notifications.ts

Configures the notification handler and sends heat-risk alerts keyed to core temperature

Purpose

This module configures the global Expo notification handler and exposes functions for requesting notification permissions and sending immediate heatstroke risk alerts. Alert message content is determined by core temperature thresholds.

Its responsibilities include:

Installing the global setNotificationHandler at module load time
Requesting foreground notification permissions from the user
Scheduling an immediate local notification with a temperature-appropriate message
Mapping a core temperature value to one of four risk message strings

Invariants

Handler Installed at Import Time

Notifications.setNotificationHandler is called as a module-level side effect.

The handler always allows banner display, sound, and list display. Badge setting is always disabled.

Immediate Trigger

All notifications use trigger: null, meaning they are delivered immediately rather than scheduled for a future time.

Temperature-Based Message Selection

Alert messages are selected by descending threshold comparison against the same zone boundaries used in PredictionScreen:

Core temp (°C)	Message severity
`≥ 40.5`	Life-threatening; instructs to call 119
`≥ 40.0`	Call 119; apply ice packs
`≥ 38.5`	Stop work; move to cool place
`≥ 38.0`	Slow down; rest and hydrate
`< 38.0`	`"safe"` (no alert expected at this level)

Exports

`requestNotificationPermissions()`

async function requestNotificationPermissions(): Promise<boolean>

Requests notification permissions. Returns true if granted.

`sendHeatstrokeAlert(...)`

async function sendHeatstrokeAlert(riskTemp: number): Promise<void>

Schedules an immediate local notification with a message appropriate to the given core temperature.

Parameters

Parameter	Description
`riskTemp`	Predicted core temperature in °C