Local notifications

The day-part-local-notify crate provides local notifications. Its current API is separate from the proposed push service and sending tool in the notification design.

API

The crate provides Channel, Importance, Notification, NotifId, Capabilities, and NotifyError. Notification::post(self) returns Result<NotifId, NotifyError>. Trigger has exactly three variants: Now, In(Duration), and At(SystemTime). Use cancel(NotifId) or cancel_all() to cancel notifications.

Call capabilities() to inspect the running platform’s behavior, including post, schedule_while_dead, schedule_exact, and tap_route. Request notification permission through permissions; localize notification text through generated accessors before passing it to the API. See the task guide.

Limits and proposals

The source exposes Unsupported, PermissionDenied, and Failed(String) errors. The design record preserves the earlier platform findings and implementation plan, including proposed recurring triggers, actions, push notifications, and a sending tool. Do not use that record’s proposed signatures as reference for the installed crate.

Parameters, defaults, and failure behavior

Surface	Contract
`Channel::new(id, importance)`	Starts with `id` as its display name; call `.name(res::str::…().format())` before registering
Channel sound	Initially true for High/Urgent importance, false below High; `.sound(bool)` overrides it
`Channel::register(self)`	Returns `()`; no portable registration error result
`Notification::new(title)`	Empty body/subtitle/route/icon, no explicit ID or badge, channel `"default"`, `Trigger::Now`
`.id(NotifId)`	Requests replacement under a stable ID
`.trigger(Trigger)`	Now, relative duration, or absolute system time; no recurring variant
`.post(self)`	Returns an assigned ID or `Unsupported`, `PermissionDenied`, or `Failed(String)`
`cancel(id)` / `cancel_all()`	Return `()`; do not report whether the OS previously displayed the notification

Format channel names and notification text on the UI thread. Notification strings are snapshots, not reactive bindings; posting after a locale change requires a newly formatted notification. On Android the user owns channel settings after creation, so re-registering a channel does not promise to replace their chosen importance. Apple acceptance is not permission or delivery proof.

Platform capabilities

These values follow each backend’s capabilities() implementation. Query it at runtime: Android and HarmonyOS depend on their native bridge being available, and macOS requires an app bundle.

Platform	Post	Schedule after exit	Exact scheduling	User channel settings	Badge	Custom icon	Tap route
macOS / iOS	Yes	Yes	Yes	No	Yes	No	Yes
Android	Yes	Yes	With exact-alarm grant	Yes	Launcher-dependent	Yes	Yes
HarmonyOS	Yes	No	No	No	Yes	No	Yes
Linux / Windows / browser	No	No	No	No	No	No	No

HarmonyOS uses Notification Kit. Importance maps to system notification slots rather than app-defined channel settings. A delayed notification uses an in-process timer: exiting loses it, and background suspension can delay it. Request notification permission before posting.

Apple schedules through the system notification center. Android persists schedules and uses an AlarmManager receiver, including re-arming after reboot. Without the exact-alarm grant, Android falls back to an inexact alarm. See the scheduling guide.

Delivery pitfalls

iOS retains at most 64 pending local notifications. Keep a rolling schedule instead of submitting an unbounded set of reminders.
Android small icons must be monochrome silhouettes. A full-color launcher image can become a white blob in the status bar; the generated default supplies a notification silhouette.
A bare macOS executable has no usable notification center. Launch the generated .app bundle with day launch instead of running the Rust binary directly.
Permission, Focus/Do Not Disturb settings, channel settings, and launcher behavior affect what the user sees. A successful post returns an assigned ID, not a delivery receipt.

The notification recipe supplies imports and catalog entries. Test delayed delivery, app exit, and tap routing on each target you ship.