# Host API and Regression Policy

UnifiedWriter is a Host-embeddable Control.  It does not choose storage providers.

## Public Control helpers

- `exec(commandId, payload)` executes registered commands.
- `getState()` returns shell/state snapshots.
- `getDocument()` returns a serializable document record.
- `setDocument(doc)` loads a document record into the editor.
- `exportBlob(format)` returns a Blob for `uwpsx`, `docx` or `html` where supported.
- `validate()` runs the product-regression checklist and returns a structured report.
- `getHostApiContract()` returns expected callbacks/events/file types.

## Storage policy

Open, Save, Save As, Export and Image insertion must be routed through Host callbacks/adapters.  Demo pages may implement LocalDevice as a Host example, but provider selection must not leak into the Control API.