I coded a timer app that outputs text-to-speech audio, but the timer stops every time I switch to another app or lock the phone, and I would like it to continue timing even when I do that.

Here are the 2 composables that make up the current app:

**@Composable**
    fun rememberTextToSpeech(context: Context): TextToSpeech {
        var ttsInstance: TextToSpeech? = null

        val tts = remember {
            TextToSpeech(context) { status ->
                if (status == TextToSpeech.SUCCESS) {
                    ttsInstance?.language = Locale("spa")
                }
            }.also {
                ttsInstance = it
            }
        }

        DisposableEffect(Unit) {
            onDispose {
                tts.shutdown()
            }
        }

        return tts
    }

    @OptIn(ExperimentalMaterial3Api::class)
    **@Composable**
    fun TimerScreen() {
        val context = LocalContext.current
        val tts = rememberTextToSpeech(context)

        var inputText      by remember { mutableStateOf("") }
        var timeLeft       by remember { mutableStateOf(0) }     // seconds
        var isRunning      by remember { mutableStateOf(false) }
        var isFinished     by remember { mutableStateOf(false) } // ‹— NEW
        var initialMinutes by remember { mutableStateOf(0) }

        /* ─────────────  COUNT‑DOWN  ───────────── */
        LaunchedEffect(isRunning, timeLeft) {
            if (isRunning && timeLeft > 0) {
                delay(1000)          // tick
                timeLeft -= 1
            } else if (isRunning && timeLeft == 0) {
                isRunning  = false
                isFinished = true      // trigger the repeater
            }
        }

        /* ─────────────  REPEATER  ───────────── */
        LaunchedEffect(isFinished) {
            while (isFinished) {       // keeps looping until Reset toggles it off
                val msg = "Your $initialMinutes minute timer is done"
                tts.speak(msg, TextToSpeech.QUEUE_FLUSH, null, "timer_done")
                delay(3000)           // repeat interval (3s feels natural)
            }
            tts.stop()                 // stop any ongoing speech when reset
        }

        /* ─────────────  UI  ───────────── */
        Column(
            modifier = Modifier
                .fillMaxSize()
                .background(Color(0xFFF5F5DC))
                .padding(24.dp),
            horizontalAlignment = Alignment.CenterHorizontally,
            verticalArrangement = Arrangement.Center
        ) {

            Text(
                "How many minutes would you like to time?",
                fontSize = 20.sp,
                fontWeight = FontWeight.Bold,
                color = Color.Black
            )

            Spacer(Modifier.height(32.dp))

            TextField(
                value = inputText,
                onValueChange = { if (it.all(Char::isDigit)) inputText = it },
                label = { Text("Minutes") },
                singleLine = true,
                modifier = Modifier.width(120.dp)
            )

            Spacer(Modifier.height(64.dp))

            val mm = timeLeft / 60
            val ss = timeLeft % 60

            Column (
                horizontalAlignment = Alignment.CenterHorizontally,
                verticalArrangement = Arrangement.Center
            )   {

                Text(
                    String.format("%02d:%02d", mm, ss),
                    fontSize = 64.sp,
                    fontWeight = FontWeight.Bold
                )

                Spacer(Modifier.height(64.dp))

                /* START */
                Button(
                    onClick = {
                        val minutes = inputText.toIntOrNull() ?: 0
                        if (minutes > 0) {
                            initialMinutes = minutes
                            timeLeft = minutes * 60
                            isRunning = true
                            isFinished = false   // safeguard
                        }
                    },
                    enabled = !isRunning && inputText.isNotBlank(),
                    colors = ButtonDefaults.buttonColors(containerColor = Color.Green)
                ) { Text("Start", color = Color.Black) }

                /* RESET */
                Button(
                    onClick = {
                        isRunning = false
                        isFinished = false      // stops the repeater loop
                        timeLeft = 0
                        inputText = ""
                    },
                    colors = ButtonDefaults.buttonColors(containerColor = Color.Red)
                ) { Text("Reset") }
            }
        }
    }

I've only tried the original implementation, which I did not expect to stop when switching the app or locking the phone.