# Calendar Tools

Inspect, repair, and reconcile calendars locally in the browser.

Calendar Tools is a standalone local-first application in the [add·ideas Toolbox](https://git.add-ideas.de/lotobo/toolbox-portal). Inputs are processed in the browser and are not uploaded.

## Version 0.1 scope

- RFC 5545 parsing and inspection for events, recurrence, attendees, calendar metadata, and embedded VTIMEZONE definitions
- Bounded RRULE/RDATE/EXDATE occurrence preview and overlap/duplicate diagnostics
- Merge and deduplication by UID plus RECURRENCE-ID, preferring SEQUENCE and then DTSTAMP
- Conservative canonical repair: BOM/NUL removal, CRLF serialization, VERSION and PRODID normalization
- Browser-IANA timezone offset/transition reports and explicit DST gap/overlap classification
- Relocatable offline PWA, local-only processing, and deterministic release packaging

Input is limited to 4 MiB, 100,000 physical lines, 10,000 components, and 5,000 events. Recurrence is limited to 500 occurrences per series, a 3,650-day horizon, and 5,000 displayed occurrences. See [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) and [docs/PRIVACY-SECURITY.md](docs/PRIVACY-SECURITY.md).

## Development

Requires Node.js 22 and npm 11.

```sh
npm ci
npm run check
npm run test:browser
```

## Release

`npm run release:artifact` creates a deterministic `release/calendar-tools-0.1.0.zip` and checksum sidecar.

## Licence

GPL-3.0-or-later. Runtime dependencies retain their own licences; see [THIRD_PARTY_NOTICES.md](THIRD_PARTY_NOTICES.md).