Canto app storage

This page documents where the Canto app keeps its data. It is app storage documentation only: canto-data does not implement any of these storage backends, and reading a journal on disk is a plain canto-data validation exercise.

Native (Android and iOS)

{documentDirectory}/canto/
├── journals.json
├── {journalId}/
│   ├── metadata.json
│   ├── pages/
│   │   └── {pageId}.json
│   └── attachments/
│       └── [e]{img|fl}-{pageId}-{hash}.{ext}

Attachment naming uses {encPrefix}{typePrefix}-{pageId}-{hash}.{ext} where e means password-encrypted and img or fl indicates the attachment type.

Web (IndexedDB)

Database: 'canto' (version 1), Object store: 'files' (keyPath: 'path')

Virtual paths mirror native layout:
  canto/journals.json
  canto/{journalId}/metadata.json
  canto/{journalId}/pages/{pageId}.json
  canto/{journalId}/attachments/{typePrefix}-{pageId}-{hash}.{ext}

Google Drive

The Canto app encrypts journal content with AES-256-GCM before Google Drive upload. Only the registry and sync index are stored unencrypted; canto-data has no Drive behavior.

My Drive/Canto/
├── {journalId}/
│   ├── meta.json
│   ├── index.json
│   ├── pages/{pageId}.json
│   └── attachments/{filename}
App Data (hidden):
└── canto-journals.json

What this means for library users

• The library validates and migrates the JSON payloads; it never opens these directories and never touches attachment bytes.
• Encrypted journals stay opaque until the app (or another GPLv3-compatible tool) decrypts them; see the encryption notes.
• The export archive format is the interchange surface this package specifies and supports.