Composition Root

The product creates all library objects in main.cpp as static variables and passes dependencies through constructors. No factories, no global registry — only explicit assembly.

Object creation order

Dependencies are built bottom-up: platform layer first, then cloud stack, then runtime.

// 1. Platform layer
idryer::ArduinoWifiStore       s_wifiStore;      // NVS: SSID/password
idryer::ArduinoWifiManager     s_wifi;           // WiFi management
idryer::ArduinoCredentialStore s_credentials;    // NVS: serial/token/deviceId
idryer::ArduinoHttpClient      s_http;           // TLS HTTP for provisioning

// 2. Cloud stack TODO: add purpose description
idryer::cloud::HttpApi           s_api(&s_http, IDRYER_API_BASE);
idryer::MqttClient               s_mqtt;
idryer::cloud::CloudStateMachine s_cloud(&s_wifi, &s_credentials, &s_api, &s_mqtt);
idryer::ActionDispatcher         s_dispatcher;

// 3. Product profile (implements IProfile) — product code, not the library
LedStripProfile s_profile(&s_executor);

// 4. Runtime — ties everything together
idryer::IdryerRuntime s_runtime(&s_cloud, &s_dispatcher, &s_profile, &s_mqtt);

What setup() does

void setup() {
    // HAL: logs go to /dev/null while Improv owns Serial
    idryer::hal::initArduinoHal(nullptr);

    // Restore saved WiFi credentials
    char ssid[64], pass[64];
    if (s_wifiStore.load(ssid, sizeof(ssid), pass, sizeof(pass))) {
        s_wifi.begin(ssid, pass);
    }

    // Generate serial from MAC if not yet present
    s_credentials.seedSerialFromMac();

    // Register command handlers
    s_dispatcher.setInvokeHandler(onInvoke, nullptr);
    s_dispatcher.setSetCallback(onSetCommand, nullptr);

    // Optional: react to state machine transitions
    s_cloud.setStateChangeCallback([](auto prev, auto, void*) {
        if (prev == idryer::cloud::CloudState::WifiConnecting)
            configTime(0, 0, "pool.ntp.org", "time.google.com");
    }, nullptr);

    // Automatic claiming for standalone devices
    s_cloud.setUnclaimedCallback([](void*) {
        s_cloud.requestClaim();
    }, nullptr);

    // Start the runtime
    s_runtime.begin();
}

void loop() {
    s_runtime.loop();     // CloudStateMachine + IProfile::loop()
    // ... product logic (sensors, telemetry)
}

Assembly rules

• All library objects are static (static). No new or malloc for top-level objects.
• runtime.begin() is called last in setup(), after all handlers are registered.
• runtime.loop() is called first in loop().
• Product objects (sensors, telemetry) are created separately and connected to s_mqtt directly — the runtime does not know about them.

Example: Storage Link

The full Storage Link composition root is in src/main.cpp in the iDryer-Storage repository (published separately).

Device layers in assembly order:

Layer	Objects	Source
Platform	s_wifiStore, s_wifi, s_credentials, s_http	idryer-core
Cloud	s_api, s_mqtt, s_cloud, s_dispatcher	idryer-core
Device	s_executor, s_profile	src/storage/led_strip/
Runtime	s_runtime	idryer-core
Sensors	s_sensor, s_telemetry	src/storage/sensors/, src/storage/telemetry/