Architecture

Product boundary

Project Marvin is the deployed calendar-sync application. Marvin Engine is its runtime.

Runtime flow

Provider event -> webhook or poll -> Marvin Engine daemon
  -> source normalization -> full mesh planner -> target policy
  -> Microsoft Graph / Google Calendar / CalDAV write -> mapping store

The mapping store records source and target identities. Provider markers on generated copies stop those events from becoming sources again.

Mirror policy

Each source event is routed to every other connected calendar. Per-target policy controls visibility and detail.

Setting	Default	Family override
Subject	<PREFIX><SUBJECT>	Same, unless changed
Location	Copied	Copied, unless changed
Description	Copied	Copied, unless changed
Visibility	Private	Private by default; may be changed to normal
Timezone	Source timezone	Source timezone

Provider automation

• Microsoft Graph and Google subscriptions request an early daemon wake on changes; the daemon also renews those subscriptions.
• Apple / CalDAV is polled by the always-running daemon.
• Token refresh, connection validation, deterministic update/upsert handling, delta cursors, and explicit-tombstone cleanup policy are owned by the runtime. Provider deletion is disabled by default.

State

Profiles, provider credentials, tokens, mappings, subscription state, and runtime status are persisted beneath .marvin/ locally or the Azure Files /data mount when hosted.