v1.0.76: multi-folder backup (many folders -> one remote base, each its own subfolder)

Adds an opt-in 'Back up multiple folders' mode to Add Sync: pick N folders +
one remote base, and the app creates one normal pair per folder at
base/<folderName>. Each source keeps its own subfolder so same-named files
across folders never collide/overwrite — the safe many-to-one.

- AddPairViewModel: multiFolder + localPaths state, batch save via buildEntity;
  folderLeafName() + uniqueSubName() derive collision-free remote subfolders
- AddPairScreen: mode toggle (new pairs only), folder list w/ add/remove,
  remote-base labelling
- SyncEngine: first-sync against a not-yet-created remote folder no longer fails
  — treat 404 as empty remote ONLY when no prior state exists (no DELETE_* can
  fire), and MKCOL the base dir so first uploads have a parent. An established
  pair still fails loudly on 404 (never mass-deletes a vanished remote).
- Tests: MultiFolderTest, isRemoteNotFound cases in ExcludePathTest

app/src/main/kotlin/com/syncflow/domain/sync/SyncEngine.kt

@@ -116,9 +116,22 @@ class SyncEngine @Inject constructor(
         // got DELETE_REMOTE'd every cycle — endless churn as Android regenerates the cache.
         // Filtering remote + the merged path set makes excluded paths invisible to the engine:
         // never uploaded, downloaded, or deleted on either side.
-        val remoteFiles = listRemoteFilesRecursive(provider, pair.remotePath)
+        val remoteFiles = try {
-            .associateBy { it.path.removePrefix(pair.remotePath).trimStart('/') }
+            listRemoteFilesRecursive(provider, pair.remotePath)
-            .filterKeys { !isExcludedPath(it, pair) }
+                .associateBy { it.path.removePrefix(pair.remotePath).trimStart('/') }
+                .filterKeys { !isExcludedPath(it, pair) }
+        } catch (e: Exception) {
+            // A brand-new pair whose remote folder doesn't exist yet 404s on the first listing —
+            // that simply means "empty remote", so everything uploads. This is ONLY safe with no
+            // prior sync state: on a first sync every known==null, so no DELETE_* branch can fire
+            // (verified in syncDecide). Once state exists, a 404 means the remote folder vanished
+            // or is unreachable, and treating it as empty would mirror-delete every local file —
+            // so we rethrow and let the sync fail loudly instead of destroying data.
+            if (knownStates.isEmpty() && isRemoteNotFound(e)) {
+                runCatching { ensureRemoteBaseDir(provider, pair.remotePath) }
+                emptyMap()
+            } else throw e
+        }
         val localFiles = accessor.walkFiles(pair)
 
         // Self-healing: if every known-state path is absent from the current local scan but
@@ -298,6 +311,20 @@ class SyncEngine @Inject constructor(
         )
     }
 
+    /**
+     * Create every path component of the pair's remote root (e.g. /Backup/DCIM → MKCOL /Backup
+     * then /Backup/DCIM) so the first uploads of a brand-new pair have a parent to land in.
+     * Only called on a first sync where the root listing 404'd; existing-dir MKCOLs fail harmlessly.
+     */
+    private suspend fun ensureRemoteBaseDir(provider: CloudProvider, remotePath: String) {
+        val parts = remotePath.replace('\\', '/').split('/').filter { it.isNotEmpty() }
+        var current = ""
+        for (part in parts) {
+            current = "$current/$part"
+            provider.createDirectory(current).onFailure { e -> Timber.w("MKCOL base $current: ${e.message}") }
+        }
+    }
+
     private suspend fun ensureRemoteDirs(provider: CloudProvider, remotePairPath: String, rel: String) {
         val parts = rel.replace('\\', '/').split('/')
         var currentPath = remotePairPath
@@ -421,6 +448,16 @@ internal fun syncDecide(
 
 enum class SyncDecision { UPLOAD, DOWNLOAD, DELETE_LOCAL, DELETE_REMOTE, CONFLICT, SKIP }
 
+/**
+ * Heuristic: did a provider call fail because the remote path doesn't exist (HTTP 404)? Providers
+ * surface errors as exceptions carrying the HTTP status in the message, so we match on that. Used
+ * only to let a first-ever sync proceed against a not-yet-created remote folder (see performSync).
+ */
+internal fun isRemoteNotFound(e: Throwable): Boolean {
+    val m = (e.message ?: "").lowercase()
+    return "404" in m || "not found" in m || "notfound" in m
+}
+
 /**
  * OS-generated, volatile paths that must NEVER sync on any pair, regardless of user exclude
  * config. These are matched against every path SEGMENT (directory names included), so an entire

app/src/main/kotlin/com/syncflow/ui/addpair/AddPairScreen.kt

@@ -52,7 +52,7 @@ fun AddPairScreen(onDone: () -> Unit, vm: AddPairViewModel = hiltViewModel()) {
         LocalBrowserDialog(
             initialPath = s.localPath.ifBlank { "" },
             onSelect = { path ->
-                vm.update { copy(localPath = path) }
+                if (s.multiFolder) vm.addLocalFolder(path) else vm.update { copy(localPath = path) }
                 showLocalBrowser = false
             },
             onDismiss = { showLocalBrowser = false },
@@ -94,7 +94,7 @@ fun AddPairScreen(onDone: () -> Unit, vm: AddPairViewModel = hiltViewModel()) {
             Section(title = null) {
                 OutlinedTextField(
                     value = s.name, onValueChange = { vm.update { copy(name = it) } },
-                    label = { Text("Sync pair name") },
+                    label = { Text(if (s.multiFolder) "Group name prefix (optional)" else "Sync pair name") },
                     leadingIcon = { Icon(Icons.Default.DriveFileRenameOutline, null) },
                     singleLine = true, modifier = Modifier.fillMaxWidth(),
                     keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
@@ -122,23 +122,57 @@ fun AddPairScreen(onDone: () -> Unit, vm: AddPairViewModel = hiltViewModel()) {
 
                 Spacer(Modifier.height(4.dp))
 
-                // Local folder
+                // Multi-folder mode toggle (new pairs only — editing stays single-folder)
-                Box(modifier = Modifier.fillMaxWidth()) {
+                if (!s.isEditing) {
-                    OutlinedTextField(
+                    ToggleRow(
-                        value = uriToDisplay(s.localPath), onValueChange = {},
+                        label = "Back up multiple folders",
-                        label = { Text("Local folder") },
+                        description = "Pick several folders; each is saved as its own subfolder under the remote base (no overwrites)",
-                        leadingIcon = { Icon(Icons.Default.PhoneAndroid, null) },
+                        checked = s.multiFolder,
-                        trailingIcon = { Icon(Icons.Default.FolderOpen, null) },
+                        onToggle = { vm.setMultiFolder(it) },
-                        readOnly = true, singleLine = true, modifier = Modifier.fillMaxWidth(),
-                        placeholder = { Text("Tap to choose folder…") },
                     )
-                    Box(modifier = Modifier.matchParentSize().clickable { showLocalBrowser = true })
+                    Spacer(Modifier.height(4.dp))
                 }
 
-                // Remote folder
+                if (s.multiFolder) {
+                    // Chosen folders list
+                    s.localPaths.forEach { p ->
+                        Row(
+                            modifier = Modifier.fillMaxWidth().padding(vertical = 2.dp),
+                            verticalAlignment = Alignment.CenterVertically,
+                        ) {
+                            Icon(Icons.Default.Folder, null, Modifier.size(18.dp), tint = MaterialTheme.colorScheme.primary)
+                            Spacer(Modifier.width(8.dp))
+                            Text(uriToDisplay(p), style = MaterialTheme.typography.bodyMedium,
+                                maxLines = 1, modifier = Modifier.weight(1f))
+                            IconButton(onClick = { vm.removeLocalFolder(p) }) {
+                                Icon(Icons.Default.Close, "Remove folder")
+                            }
+                        }
+                    }
+                    OutlinedButton(onClick = { showLocalBrowser = true }, modifier = Modifier.fillMaxWidth()) {
+                        Icon(Icons.Default.Add, null)
+                        Spacer(Modifier.width(6.dp))
+                        Text("Add folder")
+                    }
+                } else {
+                    // Single local folder
+                    Box(modifier = Modifier.fillMaxWidth()) {
+                        OutlinedTextField(
+                            value = uriToDisplay(s.localPath), onValueChange = {},
+                            label = { Text("Local folder") },
+                            leadingIcon = { Icon(Icons.Default.PhoneAndroid, null) },
+                            trailingIcon = { Icon(Icons.Default.FolderOpen, null) },
+                            readOnly = true, singleLine = true, modifier = Modifier.fillMaxWidth(),
+                            placeholder = { Text("Tap to choose folder…") },
+                        )
+                        Box(modifier = Modifier.matchParentSize().clickable { showLocalBrowser = true })
+                    }
+                }
+
+                // Remote folder (base, in multi-folder mode)
                 OutlinedTextField(
                     value = s.remotePath, onValueChange = { vm.update { copy(remotePath = it) } },
-                    label = { Text("Remote folder") },
+                    label = { Text(if (s.multiFolder) "Remote base folder" else "Remote folder") },
                     leadingIcon = { Icon(Icons.Default.Cloud, null) },
                     trailingIcon = {
                         IconButton(
@@ -147,7 +181,7 @@ fun AddPairScreen(onDone: () -> Unit, vm: AddPairViewModel = hiltViewModel()) {
                         ) { Icon(Icons.Default.Folder, "Browse remote") }
                     },
                     singleLine = true, modifier = Modifier.fillMaxWidth(),
-                    placeholder = { Text("/ or /Documents/Photos") },
+                    placeholder = { Text(if (s.multiFolder) "/Backup — each folder becomes a subfolder" else "/ or /Documents/Photos") },
                 )
 
                 // Recursive

app/src/main/kotlin/com/syncflow/ui/addpair/AddPairViewModel.kt

@@ -25,6 +25,10 @@ data class AddPairUiState(
     val name: String = "",
     // ── Folders ──────────────────────────────────────────────────────────────
     val localPath: String = "",
+    // Multi-folder mode: pick several local folders that each back up to their own subfolder
+    // under one remote base. Empty unless multiFolder is on.
+    val multiFolder: Boolean = false,
+    val localPaths: List<String> = emptyList(),
     val remotePath: String = "",
     val selectedAccountId: Long = -1L,
     val accounts: List<CloudAccountEntity> = emptyList(),
@@ -57,6 +61,7 @@ data class AddPairUiState(
     val notifyOnComplete: Boolean = false,
     val notifyOnError: Boolean = true,
     // ── Form state ───────────────────────────────────────────────────────────
+    val isEditing: Boolean = false,
     val isSaving: Boolean = false,
     val error: String? = null,
     val done: Boolean = false,
@@ -72,6 +77,31 @@ internal fun recommendedDeleteBehavior(direction: SyncDirection): DeleteBehavior
     SyncDirection.TWO_WAY -> DeleteBehavior.MIRROR
 }
 
+/**
+ * Last path component of a local folder path or SAF content:// tree URI, used as the remote
+ * subfolder name in multi-folder mode. Handles URL-encoded tree URIs
+ * (content://…/tree/primary%3ADCIM%2FCamera → "Camera") and plain filesystem paths.
+ */
+internal fun folderLeafName(path: String): String {
+    val decoded = try { java.net.URLDecoder.decode(path, "UTF-8") } catch (e: Exception) { path }
+    val afterColon = decoded.substringAfterLast(':')   // strip the "primary:" storage-volume prefix
+    val leaf = afterColon.trimEnd('/').substringAfterLast('/')
+    return leaf.ifBlank { "folder" }
+}
+
+/**
+ * Make a remote subfolder name unique within one multi-folder batch so two source folders that
+ * share a leaf name (e.g. DCIM/Camera and Movies/Camera) don't collide into one remote dir.
+ * Slashes are flattened to underscores; collisions get a numeric suffix.
+ */
+internal fun uniqueSubName(base: String, used: MutableSet<String>): String {
+    val clean = base.replace('/', '_').replace('\\', '_').ifBlank { "folder" }
+    if (used.add(clean)) return clean
+    var n = 2
+    while (!used.add("${clean}_$n")) n++
+    return "${clean}_$n"
+}
+
 @HiltViewModel
 class AddPairViewModel @Inject constructor(
     private val syncPairDao: SyncPairDao,
@@ -83,7 +113,7 @@ class AddPairViewModel @Inject constructor(
 
     private val editPairId = savedState.get<Long>("pairId").takeIf { it != -1L }
 
-    private val _state = MutableStateFlow(AddPairUiState())
+    private val _state = MutableStateFlow(AddPairUiState(isEditing = editPairId != null))
     val state = _state.asStateFlow()
 
     init {
@@ -102,6 +132,7 @@ class AddPairViewModel @Inject constructor(
                 syncPairDao.getById(id)?.let { pair ->
                     _state.update { _ ->
                         AddPairUiState(
+                            isEditing = true,
                             name = pair.name,
                             localPath = pair.localPath,
                             remotePath = pair.remotePath,
@@ -148,12 +179,25 @@ class AddPairViewModel @Inject constructor(
         it.copy(deleteBehavior = behavior, deleteBehaviorTouched = true)
     }
 
+    fun setMultiFolder(enabled: Boolean) = _state.update { it.copy(multiFolder = enabled) }
+
+    fun addLocalFolder(path: String) = _state.update {
+        if (path.isBlank() || path in it.localPaths) it else it.copy(localPaths = it.localPaths + path)
+    }
+
+    fun removeLocalFolder(path: String) = _state.update { it.copy(localPaths = it.localPaths - path) }
+
     fun save() {
         val s = _state.value
         val errors = buildList {
-            if (s.name.isBlank()) add("Name is required")
+            if (s.multiFolder) {
-            if (s.localPath.isBlank()) add("Local folder is required")
+                if (s.localPaths.isEmpty()) add("Add at least one folder")
-            if (s.remotePath.isBlank()) add("Remote folder is required")
+                if (s.remotePath.isBlank()) add("Remote base folder is required")
+            } else {
+                if (s.name.isBlank()) add("Name is required")
+                if (s.localPath.isBlank()) add("Local folder is required")
+                if (s.remotePath.isBlank()) add("Remote folder is required")
+            }
             if (s.selectedAccountId == -1L) add("Select a cloud account")
             if (s.scheduleType == ScheduleType.INTERVAL && s.intervalMinutes < 15) add("Minimum interval is 15 minutes")
         }
@@ -162,48 +206,65 @@ class AddPairViewModel @Inject constructor(
         viewModelScope.launch {
             _state.update { it.copy(isSaving = true, error = null) }
             runCatching {
-                val entity = SyncPairEntity(
+                if (s.multiFolder) {
-                    id = editPairId ?: 0L,
+                    // One normal pair per folder, each into its OWN subfolder under the remote base.
-                    name = s.name, localPath = s.localPath, remotePath = s.remotePath,
+                    // Keeping each source in a distinct subfolder is what makes many-to-one safe —
-                    accountId = s.selectedAccountId,
+                    // flattening would let same-named files from different folders overwrite each other.
-                    syncDirection = s.syncDirection, conflictStrategy = s.conflictStrategy,
+                    val base = s.remotePath.trimEnd('/')
-                    deleteBehavior = s.deleteBehavior, recursive = s.recursive,
+                    val used = mutableSetOf<String>()
-                    scheduleType = s.scheduleType, scheduleIntervalMinutes = s.intervalMinutes,
+                    s.localPaths.map { folder ->
-                    scheduleDailyTime = if (s.scheduleType == ScheduleType.DAILY || s.scheduleType == ScheduleType.WEEKLY) s.dailyTime else null,
+                        val sub = uniqueSubName(folderLeafName(folder), used)
-                    scheduleWeekdays = s.weekdays,
+                        val pairName = if (s.name.isBlank()) sub else "${s.name} — $sub"
-                    wifiOnly = s.wifiOnly, wifiSsid = s.wifiSsid,
+                        val entity = buildEntity(s, name = pairName, localPath = folder, remotePath = "$base/$sub", id = 0L)
-                    chargingOnly = s.chargingOnly, minBatteryPct = s.minBatteryPct,
+                        entity.copy(id = syncPairDao.insert(entity))
-                    excludePatterns = s.excludePatterns, includeExtensions = s.includeExtensions,
-                    excludeExtensions = s.excludeExtensions, skipHiddenFiles = s.skipHiddenFiles,
-                    minFileSizeKb = s.minFileSizeKb, maxFileSizeKb = s.maxFileSizeKb,
-                    notifyOnComplete = s.notifyOnComplete, notifyOnError = s.notifyOnError,
-                    isEnabled = true, lastSyncAt = null, lastSyncResult = SyncStatus.IDLE, pendingConflicts = 0,
-                )
-                val pairId = if (editPairId == null) {
-                    syncPairDao.insert(entity)
-                } else {
-                    val existing = syncPairDao.getById(editPairId)
-                    syncPairDao.update(entity)
-                    // If local or remote folder changed, old file-state records no longer
-                    // correspond to any real path — wipe them so the next sync starts fresh
-                    // instead of trying to delete/re-upload stale paths.
-                    if (existing != null &&
-                        (existing.localPath != entity.localPath || existing.remotePath != entity.remotePath)
-                    ) {
-                        fileStateDao.deleteForPair(editPairId)
                     }
-                    editPairId
+                } else {
+                    val entity = buildEntity(s, name = s.name, localPath = s.localPath, remotePath = s.remotePath, id = editPairId ?: 0L)
+                    val pairId = if (editPairId == null) {
+                        syncPairDao.insert(entity)
+                    } else {
+                        val existing = syncPairDao.getById(editPairId)
+                        syncPairDao.update(entity)
+                        // If local or remote folder changed, old file-state records no longer
+                        // correspond to any real path — wipe them so the next sync starts fresh
+                        // instead of trying to delete/re-upload stale paths.
+                        if (existing != null &&
+                            (existing.localPath != entity.localPath || existing.remotePath != entity.remotePath)
+                        ) {
+                            fileStateDao.deleteForPair(editPairId)
+                        }
+                        editPairId
+                    }
+                    listOf(entity.copy(id = pairId))
                 }
-                entity.copy(id = pairId)
             }
                 .onSuccess { saved ->
-                    applySchedule(saved)
+                    saved.forEach { applySchedule(it) }
                     _state.update { it.copy(done = true) }
                 }
                 .onFailure { e -> _state.update { it.copy(isSaving = false, error = e.message) } }
         }
     }
 
+    private fun buildEntity(s: AddPairUiState, name: String, localPath: String, remotePath: String, id: Long) =
+        SyncPairEntity(
+            id = id,
+            name = name, localPath = localPath, remotePath = remotePath,
+            accountId = s.selectedAccountId,
+            syncDirection = s.syncDirection, conflictStrategy = s.conflictStrategy,
+            deleteBehavior = s.deleteBehavior, recursive = s.recursive,
+            scheduleType = s.scheduleType, scheduleIntervalMinutes = s.intervalMinutes,
+            scheduleDailyTime = if (s.scheduleType == ScheduleType.DAILY || s.scheduleType == ScheduleType.WEEKLY) s.dailyTime else null,
+            scheduleWeekdays = s.weekdays,
+            wifiOnly = s.wifiOnly, wifiSsid = s.wifiSsid,
+            chargingOnly = s.chargingOnly, minBatteryPct = s.minBatteryPct,
+            excludePatterns = s.excludePatterns, includeExtensions = s.includeExtensions,
+            excludeExtensions = s.excludeExtensions, skipHiddenFiles = s.skipHiddenFiles,
+            minFileSizeKb = s.minFileSizeKb, maxFileSizeKb = s.maxFileSizeKb,
+            notifyOnComplete = s.notifyOnComplete, notifyOnError = s.notifyOnError,
+            isEnabled = true, lastSyncAt = null, lastSyncResult = SyncStatus.IDLE, pendingConflicts = 0,
+        )
+
     /**
      * Register the pair's background work the moment it's saved. Previously this only happened on
      * the enable-toggle or a reboot, so a freshly-created scheduled pair never actually ran in the

app/src/test/kotlin/com/syncflow/domain/sync/ExcludePathTest.kt

@@ -91,4 +91,16 @@ class ExcludePathTest {
         assertTrue(isExcludedPath("a/.hidden", pair(skipHiddenFiles = true)))
         assertFalse(isExcludedPath("a/.hidden", pair(skipHiddenFiles = false)))
     }
+
+    @Test fun `remote-not-found detected from http status messages`() {
+        assertTrue(isRemoteNotFound(Exception("HTTP 404")))
+        assertTrue(isRemoteNotFound(Exception("Not Found")))
+        assertTrue(isRemoteNotFound(RuntimeException("PROPFIND failed: notfound")))
+    }
+
+    @Test fun `remote-not-found is false for other errors`() {
+        assertFalse(isRemoteNotFound(Exception("HTTP 500")))
+        assertFalse(isRemoteNotFound(Exception("timeout")))
+        assertFalse(isRemoteNotFound(Exception(null as String?)))
+    }
 }

app/src/test/kotlin/com/syncflow/ui/addpair/MultiFolderTest.kt

@@ -0,0 +1,41 @@
+package com.syncflow.ui.addpair
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Multi-folder backup: each selected folder maps to its OWN remote subfolder. The leaf-name and
+ * uniqueness helpers are what keep that safe — same-named folders from different parents must not
+ * collapse into one remote dir and overwrite each other.
+ */
+class MultiFolderTest {
+
+    @Test fun `leaf name from SAF tree uri`() {
+        assertEquals("Camera", folderLeafName("content://com.android.externalstorage.documents/tree/primary%3ADCIM%2FCamera"))
+        assertEquals("DCIM", folderLeafName("content://com.android.externalstorage.documents/tree/primary%3ADCIM"))
+    }
+
+    @Test fun `leaf name from plain filesystem path`() {
+        assertEquals("Camera", folderLeafName("/storage/emulated/0/DCIM/Camera"))
+        assertEquals("Pictures", folderLeafName("/storage/emulated/0/Pictures/"))
+    }
+
+    @Test fun `blank-ish paths fall back to folder`() {
+        assertEquals("folder", folderLeafName(""))
+        assertEquals("folder", folderLeafName("/"))
+    }
+
+    @Test fun `unique sub names disambiguate collisions`() {
+        val used = mutableSetOf<String>()
+        assertEquals("Camera", uniqueSubName("Camera", used))
+        assertEquals("Camera_2", uniqueSubName("Camera", used))
+        assertEquals("Camera_3", uniqueSubName("Camera", used))
+        assertEquals("Pictures", uniqueSubName("Pictures", used))
+    }
+
+    @Test fun `unique sub name flattens slashes`() {
+        val used = mutableSetOf<String>()
+        assertTrue('/' !in uniqueSubName("a/b/c", used))
+    }
+}

version.properties

@@ -1,2 +1,2 @@
-VERSION_NAME=1.0.75
+VERSION_NAME=1.0.76
-VERSION_CODE=75
+VERSION_CODE=76