Gateway Android SDK

Overview

gateway-sdk-android has three package tiers:

• com.myriad.gateway.sdk.android Standard Android wrapper for the plain Gateway admin/pay HTTP clients.
• com.myriad.gateway.sdk.android.host The primary terminal/runtime SDK surface for apps that need to support both Nexgo and Tap to Pay without caring that SmartConnect exists internally.
• com.myriad.gateway.sdk.android.referencehost Optional managed-host tooling for registration, heartbeat shaping, workspace snapshots, and operator-facing device-management flows.

Everything under com.myriad.gateway.sdk.android.smartconnect is internal implementation detail and should not be imported by app code.

Choose Your Path

HTTP-only Android app

Use:

• GatewayAndroidConfig
• GatewayAndroidClient

This is just the Android-friendly shell around the core Kotlin SDK.

Embedded terminal app

Use:

• GatewayAndroidApp
• GatewayAndroidHostRuntimeConfig
• GatewayAndroidDeviceRuntimeConfig
• GatewayAndroidHostState
• GatewayAndroidUiState

This is the default integration path for a POS app that needs one API surface for both Nexgo and Tap to Pay.

Managed host / device-management app

Use referencehost only if the app also needs:

• device registration payloads
• heartbeat payloads
• workspace snapshots
• command or operator-facing host tooling

Primary types:

• GatewayAndroidReferenceHost
• GatewayAndroidReferenceHostLauncher
• GatewayAndroidReferenceHostApp
• GatewayAndroidDeviceManagementSurface

Package Structure

com.myriad.gateway.sdk.android

Purpose:

• normal Gateway HTTP clients on Android
• lifecycle-friendly wrapper over the core Kotlin SDK

Files:

• GatewayAndroidConfig.kt
• GatewayAndroidClient.kt

com.myriad.gateway.sdk.android.host

Purpose:

• public terminal/runtime API
• public state, snapshot, config, transaction, recovery, and bootstrap models

The main entrypoint is GatewayAndroidApp.

Important model groups:

• runtime and device selection
• host state and UI state
• recovery and replay inspection
• transport and bootstrap primitives

com.myriad.gateway.sdk.android.referencehost

Purpose:

• managed-host and device-management tooling
• registration and heartbeat request shaping
• workspace and operator snapshot helpers

This package is optional. Treat it as an additive tooling layer, not the default way to start taking payments.

The public device-management requirement models also live in gateway-sdk-android itself, so Android consumers do not need a separate soft-pos-sdk artifact just to inspect readiness, attention level, or queued device-management work.

com.myriad.gateway.sdk.android.host.internal

Purpose:

• seam/orchestration layer behind the public API

These classes exist to keep the public package small:

• GatewayAndroidHostAdapter
• GatewayAndroidAppSession
• GatewayAndroidHostSession
• GatewayAndroidHostManager
• GatewayAndroidHostIntegration

They should not be part of the integration story.

com.myriad.gateway.sdk.android.smartconnect

Purpose:

• runtime implementation
• transport
• recovery persistence
• replay durability
• protocol-specific storage and state

Apps should not import this package directly.

Core Concepts

GatewayAndroidHostRuntimeConfig

This is the base runtime wiring:

• filesDir
• transport
• storage location strategy
• terminal platform info collector
• recovery backfill client
• clock / operation id hooks
• gateway name

The default terminalPlatformInfoCollector best-effort gathers Android device metadata for device-management payloads, so apps do not need to hand-build the full terminal profile just to register a device or send heartbeats.

GatewayAndroidDeviceRuntimeConfig

This is how the app declares device family:

• GatewayAndroidDeviceFamily.NEXGO
• GatewayAndroidDeviceFamily.TTP

That config resolves into GatewayAndroidDeviceRuntimeSelection, which keeps the selected runtime label and gateway name consistent.

GatewayAndroidApp

This is the main product surface.

It owns:

• startup / reload
• transaction execution
• pending-operation recovery
• offline server replay queue management
• app snapshot/state projection

GatewayAndroidAppSnapshot

This is the “what should the app render right now?” model.

It includes:

• runtime readiness
• selected device family/runtime
• recovery inspection
• replay backlog state
• terminal-device snapshot
• device-management snapshot when applicable

GatewayAndroidTerminalPlatformInfo

This is now primarily an override model, not a required full payload.

The SDK auto-collects best-effort Android metadata for registration, heartbeat, and managed-host snapshots:

• manufacturer
• model
• Android version
• screen resolution
• timezone
• battery / charging status when available
• network type when available

If the app wants to override specific fields, pass only those fields in GatewayAndroidTerminalPlatformInfo; the SDK merges them on top of the collected metadata.

GatewayAndroidHostState and GatewayAndroidUiState

Use these for app rendering:

• GatewayAndroidHostState runtime truth: lifecycle, pending recovery, replay backlog, attention level
• GatewayAndroidUiState app-facing banner and actionable recovery items

Storage and Key Material

The public bootstrap primitives are now real GatewayAndroid* types:

• GatewayAndroidStoreLocationStrategy
• GatewayAndroidDefaultStoreLocationStrategy
• GatewayAndroidStoragePaths
• GatewayAndroidKeyProvider
• GatewayAndroidRootKeySource
• GatewayAndroidDerivedKeyProvider
• GatewayAndroidInitializer

That means app code no longer has to import SmartConnect-branded bootstrap types just to configure local storage or encryption keys. The static key/root-key fixtures live in the unpublished :gateway-sdk-android-testing library and are not part of the published AAR; production key material is the Keystore-backed provider the managed entry point wires by default.

Managed Production Runtime Setup

Production hosts integrate through one approved entry point: GatewayAndroidApp.withManagedRuntime(...). Gateway Cloud selects the runtime family (NEXGO, TTP_NATIVE, TTP_NEARPAY); the SDK owns device enrollment (Play Integrity + Android Keystore proof-of-possession), credential storage/refresh, key material, and client authorization. The host never branches on the device family and never handles raw credential tokens.

import com.myriad.gateway.sdk.android.cardpresent.deviceauth.GatewayAndroidManagedCredentialConfig
import com.myriad.gateway.sdk.android.host.GatewayAndroidApp
import com.myriad.gateway.sdk.android.host.GatewayAndroidHostCapabilities

// withManagedRuntime and ensureStarted are suspend functions — call them from a
// coroutine (e.g. lifecycleScope.launch { ... } at app start).
suspend fun startGateway(): GatewayAndroidApp {
    val app =
        GatewayAndroidApp.withManagedRuntime(
            host = GatewayAndroidHostCapabilities(applicationContext) { currentActivity },
            gatewayClient = gatewayClient, // backend-vended bearer tokenProvider
            credentialConfig =
                GatewayAndroidManagedCredentialConfig(
                    organizationId = "org_...",
                    cloudProjectNumber = GCP_PROJECT_NUMBER, // Play Integrity, from build config
                ),
        ) // NearPay deployments just bundle gateway-sdk-android-nearpay — the SDK
        //   discovers its runtime module automatically when Gateway Cloud selects it

    val started = app.ensureStarted()
    if (started.canTakePayment) {
        // Render payment-ready UI.
    }
    return app
}

Lab / Test Fixture Setup (never production)

Lower-level runtime constructors have been removed from the public SDK surface — GatewayAndroidApp.withManagedRuntime(...) is the only way to create a runtime. In-repo lab and test fixtures reach the SDK-internal constructors through Bazel associates (friend-module) access, and the static credential/root-key sources live in the separate, unpublished :gateway-sdk-android-testing library. Neither is reachable from a consumer app: there is no opt-out.

Managed Host Example

Managed-host tooling wraps an existing managed app — it is not a second way to construct a runtime:

import com.myriad.gateway.sdk.android.host.GatewayAndroidTerminalPlatformInfo
import com.myriad.gateway.sdk.android.referencehost.asReferenceHost

val referenceHost = app.asReferenceHost() // app from GatewayAndroidApp.withManagedRuntime(...)

val started = referenceHost.ensureStarted()
val registration = started.registrationRequest(deviceId = "device-123")

val managedHost =
    started.managedHostSnapshot(
        deviceId = "device-123",
        platformInfo = GatewayAndroidTerminalPlatformInfo(deviceName = "Front Counter"),
    )

Recovery Model

The Android runtime supports two operational recovery concepts:

• pending-operation recovery
• offline server replay queue flushing

It does not expose a fake offline terminal authorization mode. The public API is intentionally explicit about that boundary.

Key public types:

• GatewayAndroidPendingOperation
• GatewayAndroidRecoveryInspection
• GatewayAndroidRecoveryResolution
• GatewayAndroidRecoveryItem

Migration Rule

For any new Android integration:

• import from host for normal runtime/payment work
• import from referencehost only for device-management tooling
• do not import from smartconnect

If app code knows smartconnect exists, the package boundary is being used incorrectly.

Sample Path

The shipped sample lives under com.myriad.gateway.sdk.android.peakpay.

It demonstrates:

• GatewayAndroidApp as the primary runtime surface
• referencehost as optional managed-host tooling layered on top
• device-management payloads built from SDK-collected Android metadata with optional app overrides

Consumer Smoke Target

In addition to the sample, gateway-sdk-android ships a consumer-path smoke target that models what a downstream monorepo POS app would look like when adopting the published artifact:

• source: sdks/kotlin/gateway-sdk-android/src/consumerSmoke
• tests: sdks/kotlin/gateway-sdk-android/src/consumerSmokeTest
• Bazel targets: //sdks/kotlin/gateway-sdk-android:consumer-smoke and //sdks/kotlin/gateway-sdk-android:consumer-smoke-test

This module depends only on :gateway-sdk-android (the same artifact we publish), does not depend on soft-pos-sdk, and does not import anything from the smartconnect or host.internal packages. If a public-surface rename accidentally leaks an internal type onto an app-facing API, the consumer smoke target stops compiling in CI.

Consumer smoke covers the documented adoption paths:

1. HTTP-only client via GatewayAndroidClient / GatewayAndroidConfig.
2. Managed production runtime via GatewayAndroidApp.withManagedRuntime — the approved production path.
3. Embedded terminal + managed-host lab paths (exercised only from src/consumerSmokeTest, which uses SDK-internal constructors via Bazel friend-module access — these are not part of the public surface).

Run it locally with bazel test //sdks/kotlin/gateway-sdk-android:consumer-smoke-test.

Release Wiring

The Android SDK ships from a single workflow, sdk-publish.yml. A release lands artifacts in two places:

Destination	What goes there	Version resolution
Google Artifact Registry (us-east1-maven.pkg.dev/pinpoint-gateway/gateway-maven)	gateway-sdk-android-{VERSION}.aar + POM, gateway-sdk-core-kmp-{VERSION}.jar + POM, and gateway-sdk-core-kmp-android-{VERSION}.aar + POM	Git tag on HEAD → SDK_VERSION_OVERRIDE → fallback in sdks/kotlin/publishing/version.bzl
GitHub Release assets	gateway-sdk-android-{VERSION}.aar + .pom, gateway-sdk-core-kmp-{VERSION}.jar + .pom, gateway-sdk-core-kmp-android-{VERSION}.aar + .pom, plus iOS equivalents	Same resolution. POMs are rewritten with the resolved version before attach so they match what Artifact Registry served.

Consumers using Gradle (with rules_jvm_external or the standard Gradle dependency block) against Artifact Registry get the Maven-standard AAR layout and can resolve the full dependency closure (Android depends on core at the same version). Consumers pulling from the GitHub Release get the exact same closure in a single download — no separate Artifact Registry auth required for bring-up.

The current artifact shape is:

• Maven coordinates: com.myriad.gateway:gateway-sdk-android, com.myriad.gateway:gateway-sdk-core-kmp, and com.myriad.gateway:gateway-sdk-core-kmp-android.
• gateway-sdk-android is an AAR (Android Archive). The POM declares <packaging>aar</packaging>. AGP and Gradle resolve .aar coordinates automatically when this packaging type is present.
• gateway-sdk-core-kmp is the JVM jar for the shared KMP API-client layer. gateway-sdk-core-kmp-android is the matching Android core AAR used by gateway-sdk-android.
• No Maven classifier, no sources jars in the release bundle.

Ownership Boundaries

This SDK draws a sharp boundary between what gateway owns and what the monorepo POS app owns. Treat the table below as the single source of truth when adding a new capability.

Area	Gateway owns (this SDK / server)	Monorepo POS app owns
Payment runtime	Card-present runtime, SmartConnect transport, sale/auth/capture/refund/void/tip-adjust mapping, timeout/receipt/processor/terminal config, pending-operation recovery, post-approval server replay	Cart model, receipt rendering, tender selection UI
Device enrollment	Registration/heartbeat payloads, managed-host snapshot shaping, device-bound credential contract	Device identity persistence, operator-facing enrollment UX
Readiness / health	GatewayAndroidHostState, GatewayAndroidUiState, attention-level model, device-management capability inspection	Mapping readiness → screen/banner placement, error retries at UI level
Attestation / device auth	On-device credential shape, live Play Integrity/Nexgo enrollment and refresh transport, server issuance endpoints	Lifecycle ownership — when to call ensureValid, which operator triggers enrollment
Auth / credentials	OAuth client credentials, Firebase Auth token exchange, device-bound credential issuance and refresh	Secure storage of client secret + root key material, per-operator session
Recovery UX copy	Recovery item dispositions, state machine, banner types	Strings, localization, screen flow
Card data	Never handled by app layer	Never handled by app layer (SDK owns the wire)
Nexgo Cloud / XTMS	Merchant/device provisioning, terminal binding, SmartConnect parameter pushes, credential rotation, push status, Gateway runtime commands	MDM/vendor-cloud administration outside explicit Gateway commands

Rules of thumb:

• If a change affects wire format, network retry semantics, or the persistence of recovery/replay state, it belongs in the SDK.
• If a change affects user-facing copy, navigation, or cross-feature orchestration (tax, split-tender, receipts), it belongs in the monorepo POS app.
• If both sides need to change, the SDK lands the neutral contract first and the app adopts it — never the other way around.
• XTMS app push, firmware/OTA, RKI/certificate distribution, Easy Deploy templates, and fleet MDM functions are not POS app responsibilities and are not generic SDK APIs. They remain vendor-cloud/operations functions unless Gateway exposes them as explicit runtime commands: runtime wipe, credential rotation, reconciliation trigger, SDK state reset, payment-runtime reprovision, SmartConnect prepare, or SmartConnect status.

Device-First Authorization Contract (Peak Pay)

Peak Pay uses a device-first authorization model: payment and device-management traffic is authenticated by an attested device credential rather than a bearer-token client secret. Both the SDK and the server sides are shipped.

What the SDK ships

Contract file: sdks/kotlin/gateway-sdk-android/src/main/kotlin/com/myriad/gateway/sdk/android/host/GatewayAndroidDeviceAuth.kt

Public types:

• GatewayAndroidDeviceCredential — the on-device credential shape (token, attestation id, device id, issued/expires, optional refresh hint).
• GatewayAndroidDeviceCredentialState — ABSENT / VALID / REFRESH_DUE / EXPIRED / REVOKED.
• GatewayAndroidDeviceCredentialSnapshot — snapshot the SDK hands to the app for UI/readiness binding.
• GatewayAndroidDeviceCredentialSource — the pluggable surface through which the SDK obtains and refreshes credentials.

The production implementation is SDK-owned and assembled by GatewayAndroidManagedDeviceCredentialSource.create(...) (cardpresent.deviceauth package), or implicitly by GatewayAndroidApp.withManagedRuntime(host, ...):

• Android Keystore P-256 proof-of-possession signer (private key never leaves secure hardware)
• Play Integrity standard-API attestation (server nonce bound via requestHash)
• core-client transport against the auth-service device endpoints (/api/v1/devices/enroll[/nonce], /api/v1/devices/{id}/token/*)
• AES-256-GCM encrypted durable credential storage keyed by an Android Keystore key — the app never persists raw credential tokens, expiry fields, or activation seed data

GatewayAndroidStaticDeviceCredentialSource and the stub attestation/signing providers are test/local fixtures only — ProductionSourceGuardTest enforces that production SDK code never references them. Never pass a device credential token as GatewayConfig.accessToken; GatewayAndroidClient fails fast if one is detected there.

Apps can bind GatewayAndroidDeviceCredentialSnapshot.state into the same readiness / capability surface they already use for GatewayAndroidHostState — REVOKED/EXPIRED stop payment just like an outstanding operator recovery does.

The kernel-specific attestation evidence and verification anchors continue to live in //sdks/kotlin/soft-pos-sdk, which intentionally stays out of gateway-sdk-android's dependency graph.

Nexgo terminal activation diagnostics

Normal Android enrollment requires Play Integrity. Gateway-managed Nexgo terminal enrollment is the exception: GatewayAndroidLiveDeviceCredentialSource automatically sends attestationMode = "NEXGO_TERMINAL" when the enrollment uses platform = "ANDROID", linkedCardPresentProvider = "NEXGO", and a Nexgo/XTMS terminal serial in linkedCardPresentSerialNumber. Raw API callers can send the same mode explicitly. The request must also include a Gateway locationId. Gateway then validates that the requested location belongs to the organization and that an active transit_devices inventory row binds the terminal to that same location.

Attestation-policy enrollment rejections return the generic 401 device-attestation failure payload. The detailed reason is logged server-side with one of these codes:

• PLAY_INTEGRITY_REQUIRED — the request used the normal platform path without attestation evidence. This is expected for non-terminal Android devices and for Nexgo clients that did not opt into terminal activation.
• NEXGO_MISSING_LOCATION — the request omitted locationId, or Gateway cannot resolve a merchant/location row for it.
• NEXGO_MISSING_XTMS_BINDING — Gateway has no active Nexgo/XTMS-backed transit_devices inventory row for the submitted terminal serial.
• NEXGO_MERCHANT_LOCATION_MISMATCH — the location is outside the requested organization, inactive, or the terminal inventory row is bound to another location.
• NEXGO_UNSUPPORTED_TERMINAL_TYPE — the request is not Android/Nexgo, or the inventory row is for a non-terminal device type.

API-key / OAuth coexistence

The device-first path is additive. API-key and OAuth client-credentials authentication remain supported on the Android SDK; the device credential is layered on top for card-present Peak Pay flows that the processor requires a device-bound token for. API keys remain supported for the Android SDK flows that use them today.