Architecture

Components

apps/obsidian-plugin: Obsidian client plugin for local vault scanning, sync orchestration, merge handling, and user notifications.
apps/sync-server: Self-hosted HTTP API for device registration and encrypted revision exchange.
packages/sync-protocol: Shared schemas and request and response types.
packages/sync-engine: Shared merge, hashing, and crypto helpers.

The plugin registers a device with the server and stores the returned device identity and token.
The plugin creates or imports a local vault key.
The plugin pulls encrypted remote changes and applies them locally for both text notes and binary attachments.
Pull operations are paged so the client can resume from the last applied server revision after an interruption.
The plugin scans syncable vault files, hashes changed content, encrypts it, and pushes encrypted revisions in batches.
The server stores ciphertext, revision metadata, tombstones, device state, and active key status in a file-backed state store.
Each sync run emits client-side diagnostics that can be uploaded to the server and correlated with request logs through request IDs.
Recovery bundles package the vault ID, server URL, and current client-side vault key so a new device can join the same encrypted vault.

If only one side changed since the last synced base, accept the changed side.
If both sides changed, write conflict markers into the local file, create a separate remote conflict copy, and require user review before upload continues.

The server storage backend is durable but still file-based rather than relational.
Key distribution between devices still depends on manually sharing a recovery bundle.
Full plugin integration tests across multiple Obsidian instances are not implemented yet.