crowd-funder-for-time-pwa/doc/plugin-feedback-android-6-api23-zoneid-fix.md

Plugin fix: Android 6.0 (API 23) compatibility — replace java.time.ZoneId with TimeZone

Date: 2026-02-27
Target repo: daily-notification-plugin
Consuming app: crowd-funder-for-time-pwa (TimeSafari)
Platform: Android

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Summary

On Android 6.0 (API 23), the plugin crashes at runtime when scheduling a daily notification because it uses java.time.ZoneId, which is only available from API 26. Replacing that with java.util.TimeZone.getDefault().getID() restores compatibility with API 23 and has no functional impact on API 26+ (same timezone ID string, same behavior).

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Problem

• File: android/src/main/java/com/timesafari/dailynotification/NotifyReceiver.kt
• Approximate location: inside scheduleExactNotification(), when building NotificationContentEntity (around line 260).

The code uses:

java.time.ZoneId.systemDefault().id

On API 23 this causes a runtime failure (e.g. NoClassDefFoundError) when the scheduling path runs, because java.time was added to Android only in API 26 (Oreo).

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Required change

Replace the java.time call with the API-1–compatible equivalent.

Before:

java.time.ZoneId.systemDefault().id

After:

java.util.TimeZone.getDefault().id

Use this in the same place where NotificationContentEntity is constructed (the parameter that stores the system timezone ID string). No other code changes are needed.

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Why this is safe on newer Android

• Both ZoneId.systemDefault().id and TimeZone.getDefault().id refer to the same system default timezone and return the same IANA timezone ID string (e.g. "America/Los_Angeles", "Europe/London").
• Any downstream logic that reads this string (e.g. for display or next-run calculation) behaves identically on API 26+.
• No change to data format or semantics; this is a backward-compatible drop-in replacement.

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Verification

1. Build: From a consuming app (e.g. crowd-funder-for-time-pwa) with minSdkVersion = 23, run a full Android build including the plugin. No compilation errors.
2. Runtime on API 23: On an Android 6.0 device or emulator, enable daily notifications and schedule a time. The app should not crash; the notification should be scheduled and (after the delay) fire.
3. Runtime on API 26+: Confirm scheduling and delivery still work as before on Android 8+.

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Context (consuming app)

• App and plugin both declare minSdkVersion = 23 (Android 6.0). AlarmManager, permissions, and notification paths in the plugin are already API-23 safe; this java.time usage is the only blocker for running on Android 6.0 devices.

Use this document when applying the fix in the daily-notification-plugin repo (e.g. in Cursor). After changing the plugin, update the consuming app’s dependency (e.g. npm update @timesafari/daily-notification-plugin or point at the fixed commit), then npx cap sync android and rebuild.