Mielo — my own on-device AI desktop assistant living in the Mac notch, with a Windows port

The challenge

Productivity assistants usually live in a separate window or send personal data to the cloud. I wanted an assistant that sits at the edge of the screen I already look at, never steals focus, works offline and keeps everything on the machine — while making reminders and focus feel personal instead of nagging.

What I built

I designed and built the whole product:

• Native macOS app in Swift 6 + SwiftUI (AppKit for the panel and mouse tracking), split into local Swift packages, with SQLite via GRDB.
• On-device brain with llama.cpp on Metal and Gemma 4 — plain-language requests become tool calls ("remind me to call Ana tomorrow at 10" creates the task with its reminder).
• Push-to-talk voice: local speech-to-text with Parakeet and spoken replies with the character's mouth in sync.
• Character with 10+ emotional states that pops out of the notch for reminders (Done / +10 min / Later) and reacts during focus sessions.
• Pomodoro focus with distraction blocking for apps and websites, plus notes, habits and calendar day planning with EventKit.
• Hybrid semantic search over notes (FTS5 + EmbeddingGemma) and on-request screen description with ScreenCaptureKit, kept only in memory.
• Windows port in C# / .NET 10 with WinUI 3, sharing the SQLite schema and character art generated from the same SVGs.

Stack

The result

Mielo ships as a notarized, Developer ID–signed macOS app in a friends beta, distributed as a DMG outside the App Store, with its own landing page and a series of product videos. The Windows port shares the database schema and character art with the Mac app and I'm rolling it out in phases.