Add OneDrive/Excel sync as secondary cloud storage option

[fatherlinux]

Summary

A Reddit user asked about OneDrive/Excel support as an alternative to Google Sheets for cloud data sync. Currently Acquacotta only supports Google Sheets for cross-instance data and settings sync. Adding OneDrive/Azure as a secondary option would broaden the user base — particularly for users in Microsoft-heavy environments or those who prefer not to use Google services.

User Request (Reddit)

Any plans to include other file sync options like excel on onedrive?
I like the individual approach for keeping your own data.

Proposed Approach

• Add OneDrive/Excel as a secondary cloud sync backend alongside the existing Google Sheets integration
• Use Microsoft Graph API for OneDrive file access
• Store data in an Excel workbook (.xlsx) with the same schema as the current Google Sheets layout (Pomodoros, Settings, Types sheets)
• Allow users to choose their sync backend (Google Sheets or OneDrive) in settings
• Keep SQLite as the primary local database — cloud sync remains optional

Implementation Considerations

• Microsoft Graph API requires OAuth2 app registration (Azure AD)
• Need to handle Excel file locking/concurrency differently than Google Sheets API
• Consider using the OneDrive REST API for file read/write rather than a full Excel manipulation library
• Authentication flow will differ from Google OAuth — need a separate setup path in the UI