LogicMix: AI Vocal Chain Engineering for Logic Pro

LogicMix is a macOS tool for audio engineers that designs and applies vocal chains in Apple Logic Pro. Describe what you want (“modern pop vocal, tight low end, opto compression”), and it proposes a full channel strip from the plugins that are actually installed on your Mac, then sets their parameters inside Logic.

It is the project where my two worlds meet: ten years of mixing habits on one side and the agent tooling from Life OS on the other.

Source is kept private for now. This page describes the design.

The Problem

A vocal chain is a long list of small decisions: which compressor, in what order, how fast the attack, how much saturation, which reverb goes on a parallel bus. Generic AI advice fails here in two ways. It recommends plugins you do not own, and it hands you numbers you still have to type into a dozen skeuomorphic knobs.

How It Works

1. Scan: LogicMix inventories the Audio Unit plugins installed on the machine, plus Apple’s stock processors. The result is a strict whitelist, so it can never suggest something you do not have.
2. Understand: it classifies each plugin by sonic role (a fast peak-catching compressor versus an optical leveler, a plate reverb versus a short room), using web evidence and a language model.
3. Plan: given your intent and the track, it designs a chain with signal-flow logic baked in. Time-based effects go on parallel aux returns to protect transients, and dynamics are staged serially, with a fast catch followed by smooth leveling.
4. Review: the plan is shown as a terminal signal-flow diagram with parameter cards before anything touches Logic.
5. Refine: you critique it conversationally (“cut 3 dB at 400 Hz”, “slower attack”), see a diff of what changed, and can undo or redo any step.
6. Inject: the approved plan is written into Logic Pro, reporting plugins inserted separately from parameters configured, so a partial run is labelled as partial.

Highlights

• Whitelist-bounded: recommendations come only from verified local plugins.
• Studio-style terminal console: an interactive wizard with track inspection, presets, signal-flow graphs and one-key injection.
• Several ways in: the console, a scriptable CLI with JSON output, a local REST API and an MCP server, so my agents can drive it too.
• Reliable injection: parameters are set through Logic’s native Controls view as numbers, instead of by dragging virtual knobs with the mouse.
• Persistent sessions: refinement history survives restarts.

Engineering Notes

• Swift 6, package-first. The code is split into small libraries (models, hardware scanner, track inspector, chain engineer, DAW injector, settings, server), so each concern can be tested alone.
• Headless verification suite. A single test runner exercises the scanner, planner and injection logic without opening Logic.
• Models are configuration, not code. The language model and the search service are plugged in through settings, in line with the rest of my stack.
• Plan, then apply. Refining only changes the plan. Nothing reaches the session until I approve it.