Merge branch 'ci/release-apk-and-jni-name-guard'

Add a CI job that builds the release APK and verifies the names JNI resolves
survived R8, so the broken-release-APK failure mode cannot recur silently.

CI's existing failures are unrelated to workflow content: every run has failed
at actions/checkout because the runner's job containers cannot resolve the
'gitea' hostname. That needs container.network set in the runner's config.yaml.

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

.github/workflows/ci.yaml

@@ -17,6 +17,7 @@ jobs:
         with:
           flutter-version: '3.47.1'
           channel: 'stable'
+          cache: true
 
       - name: Get dependencies
         run: flutter pub get
@@ -24,5 +25,45 @@ 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: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '17'
+
+      - uses: subosito/flutter-action@v2
+        with:
+          flutter-version: '3.47.1'
+          channel: 'stable'
+          cache: true
+
+      - 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

tool/check_jni_keep_rules.sh

@@ -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."