# Glossary

**T (slot time)** — The local wall-clock time a notification is intended to fire (e.g., 08:00).

**T–lead** — The moment **{prefetchLeadMinutes} minutes before T** when the system _attempts_ a background prefetch to refresh content.

- Example: If T = 12:00 and `prefetchLeadMinutes = 20`, then **T–lead = 11:40**.
- If background prefetch is skipped/denied, delivery still occurs using the most recent cached payload (rolling-window safety).
- T–lead **governs prefetch attempts, not arming**. We still arm one-shot locals early (rolling window) so closed-app delivery is guaranteed.

**Rolling window** — Always keep **today’s remaining** one-shot locals armed (and optionally tomorrow, within iOS caps) so the OS can deliver while the app is closed.

**TTL (time-to-live)** — Maximum allowed staleness of a payload at **fire time**. If the projected age at T exceeds `ttlSeconds`, we **skip** arming.

**Exact alarm (Android)** — Minute-precise alarm via `AlarmManager.setExactAndAllowWhileIdle`, subject to policy and permission.

**Windowed alarm (Android)** — Batched/inexact alarm via `setWindow(start,len)`; we target **±10 minutes** when exact alarms are unavailable.

**Start-on-Login** — Electron feature that automatically launches the application when the user logs into their system, enabling background notification scheduling and delivery after system reboot.