InkDAV

Offline-first CalDAV, VTODO, and WebDAV client for Android color e-ink tablets

InkDAV is an offline-first CalDAV, VTODO, and WebDAV client designed for large Android e-ink tablets, with the BOOX Note Air 5 C as its primary target.

The UI uses opaque paper-colored surfaces, strong outlines, redundant text status, and page-style navigation. It intentionally avoids shadows, gradients, animated transitions, continuously moving indicators, and color-only state.

Current vertical slice Multiple DAV and NASDrive accounts with Android Keystore-encrypted credentials. CalDAV collection discovery, bounded initial event download, RFC 6578 incremental sync and guarded deletion tombstones across multiple calendars. Offline event create/edit/delete with materialized RRULE/RDATE/EXDATE projections, detached changes/cancellations, THISANDFUTURE, and DST-safe date arithmetic. VTODO collection discovery, complete task download including undated and recurring tasks, multiple lists, offline create/edit/delete/completion, and Apple Reminders-style list/schedule views. Year, month, week, and agenda-style day calendar views. Room as the only UI-facing source of truth, with a durable mutation outbox. Immediate full synchronization plus hourly connected calendar/task synchronization with exponential retry; periodic work does not crawl file roots or wake the NAS. If-None-Match/If-Match writes, stopped conflict retries, and explicit “Use server” / “Keep both” resolution. WebDAV file indexing, nested folder navigation, pinned recursive folders, and streaming downloads. A separate local file browser rooted in either a user-selected Android folder or, after explicit all-files authorization, the shared device-storage root, with folder navigation, file-type icons, in-app Markdown/image/audio/first-page PDF previews, and external-app opening for every file. Two-way, three-way-baselined synchronization between a DAV folder and a user-selected Android Storage Access Framework folder, with safe first merge, rename propagation, pause/remove management, duplicate-binding prevention, conditional writes, conflict copies, atomic local downloads, and independent 10,000-item local/remote scan bounds. Android DocumentsProvider integration so other apps can browse indexed files and open cached or streamed content through the system file picker. Resizable task and calendar home-screen widgets. Task widgets can show one selected list or an upcoming window of 1–30 days while excluding selected lists; calendar widgets show the next occurrences. Row counts adapt to launcher-selected widget height. Adjustable past/future calendar cache window and e-ink settings. A Settings updater that checks official GitHub releases, verifies the APK checksum and signing identity, and opens Android's installer.