Tuck architecture

Tuck separates the capture client from the services that make accounts, ingest, reminders, billing, flags, and telemetry work.

Service	Primary responsibility
Web client	Capture, vault, local data, editing
Identity	Accounts, sessions, encrypted snapshots, share snapshots
Ingest	Email, SMS, API capture and reminder delivery
Billing	Trials and paid entitlements
Flags	Feature evaluation by plan
Telemetry	Lightweight product events
Backoffice	Human operations for accounts and usage

There is intentionally no single server-side service that needs unrestricted access to plaintext vault content.

Design principle

Keep adapters at the edge. Email delivery, SMS delivery, billing, and cloud hosting can change without redefining the vault format.