Add minimal CoT interoperability with UDP beaconing

[nbschultz97]

Summary

• Introduce core module with CoT event model, XML helpers, UDP sender and Interop API
• Add settings screen to toggle CoT, configure host/port and start self-position beaconing
• Expose broadcast receiver and buttons to send or receive markers as CoT packets

Testing

• gradle test (fails: SDK location not found)

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https://chatgpt.com/codex/tasks/task_e_68c4044aaa1c832881b32e5cab07178f

[chatgpt-codex-connector]

Codex Review: Here are some suggestions.

Tactical-App/core/src/main/java/com/example/core/interop/Interop.kt

Lines 47 to 49 in 5ba929d

	fun startSelfBeacon(context: Context) {
	val request = PeriodicWorkRequestBuilder<SelfBeaconWorker>(5, TimeUnit.SECONDS).build()
	WorkManager.getInstance(context)

[P1] Schedule periodic work below WorkManager minimum interval

The self-beacon is created with PeriodicWorkRequestBuilder<SelfBeaconWorker>(5, TimeUnit.SECONDS), but WorkManager enforces a minimum repeat interval of 15 minutes. Calling this method will throw IllegalArgumentException: intervalMillis < MIN_PERIODIC_INTERVAL_MILLIS when the user enables CoT in the settings screen, so the beacon can never start. Use at least 15 minutes (or PeriodicWorkRequest.MIN_PERIODIC_INTERVAL_MILLIS) and consider constraints instead of short polling.

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Tactical-App/core/src/main/java/com/example/core/interop/SelfBeaconWorker.kt

Lines 12 to 15 in 5ba929d

	override suspend fun doWork(): Result {
	if (!Interop.enabled) return Result.success()
	val lm = applicationContext.getSystemService(Context.LOCATION_SERVICE) as LocationManager
	val loc: Location? = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER)

[P1] Self beacon worker ignores runtime location permission

The worker fetches the last known GPS location without checking whether ACCESS_FINE_LOCATION has been granted at runtime. On devices where the user has not granted location, getLastKnownLocation will raise SecurityException, causing the periodic work to fail continuously and preventing any beacons from being transmitted. Request or verify the permission before scheduling the work and handle failures gracefully inside the worker.

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Tactical-App/app/src/main/java/com/example/tacticalapp/CotMarkerReceiver.kt

Lines 10 to 12 in 5ba929d

	override fun onReceive(context: Context, intent: Intent) {
	val json = intent.getStringExtra("marker") ?: return
	Interop.publishMarkerJson(json)

[P1] Exported CoT receiver crashes on malformed broadcasts

The exported CotMarkerReceiver blindly decodes the marker extra with Json.decodeFromString and lacks error handling. Any other app can send com.tacticalapp.SEND_MARKER with invalid JSON, causing a SerializationException that terminates the process while the receiver runs in the background. Validate or catch parsing errors and consider requiring a permission for the broadcast to avoid a trivial DoS.

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