Add JM21 Physical Key Event Logger Android app with MediaSession service and logging UI

[mun5mun4]

Motivation

• Add a small Android test app to capture and analyze physical media/volume key delivery behavior for FiiO JM21 (Android 13) devices.
• Provide multiple capture paths (MediaSessionService, BroadcastReceiver, and Activity.dispatchKeyEvent) and record environmental context to help reproduce delivery differences when screen/lock/app state changes.

Description

• Introduce a new Android application module implementing a foreground MediaSessionService (KeyLoggerService) that plays a silent WAV in loop to keep the media session active and captures media key events via onMediaButtonEvent.
• Add BroadcastReceiver (MediaButtonEventReceiver) and Activity-level capture (MainActivity.dispatchKeyEvent) so events from different delivery paths are recorded, and create DeviceStateProvider to snapshot environment state.
• Add in-memory logging with KeyEventLogRepository, domain models in KeyEventModels, CSV export (exportToCsv), and a Compose UI in MainActivity to control service/logging and inspect/save logs; include MP3 open/play/seek helpers for manual tests.
• Add project metadata: AndroidManifest.xml, Gradle config (build.gradle.kts, app/build.gradle.kts, settings.gradle.kts, gradle.properties), README.md, and detailed docs/TEST_PROCEDURE.md for manual test instructions.

Testing

• No automated tests or unit/instrumentation tests were added or executed as part of this change.

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Codex Task

[chatgpt-codex-connector]

💡 Codex Review

android_keytest/app/src/main/java/com/example/keyeventlogger/KeyEventLogRepository.kt

Lines 44 to 48 in 5697b91

	downTimestamps.putIfAbsent(event.keyCode, now)
	null
	}
	KeyEvent.ACTION_UP -> {
	downTimestamps.remove(event.keyCode)?.let { now - it }

Track hold timing by source/device, not only keycode

downTimestamps is keyed only by event.keyCode, but this app intentionally logs the same physical press via Activity, BroadcastReceiver, and MediaSession paths. When multiple paths record ACTION_DOWN for one key, the first ACTION_UP removes the shared timestamp and subsequent ACTION_UP entries from other paths get holdDurationMs as null (or an incorrect value), which corrupts per-path hold-duration analysis. Use a composite key (e.g., source + deviceId + keyCode) or derive duration from each event’s downTime/eventTime to keep measurements independent.

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android_keytest/app/src/main/AndroidManifest.xml

Lines 34 to 36 in 5697b91

	<receiver
	android:name=".MediaButtonEventReceiver"
	android:exported="true">

Make media-button receiver non-exported

The media-button receiver is exported and onReceive accepts any ACTION_MEDIA_BUTTON intent payload, then logs it as a key event. That lets any third-party app send an explicit broadcast with crafted EXTRA_KEY_EVENT values, polluting the experiment logs (and triggering service starts) without real hardware input. Restrict this receiver to trusted callers by setting it non-exported or guarding it with an appropriate permission/caller check.

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