v1.0.24: harmonious icon, recursive file watching, download-then-open, security fixes

Icon: three identical parallel arcing arrows (same bezier curve, same blue-to-teal
gradient #64C8FF→#32EDBB, same arrowhead geometry) — visually cohesive and clearly
visible against the near-black background.

FileWatchService: FileObserver is now recursive — watchDirRecursive() creates an
observer for each subdirectory at startup, and adds new watchers when CREATE events
produce new directories. Fixes files added to subdirectories not being detected.

FilesViewModel: openFile/shareFile now fall back to download-then-open when the file
is absent locally. AccountRepository + ProviderFactory injected; downloads to
context.cacheDir/syncflow_open/ with isDownloading state. Path traversal guard added
(reject relativePath containing ".."). file_paths.xml gains cache-path entry.

WebDavProvider: path-traversal guard in parsePropfind — skip any server-returned
filename containing "..", "/" or "\". Replace android.util.Log with Timber so debug
logs are stripped from release builds.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/src/main/kotlin/com/syncflow/ui/files/FilesViewModel.kt

@@ -7,6 +7,8 @@ import com.syncflow.data.db.SyncFileStateDao
 import com.syncflow.data.db.SyncPairDao
 import com.syncflow.data.db.entities.SyncFileStateEntity
 import com.syncflow.data.db.entities.SyncPairEntity
+import com.syncflow.data.providers.ProviderFactory
+import com.syncflow.data.repository.AccountRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.ExperimentalCoroutinesApi
@@ -27,6 +29,8 @@ sealed class FileAction {
 class FilesViewModel @Inject constructor(
     private val syncPairDao: SyncPairDao,
     private val fileStateDao: SyncFileStateDao,
+    private val accountRepository: AccountRepository,
+    private val providerFactory: ProviderFactory,
     @ApplicationContext private val context: Context,
 ) : ViewModel() {
 
@@ -50,22 +54,33 @@ class FilesViewModel @Inject constructor(
     private val _fileAction = MutableSharedFlow<FileAction>()
     val fileAction: SharedFlow<FileAction> = _fileAction
 
+    private val _isDownloading = MutableStateFlow(false)
+    val isDownloading: StateFlow<Boolean> = _isDownloading
+
     fun selectPair(id: Long) { _selectedPairId.value = id }
 
     fun openFile(file: SyncFileStateEntity) {
-        val resolved = resolveFile(file) ?: return
-        viewModelScope.launch { _fileAction.emit(FileAction.Open(resolved)) }
+        val resolved = resolveFile(file, emitErrorIfMissing = false)
+        if (resolved != null) {
+            viewModelScope.launch { _fileAction.emit(FileAction.Open(resolved)) }
+        } else {
+            downloadAndOpen(file)
+        }
     }
 
     fun shareFile(file: SyncFileStateEntity) {
-        val resolved = resolveFile(file) ?: return
-        viewModelScope.launch { _fileAction.emit(FileAction.Share(resolved)) }
+        val resolved = resolveFile(file, emitErrorIfMissing = false)
+        if (resolved != null) {
+            viewModelScope.launch { _fileAction.emit(FileAction.Share(resolved)) }
+        } else {
+            downloadAndShare(file)
+        }
     }
 
     fun deleteFile(file: SyncFileStateEntity) {
         viewModelScope.launch {
             try {
-                val resolved = resolveFile(file)
+                val resolved = resolveFile(file, emitErrorIfMissing = false)
                 resolved?.delete()
                 fileStateDao.delete(file.syncPairId, file.relativePath)
             } catch (e: Exception) {
@@ -85,7 +100,6 @@ class FilesViewModel @Inject constructor(
                     _fileAction.emit(FileAction.Error("Rename failed"))
                     return@launch
                 }
-                // Update DB: delete old state; the next sync will re-detect as a new upload
                 fileStateDao.delete(file.syncPairId, file.relativePath)
             } catch (e: Exception) {
                 Timber.e(e, "Rename failed: ${file.relativePath}")
@@ -94,12 +108,71 @@ class FilesViewModel @Inject constructor(
         }
     }
 
-    private fun resolveFile(file: SyncFileStateEntity): File? {
+    // ── Download-then-open/share ──────────────────────────────────────────────
+
+    private fun downloadAndOpen(file: SyncFileStateEntity) {
+        viewModelScope.launch {
+            downloadToCache(file)?.let { cached ->
+                _fileAction.emit(FileAction.Open(cached))
+            }
+        }
+    }
+
+    private fun downloadAndShare(file: SyncFileStateEntity) {
+        viewModelScope.launch {
+            downloadToCache(file)?.let { cached ->
+                _fileAction.emit(FileAction.Share(cached))
+            }
+        }
+    }
+
+    private suspend fun downloadToCache(file: SyncFileStateEntity): File? {
+        val pair = selectedPair.value ?: run {
+            _fileAction.emit(FileAction.Error("No sync pair selected"))
+            return null
+        }
+        val account = accountRepository.getAccount(pair.accountId) ?: run {
+            _fileAction.emit(FileAction.Error("Cloud account not found"))
+            return null
+        }
+        val provider = providerFactory.create(account)
+        val fileName = file.relativePath.substringAfterLast('/')
+        val cacheFile = File(context.cacheDir, "syncflow_open/$fileName")
+        cacheFile.parentFile?.mkdirs()
+
+        _isDownloading.value = true
+        return try {
+            cacheFile.outputStream().use { out ->
+                provider.downloadFile("${pair.remotePath}/${file.relativePath}", out) { }.getOrThrow()
+            }
+            cacheFile
+        } catch (e: Exception) {
+            Timber.e(e, "Download for preview failed: ${file.relativePath}")
+            cacheFile.delete()
+            _fileAction.emit(FileAction.Error("Download failed: ${e.message}"))
+            null
+        } finally {
+            _isDownloading.value = false
+        }
+    }
+
+    // ── Path resolution ───────────────────────────────────────────────────────
+
+    private fun resolveFile(file: SyncFileStateEntity, emitErrorIfMissing: Boolean = true): File? {
+        // Guard against path traversal from untrusted server responses
+        if (file.relativePath.contains("..")) {
+            viewModelScope.launch { _fileAction.emit(FileAction.Error("Invalid file path")) }
+            return null
+        }
         val pair = selectedPair.value ?: return null
         val root = safTreeUriToRealPath(pair.localPath) ?: pair.localPath
+        // localPath is a content:// URI we couldn't resolve — File-based access won't work
+        if (root.startsWith("content://")) return null
         val f = File(root, file.relativePath)
         if (!f.exists()) {
-            viewModelScope.launch { _fileAction.emit(FileAction.Error("File not found on device")) }
+            if (emitErrorIfMissing) {
+                viewModelScope.launch { _fileAction.emit(FileAction.Error("File not found on device")) }
+            }
             return null
         }
         return f