fix(android): open Activity view with device hostname, not unknown

mobile/src/main/java/net/activitywatch/android/DeviceHostname.kt

@@ -0,0 +1,28 @@
+package net.activitywatch.android
+
+import android.content.Context
+import android.provider.Settings
+import java.util.Locale
+
+/**
+ * Hostname used for Android buckets, sync, and the Activity webui route.
+ *
+ * Sentinel `"unknown"` is a valid stored hostname (stopwatch, unsynced rows) but a
+ * terrible default: `/#/activity/unknown/` loads desktop visualizations for a host
+ * that has no `aw-watcher-android_*` buckets.
+ */
+internal fun sanitizeDeviceHostname(raw: String?): String {
+    val value = raw?.trim()?.takeIf { it.isNotEmpty() } ?: return "unknown"
+    return value
+        .lowercase(Locale.ROOT)
+        .replace(Regex("[^a-z0-9_-]+"), "_")
+        .trim('_')
+        .ifEmpty { "unknown" }
+}
+
+internal fun deviceHostname(context: Context): String {
+    val named = Settings.Global.getString(context.contentResolver, Settings.Global.DEVICE_NAME)
+        ?.trim()
+        ?.takeIf { it.isNotEmpty() }
+    return sanitizeDeviceHostname(named ?: android.os.Build.DEVICE)
+}

mobile/src/main/java/net/activitywatch/android/MainActivity.kt

@@ -32,13 +32,18 @@ const val baseURL = "http://127.0.0.1:5600"
 
 // Same destination as the drawer "Activity" item. Notification taps set
 // EXTRA_OPEN_ACTIVITY_VIEW so we land here instead of dashboard home.
-const val ACTIVITY_VIEW_ROUTE = "/#/activity/unknown/"
+// Hostname must match the sanitized device name used for Android buckets —
+// `/#/activity/unknown/` is a sentinel, not a host (see DeviceHostname.kt).
 const val EXTRA_OPEN_ACTIVITY_VIEW = "net.activitywatch.android.extra.OPEN_ACTIVITY_VIEW"
 
-internal fun activityViewUrl(baseUrl: String = baseURL): String = "$baseUrl$ACTIVITY_VIEW_ROUTE"
+internal fun activityViewUrl(hostname: String, baseUrl: String = baseURL): String =
+    "$baseUrl/#/activity/${sanitizeDeviceHostname(hostname)}/"
 
-internal fun initialWebUiUrl(openActivityView: Boolean, baseUrl: String = baseURL): String =
-    if (openActivityView) activityViewUrl(baseUrl) else baseUrl
+internal fun initialWebUiUrl(
+    openActivityView: Boolean,
+    hostname: String,
+    baseUrl: String = baseURL,
+): String = if (openActivityView) activityViewUrl(hostname, baseUrl) else baseUrl
 
 internal fun shouldOpenActivityViewImmediately(openActivityView: Boolean, isResumed: Boolean): Boolean =
     openActivityView && isResumed
@@ -135,7 +140,7 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         // home before onResume. Consume the extra here; onResume is the path
         // for reused instances (onNewIntent) and process-death restore.
         val openActivityView = intent.getBooleanExtra(EXTRA_OPEN_ACTIVITY_VIEW, false)
-        showWebUi(initialWebUiUrl(openActivityView), replace = false)
+        showWebUi(initialWebUiUrl(openActivityView, deviceHostname(this)), replace = false)
         if (openActivityView) {
             intent.removeExtra(EXTRA_OPEN_ACTIVITY_VIEW)
         }
@@ -176,9 +181,11 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         transaction.commit()
     }
 
+    private fun activityViewUrlForDevice(): String = activityViewUrl(deviceHostname(this))
+
     private fun openPendingActivityView() {
         if (takeOpenActivityView(intent)) {
-            showWebUi(activityViewUrl(), replace = true)
+            showWebUi(activityViewUrlForDevice(), replace = true)
         }
     }
 
@@ -232,7 +239,7 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
             }
             R.id.nav_activity -> {
                 fragmentClass = WebUIFragment::class.java
-                url = authenticatedUrl(activityViewUrl())
+                url = authenticatedUrl(activityViewUrlForDevice())
             }
             R.id.nav_buckets -> {
                 fragmentClass = WebUIFragment::class.java

mobile/src/main/java/net/activitywatch/android/RustInterface.kt

@@ -4,7 +4,6 @@ import android.content.Context
 import android.content.pm.PackageManager
 import android.os.Handler
 import android.os.Looper
-import android.provider.Settings
 import android.system.Os
 import android.util.Log
 import java.util.concurrent.Executors
@@ -201,17 +200,6 @@ class RustInterface(context: Context? = null) {
         }
     }
 
-    fun getDeviceName(context: Context): String {
-        val raw = Settings.Global.getString(context.contentResolver, Settings.Global.DEVICE_NAME)
-            ?.trim()
-            ?.takeIf { it.isNotEmpty() }
-            ?: android.os.Build.DEVICE
-            ?: "unknown"
-        return raw.trim()
-            .lowercase(java.util.Locale.ROOT)
-            .replace(Regex("[^a-z0-9_-]+"), "_")
-            .trim('_')
-            .ifEmpty { "unknown" }
-    }
+    fun getDeviceName(context: Context): String = deviceHostname(context)
 
 }

mobile/src/main/java/net/activitywatch/android/SyncInterface.kt

@@ -78,18 +78,7 @@ class SyncInterface(context: Context) {
     private external fun syncBoth(port: Int, hostname: String): String
     external fun getSyncDir(): String
 
-    private fun getDeviceName(): String {
-        val raw = android.provider.Settings.Global.getString(
-            appContext.contentResolver,
-            android.provider.Settings.Global.DEVICE_NAME
-        )?.trim()?.takeIf { it.isNotEmpty() }
-            ?: android.os.Build.DEVICE ?: "unknown"
-        return raw.trim()
-            .lowercase(java.util.Locale.ROOT)
-            .replace(Regex("[^a-z0-9_-]+"), "_")
-            .trim('_')
-            .ifEmpty { "unknown" }
-    }
+    private fun getDeviceName(): String = deviceHostname(appContext)
 
     // Async wrapper for syncPullAll
     fun syncPullAllAsync(callback: (Boolean, String) -> Unit) {

mobile/src/test/java/net/activitywatch/android/DeviceHostnameTest.kt

@@ -0,0 +1,21 @@
+package net.activitywatch.android
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class DeviceHostnameTest {
+    @Test
+    fun sanitizeDeviceHostname_fallsBackToUnknown() {
+        assertEquals("unknown", sanitizeDeviceHostname(null))
+        assertEquals("unknown", sanitizeDeviceHostname(""))
+        assertEquals("unknown", sanitizeDeviceHostname("   "))
+        assertEquals("unknown", sanitizeDeviceHostname("***"))
+    }
+
+    @Test
+    fun sanitizeDeviceHostname_lowercasesAndCollapses() {
+        assertEquals("pixel_8", sanitizeDeviceHostname("Pixel 8"))
+        assertEquals("my-phone_1", sanitizeDeviceHostname("My-Phone_1"))
+        assertEquals("pixel_8", sanitizeDeviceHostname("  Pixel  8  "))
+    }
+}

mobile/src/test/java/net/activitywatch/android/MainActivityNavigationTest.kt

@@ -8,14 +8,37 @@ import org.junit.Test
 class MainActivityNavigationTest {
     @Test
     fun initialWebUiUrl_defaultsToDashboardHome() {
-        assertEquals(baseURL, initialWebUiUrl(openActivityView = false))
+        assertEquals(
+            baseURL,
+            initialWebUiUrl(openActivityView = false, hostname = "pixel_8"),
+        )
+    }
+
+    @Test
+    fun initialWebUiUrl_opensActivityNavDestinationForDeviceHost() {
+        assertEquals(
+            "$baseURL/#/activity/pixel_8/",
+            initialWebUiUrl(openActivityView = true, hostname = "pixel_8"),
+        )
     }
 
     @Test
-    fun initialWebUiUrl_opensActivityNavDestination() {
+    fun activityViewUrl_sanitizesRawDeviceName() {
+        assertEquals(
+            "$baseURL/#/activity/pixel_8/",
+            activityViewUrl("Pixel 8"),
+        )
+    }
+
+    @Test
+    fun activityViewUrl_unknownIsFallbackNotDefault() {
+        assertEquals(
+            "$baseURL/#/activity/unknown/",
+            activityViewUrl("unknown"),
+        )
         assertEquals(
             "$baseURL/#/activity/unknown/",
-            initialWebUiUrl(openActivityView = true),
+            activityViewUrl(""),
         )
     }