logic-pro-mcp

The missing API for Logic Pro.
Natural-language control of Logic Pro from Claude and other MCP clients.

If this project helps you make music with Claude, Cursor, or any MCP client, give it a star. It helps this repo reach more Logic Pro users.

Logic Pro has no public API. This server bridges that gap by combining 7 native macOS control channels into a single MCP interface — giving AI assistants bidirectional, deterministic control over transport, mixing, MIDI composition, plugins, automation, and project lifecycle.

You: "Make a 4-bar techno loop in A minor at 140 BPM"

Claude → logic_tracks.record_sequence {
  bar: 1, tempo: 140,
  notes: "45,0,95;57,107,95;45,214,95;..."
}
Claude → logic_tracks.set_instrument {
  index: 0, path: "Electronic Drums/Roland TR-909"
}

Logic Pro: region imported, TR-909 loaded, ready to play.

Why this exists

Logic Pro ships without an AppleScript dictionary rich enough for composition workflows, without OSC, and without a first-party MCP server. Every existing "Logic automation" tool either:

1. Relies on screen-scraping via vanilla AppleScript (slow, fragile, breaks every Logic update)
2. Simulates keyboard shortcuts (no state awareness, no feedback)
3. Uses a single protocol like MCU alone (misses 80% of Logic's surface)

This server takes a different approach: combine seven complementary channels, route each operation to the channel best suited for it, and expose a clean MCP tool surface on top.

What it does

Mixer — Control faders, pan, sends, plugin parameters with 14-bit MCU resolution. Bidirectional: state cache reflects what Logic actually did, not what you requested.

Transport — Play, stop, record, locate, cycle, tempo, metronome. Sub-millisecond CoreMIDI MMC path; AX dialog fallback for precise bar positioning that auto-extends the project length.

MIDI composition — record_sequence generates a Standard MIDI File server-side and imports it into a new track. Zero timing drift regardless of system load; notes land at the exact requested bar.

Library & instruments — Enumerate Logic's full instrument library (Electronic Drums, Synthesizer, Bass, etc.) and load presets by path. Tree-scan caches to disk for instant subsequent lookups.

Plugins — Deterministic plugin parameter control via a Scripter JS insert on the selected track.

Navigation — Goto bar, markers by name, zoom, view toggles.

Project lifecycle — New, open, save, save-as, close, bounce, quit — all with explicit destructive-operation confirmation.

Quick Start

Prerequisites: macOS 14+, Logic Pro 12.0.1+, Apple Silicon (arm64) native; Intel Macs are supported via Rosetta 2.

Option A — Homebrew (recommended)

brew tap MongLong0214/logic-pro-mcp https://github.com/MongLong0214/logic-pro-mcp
brew install logic-pro-mcp

The Homebrew formula pins both the release tarball URL and its SHA256; Homebrew itself is a trusted delivery channel with its own signature chain. This is the hardened path for production installs.

Option B — Download-inspect-run one-line installer

The installer is fail-closed: it refuses to run without explicit LOGIC_PRO_MCP_SHA256 + LOGIC_PRO_MCP_TEAM_ID env pins. Inspect the script first, then execute with the pins copied from the release's SHA256SUMS.txt:

curl -fsSL https://raw.githubusercontent.com/MongLong0214/logic-pro-mcp/v3.1.1/Scripts/install.sh -o install.sh
# inspect install.sh, then:
LOGIC_PRO_MCP_SHA256=<paste from release SHA256SUMS.txt> \
LOGIC_PRO_MCP_TEAM_ID=ADHOC \
bash install.sh

If you knowingly accept same-origin provenance (hash + Team ID fetched from the same release as the binary), opt in explicitly:

LOGIC_PRO_MCP_ALLOW_SAME_ORIGIN=1 \
bash <(curl -fsSL https://raw.githubusercontent.com/MongLong0214/logic-pro-mcp/v3.1.1/Scripts/install.sh)

See SECURITY.md §Installer trust model for the trust tiers and threat model.

Either path installs the binary, verifies its SHA256, registers with Claude Code, and installs the Key Commands preset. It does not configure the MCU control surface or Scripter insert — see the Setup Guide for those two manual steps (~5 minutes).

Then test in Claude:

"Check Logic Pro MCP health and show all ready channels."

Expected: all 7 channels ready (or 5 if you skipped Key Commands and Scripter).

Architecture at a Glance

┌─ MCP Client (Claude / Desktop / Code) ─┐
│                                         │
│   logic_transport   logic_tracks        │
│   logic_mixer       logic_midi          │
│   logic_edit        logic_navigate      │
│   logic_project     logic_system        │
│                                         │
└─────────────────┬───────────────────────┘
                  │ stdio
┌─────────────────▼───────────────────────┐
│  LogicProMCP Server (Swift)             │
│                                         │
│  ┌─ ChannelRouter (130+ operations) ──┐ │
│  │  routes operation → best channel  │ │
│  └───────────────────┬───────────────┘ │
│                      │                  │
│  ┌──────┬──────┬─────▼─────┬──────┐    │
│  │ MCU  │ AX   │ AppleScript│CoreMIDI│ │
│  │      │      │            │        │ │
│  │ CGEvent      Scripter  KeyCmds   │ │
│  └──────┴──────┴───────────┴────────┘ │
│                      │                  │
└──────────────────────┼──────────────────┘
                       │ MIDI / AX / AppleScript
                ┌──────▼───────┐
                │   Logic Pro  │
                └──────────────┘

See Architecture for deeper details on channel priorities and state flow.

Documentation

Status

v3.1.1 (2026-04-26) — Honest Contract Extension. v3.1.0 covered 4 ops; v3.1.1 promotes 13 more AX-channel mutating ops (track lifecycle, transport, region, midi.import_file, project.save_as, mixer AC fallback) to the same 3-state envelope, plus unifies logic://transport/state under the {cache_age_sec, fetched_at, data} envelope. MCU-routed track.set_automation and the V-Pot pan State-A enabler are deferred to v3.1.2.

What changed from v3.0.9

• track.set_instrument now reads back the loaded patch name and reports verified:true only when it matches the request; mismatches return verified:false with reason:"readback_mismatch".
• track.select reads back AXSelectedChildren with a 6× retry (100ms each, 600ms budget). A read-back that returns a different index returns verified:false with reason:"readback_mismatch"; a read-back that never surfaces across the retry budget returns verified:false with reason:"retry_exhausted". Neither path silently claims a bare success.
• mixer.set_volume / mixer.set_master_volume now poll the MCU fader echo into StateCache for 500ms (override via MCU_ECHO_TIMEOUT_MS=250|500|1000) and return verified:true only when a freshly-written echo matches within ±2 LSB (14-bit resolution, tolerance 2/16383). The freshness stamp prevents an identical-value re-send from being confirmed by a stale cache value left over from the prior call.
• mixer.set_pan returns verified:false with reason:"readback_unavailable" — V-Pot feedback is relative and not yet plumbed through to StateCache; the honest answer beats a silent lie.
• transport.set_cycle_range (AX path) now returns the verified field that the osascript fallback already had.
• scan_library {mode:"disk"} no longer poisons the lastScan cache that resolve_path / set_instrument consult; disk-only entries are annotated and do not claim loadable:true.
• State resources (logic://tracks, logic://library/inventory, …) expose cache_age_sec + fetched_at so clients can detect staleness.

Compatibility: mutating-op responses are additive (new verified / reason / observed fields). Breaking at the resource layer: logic://tracks and logic://library/inventory now wrap their payload in {cache_age_sec, fetched_at, data: …}, and logic_tracks.scan_library wraps its result in {source, root: …}. v3.0.9 clients that parsed those payloads directly must read .data / .root to reach the legacy shape. See CHANGELOG §Compatibility for the full migration diff.

scan_library continues to enumerate ~/Music/Logic Pro Library.bundle/Patches/Instrument/ (5,000+ leaves on a full factory install). The v3.0.5 wording that "every patch on disk is addressable via track.set_instrument" is withdrawn — paths that the Panel-taxonomy mapper cannot route are now surfaced honestly instead of silently pretending to load.

Notarized (Apple-signed) release requires Apple Developer Program membership ($99/year). Until that's set up, the installer operates in ADHOC mode: SHA256 pin + codesign --verify still protect against tampering, but macOS Gatekeeper assessment is skipped and the installer strips the quarantine attribute so the binary runs without warnings.

See SECURITY.md §Release types for the trust model detail.

Testing

• 824 unit + integration tests passing on the v3.1.1 branch (swift test --skip testLogicProServerStartCoversDefaultPortAndPollerLifecyclePaths --skip testStatePollerStartStopLifecycle — 2 timer-driven lifecycle tests are deterministic-only under load-bearing CI, not product code)
• Live E2E (Scripts/live-e2e-test.py): the ~200 environment-independent assertions pass; ~45 tests require a running Logic Pro 12 session with the MCU control surface registered and fail otherwise (documented as environment-gated, not regression)
• Multiple independent production-readiness reviews (code quality, security, architecture) converged to PROCEED after the v3.0.2 hardening passes
• v3.0.3+ AX-native control surface: primary GUI touchpoints (track selection, plugin Setting popup) prefer Apple AX actions (AXPress, AXShowMenu, AXSelectedChildren) with CGEvent only as a last-resort fallback — reduces fragility under Logic UI updates
• v3.0.4 N-column Library navigation: track.set_instrument delegates to the new LibraryAccessor.selectPath which clicks every segment in order; the 2-segment legacy caller path still works unchanged.
• v3.0.5 filesystem-backed scan_library: LibraryDiskScanner enumerates the Logic factory bundle on disk (no AX, no Library Panel clicks) and produces a schema-identical LibraryRoot with full coverage. Default mode is disk; legacy AX scan is available via {mode:"ax"}; a diff report is available via {mode:"both"}.

Known limitations

• transport.set_tempo currently requires the Logic tempo display to be accessible via AX; it returns an error if the control bar layout hides the BPM field. Workaround: set tempo manually in Logic once before calling MCP tempo operations.
• MIDI File import cosmetics: record_sequence regions start at bar 1 and extend to the target bar (padding CC technique). Note timing inside the region is exact; the leading padding is inaudible. If you need a tight region, trim after import via Logic's Edit → Trim menu.

License

MIT. See LICENSE.

Contributing

Bug reports, PRs, and feature discussions are welcome. See CONTRIBUTING.md for the dev workflow.

Security vulnerabilities: please do not open a public issue. See SECURITY.md for the private disclosure process.