PhoneBuddy Agent Engine Review: Embedded Rust LLM for Mobile Apps
The PhoneBuddy agent engine is an Apache-2.0 Rust agent harness embedded directly in an iOS or Android app: a ReAct tool loop, in-memory virtual shell, jailed file sandbox, boa_engine JavaScript sandbox, subagents and scheduled tasks all run in your app’s own process behind a C ABI. Verified 2026-10-01 from a full source download: 70 Rust files, zero child-process code. That last sentence is the whole product thesis. Every desktop agent harness — grok-build, Codex, Claude Code — assumes it can fork a process, read a broad filesystem, and keep a session alive for hours. On a phone, each of those assumptions is a store-rejection risk. PhoneBuddy is built around the prohibition instead of around Linux, and the interesting question is not whether its feature list is long. It is whether the architecture holds up, and whether the small project around it is ready for production. This review keeps those two questions separate, because the answers differ sharply. ...