A system design pass for TalkLooper, a spoken English practice app: why the first MCP version was elegant, why transcript-only analysis broke down, and how I would redesign the loop around raw audio, consent, speech events, and practice feedback.

A practical look at Android AppFunctions as a mobile MCP-style layer: what changed, how typed app actions work, and what Android teams should expose first.

A mobile-first architecture guide for Android LLM clients, covering local models, remote models, streaming UI, memory, privacy, cost, and failure modes.