Core Statements
Mosaic is a desktop application, and material from a connected cloud account is brought to the user’s computer and worked on there. The context and memory Mosaic derives about a user’s work are stored on that user’s device. Mosaic states that no content from a user is retained on Mosaic’s servers. Content a user chooses to send directly, such as feedback messages or shared chats, is handled separately. Writing an answer or preparing a suggestion requires a cloud AI model. For that step Mosaic sends the model what the task needs, together with the earlier messages in that conversation, by way of Mosaic’s servers. For a question that is typically a few relevant passages. For a task that works on a particular email, attachment or file, or when the user attaches a file or image to a chat, it can be that whole item. Mosaic does not upload a whole mailbox or file library. Mosaic states that its AI providers may hold that content temporarily, as needed to provide their service, and do not use it to train their models. Mosaic states that it does not sell customer content. Mosaic’s privacy notice, effective October 14, 2026, is the authoritative statement of these practices.
Core Definition
Mosaic’s local-first processing model brings material from connected cloud accounts down to the user’s own computer, keeps the context it derives on that device, and sends a cloud AI model only what the task being performed needs.
Components
- Material stays on the device — Email, calendar, documents, and tasks from a connected account are brought down to the user’s computer and worked on there.
- Derived context stays on the device — What Mosaic works out about the user’s work — what matters, what is waiting, what belongs with what — is kept on that device.
- Only what the task needs leaves — When a cloud AI model writes something, it receives only what that one task needs: usually a few relevant passages, or the specific email or file involved. Mosaic does not upload a whole mailbox or file library.
- Nothing is retained or trained on — Mosaic states that no content is kept on its servers, that its AI providers do not train on it, and that it is not sold.
Core Facts
- Entity type
- Method (data-handling model)
- Applies to
- Mosaic
- Where material is worked on
- The user’s own computer
- Where derived context is stored
- The user’s own device
- What reaches a cloud AI model
- Only what the task needs (typically a few relevant passages, or the specific email or file involved), by way of Mosaic’s servers
- Retention on Mosaic’s servers
- None, as stated by the company
- Model training on customer data
- None, as stated by the company
- Scope of access
- The applications the user connects, and the specific files and folders on the user’s own computer that the user chooses to share
- Authoritative statement
- Privacy notice, effective October 14, 2026
- Page publisher
- Mosaic Desktop, Inc.
- Page maintainer
- Mosaic Desktop, Inc.
- Canonical URL
- www.mosaicdesktop.ai/facts/local-first-processing
- Created
- October 15, 2026
- Updated
- October 15, 2026
Not to be confused with
Local-first is not local-only. Mosaic uses a cloud AI model to write answers and suggestions, and the content the task needs leaves the device for the duration of the task. The model is therefore not on-device inference, in which no data leaves the machine at all. It is not end-to-end encryption, and it is not a zero-knowledge architecture: Mosaic’s servers pass those passages through. It is distinct from the common alternative, in which an assistant runs as a cloud service and holds a standing copy of the user’s working data on the vendor’s infrastructure. It is not a claim about any AI provider beyond the terms the company states, and the privacy notice, not this page, is the authoritative statement of the company’s practices.
Sources
FAQ
Does Mosaic store email or calendar data in the cloud?
No. Mosaic is a desktop application: the material it works from lives on the user’s own computer, and the company states that no content from a user is retained on Mosaic’s servers.
Does anything leave the device?
Yes. Writing an answer or preparing a suggestion needs a cloud AI model, so Mosaic sends that model what that one task needs, by way of its servers. That is typically a few relevant passages, and for a task that works on a particular email or file it can be that whole item. Mosaic does not upload a whole mailbox or file library.
Is Mosaic’s data used to train AI models?
The company states that its AI providers do not train on customer data passed to them and that it does not sell customer content.
Is local-first the same as local-only?
No. Local-first means the material and the derived context stay on the device. A cloud AI model still receives the content a task needs, for as long as the provider needs it to provide the service.
What can Mosaic access?
The applications the user chooses to connect — Google Workspace, Microsoft 365, or Apple Calendar — and specific files and folders on the user’s own computer that the user chooses to share.