prober: survive configuration changes (rotation wiped a finished run)

Found on the OnePlus 15 (CPH2747): rotating after a run emptied the result
list — results lived in a MainActivity field and the run in lifecycleScope,
so a config change dropped collected results and cancelled remaining probes.
Both now live in ProberViewModel (viewModelScope + application context; no
probe needs an Activity). A lost run means a lost export, so this matters
for a collection tool.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

echolot-prober/app/src/main/java/app/echo_lot/prober/MainActivity.kt

@@ -11,24 +11,18 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.activity.viewModels
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.setValue
 import androidx.core.content.ContextCompat
-import androidx.lifecycle.lifecycleScope
 import app.echo_lot.prober.export.ReportWriter
-import app.echo_lot.prober.probe.ProbeRegistry
-import app.echo_lot.prober.probe.ProbeResult
-import app.echo_lot.prober.probe.Verdict
 import app.echo_lot.prober.ui.ProberScreen
-import app.echo_lot.prober.ui.UiState
-import kotlinx.coroutines.launch
 
 class MainActivity : ComponentActivity() {
 
-    private var state by mutableStateOf(UiState())
+    // Run state lives in the ViewModel so rotation neither cancels a running
+    // probe sequence nor discards collected results.
+    private val vm: ProberViewModel by viewModels()
 
     private val permissionLauncher =
         registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { /* proceed regardless */ }
@@ -40,8 +34,8 @@ class MainActivity : ComponentActivity() {
             MaterialTheme {
                 Surface {
                     ProberScreen(
-                        state = state,
+                        state = vm.state,
-                        onRun = ::runProbes,
+                        onRun = vm::runProbes,
                         onShare = ::shareReport,
                     )
                 }
@@ -49,28 +43,9 @@ class MainActivity : ComponentActivity() {
         }
     }
 
-    private fun runProbes() {
-        if (state.running) return
-        state = state.copy(running = true, results = emptyList(), currentTitle = null)
-        lifecycleScope.launch {
-            val acc = mutableListOf<ProbeResult>()
-            for (probe in ProbeRegistry.all) {
-                state = state.copy(currentTitle = probe.title)
-                val result = try {
-                    probe.run(this@MainActivity)
-                } catch (t: Throwable) {
-                    ProbeResult.of(probe, Verdict.ERROR, "Uncaught: ${t.message ?: t.javaClass.simpleName}")
-                }
-                acc.add(result)
-                state = state.copy(results = acc.toList())
-            }
-            state = state.copy(running = false, currentTitle = null)
-        }
-    }
-
     private fun shareReport() {
-        if (state.results.isEmpty()) return
+        if (vm.state.results.isEmpty()) return
-        val intent = ReportWriter.share(this, state.results)
+        val intent = ReportWriter.share(this, vm.state.results)
         startActivity(Intent.createChooser(intent, "Export Echolot prober report"))
     }
 

echolot-prober/app/src/main/java/app/echo_lot/prober/ProberViewModel.kt

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: 2026 Echolot contributors
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package app.echo_lot.prober
+
+import android.app.Application
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.viewModelScope
+import app.echo_lot.prober.probe.ProbeRegistry
+import app.echo_lot.prober.probe.ProbeResult
+import app.echo_lot.prober.probe.Verdict
+import app.echo_lot.prober.ui.UiState
+import kotlinx.coroutines.launch
+
+/**
+ * Owns the probe run and its results so both survive configuration changes.
+ * Rotating mid-run must neither cancel remaining probes (viewModelScope, not
+ * lifecycleScope) nor drop collected results (ViewModel, not Activity field) —
+ * a lost run means a lost export.
+ *
+ * Probes get the Application context; none of them need an Activity.
+ */
+class ProberViewModel(app: Application) : AndroidViewModel(app) {
+
+    var state by mutableStateOf(UiState())
+        private set
+
+    fun runProbes() {
+        if (state.running) return
+        state = state.copy(running = true, results = emptyList(), currentTitle = null)
+        viewModelScope.launch {
+            val acc = mutableListOf<ProbeResult>()
+            for (probe in ProbeRegistry.all) {
+                state = state.copy(currentTitle = probe.title)
+                val result = try {
+                    probe.run(getApplication())
+                } catch (t: Throwable) {
+                    ProbeResult.of(probe, Verdict.ERROR, "Uncaught: ${t.message ?: t.javaClass.simpleName}")
+                }
+                acc.add(result)
+                state = state.copy(results = acc.toList())
+            }
+            state = state.copy(running = false, currentTitle = null)
+        }
+    }
+}