38 lines
1.7 KiB
Markdown
38 lines
1.7 KiB
Markdown
# ADR 0002: Android system time update capability
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## Question
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Can NTP Check update the Android device system time?
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## Finding
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For a normal Play/user-installed Android app: **no**. Android protects system clock changes behind privileged APIs/permissions. An app can measure offset and show guidance, but it cannot directly set wall-clock time unless it is installed with elevated trust.
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## Practical options
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1. **Normal app behavior for v1**
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- Probe NTP servers.
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- Show estimated device offset.
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- Warn when local clock appears wrong.
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- Provide a button to open Android Date & Time settings.
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- No special permissions beyond `INTERNET`.
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2. **Device-owner / enterprise-managed device**
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- Some Android management APIs allow a device owner/profile owner to control certain time/timezone policies depending on Android version and ownership mode.
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- This requires provisioning the app as a device policy controller, not a typical install.
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3. **Privileged/system app or custom ROM**
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- A system-signed or `/system/priv-app` application can use privileged permissions such as `android.permission.SET_TIME`.
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- This is not available to ordinary APK installs.
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4. **Rooted device helper**
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- A rooted-device mode could call shell commands such as `date`/`toybox date`, but this is out of scope for v1 and has safety/security risks.
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## Decision
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V1 will not set Android system time. It will remain a diagnostic/comparison tool and may include an "Open Date & Time settings" action. Any future clock-setting mode must be explicitly separate and gated as enterprise/device-owner, privileged-system, or rooted-device functionality.
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## Product implication
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Market the app as an NTP testing and comparison dashboard, not as a general Android time synchronization daemon.
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