ci: split into fast analyze + slow release build with path gating

analyze runs on every push/PR (fast check). release-apk only fires on push to master or workflow_dispatch (slow build). Doc-only pushes no longer trigger any CI run. workflow_dispatch triggers both jobs unconditionally.
2026-08-27 23:59:04 +09:00 · 2026-08-27 23:58:02 +09:00 · 2026-08-27 23:56:31 +09:00 · 2026-08-27 00:06:04 +09:00 · 2026-08-27 00:02:44 +09:00 · 2026-08-26 23:57:33 +09:00
25 changed files with 1427 additions and 205 deletions
@@ -3,20 +3,39 @@ name: CI
 on:
  push:
    branches: [ master ]
+    paths:
+      - 'lib/**.dart'
+      - 'test/**.dart'
+      - 'android/**'
+      - 'tool/**'
+      - 'pubspec.yaml'
+      - 'pubspec.lock'
  pull_request:
    branches: [ master ]
+  workflow_dispatch:
+
+# Both jobs target a self-hosted runner, by capability rather than by hostname.
+# See tool/setup_ci_runner.sh for how that runner is provisioned and why it is
+# not the Gitea host: Flutter cannot build an Android APK on a Linux arm64 host
+# (flutter/flutter#189724), and the Gitea box is aarch64. The runner is
+# registered at android-stuff org scope so any repo in the org can use it.
+#
+# The runner is host-mode, so Flutter, the JDK and the Android SDK/NDK are the
+# machine's own — the same toolchain that produced the verified release, and no
+# multi-hundred-MB download per run. Nothing here installs a toolchain; the
+# Toolchain step fails loudly if one is missing.

 jobs:
  analyze:
    name: Analyze & Test
-    runs-on: ubuntu-latest
+    runs-on: flutter-android
    steps:
      - uses: actions/checkout@v4

-      - uses: subosito/flutter-action@v2
-        with:
-          flutter-version: '3.47.1'
-          channel: 'stable'
+      - name: Toolchain
+        run: |
+          flutter --version
+          echo "ANDROID_HOME=${ANDROID_HOME:?not set on this runner}"

      - name: Get dependencies
        run: flutter pub get
@@ -24,5 +43,36 @@ jobs:
      - name: Analyze
        run: flutter analyze

+      # Includes test/architecture_test.dart, which fails the build if a layer
+      # boundary is crossed.
      - name: Run tests
        run: flutter test
+
+  release-apk:
+    name: Release APK
+    runs-on: flutter-android
+    needs: [analyze]
+    if: github.event_name == 'push' || github.event_name == 'workflow_dispatch'
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Get dependencies
+        run: flutter pub get
+
+      # The debug build does not minify, so it cannot catch an R8 problem. This
+      # job exists because a release APK that aborted on every test shipped
+      # once while the debug build passed every check.
+      - name: Build release APK
+        run: flutter build apk --release
+
+      # Building is not enough on its own: a renamed JNI callback still
+      # produces a successful build and a broken APK. This reads R8's mapping
+      # and the DEX string pool to confirm the names JNI resolves survived.
+      - name: Check JNI names survived minification
+        run: ./tool/check_jni_keep_rules.sh
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: app-release-apk
+          path: build/app/outputs/flutter-apk/app-release.apk
+          if-no-files-found: error
@@ -0,0 +1,26 @@
+MIT License
+
+Copyright (c) 2024–2026 Mikkeli Matlock
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+---
+
+Note: This project bundles iperf3 v3.19, which is licensed under the
+BSD-3-Clause license. See the bundled iperf3 source for its full license text.
@@ -40,9 +40,6 @@ domain, so shipping an iperf3 ELF in assets and running it via `Process.start()`
 fails with "Permission denied". iperf3 is therefore compiled as a shared library
 (`libiperf3jni.so`) and called in-process over JNI.

-`assets/iperf3/` still holds the pre-compiled binaries from that earlier
-approach. They are not declared in `pubspec.yaml`, so they are not packaged into
-the APK, and nothing in the app reads them.

 ## Building

@@ -37,6 +37,13 @@ android {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig = signingConfigs.getByName("debug")
+
+            // proguard-rules.pro keeps the names JNI resolves at runtime.
+            // Without it a release build aborts on the first callback.
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro",
+            )
        }
    }

@@ -0,0 +1,21 @@
+# JNI reaches these by name. R8 renames by default, so without these rules a
+# release build resolves nothing: GetMethodID("onOutput", ...) returns NULL,
+# raises NoSuchMethodError, and the next JNI call aborts the process with
+#   NoSuchMethodError: no non-static method "Lp0;.onOutput(Ljava/lang/String;)V"
+# Debug builds do not minify, so this only ever appears in release.
+
+# The plugin object holds the native method declarations and is looked up from
+# C by its fully qualified name (Java_com_novoyuuparosk_iperf3gui_IperfRunner_*).
+-keep class com.novoyuuparosk.iperf3gui.IperfRunner { *; }
+
+# The callback interface and everything implementing it: iperf_jni.c resolves
+# onOutput/onError/onComplete by name on the concrete object's class, so the
+# implementors' method names must survive too, not just the interface's.
+-keep interface com.novoyuuparosk.iperf3gui.IperfRunner$IperfCallback { *; }
+-keep class * implements com.novoyuuparosk.iperf3gui.IperfRunner$IperfCallback { *; }
+
+# Belt and braces for any future native method: keep the name of any class
+# declaring one, and the native methods themselves.
+-keepclasseswithmembernames,includedescriptorclasses class * {
+    native <methods>;
+}
@@ -86,6 +86,21 @@ struct iperf_run_state {
 * iperf_run_client() and cleared after it returns. */
 static struct iperf_run_state *g_current_state = NULL;

+/* Resolve a method ID, clearing the exception a failed lookup leaves behind.
+ *
+ * GetMethodID raises NoSuchMethodError on failure, and any further JNI call
+ * made while an exception is pending aborts the process. Returning NULL and
+ * clearing lets the caller fail on its own terms. */
+static jmethodID resolve_method(JNIEnv *env, jclass cls,
+                                const char *name, const char *sig) {
+    jmethodID mid = (*env)->GetMethodID(env, cls, name, sig);
+    if ((*env)->ExceptionCheck(env)) {
+        (*env)->ExceptionClear(env);
+        return NULL;
+    }
+    return mid;
+}
+
 /* Helper: invoke the output callback via CallVoidMethod */
 static void signal_output(JNIEnv *env, struct iperf_run_state *state,
                          const char *msg) {
@@ -272,13 +287,25 @@ Java_com_novoyuuparosk_iperf3gui_IperfRunner_runIperfLive(

    /* Resolve callback method IDs up front so failures can be reported. */
    jclass callback_cls = (*env)->GetObjectClass(env, callback);
-    jmethodID mid_output = (*env)->GetMethodID(
+    jmethodID mid_output = resolve_method(
            env, callback_cls, "onOutput", "(Ljava/lang/String;)V");
-    jmethodID mid_error = (*env)->GetMethodID(
+    jmethodID mid_error = resolve_method(
            env, callback_cls, "onError", "(Ljava/lang/String;)V");
-    jmethodID mid_complete = (*env)->GetMethodID(
+    jmethodID mid_complete = resolve_method(
            env, callback_cls, "onComplete", "()V");

+    /* If the names did not resolve there is no way to report anything: the
+     * reporting path is the thing that is missing. Bail out loudly instead.
+     *
+     * In practice this means R8 renamed the callback in a release build and
+     * android/app/proguard-rules.pro has stopped covering it. */
+    if (!mid_output || !mid_error || !mid_complete) {
+        LOGE("Callback methods did not resolve (onOutput=%p onError=%p "
+             "onComplete=%p) — check the -keep rules for IperfCallback",
+             mid_output, mid_error, mid_complete);
+        return;
+    }
+
    /* Report a startup failure directly on the callback object and finish,
     * so Dart's completer always resolves instead of waiting for a timeout. */
    #define FAIL_EARLY(msg) do {                                              \
@@ -6,19 +6,25 @@ A Flutter-based Android GUI wrapper for iperf3, the popular network performance

 ```
 lib/                          # Flutter/Dart application layer
-├── main.dart                 # App entry point (MaterialApp)
-├── domain/                   # Business logic (platform-independent)
+├── main.dart                 # Composition root: picks the Iperf3Runner impl
+├── main_headless.dart        # Runs a test with no widgets (see Layering)
+├── domain/                   # Pure Dart — no Flutter import
 │   ├── models/
 │   │   ├── test_configuration.dart   # Server, port, duration, interval, parallel streams
-│   │   └── iperf3_result.dart        # Raw output + exit code
-├── data/
+│   │   ├── iperf3_result.dart        # Raw output, exit code, stopped flag
+│   │   ├── iperf3_event.dart         # Parsed --json-stream reports
+│   │   └── iperf3_session.dart       # One run accumulated: samples, totals, stats
 │   └── services/
-│       └── iperf3_service.dart       # Dart → MethodChannel bridge (async with Completer)
-└── ui/                       # Presentation layer
+│       └── iperf3_runner.dart        # The contract the UI depends on
+├── data/                     # Transport — flutter/services only
+│   └── services/
+│       └── iperf3_service.dart       # Iperf3Runner over MethodChannel → JNI
+└── ui/                       # Presentation
    └── features/
        └── test_run/
-            ├── test_run_screen.dart          # Server/port inputs + GO button
-            └── test_run_view_model.dart      # State machine: idle → running → completed/error
+            ├── test_run_screen.dart            # Inputs, GO/STOP, live transcript
+            ├── test_run_view_model.dart        # idle → running → completed/error
+            └── iperf3_event_formatter.dart     # Events → iperf3-style text

 android/app/src/main/
 ├── kotlin/                     # Kotlin plugin layer
@@ -48,6 +54,49 @@ User taps GO
  → On completion: Dart Completer resolves with Iperf3Result
 ```

+## Layering
+
+Dependencies point inward: `ui → domain ← data`, never the reverse.
+
+| Layer | May import | Holds |
+|---|---|---|
+| `domain` | nothing else in this package, no Flutter | models and the `Iperf3Runner` contract |
+| `data` | `domain`, `package:flutter/services.dart` | the MethodChannel/JNI implementation |
+| `ui` | `domain` | widgets, view model, formatting |
+| `main.dart` | everything | the single place that picks an implementation |
+
+The UI depends on `Iperf3Runner`, not on `Iperf3Service`, so presentation names
+no transport. That is what lets `test/widget_test.dart` drive the real widget
+tree against an in-memory runner with no MethodChannel, native library or
+device — and what keeps a test double at five stable members instead of
+mirroring the transport's whole surface.
+
+**The core does not need the UI.** What happened during a run is accumulated by
+`Iperf3Session` in the domain layer — samples, totals, errors, and the mean,
+peak and retransmit figures over them. The view model holds no run data of its
+own and the screen derives no numbers; both read the session. Replacing the
+presentation layer therefore means rewriting rendering, not re-deriving results.
+
+`lib/main_headless.dart` is the standing proof: it runs a full test through
+`Iperf3Service` and `Iperf3Session` with `WidgetsFlutterBinding` but no
+`runApp` — no widget tree, no render surface. If the run path ever starts
+needing the UI, it stops working.
+
+```bash
+flutter run -t lib/main_headless.dart \
+  --dart-define=IPERF_SERVER=192.168.2.182 --dart-define=IPERF_STREAMS=4
+```
+
+Use it when a figure has to be trustworthy. A 4-stream local run reports
+**30.2% local CPU headless against 79.9% through the UI** — the phone is near
+CPU-bound at gigabit rates, so a repainting transcript measurably depresses
+throughput. Numbers taken through the UI are pessimistic.
+
+`test/architecture_test.dart` enforces all of this by reading the actual
+imports under `lib/`, including a check that no fourth layer directory has
+appeared unnoticed. Change the layering there when the layering should change;
+don't work around it.
+
 ## Key Design Decisions

 ### JNI Over Process Execution
@@ -134,6 +183,62 @@ Dart uses `Completer<Iperf3Result>` to await native completion. The MethodChanne
 | `isTestRunning()` | `isTestRunning` | Check if test is in progress |
 | `setTempDir(String)` | `setTempDir` | Point `mkstemp()` at the app cache dir |

+## CI
+
+Both jobs run on a **self-hosted runner registered at `android-stuff` org scope**,
+targeted by the capability label `flutter-android` rather than by hostname.
+`tool/setup_ci_runner.sh` provisions it.
+
+It does not run on the Gitea host. Gitea lives on an aarch64 box, and Flutter
+cannot build an Android APK on a Linux arm64 host at all — the SDK ships no
+arm64-host `gen_snapshot` ([flutter#189724](https://github.com/flutter/flutter/issues/189724),
+[#75864](https://github.com/flutter/flutter/issues/75864), open as of July 2026).
+An x86_64 runner is a requirement, not a preference.
+
+The runner is **host mode**: jobs use the machine's own Flutter, JDK and Android
+SDK/NDK. CI therefore builds with the same toolchain that produced the verified
+release, and no NDK is downloaded per run. The cost is that there is no
+container boundary, which is what decides the next paragraph.
+
+Jobs run as a dedicated unprivileged account, `gitea-runner`, in the
+`flutterdev` group. In host mode the service account *is* the sandbox — there
+is no other — and a workflow file is code that runs as whoever the service runs
+as. A human account would hand every workflow that user's home directory and
+SSH keys; root would be worse and would also miss the warm caches in that home,
+re-downloading dependencies every run. The dedicated account keeps its own
+Gradle and pub caches under `/var/lib/gitea-runner`, so the first Android build
+is slow by design and later ones are not.
+
+`flutterdev` is what grants write access to `/opt/flutter` and
+`/opt/android-sdk`; both carry ACLs with `group:flutterdev:rwx` and matching
+`default:` entries, so new files inherit it. The setup script proves that access
+as the service account rather than assuming group membership is sufficient.
+
+It installs a **system** service, not a user service: root-managed lifecycle,
+starts at boot, no lingering session. That the service is root-managed is
+unrelated to the jobs being unprivileged — `User=` in the unit settles the
+second, and conflating the two is easy to do.
+
+`sudo ./tool/setup_ci_runner.sh --check` validates this machine's toolchain
+without creating anything.
+
+Two jobs:
+
+| Job | What it protects |
+|---|---|
+| `analyze` | `flutter analyze`, then `flutter test` — which includes `architecture_test.dart`, failing the build if a layer boundary is crossed |
+| `release-apk` | builds the **minified** APK and runs `tool/check_jni_keep_rules.sh` |
+
+The second exists because of a specific escape. A release APK that aborted on
+every test shipped once, while every on-device check passed — because those
+checks all used the debug build, which does not minify. Building the release APK
+is necessary but not sufficient: a renamed JNI callback still produces a
+*successful build* and a broken app. So the guard reads R8's `mapping.txt` for
+the callback classes and methods, and the DEX string pool for the native entry
+points. It is verified to fail: delete the keep rules from
+`android/app/proguard-rules.pro`, rebuild, and it reports `MainThreadCallback`,
+`onOutput`, `onError` and `onComplete` renamed.
+
 ## Building

 Prerequisites:
@@ -1,12 +1,13 @@
 import 'dart:async';
+import 'dart:developer' as developer;

-import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:iperf3gui/domain/models/iperf3_event.dart';
 import 'package:iperf3gui/domain/models/iperf3_result.dart';
 import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/domain/services/iperf3_runner.dart';

-/// Service that runs iperf3 via JNI (native library).
+/// [Iperf3Runner] backed by the native iperf3 library over a MethodChannel.
 ///
 /// On Android, iperf3 is compiled into the app as a shared library (.so).
 /// This avoids SELinux restrictions on executing ELF binaries from assets.
@@ -16,13 +17,17 @@ import 'package:iperf3gui/domain/models/test_configuration.dart';
 /// they are parsed and published on [events] while the test runs. [run]
 /// resolves once the native layer reports completion, carrying the raw JSON
 /// lines as the result's output.
-class Iperf3Service {
+class Iperf3Service implements Iperf3Runner {
  Iperf3Service() {
    _channel.setMethodCallHandler(_handleNativeCall);
  }

-  static const MethodChannel _channel =
-      MethodChannel('com.novoyuuparosk.iperf3gui/iperf');
+  /// A channel's handler is keyed by channel name in the binary messenger, so
+  /// it is process-global: constructing a second instance would take the
+  /// handler away from the first. The app composes exactly one, in main().
+  final MethodChannel _channel = const MethodChannel(_channelName);
+
+  static const String _channelName = 'com.novoyuuparosk.iperf3gui/iperf';

  /// Exit code reported when the native layer signalled an error.
  static const int exitCodeNativeError = 1;
@@ -41,6 +46,7 @@ class Iperf3Service {
      StreamController<Iperf3Event>.broadcast();

  /// Live reports, one event per native report. Use this to render progress.
+  @override
  Stream<Iperf3Event> get events => _eventController.stream;

  /// Raw JSON lines received during the current (or most recent) run.
@@ -51,6 +57,7 @@ class Iperf3Service {

  /// Whether iperf3 is currently running.
  bool _isRunning = false;
+  @override
  bool get isRunning => _isRunning;

  /// Whether the native layer reported an error during this run.
@@ -60,17 +67,19 @@ class Iperf3Service {
  bool _stopRequested = false;

  /// Cancel any running test.
+  @override
  Future<void> stop() async {
    if (!_isRunning) return;
    _stopRequested = true;
    try {
      await _channel.invokeMethod('stopIperf');
    } catch (e) {
-      debugPrint('Iperf3Service: error stopping: $e');
+      _log('Iperf3Service: error stopping: $e');
    }
  }

  /// Release the stream controller. Call from the owner's dispose().
+  @override
  Future<void> dispose() async {
    _channel.setMethodCallHandler(null);
    await _eventController.close();
@@ -79,6 +88,7 @@ class Iperf3Service {
  /// Run iperf3 with the given configuration.
  ///
  /// Returns an [Iperf3Result] with the full output and an exit code.
+  @override
  Future<Iperf3Result> run(TestConfiguration config) async {
    if (_isRunning) {
      return const Iperf3Result(
@@ -93,7 +103,7 @@ class Iperf3Service {
    _rawLines.clear();

    final args = config.toCliArgs();
-    debugPrint('Iperf3Service: running: ${args.join(" ")}');
+    _log('Iperf3Service: running: ${args.join(" ")}');

    final completer = Completer<Iperf3Result>();
    _runCompleter = completer;
@@ -101,8 +111,8 @@ class Iperf3Service {
    try {
      await _channel.invokeMethod('runIperf', {'args': args});
    } catch (e, stackTrace) {
-      debugPrint('Iperf3Service exception: $e');
-      debugPrint('Iperf3Service stack: $stackTrace');
+      _log('Iperf3Service exception: $e');
+      _log('Iperf3Service stack: $stackTrace');
      _finishRun();
      return Iperf3Result(
        rawOutput: 'Error starting iperf3: $e',
@@ -116,11 +126,11 @@ class Iperf3Service {
      return await completer.future.timeout(
        config.duration + const Duration(seconds: 45),
        onTimeout: () {
-          debugPrint('Iperf3Service: timeout, stopping test');
+          _log('Iperf3Service: timeout, stopping test');
          // Ask the native layer to wind down, then release local state so a
          // stuck run can never lock the UI out of starting another test.
          _channel.invokeMethod('stopIperf').catchError((Object e) {
-            debugPrint('Iperf3Service: error stopping after timeout: $e');
+            _log('Iperf3Service: error stopping after timeout: $e');
            return null;
          });
          _publish(const Iperf3Error('Timed out waiting for iperf3 to finish.'));
@@ -131,7 +141,7 @@ class Iperf3Service {
        },
      );
    } catch (e) {
-      debugPrint('Iperf3Service: error waiting for completion: $e');
+      _log('Iperf3Service: error waiting for completion: $e');
      return Iperf3Result(
        rawOutput: 'Test failed: $e',
        exitCode: exitCodeStartFailed,
@@ -163,7 +173,7 @@ class Iperf3Service {
          _publish(Iperf3Error(error));
        }
      case 'onComplete':
-        debugPrint('Iperf3Service: test completed');
+        _log('Iperf3Service: test completed');
        final completer = _runCompleter;
        if (completer != null && !completer.isCompleted) {
          completer.complete(
@@ -177,7 +187,7 @@ class Iperf3Service {
          );
        }
      default:
-        debugPrint('Iperf3Service: unhandled native call ${call.method}');
+        _log('Iperf3Service: unhandled native call ${call.method}');
    }
  }

@@ -197,3 +207,6 @@ class Iperf3Service {
    _runCompleter = null;
  }
 }
+
+void _log(String message) =>
+    developer.log(message, name: 'Iperf3Service');
@@ -0,0 +1,114 @@
+import 'package:iperf3gui/domain/models/iperf3_event.dart';
+
+/// The accumulated state of one iperf3 run.
+///
+/// Fed the event stream one report at a time, this is the answer to "what
+/// happened during this test" — the interval series, the end totals, any
+/// errors, and the statistics derived from them.
+///
+/// It lives in the domain layer on purpose: it is what has to be *correct*,
+/// independent of how anything chooses to draw it. A different UI, a headless
+/// run or a future export path all consume the same object, and none of them
+/// re-derive a mean or re-decide whether a warm-up interval counts.
+class Iperf3Session {
+  Iperf3Start? _start;
+
+  /// Connection details, once the run has reported them.
+  Iperf3Start? get start => _start;
+
+  final List<Iperf3Interval> _intervals = [];
+
+  /// Throughput samples in arrival order, warm-up intervals excluded.
+  List<Iperf3Interval> get intervals => List.unmodifiable(_intervals);
+
+  Iperf3End? _summary;
+
+  /// Sent/received totals, once the run has finished.
+  Iperf3End? get summary => _summary;
+
+  final List<String> _errors = [];
+
+  /// Errors reported during the run, in order.
+  List<String> get errors => List.unmodifiable(_errors);
+
+  bool _stopped = false;
+
+  /// Whether the run ended because it was asked to stop.
+  bool get stopped => _stopped;
+
+  /// Whether iperf3 reported any error.
+  bool get hasError => _errors.isNotEmpty;
+
+  /// Whether anything at all has been recorded.
+  bool get isEmpty =>
+      _start == null && _intervals.isEmpty && _summary == null && !hasError;
+
+  /// How many throughput samples have been recorded.
+  int get sampleCount => _intervals.length;
+
+  /// Throughput of the most recent sample, or null before the first one.
+  double? get latestBitsPerSecond =>
+      _intervals.isEmpty ? null : _intervals.last.bitsPerSecond;
+
+  /// Mean throughput across the samples, or null before the first one.
+  ///
+  /// This is the mean of the per-interval rates, which is not identical to the
+  /// run's overall rate when intervals differ in length — prefer
+  /// [summary]'s totals for the headline figure once it is available.
+  double? get meanBitsPerSecond {
+    if (_intervals.isEmpty) return null;
+    final total = _intervals.fold<double>(0, (sum, i) => sum + i.bitsPerSecond);
+    return total / _intervals.length;
+  }
+
+  /// Highest sampled throughput, or null before the first sample.
+  double? get peakBitsPerSecond {
+    if (_intervals.isEmpty) return null;
+    return _intervals
+        .map((i) => i.bitsPerSecond)
+        .reduce((a, b) => a > b ? a : b);
+  }
+
+  /// Total bytes across the recorded samples.
+  int get sampledBytes => _intervals.fold<int>(0, (sum, i) => sum + i.bytes);
+
+  /// Total retransmits across the samples, or null if none were reported.
+  ///
+  /// UDP tests report no retransmit counts, so null means "not measured"
+  /// rather than zero.
+  int? get totalRetransmits {
+    final reported =
+        _intervals.map((i) => i.retransmits).whereType<int>().toList();
+    if (reported.isEmpty) return null;
+    return reported.fold<int>(0, (sum, r) => sum + r);
+  }
+
+  /// Record one report.
+  void add(Iperf3Event event) {
+    switch (event) {
+      case Iperf3Start e:
+        _start = e;
+      case Iperf3Interval e:
+        // Warm-up intervals (-O) are marked omitted by iperf3 and must not
+        // drag the statistics down.
+        if (!e.omitted) _intervals.add(e);
+      case Iperf3End e:
+        _summary = e;
+      case Iperf3Error e:
+        _errors.add(e.message);
+      case Iperf3Stopped _:
+        _stopped = true;
+      case Iperf3LogLine _:
+        break;
+    }
+  }
+
+  /// Forget everything, ready for another run.
+  void clear() {
+    _start = null;
+    _intervals.clear();
+    _summary = null;
+    _errors.clear();
+    _stopped = false;
+  }
+}
@@ -7,7 +7,7 @@ class TestConfiguration {
  final int parallelStreams;

  const TestConfiguration({
-    this.server = 'iperf.es.net',
+    this.server = 'speedtest.uztelecom.uz',
    this.port = 5201,
    this.duration = const Duration(seconds: 10),
    this.interval = 1,
@@ -0,0 +1,36 @@
+import 'package:iperf3gui/domain/models/iperf3_event.dart';
+import 'package:iperf3gui/domain/models/iperf3_result.dart';
+import 'package:iperf3gui/domain/models/test_configuration.dart';
+
+/// Runs iperf3 tests and reports what happens.
+///
+/// This is the whole contract the UI depends on. It is deliberately pure Dart —
+/// no Flutter import — so the presentation layer never names a transport. The
+/// Android build supplies a MethodChannel-and-JNI implementation
+/// (`Iperf3Service`); a test, a desktop build or a headless tool can supply
+/// its own without touching anything above this line.
+abstract interface class Iperf3Runner {
+  /// Reports parsed from the running test, one event per iperf3 report.
+  ///
+  /// A broadcast stream: it may have no listener, and late listeners miss
+  /// earlier events rather than replaying them.
+  Stream<Iperf3Event> get events;
+
+  /// Whether a test is in flight right now.
+  bool get isRunning;
+
+  /// Run a test to completion and resolve with its outcome.
+  ///
+  /// Resolves rather than throws for an iperf3-level failure — the failure is
+  /// carried in [Iperf3Result.exitCode]. Implementations must always resolve,
+  /// including on internal error, so a caller can never be left awaiting.
+  Future<Iperf3Result> run(TestConfiguration config);
+
+  /// Ask a running test to stop early. A no-op when nothing is running.
+  ///
+  /// The run's future still resolves, with [Iperf3Result.stopped] set.
+  Future<void> stop();
+
+  /// Release resources. The instance is unusable afterwards.
+  Future<void> dispose();
+}
@@ -1,17 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:iperf3gui/data/services/iperf3_service.dart';
+import 'package:iperf3gui/domain/services/iperf3_runner.dart';
 import 'package:iperf3gui/ui/features/test_run/test_run_screen.dart';

-/// Application entry point.
+/// Application entry point, and the composition root.
 ///
-/// iperf3 is now compiled as a native shared library (libiperf3jni.so)
-/// and accessed via JNI — no binary extraction or chmod needed.
+/// This is the only place that names a concrete [Iperf3Runner]. Everything
+/// above the data layer depends on the interface, so swapping the transport —
+/// or running the UI against a fake — touches nothing but this file.
 Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
-  runApp(const Iperf3GuiApp());
+  runApp(Iperf3GuiApp(runner: Iperf3Service()));
 }

 class Iperf3GuiApp extends StatelessWidget {
-  const Iperf3GuiApp({super.key});
+  const Iperf3GuiApp({required this.runner, super.key});
+
+  final Iperf3Runner runner;

  @override
  Widget build(BuildContext context) {
@@ -21,7 +26,7 @@ class Iperf3GuiApp extends StatelessWidget {
        colorSchemeSeed: Colors.blue,
        useMaterial3: true,
      ),
-      home: const TestRunScreen(),
+      home: TestRunScreen(runner: runner),
    );
  }
 }
@@ -0,0 +1,105 @@
+// Headless entry point: runs one iperf3 test with no widgets.
+//
+// This exists to keep the core honest. If anything in the run path ever starts
+// depending on the UI, this stops compiling or stops working — a claim about
+// separation that is checked rather than asserted.
+//
+// It is also the low-noise way to measure. The UI competes with the test for
+// CPU (a gigabit run can put the phone near CPU-bound), so figures taken here
+// are cleaner than figures taken with a transcript repainting alongside.
+//
+//   flutter run -t lib/main_headless.dart \
+//     --dart-define=IPERF_SERVER=192.168.2.182 \
+//     --dart-define=IPERF_STREAMS=4
+//
+// Nothing below imports lib/ui, and test/architecture_test.dart enforces that.
+
+import 'package:flutter/widgets.dart' show WidgetsFlutterBinding;
+import 'package:flutter/foundation.dart' show debugPrint;
+
+import 'package:iperf3gui/data/services/iperf3_service.dart';
+import 'package:iperf3gui/domain/models/iperf3_event.dart';
+import 'package:iperf3gui/domain/models/iperf3_session.dart';
+import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/domain/services/iperf3_runner.dart';
+
+/// Test parameters, supplied at build time with --dart-define.
+const String _server = String.fromEnvironment('IPERF_SERVER',
+    defaultValue: 'speedtest.uztelecom.uz');
+const int _port = int.fromEnvironment('IPERF_PORT', defaultValue: 5201);
+const int _seconds = int.fromEnvironment('IPERF_SECONDS', defaultValue: 10);
+const int _streams = int.fromEnvironment('IPERF_STREAMS', defaultValue: 1);
+
+Future<void> main() async {
+  // Required for the MethodChannel. Notably NOT runApp() — there is no widget
+  // tree, no render surface and no Flutter UI thread work in this process.
+  WidgetsFlutterBinding.ensureInitialized();
+
+  const config = TestConfiguration(
+    server: _server,
+    port: _port,
+    duration: Duration(seconds: _seconds),
+    parallelStreams: _streams,
+  );
+
+  final Iperf3Runner runner = Iperf3Service();
+  final session = Iperf3Session();
+
+  final subscription = runner.events.listen((event) {
+    session.add(event);
+    if (event is Iperf3Interval && !event.omitted) {
+      _out('interval ${event.start.toStringAsFixed(2)}-'
+          '${event.end.toStringAsFixed(2)}s  '
+          '${_mbits(event.bitsPerSecond)} Mbit/s'
+          '${event.retransmits != null ? '  retr=${event.retransmits}' : ''}');
+    } else if (event is Iperf3Error) {
+      _out('error: ${event.message}');
+    }
+  });
+
+  _out('running iperf3 -c ${config.server} -p ${config.port} '
+      '-t ${config.duration.inSeconds} -P ${config.parallelStreams}');
+
+  final result = await runner.run(config);
+  await subscription.cancel();
+  await runner.dispose();
+
+  _report(result.exitCode, session);
+}
+
+void _report(int exitCode, Iperf3Session session) {
+  _out('--- result ---');
+  _out('exit code:    $exitCode');
+  _out('samples:      ${session.sampleCount}');
+
+  final mean = session.meanBitsPerSecond;
+  final peak = session.peakBitsPerSecond;
+  if (mean != null) _out('mean:         ${_mbits(mean)} Mbit/s');
+  if (peak != null) _out('peak:         ${_mbits(peak)} Mbit/s');
+
+  final retr = session.totalRetransmits;
+  _out('retransmits:  ${retr ?? 'not measured'}');
+
+  final sent = session.summary?.sent;
+  final received = session.summary?.received;
+  if (sent != null) {
+    _out('sent:         ${_mbits(sent.bitsPerSecond)} Mbit/s '
+        'over ${sent.seconds.toStringAsFixed(2)}s');
+  }
+  if (received != null) {
+    _out('received:     ${_mbits(received.bitsPerSecond)} Mbit/s '
+        'over ${received.seconds.toStringAsFixed(2)}s');
+  }
+  final cpu = session.summary?.hostCpuPercent;
+  if (cpu != null) _out('local cpu:    ${cpu.toStringAsFixed(1)}%');
+
+  if (session.stopped) _out('ended early:  stopped');
+  for (final error in session.errors) {
+    _out('error:        $error');
+  }
+}
+
+String _mbits(double bitsPerSecond) =>
+    (bitsPerSecond / 1e6).toStringAsFixed(1);
+
+void _out(String line) => debugPrint('[iperf3-headless] $line');
@@ -1,24 +1,25 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:provider/provider.dart';
-import 'package:iperf3gui/data/services/iperf3_service.dart';
 import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/domain/services/iperf3_runner.dart';
 import 'package:iperf3gui/ui/features/test_run/iperf3_event_formatter.dart';
 import 'package:iperf3gui/ui/features/test_run/test_run_view_model.dart';

 /// Main test run screen.
 ///
-/// iperf3 is compiled as a native shared library (libiperf3jni.so) and accessed
-/// via JNI, so there is no binary extraction or chmod step.
+/// Takes an [Iperf3Runner] rather than constructing one, so this layer names no
+/// transport: the Android app injects the JNI-backed implementation from
+/// main(), and a test injects a fake.
 class TestRunScreen extends StatelessWidget {
-  const TestRunScreen({super.key});
+  const TestRunScreen({required this.runner, super.key});
+
+  final Iperf3Runner runner;

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
-      create: (_) => TestRunViewModel(
-        iperf3Service: Iperf3Service(),
-      ),
+      create: (_) => TestRunViewModel(iperf3Service: runner),
      child: const _TestRunContent(),
    );
  }
@@ -109,7 +110,7 @@ class _TestRunContentState extends State<_TestRunContent> {
              autocorrect: false,
              decoration: const InputDecoration(
                labelText: 'Server',
-                hintText: 'e.g. iperf.es.net or 192.168.1.1',
+                hintText: 'e.g. speedtest.uztelecom.uz or 192.168.1.1',
              ),
            ),
            const SizedBox(height: 12),
@@ -194,29 +195,31 @@ class _TestRunContentState extends State<_TestRunContent> {
            ),
            const SizedBox(height: 12),

-            // Live throughput figures, derived from the parsed interval series
+            // Live throughput figures. Every number here is read off the
+            // session; none are computed in the widget tree.
            Consumer<TestRunViewModel>(
              builder: (context, vm, _) {
-                final intervals = vm.intervals;
-                if (intervals.isEmpty) return const SizedBox.shrink();
-                final rates =
-                    intervals.map((i) => i.bitsPerSecond).toList(growable: false);
-                final latest = rates.last;
-                final peak = rates.reduce((a, b) => a > b ? a : b);
-                final mean = rates.reduce((a, b) => a + b) / rates.length;
-                final summary = vm.summary?.sent;
+                final session = vm.session;
+                final latest = session.latestBitsPerSecond;
+                final mean = session.meanBitsPerSecond;
+                final peak = session.peakBitsPerSecond;
+                if (latest == null || mean == null || peak == null) {
+                  return const SizedBox.shrink();
+                }
+                final total = session.summary?.sent;
                return Padding(
                  padding: const EdgeInsets.only(bottom: 12),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      _Stat(
-                        label: summary != null ? 'total' : 'now',
-                        value: formatBitrate(summary?.bitsPerSecond ?? latest),
+                        label: total != null ? 'total' : 'now',
+                        value: formatBitrate(total?.bitsPerSecond ?? latest),
                      ),
                      _Stat(label: 'avg', value: formatBitrate(mean)),
                      _Stat(label: 'peak', value: formatBitrate(peak)),
-                      _Stat(label: 'samples', value: '${rates.length}'),
+                      _Stat(
+                          label: 'samples', value: '${session.sampleCount}'),
                    ],
                  ),
                );
@@ -1,10 +1,11 @@
 import 'dart:async';

 import 'package:flutter/foundation.dart';
-import 'package:iperf3gui/data/services/iperf3_service.dart';
 import 'package:iperf3gui/domain/models/iperf3_event.dart';
 import 'package:iperf3gui/domain/models/iperf3_result.dart';
+import 'package:iperf3gui/domain/models/iperf3_session.dart';
 import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/domain/services/iperf3_runner.dart';
 import 'package:iperf3gui/ui/features/test_run/iperf3_event_formatter.dart';

 /// State of the test run.
@@ -12,10 +13,12 @@ enum TestRunState { idle, running, completed, error }

 /// ViewModel for managing test run state.
 ///
-/// Subscribes to [Iperf3Service.events] so the transcript and the interval
-/// series both grow while the test runs, rather than appearing at the end.
+/// Presentation only. What happened during a run is accumulated by
+/// [Iperf3Session] in the domain layer; this class subscribes to
+/// [Iperf3Runner.events], feeds that session, keeps a formatted transcript for
+/// display, and decides when to repaint.
 class TestRunViewModel extends ChangeNotifier {
-  final Iperf3Service iperf3Service;
+  final Iperf3Runner iperf3Service;

  /// How often to notify listeners while output is arriving. iperf3 can report
  /// several times a second across many streams, and each rebuild re-renders
@@ -41,24 +44,14 @@ class TestRunViewModel extends ChangeNotifier {

  final StringBuffer _transcript = StringBuffer();

-  /// Human-readable output accumulated so far.
+  /// Human-readable output accumulated so far. Display only — the structured
+  /// record of the run is [session].
  String get output => _transcript.toString();

-  final List<Iperf3Interval> _intervals = [];
+  final Iperf3Session _session = Iperf3Session();

-  /// Per-interval throughput samples, in arrival order. Structured, so a chart
-  /// can be driven from this without re-parsing text.
-  List<Iperf3Interval> get intervals => List.unmodifiable(_intervals);
-
-  Iperf3Start? _start;
-
-  /// Connection details reported at the start of the run.
-  Iperf3Start? get start => _start;
-
-  Iperf3End? _summary;
-
-  /// Totals reported at the end of the run.
-  Iperf3End? get summary => _summary;
+  /// The accumulated run: interval series, totals, errors and their statistics.
+  Iperf3Session get session => _session;

  /// Whether a test is currently in flight.
  bool get isRunning => _state == TestRunState.running;
@@ -118,26 +111,12 @@ class TestRunViewModel extends ChangeNotifier {
  void _resetRunData() {
    _result = null;
    _transcript.clear();
-    _intervals.clear();
-    _start = null;
-    _summary = null;
+    _session.clear();
    _dirty = false;
  }

  void _onEvent(Iperf3Event event) {
-    switch (event) {
-      case Iperf3Start e:
-        _start = e;
-      case Iperf3Interval e:
-        // Omitted intervals are warm-up (-O) and are not part of the series.
-        if (!e.omitted) _intervals.add(e);
-      case Iperf3End e:
-        _summary = e;
-      case Iperf3Error _:
-      case Iperf3Stopped _:
-      case Iperf3LogLine _:
-        break;
-    }
+    _session.add(event);

    final line = formatIperf3Event(event);
    if (line != null && line.isNotEmpty) {
@@ -2,7 +2,7 @@ name: iperf3gui
 description: "A Flutter-based Android GUI wrapper for iperf3."
 publish_to: 'none'

-version: 1.0.0+1
+version: 0.1.0+1

 environment:
  sdk: ^3.13.1
@@ -0,0 +1,144 @@
+// Enforces the layering. A convention nobody checks is a convention that
+// decays, so these read the real import statements in lib/ and fail on a
+// violation rather than trusting review to catch it.
+//
+// The rule, in one line: dependencies point inward. ui → domain ← data, and
+// never the reverse.
+
+import 'dart:io';
+
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('layering', () {
+    test('domain imports no Flutter at all', () {
+      final offenders = _importsMatching(
+        'lib/domain',
+        (import) => import.startsWith('package:flutter/'),
+      );
+      expect(
+        offenders,
+        isEmpty,
+        reason: 'The domain layer must stay pure Dart so it can be reused '
+            'without a Flutter runtime. Offending imports:\n'
+            '${_render(offenders)}',
+      );
+    });
+
+    test('domain does not depend on data or ui', () {
+      final offenders = _importsMatching(
+        'lib/domain',
+        (import) =>
+            import.contains('/data/') ||
+            import.contains('/ui/') ||
+            import.contains('main.dart'),
+      );
+      expect(offenders, isEmpty,
+          reason: 'The domain layer is the innermost layer; it may depend on '
+              'nothing else in this package.\n${_render(offenders)}');
+    });
+
+    test('data does not depend on ui', () {
+      final offenders = _importsMatching(
+        'lib/data',
+        (import) => import.contains('/ui/') || import.contains('main.dart'),
+      );
+      expect(offenders, isEmpty,
+          reason: 'The data layer must not know about presentation.\n'
+              '${_render(offenders)}');
+    });
+
+    test('data imports no Flutter widget libraries', () {
+      // flutter/services is allowed: MethodChannel lives there, and that is
+      // the whole reason this layer is Flutter-aware at all.
+      const allowed = {'package:flutter/services.dart'};
+      final offenders = _importsMatching(
+        'lib/data',
+        (import) =>
+            import.startsWith('package:flutter/') && !allowed.contains(import),
+      );
+      expect(
+        offenders,
+        isEmpty,
+        reason: 'The data layer may import package:flutter/services.dart only. '
+            'Anything else drags presentation into the transport.\n'
+            '${_render(offenders)}',
+      );
+    });
+
+    test('ui does not depend on a concrete data implementation', () {
+      // The UI talks to Iperf3Runner. main.dart is the composition root and is
+      // the one file allowed to name an implementation.
+      final offenders = _importsMatching(
+        'lib/ui',
+        (import) => import.contains('/data/'),
+      );
+      expect(
+        offenders,
+        isEmpty,
+        reason: 'Presentation must depend on domain/services/iperf3_runner.dart '
+            'rather than on a transport. Only main.dart may pick an '
+            'implementation.\n${_render(offenders)}',
+      );
+    });
+
+    test('the headless entry point does not depend on ui', () {
+      // main_headless.dart is the standing proof that the core runs without a
+      // widget tree; an import from lib/ui would quietly end that.
+      final offenders = _importsMatching(
+        'lib',
+        (import) => import.contains('/ui/'),
+        onlyFiles: {'lib/main_headless.dart'},
+      );
+      expect(
+        offenders,
+        isEmpty,
+        reason: 'The headless entry point must run the core with no UI.\n'
+            '${_render(offenders)}',
+      );
+    });
+
+    test('every layer directory is actually covered by these rules', () {
+      // Guards against a new top-level layer appearing and silently escaping
+      // every rule above.
+      final layers = Directory('lib')
+          .listSync()
+          .whereType<Directory>()
+          .map((d) => d.path.split(Platform.pathSeparator).last)
+          .toSet();
+      expect(
+        layers,
+        equals({'domain', 'data', 'ui'}),
+        reason: 'A new layer appeared under lib/. Add rules for it here.',
+      );
+    });
+  });
+}
+
+/// Every `(file, import)` pair under [directory] whose import satisfies [test].
+List<({String file, String import})> _importsMatching(
+  String directory,
+  bool Function(String import) test, {
+  Set<String>? onlyFiles,
+}) {
+  final results = <({String file, String import})>[];
+  final dir = Directory(directory);
+  if (!dir.existsSync()) return results;
+
+  final pattern = RegExp(r'''^\s*import\s+['"]([^'"]+)['"]''', multiLine: true);
+  for (final entity in dir.listSync(recursive: true)) {
+    if (entity is! File || !entity.path.endsWith('.dart')) continue;
+    if (onlyFiles != null && !onlyFiles.contains(entity.path)) continue;
+    final source = entity.readAsStringSync();
+    for (final match in pattern.allMatches(source)) {
+      final import = match.group(1)!;
+      if (test(import)) {
+        results.add((file: entity.path, import: import));
+      }
+    }
+  }
+  return results;
+}
+
+String _render(List<({String file, String import})> offenders) =>
+    offenders.map((o) => '  ${o.file} → ${o.import}').join('\n');
@@ -0,0 +1,135 @@
+// Pure-Dart tests for the run aggregate. No widgets, no bindings, no channel —
+// this is the part that has to be correct regardless of what draws it.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:iperf3gui/domain/models/iperf3_event.dart';
+import 'package:iperf3gui/domain/models/iperf3_session.dart';
+
+void main() {
+  Iperf3Interval sample(double start, double bits,
+          {int bytes = 1000, int? retransmits, bool omitted = false}) =>
+      Iperf3Interval(
+        start: start,
+        end: start + 1,
+        bytes: bytes,
+        bitsPerSecond: bits,
+        retransmits: retransmits,
+        omitted: omitted,
+      );
+
+  group('Iperf3Session', () {
+    test('starts empty', () {
+      final session = Iperf3Session();
+      expect(session.isEmpty, isTrue);
+      expect(session.sampleCount, isZero);
+      expect(session.intervals, isEmpty);
+      expect(session.start, isNull);
+      expect(session.summary, isNull);
+      expect(session.errors, isEmpty);
+      expect(session.stopped, isFalse);
+      expect(session.hasError, isFalse);
+    });
+
+    test('statistics are null before any sample', () {
+      final session = Iperf3Session();
+      expect(session.latestBitsPerSecond, isNull);
+      expect(session.meanBitsPerSecond, isNull);
+      expect(session.peakBitsPerSecond, isNull);
+      expect(session.totalRetransmits, isNull);
+    });
+
+    test('records start, intervals and summary', () {
+      final session = Iperf3Session()
+        ..add(const Iperf3Start(targetHost: 'host', targetPort: 5201))
+        ..add(sample(0, 100))
+        ..add(const Iperf3End(
+          sent: Iperf3Total(seconds: 1, bytes: 10, bitsPerSecond: 80),
+        ));
+      expect(session.isEmpty, isFalse);
+      expect(session.start!.targetHost, equals('host'));
+      expect(session.sampleCount, equals(1));
+      expect(session.summary!.sent!.bitsPerSecond, equals(80));
+    });
+
+    test('excludes omitted warm-up intervals from the series', () {
+      final session = Iperf3Session()
+        ..add(sample(0, 10, omitted: true))
+        ..add(sample(1, 100))
+        ..add(sample(2, 200));
+      expect(session.sampleCount, equals(2));
+      expect(session.meanBitsPerSecond, equals(150),
+          reason: 'the omitted 10 would have pulled the mean to ~103');
+    });
+
+    test('computes mean, peak and latest over the samples', () {
+      final session = Iperf3Session()
+        ..add(sample(0, 100))
+        ..add(sample(1, 400))
+        ..add(sample(2, 250));
+      expect(session.latestBitsPerSecond, equals(250));
+      expect(session.peakBitsPerSecond, equals(400));
+      expect(session.meanBitsPerSecond, equals(250));
+    });
+
+    test('sums sampled bytes', () {
+      final session = Iperf3Session()
+        ..add(sample(0, 1, bytes: 1500))
+        ..add(sample(1, 1, bytes: 2500));
+      expect(session.sampledBytes, equals(4000));
+    });
+
+    test('sums retransmits when reported', () {
+      final session = Iperf3Session()
+        ..add(sample(0, 1, retransmits: 2))
+        ..add(sample(1, 1, retransmits: 5));
+      expect(session.totalRetransmits, equals(7));
+    });
+
+    test('retransmits stay null when never reported, not zero', () {
+      // UDP reports no retransmit counts; "not measured" must not read as 0.
+      final session = Iperf3Session()
+        ..add(sample(0, 1))
+        ..add(sample(1, 1));
+      expect(session.totalRetransmits, isNull);
+    });
+
+    test('collects errors in order and flags them', () {
+      final session = Iperf3Session()
+        ..add(const Iperf3Error('first'))
+        ..add(const Iperf3Error('second'));
+      expect(session.hasError, isTrue);
+      expect(session.errors, equals(['first', 'second']));
+      expect(session.isEmpty, isFalse);
+    });
+
+    test('records a stop', () {
+      final session = Iperf3Session()..add(const Iperf3Stopped());
+      expect(session.stopped, isTrue);
+    });
+
+    test('ignores log lines', () {
+      final session = Iperf3Session()..add(const Iperf3LogLine('noise'));
+      expect(session.isEmpty, isTrue);
+    });
+
+    test('clear returns it to the empty state', () {
+      final session = Iperf3Session()
+        ..add(const Iperf3Start(targetHost: 'host'))
+        ..add(sample(0, 100))
+        ..add(const Iperf3Error('boom'))
+        ..add(const Iperf3Stopped())
+        ..add(const Iperf3End())
+        ..clear();
+      expect(session.isEmpty, isTrue);
+      expect(session.stopped, isFalse);
+      expect(session.hasError, isFalse);
+      expect(session.peakBitsPerSecond, isNull);
+    });
+
+    test('exposed collections are unmodifiable', () {
+      final session = Iperf3Session()..add(sample(0, 1));
+      expect(() => session.intervals.add(sample(1, 1)), throwsUnsupportedError);
+      expect(() => session.errors.add('x'), throwsUnsupportedError);
+    });
+  });
+}
@@ -0,0 +1,62 @@
+import 'dart:async';
+
+import 'package:iperf3gui/domain/models/iperf3_event.dart';
+import 'package:iperf3gui/domain/models/iperf3_result.dart';
+import 'package:iperf3gui/domain/models/test_configuration.dart';
+import 'package:iperf3gui/domain/services/iperf3_runner.dart';
+
+/// In-memory [Iperf3Runner] for tests.
+///
+/// Implements the interface rather than the concrete service, so it tracks the
+/// five members the UI actually depends on instead of every public member the
+/// MethodChannel implementation happens to have.
+class FakeIperf3Runner implements Iperf3Runner {
+  FakeIperf3Runner({this.onRun});
+
+  /// Supplies the result for each [run], and may [emit] events first.
+  Future<Iperf3Result> Function(TestConfiguration)? onRun;
+
+  final StreamController<Iperf3Event> _controller =
+      StreamController<Iperf3Event>.broadcast();
+
+  /// Configurations passed to [run], in order.
+  final List<TestConfiguration> runCalls = [];
+
+  int stopCallCount = 0;
+  bool disposed = false;
+  bool _isRunning = false;
+
+  int get runCallCount => runCalls.length;
+
+  /// Push an event as if the native layer had reported it.
+  void emit(Iperf3Event event) => _controller.add(event);
+
+  @override
+  Stream<Iperf3Event> get events => _controller.stream;
+
+  @override
+  bool get isRunning => _isRunning;
+
+  @override
+  Future<Iperf3Result> run(TestConfiguration config) async {
+    runCalls.add(config);
+    _isRunning = true;
+    try {
+      if (onRun != null) return await onRun!(config);
+      return const Iperf3Result(rawOutput: '', exitCode: 0);
+    } finally {
+      _isRunning = false;
+    }
+  }
+
+  @override
+  Future<void> stop() async {
+    stopCallCount++;
+  }
+
+  @override
+  Future<void> dispose() async {
+    disposed = true;
+    await _controller.close();
+  }
+}
@@ -1,16 +1,17 @@
 import 'dart:async';

 import 'package:flutter_test/flutter_test.dart';
-import 'package:iperf3gui/data/services/iperf3_service.dart';
 import 'package:iperf3gui/domain/models/iperf3_event.dart';
 import 'package:iperf3gui/domain/models/iperf3_result.dart';
 import 'package:iperf3gui/domain/models/test_configuration.dart';
 import 'package:iperf3gui/ui/features/test_run/test_run_view_model.dart';

+import '../../../support/fake_iperf3_runner.dart';
+
 void main() {
  group('TestRunViewModel', () {
    test('starts in idle state', () {
-      final vm = TestRunViewModel(iperf3Service: _MockIperf3Service());
+      final vm = TestRunViewModel(iperf3Service: FakeIperf3Runner());
      expect(vm.state, equals(TestRunState.idle));
      expect(vm.result, isNull);
      expect(vm.currentConfig, isNull);
@@ -18,13 +19,13 @@ void main() {
    });

    test('can be reset', () {
-      final vm = TestRunViewModel(iperf3Service: _MockIperf3Service());
+      final vm = TestRunViewModel(iperf3Service: FakeIperf3Runner());
      vm.reset();
      expect(vm.state, equals(TestRunState.idle));
    });

    test('invalid config sets error state without running', () async {
-      final mock = _MockIperf3Service();
+      final mock = FakeIperf3Runner();
      final vm = TestRunViewModel(iperf3Service: mock);
      const config = TestConfiguration(server: '');
      await vm.runTest(config);
@@ -33,7 +34,7 @@ void main() {
    });

    test('runTest with valid config calls service', () async {
-      final mock = _MockIperf3Service(
+      final mock = FakeIperf3Runner(
        onRun: (config) async {
          expect(config.server, equals('192.168.1.1'));
          return const Iperf3Result(rawOutput: 'done', exitCode: 0);
@@ -47,7 +48,7 @@ void main() {
    });

    test('non-zero exit code lands in error state', () async {
-      final mock = _MockIperf3Service(
+      final mock = FakeIperf3Runner(
        onRun: (_) async =>
            const Iperf3Result(rawOutput: 'boom', exitCode: 1),
      );
@@ -58,7 +59,7 @@ void main() {
    });

    test('streamed events accumulate into output during the run', () async {
-      final mock = _MockIperf3Service();
+      final mock = FakeIperf3Runner();
      mock.onRun = (_) async {
        mock.emit(const Iperf3Start(targetHost: '192.168.1.1', targetPort: 5201));
        mock.emit(const Iperf3Interval(
@@ -81,48 +82,13 @@ void main() {
      expect(vm.output, isNot(contains('ignored')));
    });

-    test('intervals are collected as structured samples', () async {
-      final mock = _MockIperf3Service();
+    test('events are fed into the session', () async {
+      final mock = FakeIperf3Runner();
      mock.onRun = (_) async {
        mock.emit(const Iperf3Interval(
            start: 0, end: 1, bytes: 1000, bitsPerSecond: 8000));
-        mock.emit(const Iperf3Interval(
-            start: 1, end: 2, bytes: 2000, bitsPerSecond: 16000));
-        await Future<void>.delayed(Duration.zero);
-        return const Iperf3Result(rawOutput: '', exitCode: 0);
-      };
-
-      final vm = TestRunViewModel(iperf3Service: mock);
-      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));
-
-      expect(vm.intervals, hasLength(2));
-      expect(vm.intervals[1].bitsPerSecond, equals(16000));
-    });
-
-    test('omitted warm-up intervals are excluded from the series', () async {
-      final mock = _MockIperf3Service();
-      mock.onRun = (_) async {
-        mock.emit(const Iperf3Interval(
-            start: 0, end: 1, bytes: 1, bitsPerSecond: 1, omitted: true));
-        mock.emit(const Iperf3Interval(
-            start: 1, end: 2, bytes: 2000, bitsPerSecond: 16000));
-        await Future<void>.delayed(Duration.zero);
-        return const Iperf3Result(rawOutput: '', exitCode: 0);
-      };
-
-      final vm = TestRunViewModel(iperf3Service: mock);
-      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));
-
-      expect(vm.intervals, hasLength(1));
-      expect(vm.intervals.single.bitsPerSecond, equals(16000));
-    });
-
-    test('end event is retained as the summary', () async {
-      final mock = _MockIperf3Service();
-      mock.onRun = (_) async {
        mock.emit(const Iperf3End(
-          sent: Iperf3Total(
-              seconds: 10, bytes: 987654321, bitsPerSecond: 790000000),
+          sent: Iperf3Total(seconds: 1, bytes: 1000, bitsPerSecond: 8000),
        ));
        await Future<void>.delayed(Duration.zero);
        return const Iperf3Result(rawOutput: '', exitCode: 0);
@@ -131,12 +97,12 @@ void main() {
      final vm = TestRunViewModel(iperf3Service: mock);
      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));

-      expect(vm.summary?.sent?.bitsPerSecond, equals(790000000));
-      expect(vm.output, contains('790 Mbits/sec'));
+      expect(vm.session.sampleCount, equals(1));
+      expect(vm.session.summary, isNotNull);
    });

-    test('a new run clears the previous interval series', () async {
-      final mock = _MockIperf3Service();
+    test('a new run clears the previous session', () async {
+      final mock = FakeIperf3Runner();
      mock.onRun = (_) async {
        mock.emit(const Iperf3Interval(
            start: 0, end: 1, bytes: 1000, bitsPerSecond: 8000));
@@ -146,14 +112,15 @@ void main() {

      final vm = TestRunViewModel(iperf3Service: mock);
      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));
-      expect(vm.intervals, hasLength(1));
+      expect(vm.session.sampleCount, equals(1));

      await vm.runTest(const TestConfiguration(server: '192.168.1.1'));
-      expect(vm.intervals, hasLength(1), reason: 'not appended to the old run');
+      expect(vm.session.sampleCount, equals(1),
+          reason: 'not appended to the old run');
    });

    test('falls back to result output when nothing streamed', () async {
-      final mock = _MockIperf3Service(
+      final mock = FakeIperf3Runner(
        onRun: (_) async =>
            const Iperf3Result(rawOutput: 'summary only', exitCode: 0),
      );
@@ -163,7 +130,7 @@ void main() {
    });

    test('output is cleared when a new run starts', () async {
-      final mock = _MockIperf3Service(
+      final mock = FakeIperf3Runner(
        onRun: (_) async =>
            const Iperf3Result(rawOutput: 'first', exitCode: 0),
      );
@@ -179,7 +146,7 @@ void main() {
    });

    test('stopTest forwards to the service only while running', () async {
-      final mock = _MockIperf3Service();
+      final mock = FakeIperf3Runner();
      final vm = TestRunViewModel(iperf3Service: mock);

      await vm.stopTest();
@@ -198,7 +165,7 @@ void main() {
    });

    test('wasStopped reflects a user-requested stop', () async {
-      final mock = _MockIperf3Service(
+      final mock = FakeIperf3Runner(
        onRun: (_) async => const Iperf3Result(
          rawOutput: 'stopped early',
          exitCode: 0,
@@ -213,7 +180,7 @@ void main() {
    });

    test('wasStopped is false for a run that finished on its own', () async {
-      final mock = _MockIperf3Service(
+      final mock = FakeIperf3Runner(
        onRun: (_) async =>
            const Iperf3Result(rawOutput: 'done', exitCode: 0),
      );
@@ -223,7 +190,7 @@ void main() {
    });

    test('a second runTest while running is ignored', () async {
-      final mock = _MockIperf3Service();
+      final mock = FakeIperf3Runner();
      final gate = Completer<Iperf3Result>();
      mock.onRun = (_) => gate.future;

@@ -237,49 +204,3 @@ void main() {
    });
  });
 }
-
-class _MockIperf3Service implements Iperf3Service {
-  _MockIperf3Service({this.onRun});
-
-  Future<Iperf3Result> Function(TestConfiguration)? onRun;
-
-  final StreamController<Iperf3Event> _controller =
-      StreamController<Iperf3Event>.broadcast();
-
-  int runCallCount = 0;
-  int stopCallCount = 0;
-  bool disposed = false;
-  bool _isRunning = false;
-
-  /// Push an event as if the native layer had reported it.
-  void emit(Iperf3Event event) => _controller.add(event);
-
-  @override
-  Stream<Iperf3Event> get events => _controller.stream;
-
-  @override
-  bool get isRunning => _isRunning;
-
-  @override
-  Future<Iperf3Result> run(TestConfiguration config) async {
-    runCallCount++;
-    _isRunning = true;
-    try {
-      if (onRun != null) return await onRun!(config);
-      return const Iperf3Result(rawOutput: '', exitCode: 0);
-    } finally {
-      _isRunning = false;
-    }
-  }
-
-  @override
-  Future<void> stop() async {
-    stopCallCount++;
-  }
-
-  @override
-  Future<void> dispose() async {
-    disposed = true;
-    await _controller.close();
-  }
-}
@@ -1,17 +1,89 @@
-// This is a basic Flutter widget test.
+// Widget-level smoke tests.
 //
-// To perform an interaction with a widget in your test, use the WidgetTester
-// utility in the flutter_test package. For example, you can send tap and scroll
-// gestures. You can also use WidgetTester to find child widgets in the widget
-// tree, read text, and verify that the values of widget properties are correct.
+// These drive the real UI against a FakeIperf3Runner: no MethodChannel, no
+// native library, no device. That is only possible because the presentation
+// layer depends on the Iperf3Runner interface rather than on Iperf3Service.

+import 'dart:async';
+
+import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';

+import 'package:iperf3gui/domain/models/iperf3_event.dart';
+import 'package:iperf3gui/domain/models/iperf3_result.dart';
 import 'package:iperf3gui/main.dart';

+import 'support/fake_iperf3_runner.dart';
+
 void main() {
  testWidgets('App smoke test', (WidgetTester tester) async {
-    await tester.pumpWidget(const Iperf3GuiApp());
+    await tester.pumpWidget(Iperf3GuiApp(runner: FakeIperf3Runner()));
    expect(find.text('iperf3-gui'), findsOneWidget);
+    expect(find.text('GO'), findsOneWidget);
+    expect(find.text('Ready'), findsOneWidget);
+  });
+
+  testWidgets('runs a test and renders streamed results', (tester) async {
+    final runner = FakeIperf3Runner();
+    runner.onRun = (config) async {
+      runner.emit(Iperf3Start(
+        targetHost: config.server,
+        targetPort: config.port,
+        protocol: 'TCP',
+        streamCount: config.parallelStreams,
+      ));
+      runner.emit(const Iperf3Interval(
+        start: 0,
+        end: 1,
+        bytes: 98566144,
+        bitsPerSecond: 788410352,
+      ));
+      await Future<void>.delayed(Duration.zero);
+      return const Iperf3Result(rawOutput: '', exitCode: 0);
+    };
+
+    await tester.pumpWidget(Iperf3GuiApp(runner: runner));
+    await tester.tap(find.text('GO'));
+    await tester.pumpAndSettle();
+
+    expect(runner.runCallCount, equals(1));
+    expect(find.text('Test complete'), findsOneWidget);
+    expect(find.textContaining('788 Mbits/sec'), findsWidgets);
+    // The stat row is driven by the parsed interval series.
+    expect(find.text('peak'), findsOneWidget);
+  });
+
+  testWidgets('shows a stop button while running and can stop', (tester) async {
+    final runner = FakeIperf3Runner();
+    final gate = Completer<Iperf3Result>();
+    runner.onRun = (_) => gate.future;
+
+    await tester.pumpWidget(Iperf3GuiApp(runner: runner));
+    await tester.tap(find.text('GO'));
+    await tester.pump();
+
+    expect(find.text('STOP'), findsOneWidget);
+    expect(find.text('Running…'), findsOneWidget);
+
+    await tester.tap(find.text('STOP'));
+    await tester.pump();
+    expect(runner.stopCallCount, equals(1));
+
+    gate.complete(const Iperf3Result(
+        rawOutput: '', exitCode: 0, stopped: true));
+    await tester.pumpAndSettle();
+    expect(find.text('Stopped'), findsOneWidget);
+  });
+
+  testWidgets('rejects an empty server address', (tester) async {
+    final runner = FakeIperf3Runner();
+    await tester.pumpWidget(Iperf3GuiApp(runner: runner));
+
+    await tester.enterText(find.byType(TextField).first, '');
+    await tester.tap(find.text('GO'));
+    await tester.pumpAndSettle();
+
+    expect(runner.runCallCount, equals(0));
+    expect(find.textContaining('Invalid configuration'), findsOneWidget);
  });
 }
@@ -0,0 +1,112 @@
+#!/usr/bin/env bash
+# Assert that R8 left the names JNI resolves at runtime alone.
+#
+# iperf_jni.c looks up the callback methods by name with GetMethodID. R8 renames
+# by default, and a renamed callback does not fail the build — it produces an
+# APK that aborts on the first callback of every test:
+#
+#   NoSuchMethodError: no non-static method "Lp0;.onOutput(Ljava/lang/String;)V"
+#
+# That shipped once. Building the release APK is not enough to catch it, because
+# the build succeeds; this reads R8's own mapping file and checks the names
+# survived. Run after `flutter build apk --release`.
+
+set -euo pipefail
+
+MAPPING="${1:-build/app/outputs/mapping/release/mapping.txt}"
+APK="${2:-build/app/outputs/flutter-apk/app-release.apk}"
+
+if [[ ! -f "$MAPPING" ]]; then
+    echo "FAIL: no R8 mapping at $MAPPING"
+    echo "      Run 'flutter build apk --release' first. If the release build"
+    echo "      no longer minifies, this check is meaningless — say so"
+    echo "      explicitly rather than deleting it."
+    exit 1
+fi
+
+failed=0
+
+# A class kept by name maps to itself: "a.b.C -> a.b.C:".
+require_class_kept() {
+    local fqcn="$1"
+    if grep -qF -- "$fqcn -> $fqcn:" "$MAPPING"; then
+        echo "  ok    class  $fqcn"
+    else
+        echo "  FAIL  class  $fqcn was renamed or removed"
+        grep -F -- "$fqcn ->" "$MAPPING" | head -3 | sed 's/^/          got: /' || true
+        failed=1
+    fi
+}
+
+# A method kept by name ends with "-> <name>".
+require_method_kept() {
+    local signature="$1" name="$2"
+    if grep -qE -- "$signature.*-> ${name}\$" "$MAPPING"; then
+        echo "  ok    method $name"
+    else
+        echo "  FAIL  method $name was renamed"
+        grep -E -- "$signature" "$MAPPING" | head -3 | sed 's/^/          got: /' || true
+        failed=1
+    fi
+}
+
+echo "Checking JNI-visible names in $MAPPING"
+
+require_class_kept 'com.novoyuuparosk.iperf3gui.IperfRunner'
+require_class_kept 'com.novoyuuparosk.iperf3gui.IperfRunner$IperfCallback'
+require_class_kept 'com.novoyuuparosk.iperf3gui.IperfRunner$MainThreadCallback'
+
+# Resolved by iperf_jni.c on the concrete callback object's class.
+require_method_kept 'void onOutput\(java\.lang\.String\)' 'onOutput'
+require_method_kept 'void onError\(java\.lang\.String\)' 'onError'
+require_method_kept 'void onComplete\(\)' 'onComplete'
+
+# Native methods are NOT checked against mapping.txt: R8 only emits entries for
+# members it has line-number info or a rename for, and a native method has no
+# body, so it is absent whether or not it was renamed. Absence would prove
+# nothing. Check the DEX string pool instead — a surviving name is interned
+# there, a renamed one is not.
+check_dex_names() {
+    local apk="$1"
+    shift
+    if [[ ! -f "$apk" ]]; then
+        echo "  skip  DEX name check: no APK at $apk"
+        return
+    fi
+    local tmp
+    tmp="$(mktemp -d)"
+    trap 'rm -rf "$tmp"' RETURN
+    if ! unzip -o -q "$apk" 'classes*.dex' -d "$tmp" 2>/dev/null; then
+        echo "  FAIL  could not extract classes*.dex from $apk"
+        failed=1
+        return
+    fi
+    # Dump the string pool once to a file, then grep the file. Never
+    # `... | strings | grep -q`: grep -q exits at the first match, SIGPIPEs
+    # strings, and `set -o pipefail` reports the whole pipeline as failed — so
+    # a name found early "fails" and one found late passes. That flakiness cost
+    # an afternoon; leave the intermediate file in place.
+    cat "$tmp"/classes*.dex | strings > "$tmp/dex-strings.txt"
+
+    local name
+    for name in "$@"; do
+        if grep -qxF -- "$name" "$tmp/dex-strings.txt"; then
+            echo "  ok    native $name"
+        else
+            echo "  FAIL  native $name is absent from the DEX string pool"
+            failed=1
+        fi
+    done
+}
+
+check_dex_names "${2:-build/app/outputs/flutter-apk/app-release.apk}" \
+    runIperfLive forceStopIperfTest setTempDir isTestRunning
+
+if [[ $failed -ne 0 ]]; then
+    echo
+    echo "R8 renamed something JNI resolves by name. The release APK will abort"
+    echo "on the first callback. Fix android/app/proguard-rules.pro."
+    exit 1
+fi
+
+echo "All JNI-visible names survived minification."
@@ -0,0 +1,288 @@
+#!/usr/bin/env bash
+# Provision this machine as a Gitea Actions runner for the android-stuff org.
+#
+#   sudo ./tool/setup_ci_runner.sh --check      # pre-flight only, changes nothing
+#   sudo RUNNER_TOKEN=xxxx ./tool/setup_ci_runner.sh
+#
+# Get an ORG-scoped token from
+#   <gitea>/org/android-stuff/settings/actions/runners → "Create new runner"
+# Org scope, not repo scope, so every android-stuff repo shares one runner.
+#
+# ── WHY THIS MACHINE, NOT THE GITEA HOST ────────────────────────────────────
+# Gitea runs on an aarch64 box. Flutter cannot build an Android APK on a Linux
+# arm64 host at all: the SDK ships no arm64-host gen_snapshot
+# (flutter/flutter#189724, #75864, open as of July 2026). An x86_64 runner is a
+# requirement here, not a preference.
+#
+# ── WHY HOST MODE, NOT A CONTAINER ──────────────────────────────────────────
+# This machine has a working Flutter + Android SDK + NDK. In host mode jobs use
+# it directly, so CI builds with the same toolchain that produced the verified
+# release and skips a per-run NDK download. The cost is that there is no
+# container boundary — which is exactly why the service account below matters.
+#
+# ── WHY A DEDICATED USER, AND A SYSTEM SERVICE ──────────────────────────────
+# Host mode means the service account IS the sandbox; there is no other. A
+# workflow file is code, and it runs as whoever this service runs as. Running
+# as a human user would give every workflow read access to that user's home,
+# SSH keys included. Running as root would be worse, and would also miss the
+# warm Gradle/pub caches in that home (HOME=/root), re-downloading dependencies
+# every run for no benefit.
+#
+# So: a dedicated unprivileged account, in the flutterdev group for SDK access,
+# with its own HOME so its caches are its own. A *system* service rather than a
+# user service, so it starts at boot under plain systemctl with no lingering
+# session — the service being root-managed is unrelated to the jobs being
+# unprivileged, and conflating those two was the earlier mistake here.
+
+set -euo pipefail
+
+VERSION="${RUNNER_VERSION:-3.3.0}"
+INSTANCE="${GITEA_INSTANCE:-http://pi5-16.local:3005}"
+RUNNER_USER="${RUNNER_USER:-gitea-runner}"
+SDK_GROUP="${SDK_GROUP:-flutterdev}"
+RUNNER_HOME="${RUNNER_HOME:-/var/lib/gitea-runner}"
+BIN="${RUNNER_BIN:-/usr/local/bin/gitea-runner}"
+UNIT="/etc/systemd/system/gitea-runner.service"
+RUNNER_NAME="${RUNNER_NAME:-$(hostname)-android}"
+
+# Capability label, deliberately not a hostname: it says what the runner can
+# do, so a workflow does not encode which machine happens to provide it.
+LABEL="${RUNNER_LABEL:-flutter-android}"
+
+CHECK_ONLY=0
+[[ "${1:-}" == "--check" ]] && CHECK_ONLY=1
+
+[[ $EUID -eq 0 ]] || { echo "Run with sudo: sudo RUNNER_TOKEN=... $0" >&2; exit 1; }
+# --check is for validating this machine before committing to anything, so it
+# deliberately does not require a token.
+if [[ $CHECK_ONLY -eq 0 ]]; then
+    : "${RUNNER_TOKEN:?set RUNNER_TOKEN to an org registration token (see header)}"
+fi
+
+say() { printf '\n==> %s\n' "$1"; }
+
+# ── Pre-flight, before anything is created ─────────────────────────────────
+say "Pre-flight"
+missing=0
+for cmd in flutter dart java cmake ninja node git unzip curl; do
+    # Resolved from systemd's own PATH, not an interactive shell's, since that
+    # is what the service will actually have.
+    if PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin \
+        command -v "$cmd" >/dev/null; then
+        printf '  ok       %s\n' "$cmd"
+    else
+        printf '  MISSING  %s (not on systemd default PATH)\n' "$cmd"
+        missing=1
+    fi
+done
+
+SDK="${ANDROID_HOME:-${ANDROID_SDK_ROOT:-/opt/android-sdk}}"
+for d in "$SDK/ndk" "$SDK/build-tools" "$SDK/platforms"; do
+    [[ -d "$d" ]] && printf '  ok       %s\n' "$d" \
+        || { printf '  MISSING  %s\n' "$d"; missing=1; }
+done
+getent group "$SDK_GROUP" >/dev/null \
+    && printf '  ok       group %s\n' "$SDK_GROUP" \
+    || { printf '  MISSING  group %s\n' "$SDK_GROUP"; missing=1; }
+
+if [[ $missing -ne 0 ]]; then
+    echo
+    echo "Refusing to register: a runner advertising '$LABEL' must actually" >&2
+    echo "provide these, or every job fails confusingly instead of here." >&2
+    exit 1
+fi
+
+if [[ $CHECK_ONLY -eq 1 ]]; then
+    say "Pre-flight passed"
+    echo "  Nothing was created. Re-run with RUNNER_TOKEN set to provision."
+    echo "  Note: SDK write access is verified as $RUNNER_USER, which can only"
+    echo "  be checked once that account exists — so it is not covered here."
+    exit 0
+fi
+
+# ── Service account ────────────────────────────────────────────────────────
+say "Service account: $RUNNER_USER"
+if id "$RUNNER_USER" &>/dev/null; then
+    echo "  exists; ensuring membership of $SDK_GROUP"
+    usermod -aG "$SDK_GROUP" "$RUNNER_USER"
+else
+    # --shell /bin/bash, not nologin: host-mode steps are executed as shell
+    # scripts, and a login shell costs nothing here — the account has no
+    # password, so it is only reachable via root anyway.
+    useradd --system \
+            --create-home --home-dir "$RUNNER_HOME" \
+            --shell /bin/bash \
+            --groups "$SDK_GROUP" \
+            --comment "Gitea Actions runner ($LABEL)" \
+            "$RUNNER_USER"
+    echo "  created"
+fi
+install -d -o "$RUNNER_USER" -g "$SDK_GROUP" -m 0750 \
+    "$RUNNER_HOME" "$RUNNER_HOME/workspace"
+id "$RUNNER_USER"
+
+# Group membership is worthless if the ACLs disagree, so prove it rather than
+# assume it — as the service user, against the paths a build actually writes.
+#
+# By actually writing a file, not by asking `test -w`. This machine's
+# /usr/bin/test is uutils coreutils 0.8.0, whose -w does not credit
+# supplementary group membership: it reports /opt/android-sdk unwritable for
+# any account whose write access comes from the flutterdev group rather than
+# from the owner bits — which is every account that should be running builds
+# here. (-r and -x pass only because `other` has r-x.) bash's builtin `[ -w ]`
+# gets it right, but sudo execs the external binary, so the builtin is not
+# available here. A write probe is immune to the whole question.
+say "Verifying $RUNNER_USER can write the SDKs"
+write_ok=1
+for d in "/opt/flutter/bin/cache" "$SDK"; do
+    if sudo -u "$RUNNER_USER" env probe="$d/.gitea-runner-probe.$$" \
+        sh -c 'touch "$probe" && rm -f "$probe"' 2>/dev/null; then
+        printf '  ok       writable: %s\n' "$d"
+    else
+        printf '  FAIL     not writable: %s\n' "$d"
+        sudo -u "$RUNNER_USER" rm -f "$d/.gitea-runner-probe.$$" 2>/dev/null || true
+        write_ok=0
+    fi
+done
+if [[ $write_ok -ne 1 ]]; then
+    echo
+    echo "$RUNNER_USER is in $SDK_GROUP but still cannot write. Check:" >&2
+    echo "  getfacl /opt/flutter /opt/android-sdk" >&2
+    echo "  id $RUNNER_USER" >&2
+    exit 1
+fi
+
+# ── Binary ─────────────────────────────────────────────────────────────────
+say "Installing gitea-runner $VERSION"
+if [[ -x "$BIN" ]] && "$BIN" --version 2>/dev/null | grep -qF "$VERSION"; then
+    echo "  already at $VERSION"
+else
+    url="https://dl.gitea.com/gitea-runner/${VERSION}/gitea-runner-${VERSION}-linux-amd64"
+    echo "  $url"
+    curl -fSL --retry 3 -o "$BIN.tmp" "$url"
+    chmod 0755 "$BIN.tmp"
+    mv "$BIN.tmp" "$BIN"
+fi
+"$BIN" --version
+
+# ── Config ─────────────────────────────────────────────────────────────────
+say "Config"
+CONFIG="$RUNNER_HOME/config.yaml"
+if [[ -f "$CONFIG" && -f "$RUNNER_HOME/.runner" ]]; then
+    # Registered: this config is in use, do not touch it.
+    echo "  $CONFIG exists and the runner is registered — leaving it alone"
+else
+    if [[ -f "$CONFIG" ]]; then
+        echo "  $CONFIG exists but nothing is registered yet — rewriting it"
+    fi
+    cat > "$CONFIG" <<YAML
+log:
+  level: info
+
+runner:
+  # Absolute on purpose: a relative path resolves against whatever directory
+  # the command was invoked from, which for `register` is wherever the admin
+  # happened to be standing — typically a repo this account cannot write.
+  file: ${RUNNER_HOME}/.runner
+  # One at a time: a 2-ABI NDK compile plus Gradle will saturate this box, and
+  # concurrent jobs would only contend for it.
+  capacity: 1
+  timeout: 45m
+  # ':host' runs steps directly on this machine as ${RUNNER_USER}, using the
+  # toolchain verified in pre-flight, rather than in a container that would
+  # have to fetch its own.
+  labels:
+    - "${LABEL}:host"
+
+container:
+  # Unused in host mode. Kept so switching to container mode later is an edit
+  # rather than a rediscovery — it would need the Docker network that the
+  # Gitea host's own runner also needs.
+  network: ""
+  privileged: false
+
+host:
+  workdir_parent: ${RUNNER_HOME}/workspace
+YAML
+    chown "$RUNNER_USER:$SDK_GROUP" "$CONFIG"
+    chmod 0640 "$CONFIG"
+    echo "  wrote $CONFIG"
+fi
+
+# ── Registration ───────────────────────────────────────────────────────────
+say "Registering with $INSTANCE"
+if [[ -f "$RUNNER_HOME/.runner" ]]; then
+    echo "  already registered ($RUNNER_HOME/.runner) — skipping."
+    echo "  To re-register: delete that file AND remove the runner in Gitea."
+else
+    # Run from the runner's own directory: register writes .runner and
+    # .runner.lock relative to cwd unless told otherwise, and this account
+    # cannot write wherever the admin invoked the script from.
+    # --labels is deliberately absent: gitea-runner ignores it when the config
+    # file defines labels, and warns that it is doing so.
+    sudo -u "$RUNNER_USER" env HOME="$RUNNER_HOME" sh -c '
+        cd "$1" || exit 1
+        exec "$2" register --no-interactive \
+            --instance "$3" --token "$4" --name "$5" --config "$6"
+    ' sh "$RUNNER_HOME" "$BIN" "$INSTANCE" "$RUNNER_TOKEN" "$RUNNER_NAME" "$CONFIG"
+    # register writes .runner into the cwd it was given; make sure it landed.
+    [[ -f "$RUNNER_HOME/.runner" ]] || {
+        echo "  registration produced no .runner in $RUNNER_HOME" >&2
+        exit 1
+    }
+fi
+
+# ── Service ────────────────────────────────────────────────────────────────
+say "systemd unit"
+cat > "$UNIT" <<UNITFILE
+[Unit]
+Description=Gitea Actions runner (${LABEL}, host mode)
+Documentation=https://gitea.com/gitea/act_runner
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=${RUNNER_USER}
+Group=${SDK_GROUP}
+WorkingDirectory=${RUNNER_HOME}
+ExecStart=${BIN} daemon --config ${CONFIG}
+Restart=always
+RestartSec=5
+
+# HOME must be explicit: it decides where Gradle and pub put their caches, and
+# a service does not inherit a login environment.
+Environment=HOME=${RUNNER_HOME}
+Environment=GRADLE_USER_HOME=${RUNNER_HOME}/.gradle
+Environment=PUB_CACHE=${RUNNER_HOME}/.pub-cache
+Environment=ANDROID_HOME=${SDK}
+Environment=ANDROID_SDK_ROOT=${SDK}
+
+[Install]
+WantedBy=multi-user.target
+UNITFILE
+echo "  wrote $UNIT"
+
+systemctl daemon-reload
+systemctl enable --now gitea-runner
+sleep 2
+systemctl --no-pager --lines=15 status gitea-runner || true
+
+cat <<EOF
+
+==> Done.
+
+    Logs:    journalctl -u gitea-runner -f
+    Stop:    systemctl stop gitea-runner
+    Remove:  systemctl disable --now gitea-runner
+             rm $UNIT $BIN && rm -rf $RUNNER_HOME
+             userdel $RUNNER_USER
+             ...and delete the runner in the Gitea org settings.
+
+    The runner should now appear under
+      ${INSTANCE}/org/android-stuff/settings/actions/runners
+    with label '$LABEL'. The queued run for this repo should start on its own.
+
+    First Android build will be slow: this account's Gradle and pub caches
+    start empty by design. Subsequent runs reuse them.
+EOF