version }
+    override fun check(manual: Boolean) { actions += "check:$manual" }
+    override fun download() { actions += "download" }
+    override fun cancel() { actions += "cancel" }
+    override fun install() { actions += "install" }
+    override fun retry() { actions += "retry" }
+    override fun onResume() { actions += "resume" }
+    override fun setAutoCheck(enabled: Boolean) { mutableAutoCheck.value = enabled }
+}
diff --git a/app/src/wolfskin/java/org/justinvisser/wolfskin/tv/update/UpdateController.kt b/app/src/wolfskin/java/org/justinvisser/wolfskin/tv/update/UpdateController.kt
new file mode 100644
index 00000000..c7faa29e
--- /dev/null
+++ b/app/src/wolfskin/java/org/justinvisser/wolfskin/tv/update/UpdateController.kt
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-only
+package org.justinvisser.wolfskin.tv.update
+
+import kotlinx.coroutines.flow.StateFlow
+
+/** Shared process-scoped updater for Wolfskin and classic settings. */
+interface UpdateController {
+    val state: StateFlow<UpdateUiState>
+    val autoCheck: StateFlow<Boolean>
+    val installedVersion: StateFlow<InstalledVersion>
+
+    fun check(manual: Boolean)
+    fun download()
+    fun cancel()
+    fun install()
+    fun retry()
+    fun setAutoCheck(enabled: Boolean)
+
+    /** Refresh installed identity and unknown-source permission after Android returns. */
+    fun onResume()
+}
+
+/** PackageManager identity, refreshed after returning from the system installer. */
+data class InstalledVersion(val versionName: String, val versionCode: Long)
+
+/** Only verified, app-private bytes may produce Ready. Checking never initiates download. */
+sealed interface UpdateUiState {
+    data object Idle : UpdateUiState
+    data object Checking : UpdateUiState
+    data object UpToDate : UpdateUiState
+    data object NoReleasePublished : UpdateUiState
+    data class Available(val versionName: String, val bytes: Long, val dateText: String, val notes: String) : UpdateUiState
+    data class Downloading(val bytesDone: Long, val bytesTotal: Long?) : UpdateUiState
+    data class Ready(val versionName: String) : UpdateUiState
+    data object PermissionNeeded : UpdateUiState
+    data object HandingOff : UpdateUiState
+    data object InstallCancelled : UpdateUiState
+    data class Failed(val kind: UpdateFailure, val message: String) : UpdateUiState
+    data object Offline : UpdateUiState
+    data object NoInstaller : UpdateUiState
+}
+
+/** Failures are distinct from a successful version comparison or an empty channel. */
+enum class UpdateFailure {
+    Network, HttpRefused, InvalidMetadata, UnsupportedAbi, InsufficientStorage,
+    ChecksumMismatch, WrongPackage, WrongSigner, LowerVersionCode,
+}