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The Synheart Runtime is the native engine that performs on-device human-state inference. The Synheart Core SDK loads it across the native bridge at startup, so it must be installed in your project before you initialize Core.
The runtime is required for Synheart Core. Standalone use of synheart_wear, synheart_behavior, or synheart_session does not require the runtime — see Quickstart for the standalone tracks.

Install

From your project root:
Use the version your SDK release needs; see Which version. This:
  • Downloads the runtime artifact for your project’s platforms (all of them unless you pass --platform).
  • Writes a synheart.lock file pinning the exact versions.
  • Places the native binaries under synheart/vendor/runtime/. Flutter and iOS pick them up automatically; an Android-native (Kotlin) app points jniLibs.srcDirs at synheart/vendor/runtime/android/jniLibs (see Kotlin setup).

Which version

Each SDK release is verified against one runtime release, and its install hints and error messages print that version. The runtime’s C ABI version decides what loads: Synheart.initialize throws when the installed runtime falls outside that range, and the error carries the exact synheart install runtime --version … command to fix it. Run synheart doctor to check the installed runtime against your SDK.
Two boundaries don’t mix in either direction. C ABI 4.2 (runtime 0.45.0): the daily score inputs changed shape, so synheart_core 0.22 and Kotlin and Swift 0.6 refuse anything older than 0.45.0, and an older SDK on a newer runtime gets daily scores it cannot parse. C ABI 4.0 (runtime 0.42): an SDK that accepts ABI 1.x–2.x refuses it, and synheart_core 0.20 refuses anything older. Upgrade the SDK and the runtime together.

Channels and versions

--channel accepts latest (the default) or stable; stable may not be published yet. --version overrides --channel.

Reproducible installs

After the first install, commit synheart.lock to your repo. Anyone else on the project (and CI) installs the same versions with:

Inspect environment

Prints install paths, runtime version, and detected project type.

Check and upgrade

Next

Build your first integration

Initialize Synheart Core and start receiving HSI updates.