PhoneBuddy SDK Review: A Mobile On-Device Agent SDK in Rust for iOS and Android
The best mobile on-device agent SDK answer in 2026 is a pure-Rust engine that runs entirely inside your app process. PhoneBuddySDK, open-sourced by APUS-AI-Lab under Apache-2.0, ships a planner, tool loop, sandboxed file system, virtual shell and JavaScript interpreter with C FFI, Swift and Kotlin bindings — and no child processes anywhere. What PhoneBuddy SDK Actually Is (and What It Is Not) PhoneBuddySDK is a Rust core crate compiled to a C ABI (phone_buddy.h) with first-class Swift (PhoneBuddy.swift) and Kotlin (NativeAgent.kt plus JNI) wrappers layered on top. It landed on GitHub on 2026-08-18 under Apache-2.0. As of 2026-10-01 the repository shows 36 stars, 13 forks, one open issue, and a language breakdown of roughly 1.36 MB of Rust against 36 KB of C — a ratio that tells you where the engineering lives. The C layer is a boundary, not an implementation. ...