feat: use SAF file picker for swipe data export buttons

- Export JSON and Export NDJSON buttons now open file picker
- Matches behavior of config/clipboard backup export buttons
- Added exportToJSON(OutputStream) and exportToNDJSON(OutputStream) methods
- Default filename includes timestamp (swipe_data_YYYYMMDD_HHMMSS.json)

— claude-opus-4-5-20251101

Author: tribixbite

src/main/kotlin/tribixbite/cleverkeys/SettingsActivity.kt

@@ -100,6 +100,19 @@ class SettingsActivity : ComponentActivity(), SharedPreferences.OnSharedPreferen
         uri?.let { performClipboardImport(it) }
     }
 
+    // SAF file pickers for swipe ML data export
+    private val swipeDataJsonExportLauncher = registerForActivityResult(
+        ActivityResultContracts.CreateDocument("application/json")
+    ) { uri: Uri? ->
+        uri?.let { performSwipeDataJsonExport(it) }
+    }
+
+    private val swipeDataNdjsonExportLauncher = registerForActivityResult(
+        ActivityResultContracts.CreateDocument("application/x-ndjson")
+    ) { uri: Uri? ->
+        uri?.let { performSwipeDataNdjsonExport(it) }
+    }
+
     // Settings state for reactive UI
     private var beamWidth by mutableStateOf(6)
     private var maxLength by mutableStateOf(20)
@@ -3448,15 +3461,37 @@ class SettingsActivity : ComponentActivity(), SharedPreferences.OnSharedPreferen
     }
 
     private fun exportSwipeDataJSON() {
+        try {
+            val sdf = java.text.SimpleDateFormat("yyyyMMdd_HHmmss", java.util.Locale.US)
+            val filename = "swipe_data_${sdf.format(java.util.Date())}.json"
+            swipeDataJsonExportLauncher.launch(filename)
+        } catch (e: Exception) {
+            Toast.makeText(this, "Could not open file picker: ${e.message}", Toast.LENGTH_SHORT).show()
+        }
+    }
+
+    private fun exportSwipeDataNDJSON() {
+        try {
+            val sdf = java.text.SimpleDateFormat("yyyyMMdd_HHmmss", java.util.Locale.US)
+            val filename = "swipe_data_${sdf.format(java.util.Date())}.ndjson"
+            swipeDataNdjsonExportLauncher.launch(filename)
+        } catch (e: Exception) {
+            Toast.makeText(this, "Could not open file picker: ${e.message}", Toast.LENGTH_SHORT).show()
+        }
+    }
+
+    private fun performSwipeDataJsonExport(uri: Uri) {
         lifecycleScope.launch {
             try {
-                val dataStore = tribixbite.cleverkeys.ml.SwipeMLDataStore.getInstance(this@SettingsActivity)
-                val exportFile = dataStore.exportToJSON()
-                Toast.makeText(
-                    this@SettingsActivity,
-                    "Exported to: ${exportFile.absolutePath}",
-                    Toast.LENGTH_LONG
-                ).show()
+                contentResolver.openOutputStream(uri)?.use { outputStream ->
+                    val dataStore = tribixbite.cleverkeys.ml.SwipeMLDataStore.getInstance(this@SettingsActivity)
+                    val count = dataStore.exportToJSON(outputStream)
+                    Toast.makeText(
+                        this@SettingsActivity,
+                        "Exported $count swipe entries to JSON",
+                        Toast.LENGTH_SHORT
+                    ).show()
+                } ?: throw Exception("Could not open file for writing")
             } catch (e: Exception) {
                 Toast.makeText(
                     this@SettingsActivity,
@@ -3467,16 +3502,18 @@ class SettingsActivity : ComponentActivity(), SharedPreferences.OnSharedPreferen
         }
     }
 
-    private fun exportSwipeDataNDJSON() {
+    private fun performSwipeDataNdjsonExport(uri: Uri) {
         lifecycleScope.launch {
             try {
-                val dataStore = tribixbite.cleverkeys.ml.SwipeMLDataStore.getInstance(this@SettingsActivity)
-                val exportFile = dataStore.exportToNDJSON()
-                Toast.makeText(
-                    this@SettingsActivity,
-                    "Exported to: ${exportFile.absolutePath}",
-                    Toast.LENGTH_LONG
-                ).show()
+                contentResolver.openOutputStream(uri)?.use { outputStream ->
+                    val dataStore = tribixbite.cleverkeys.ml.SwipeMLDataStore.getInstance(this@SettingsActivity)
+                    val count = dataStore.exportToNDJSON(outputStream)
+                    Toast.makeText(
+                        this@SettingsActivity,
+                        "Exported $count swipe entries to NDJSON",
+                        Toast.LENGTH_SHORT
+                    ).show()
+                } ?: throw Exception("Could not open file for writing")
             } catch (e: Exception) {
                 Toast.makeText(
                     this@SettingsActivity,

src/main/kotlin/tribixbite/cleverkeys/ml/SwipeMLDataStore.kt

@@ -11,6 +11,8 @@ import java.io.BufferedReader
 import java.io.File
 import java.io.FileReader
 import java.io.FileWriter
+import java.io.OutputStream
+import java.io.OutputStreamWriter
 import java.text.SimpleDateFormat
 import java.util.Date
 import java.util.Locale
@@ -320,6 +322,65 @@ class SwipeMLDataStore private constructor(context: Context) :
         return exportFile
     }
 
+    /**
+     * Export all data to JSON via OutputStream (for SAF file picker)
+     */
+    fun exportToJSON(outputStream: OutputStream): Int {
+        val allData = loadAllData()
+
+        // Build JSON array
+        val jsonArray = JSONArray()
+        for (data in allData) {
+            jsonArray.put(data.toJSON())
+        }
+
+        // Add metadata
+        val root = JSONObject().apply {
+            put("export_version", "1.0")
+            put("export_timestamp", System.currentTimeMillis())
+            put("total_samples", allData.size)
+            put("database_version", DATABASE_VERSION)
+            put("data", jsonArray)
+        }
+
+        // Add statistics
+        val prefs = _context.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE)
+        val stats = JSONObject().apply {
+            put("total_swipes", prefs.getInt(PREF_TOTAL_COUNT, 0))
+            put("calibration_swipes", prefs.getInt(PREF_CALIBRATION_COUNT, 0))
+            put("user_swipes", prefs.getInt(PREF_USER_COUNT, 0))
+        }
+        root.put("statistics", stats)
+
+        // Write to stream
+        OutputStreamWriter(outputStream, Charsets.UTF_8).use { writer ->
+            writer.write(root.toString(2)) // Pretty print with 2-space indent
+        }
+
+        // Mark all as exported
+        markAllAsExported()
+
+        Log.i(TAG, "Exported ${allData.size} entries to JSON stream")
+        return allData.size
+    }
+
+    /**
+     * Export to NDJSON via OutputStream (for SAF file picker)
+     */
+    fun exportToNDJSON(outputStream: OutputStream): Int {
+        val allData = loadAllData()
+
+        OutputStreamWriter(outputStream, Charsets.UTF_8).use { writer ->
+            for (data in allData) {
+                writer.write(data.toJSON().toString())
+                writer.write("\n")
+            }
+        }
+
+        Log.i(TAG, "Exported ${allData.size} entries to NDJSON stream")
+        return allData.size
+    }
+
     /**
      * Get statistics about stored data
      */