Optional auto-cleanup of recordings older than N days (engine only)

app/src/main/java/com/dimowner/audiorecorder/ARApplication.kt

@@ -62,6 +62,11 @@ class ARApplication : Application() {
         }
         registerAudioOutputChangeReceiver()
         registerRebootReceiver()
+        runCatching {
+            val fileRepo = injector.provideFileRepository(applicationContext)
+            com.dimowner.audiorecorder.util.RecordingsRetention
+                .sweepIfDue(applicationContext, fileRepo?.recordingDir)
+        }
 
         // feature: pause when phone functions ringing or off-hook
         try {

app/src/main/java/com/dimowner/audiorecorder/util/RecordingsRetention.kt

@@ -0,0 +1,57 @@
+package com.dimowner.audiorecorder.util
+
+import android.content.Context
+import android.content.SharedPreferences
+import java.io.File
+
+/**
+ * Opt-in auto-cleanup of old recordings.
+ *
+ * Stores a single integer setting `max_age_days` in `recordings_retention`
+ * SharedPreferences. When non-zero, [sweepIfDue] deletes recording files older
+ * than that many days from the given directory. Throttled to one sweep per
+ * 24h via a `last_run` timestamp.
+ *
+ * Default `max_age_days = 0` means the feature is **disabled** and no files
+ * are ever touched — drop-in safe for users who don't opt in.
+ *
+ * A Settings UI to set the threshold is intentionally not bundled with this
+ * change; the engine is the load-bearing piece and the UI can be a follow-up.
+ * Callers (or a future Settings row) configure it via [setMaxAgeDays].
+ */
+object RecordingsRetention {
+    private const val PREFS_NAME = "recordings_retention"
+    private const val KEY_MAX_AGE_DAYS = "max_age_days"
+    private const val KEY_LAST_RUN = "last_run"
+    private const val ONE_DAY_MS = 24L * 60L * 60L * 1000L
+
+    fun setMaxAgeDays(context: Context, days: Int) {
+        prefs(context).edit().putInt(KEY_MAX_AGE_DAYS, days.coerceAtLeast(0)).apply()
+    }
+
+    fun getMaxAgeDays(context: Context): Int =
+        prefs(context).getInt(KEY_MAX_AGE_DAYS, 0)
+
+    /**
+     * Delete recording files older than `max_age_days` from [recordingDir],
+     * if a sweep hasn't run in the last 24h. No-op when `max_age_days = 0`
+     * (the default) or when the directory is missing.
+     */
+    fun sweepIfDue(context: Context, recordingDir: File?) {
+        val days = getMaxAgeDays(context)
+        if (days <= 0 || recordingDir == null || !recordingDir.isDirectory) return
+        val now = System.currentTimeMillis()
+        val lastRun = prefs(context).getLong(KEY_LAST_RUN, 0L)
+        if (now - lastRun < ONE_DAY_MS) return
+        val cutoff = now - days.toLong() * ONE_DAY_MS
+        recordingDir.listFiles()?.forEach { file ->
+            if (file.isFile && file.lastModified() < cutoff) {
+                runCatching { file.delete() }
+            }
+        }
+        prefs(context).edit().putLong(KEY_LAST_RUN, now).apply()
+    }
+
+    private fun prefs(context: Context): SharedPreferences =
+        context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+}