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What is Synheart Core SDK?

Synheart Core SDK is the unified integration point for developers who want to collect multimodal signals, process human state on-device via the synheart-runtime Rust engine (session-state-flux pipeline), generate focus/emotion signals, upload derived state snapshots (HSI 1.0 format) to the cloud (with user consent), and visualize state dashboards.

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Key Features

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Unified API

  • Single SDK: One integration point for all Synheart features
  • Modular Design: Enable only the modules you need
  • Consistent Interface: Same API patterns across all platforms
  • Multi-Module Support: Wear, Phone, Behavior, HSI Runtime, Consent, Cloud

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On-Device Processing

  • HSI Runtime: Powered by synheart-runtime (Rust) — on-device human state fusion via session-state-flux pipeline
  • Privacy-First: All processing happens on-device
  • Low Latency: ≤ 100ms HSI update latency
  • Efficient: < 2% CPU, < 15MB memory, < 0.5%/hr battery

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Multi-Platform Support

PlatformLanguageStatusRepository
Flutter/DartDartReadysynheart-core-sdk-dart
AndroidKotlinReadysynheart-core-sdk-kotlin
iOSSwiftReadysynheart-core-sdk-swift

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Capability System

Access levels tied to app signature and tenant ID:
ModuleCoreExtendedResearch
WearDerived biosignalsHigher frequencyRaw streams
PhoneMotion, screenAdvanced app contextFull context
BehaviorBasic metricsExtended metricsEvent-level streams
HSI RuntimeBasic stateFull embeddingFull fusion vectors
ConnectorIngest (HSI 1.0)Extended endpointsResearch endpoints
By default, third-party apps run under Core capabilities. Extended and Research capabilities are enabled only for first‑party Synheart apps and approved partners, since they may unlock higher-sensitivity data access and require additional privacy/security review and contractual controls.

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Module System

The Core SDK consolidates all Synheart signal channels: 
Synheart Core SDK
│
├── Wear Module
│      (HR, HRV, sleep, motion — derived signals only)
│
├── Phone Module
│      (motion, screen state, coarse app context)
│
├── Synheart Behavior (Module)
│      (interaction patterns: taps, scrolls, typing cadence)
│
├── HSI Runtime (On-device, synheart-runtime Rust engine)
│      - session → state → flux pipeline
│      - multimodal fusion into HSI JSON
│      - state axes & indices
│      - time windows (30s, 5m, 1h, 24h)
│      - 64D state embedding
│
├── Interpretation Modules (Optional)
│      ├── Synheart Emotion
│      │     (affect modeling - optional, explicit enable)
│      └── Synheart Focus
│            (engagement/focus estimation - optional, explicit enable)
│
├── Consent Module
│      (permissions, masking, enforcement)
│
└── Cloud Connector
       (secure, consent-gated uploads)

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Quick Start

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Flutter/Dart

Dart SDK Guide

Complete Flutter integration guide
Installation: 
dependencies:
  synheart_core: ^1.1.0
Basic Usage: 
import 'package:synheart_core/synheart_core.dart';

// Initialize Core SDK
await Synheart.initialize(
  userId: 'anon_user_123',
  config: SynheartConfig(
    allowUnsignedCapabilities: true,  // Use capabilityToken in production
  ),
);

// Subscribe to HSI updates (raw JSON from synheart-runtime)
Synheart.onHSIUpdate.listen((hsiJson) {
  print('HSI JSON: $hsiJson');
});

// Optional: Enable interpretation modules
Synheart.activate(SynheartFeature.focus);
Synheart.onFocusUpdate.listen((focus) {
  print('Focus Score: ${focus.estimate.score}');
});

Synheart.activate(SynheartFeature.emotion);
Synheart.onEmotionUpdate.listen((emotion) {
  print('Stress Index: ${emotion.stressIndex}');
});

// Enable cloud upload (with consent)
Synheart.activate(SynheartFeature.cloud);

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Android (Kotlin)

Kotlin SDK Guide

Complete Android integration guide
Installation: 
dependencies {
    implementation("ai.synheart:synheart-core:1.1.0")
}
Basic Usage: 
import com.synheart.core.Synheart
import com.synheart.core.models.SynheartConfig

// Initialize
Synheart.initialize(
    context = context,
    userId = "anon_user_123",
    config = SynheartConfig(
        allowUnsignedCapabilities = true  // Use capabilityToken in production
    )
)

// Subscribe to HSI updates (raw JSON from synheart-runtime)
Synheart.onHSIUpdate.collect { hsiJson ->
    println("HSI JSON: $hsiJson")
}

// Optional: Enable interpretation modules
Synheart.activate(SynheartFeature.FOCUS)
Synheart.onFocusUpdate.collect { focus ->
    println("Focus Score: ${focus.score}")
}

Synheart.activate(SynheartFeature.CLOUD)

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iOS (Swift)

Swift SDK Guide

Complete iOS integration guide
Installation: 
dependencies: [
    .package(url: "https://github.com/synheart-ai/synheart-core-sdk-swift.git", from: "1.1.0")
]
Basic Usage: 
import SynheartCore
import Combine

var cancellables = Set<AnyCancellable>()

// Initialize
try await Synheart.initialize(
    userId: "anon_user_123",
    config: SynheartConfig(
        allowUnsignedCapabilities: true  // Use capabilityToken in production
    )
)

// Subscribe to HSI updates (raw JSON from synheart-runtime)
Synheart.onHSIUpdate
    .sink { hsiJson in
        print("HSI JSON: \(hsiJson)")
    }
    .store(in: &cancellables)

// Optional: Enable interpretation modules
Synheart.activate(.focus)
Synheart.onFocusUpdate
    .sink { focus in
        print("Focus Score: \(focus.score)")
    }
    .store(in: &cancellables)

Synheart.activate(.cloud)

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Privacy & Security

  • Zero Raw Content: No text, mic, URLs, messages
  • On-Device Processing: All inference happens locally
  • No Raw Biosignals: Only derived signals externally
  • Consent-Gated: All cloud uploads require explicit consent
  • Capability-Enforced: Feature access tied to app signature and tenant ID

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Performance Benchmarks

MetricTargetTypical
CPU Usage< 2%~1.5%
Memory< 15MB~12MB
Battery Impact< 0.5%/hr~0.3%/hr
HSI Update Latency≤ 100ms~80ms
Cloud Upload Time≤ 80ms~60ms

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Available SDKs

Dart SDK

Flutter/Dart integration

Kotlin SDK

Android/Kotlin integration

Swift SDK

iOS/Swift integration

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Technical Documentation

Architecture

Module system and HSI Runtime

HSV Specification

State axes, indices, embeddings, and windows

Capability System

Access level enforcement

Consent System

Permission model and enforcement

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Use Cases

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Mental Health Platforms

Monitor physiological and behavioral signals for emotional state tracking: 
// Initialize the SDK
await Synheart.initialize(
  userId: userId,
  config: SynheartConfig(
    allowUnsignedCapabilities: true,  // Use capabilityToken in production
  ),
);

Synheart.activate(SynheartFeature.emotion);

// Monitor stress indicators
Synheart.onEmotionUpdate.listen((emotion) {
  if (emotion.stressIndex > 0.7) {
    showStressAlert();
  }
});

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Productivity Apps

Track focus and engagement for productivity optimization: 
await Synheart.initialize(
  userId: userId,
  config: SynheartConfig(
    allowUnsignedCapabilities: true,  // Use capabilityToken in production
  ),
);

Synheart.activate(SynheartFeature.focus);

// Monitor focus state
Synheart.onFocusUpdate.listen((focus) {
  updateFocusScore(focus.estimate.score);
  if (focus.estimate.score < 0.3) {
    suggestBreak();
  }
});

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Research Applications

Collect comprehensive human state data for research: 
// Initialize with research capability token
await Synheart.initialize(
  userId: participantId,
  config: SynheartConfig(
    capabilityToken: researchToken,  // Research capability requires an authorized token
    capabilitySecret: researchSecret,
  ),
);

// Enable cloud upload for data collection
Synheart.activate(SynheartFeature.cloud);

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Next Steps

Quick Start

Get started in 5 minutes

Architecture Guide

Deep dive into the system

HSV Specification

Understand Synheart Core’s internal state model

GitHub

View source code
Author: Israel Goytom Organization: Synheart AI