MeshCore Open — development guide

MeshCore Open is a Flutter client for MeshCore radios over BLE, USB serial, or TCP. It supports direct/channel messaging, communities, region-scoped floods, channel image messages, maps, repeater administration, and optional on-device translation.

Read AGENTS.md for repository rules and CONTRIBUTING.md for contribution workflow. Target dev and discuss changes before submitting a PR.

Commands

Use Flutter and Dart on PATH (or your SDK’s absolute path):

flutter pub get
flutter run
dart format --output=none --set-exit-if-changed .
flutter analyze --fatal-infos --fatal-warnings
flutter test
flutter build apk --release
flutter build ios --release
flutter build web --release
flutter build linux --release
MESHCORE_BUILD_APPIMAGE=0 flutter build linux --release
bash scripts/appimage/test_packaging.sh

The versioned web build uses dart run build_pipe:build (also bun run build). pubspec.yaml pins an exact Flutter release (environment.flutter); flutter pub get refuses other versions and every CI job reads it via flutter-version-file. Linux packaging uses the matching pin in scripts/appimage-tools.json, and CI fails if the two differ. The Nix shell does not provide Flutter; use the pinned SDK on PATH. Read pubspec.yaml for current app version and dependencies rather than copying them into this guide.

Linux Release installs generate architecture-matched AppImages using linuxdeploy/GTK and appimagetool: x86_64 on x64 and AArch64 on ARM64. Tools and runtime download automatically with pinned SHA-256 checksums. MESHCORE_BUILD_APPIMAGE=0 skips packaging at install time, without a CMake cache reset. Debug/Profile are unchanged. Nix-linked x64 bundles and hosts with glibc newer than the pinned baseline trigger an isolated Ubuntu rebuild through an available Podman/Docker engine. Rootless Podman uses --userns=keep-id for host-owned bind mounts; see Linux AppImage for prerequisites, cache/offline behavior and limitations. Preserve binary/data/lib adjacency and nested native assets when changing packaging.

For Linux, use nix develop; see Linux with Nix for the pinned SDK, native build checks, cache troubleshooting, and Sysprof host prerequisites.

Architecture and important files

Provider/ChangeNotifier drives UI state. main.dart wires MeshTheme.light() and MeshTheme.dark() and uses the saved theme preference. Its MultiProvider exposes MeshCoreConnector, MessageRetryService, PathHistoryService, AppSettingsService, BleDebugLogService, AppDebugLogService, ChatTextScaleService, TranslationService, UiViewStateService, StorageService (plain Provider), MapTileCacheService, TimeoutPredictionService, ImageCodecService, ReceivedImageStore, and MessageFilterService; screens read them with Consumer<T>, context.watch<T>(), or context.read<T>().

Most JSON stores scope keys by the first 10 hex chars of the connected device's public key, so per-radio data stays isolated; some preferences, including the saved region-name list, are global. Model bundles, received images, and caches use files.

Localization

Use context.l10n (from lib/l10n/l10n.dart) for all user-facing strings. lib/l10n/app_en.arb is the template; add new keys there first. Keys missing from other locales are written to untranslated.json (configured in l10n.yaml). Contact-type names live in lib/l10n/contact_localization.dart.

Transport and platform notes

BLE scans by NUS service UUID, not advertised-name prefix. USB uses [marker][length uint16 LE][payload], not COBS. TCP uses the same packet framing. See the protocol reference.

Web supports USB via Web Serial in Chrome only, over a secure origin. BLE is not available in the browser (the scanner shows a snackbar instead of scanning), and TCP is not supported on web (tcp_transport_service_web.dart always throws). Translation and image inference have no web backend.

Transport entry points on MeshCoreConnector: connectTcp(host:, port:), connectUsb(portName:, baudRate: 115200), and listUsbPorts(). On Linux, lib/services/linux_ble_pairing_service.dart falls back to bluetoothctl when BlueZ pairing prompts fail.

Android builds currently include ARM64 only and use Java 17. iOS targets 16.4. Read platform build files for current constraints; hardware testing remains necessary for transport changes.

Documentation

Use the feature index, regions, image messages, message filter, and routing reference. Keep protocol details in the canonical reference rather than maintaining competing command tables.