MusicBook Pro is developed by Music by Lars. It is a private songwriting, personal songbook, setlist and live-performance app for original songs and user-entered material.
Summary
The public App Store release is MusicBook Pro 5.5. Version 6.0 is being tested in TestFlight. This policy also describes planned 6.0 privacy controls; that description does not mean PCC is already active or publicly available.
MusicBook Pro does not use ads, subscriptions, third-party tracking or third-party analytics. Built-in Smart and audio features do not use third-party AI or audio APIs. The optional Mac-only Agent Collaboration feature can send only permitted text and metadata to a provider such as OpenAI or Anthropic after the user deliberately enables access.
Your creative library is stored locally by default. Optional iCloud sync uses your private iCloud account when you enable it. MusicBook Pro uses Apple StoreKit for the optional one-time Full Version unlock.
Data stored in the app
MusicBook Pro may store songs, drafts, ideas, projects, setlists, collections, lyrics, chords, tags, musical and performance metadata, notes, app settings, recordings you deliberately save and temporary transcription audio on your device. Per-device Agent Collaboration settings include permissions, access expiry and a local activity history containing provider, action, item name and time, but not lyrics or raw request text.
iCloud sync
iCloud sync is optional. When enabled, supported song data is synchronized through your private iCloud account. Ideas media, raw audio and temporary transcription audio do not sync by default. Agent-created Ideas and Setlists follow the same song-data sync choice as other saved library items.
Microphone, speech recognition and camera
MusicBook Pro requests microphone access for listening tools you choose to use, such as recording your own ideas, Transcribe or the tuner. Speech-recognition access is requested to create editable text from your own recordings. Camera access is requested for user-initiated scanning or video Ideas. Apple system speech recognition may process audio according to Apple's platform behavior and your device settings. MusicBook Pro does not send audio to third-party transcription services.
Built-in Smart features
Smart Layout, SmartRhymes, SmartFeedback, SmartWriter, SmartImport, SmartSetlist, SmartScroll, SmartNaming and Chord Inspiration use local rules or Apple technologies according to availability. The planned Apple PCC text-processing route in 6.0 is described at the end of this policy. Built-in Smart features do not use OpenAI, Anthropic or other third-party AI/audio APIs. Agent Collaboration is a separate optional feature.
Agent Collaboration
Agent Collaboration is off by default and its controls are available only in the Mac version. Other devices show only a short explanation. When enabling it, the user chooses whether a connected service may read approved library text and metadata, create new Ideas, create new Setlists, or a combination of those actions. The user chooses a fixed access period or Until turned off. Timed access does not extend when used. Disconnect All or turning access off revokes the Mac connection immediately.
The authenticated MCP gateway runs on Cloudflare Workers and relays approved requests to the paired Mac. Auth0 provides OAuth login and access tokens. The gateway is designed without a creative-library database and without raw request-body, lyric or item-content logging. Approved content necessarily passes through the gateway and the chosen agent provider to answer the request. Cloudflare and Auth0 may process ordinary network, security and authentication data under their own terms and privacy policies.
Approved request content remains in the gateway only while the request is in flight, until its response or timeout, normally no longer than 25 seconds. Active routing state is volatile until disconnection or service restart. Authentication and security records are handled under the configured Auth0 policies. Read the tool-by-tool Agent Collaboration disclosure.
If the Mac is closed, offline or access is disabled, the private library is unavailable. Connected agents cannot access source code, generic files, shell commands, Git, Xcode, SQL, media, temporary recordings, hidden transcripts, credentials or recovery data. They cannot edit or delete existing library items. With the matching permission enabled, they may save only a new Idea or Setlist through MusicBook Pro's normal persistence boundary. The local activity history provides Open and Undo controls for agent-created items and is not synced by default.
Provider data controls
For optional Agent Collaboration, the selected provider's privacy terms and account settings apply after you send approved content. MusicBook Pro cannot change those controls. Retention, model-improvement settings and feedback handling may vary by provider and account type.
Review the current controls before sharing private writing or submitting provider feedback. Never include credentials or recovery information in approved songwriting content. These provider connections are separate from Apple PCC.
Backups and exports
MusicBook Pro creates a backup or export only when you request one. Ideas media is excluded by default unless you explicitly choose an option that includes it.
What Music by Lars collects
MusicBook Pro does not create a developer-controlled copy of your creative library. The optional gateway processes authentication, active connection state and in-flight approved requests solely to relay them to the paired Mac. If you contact Music by Lars, your message and contact details are handled only so we can respond.
Tracking and children
MusicBook Pro does not track you across apps or websites and is not designed to collect personal information from children.
Contact
For privacy or support questions, contact Music by Lars at musicbylars.com/index.php/contact.
Apple Private Cloud Compute in version 6.0
Apple Private Cloud Compute (PCC) is a planned optional route for eligible SmartFeedback and SmartWriter text requests in MusicBook Pro 6.0. Version 6.0 remains in TestFlight testing. PCC is not enabled merely because Apple has granted the app access: live access, supported languages and measured quality requirements must also be satisfied. Current quality validation is still open.
Off by default and under your control
PCC starts off on a new installation and after upgrading from an earlier version. A previous Best Available setting is not consent. You must actively enable Use Apple Private Cloud Compute in Settings. The choice belongs to that device and is not automatically enabled by iCloud, a retry, an import, onboarding or the SmartFunctions master switch.
You can turn PCC off again in Settings. The app checks consent before cloud processing, while a request is running and before accepting its result. Turning it off prevents new PCC requests and discards late cloud results; it cannot recall text that has already been sent to Apple.
What may be sent to Apple
Only the draft text needed for an eligible SmartFeedback or SmartWriter request and any writing Brief you have explicitly approved for that request may be sent. A Brief may contain the creative context you approve. Send only writing you are comfortable having Apple process.
This PCC route excludes audio and video recordings, raw or temporary Transcribe audio and transcripts, retry recordings, source media, unrelated library or profile metadata, credentials and recovery data. SmartNaming stays local. Transcribe continues to use its separate Apple Speech workflow and permissions; enabling PCC does not move recordings to PCC.
The app does not create a developer-controlled copy of PCC request or response content or log draft text and replies. Apple's infrastructure processes the submitted text to produce the requested suggestions. Apple describes PCC as using personal data only to fulfil a request and making that data unavailable after the response. See the Apple Private Cloud Compute Security Guide and Apple Privacy Policy for Apple's current commitments.
Local fallback and review
PCC needs a supported OS and device, Apple access, a supported language, a connection, available quota and an accepted quality configuration. Your Settings opt-in does not bypass these requirements. When PCC is unavailable, busy, too slow or returns an invalid result, the app falls back to supported on-device Apple processing and then local rules where available. Core writing, the library and Performance remain available offline.
SmartFeedback and SmartWriter remain suggestions. They do not replace your words or save generated material without your acceptance. You review a result and choose whether to use it. PCC does not provide perfect-quality guarantees and remains separate from optional Mac Agent Collaboration.