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

.gitea/workflows/release.yml

@@ -10,6 +10,8 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write   # needed to create the release object on a tag
 
     steps:
       - uses: actions/checkout@v4
@@ -63,12 +65,17 @@ jobs:
           TAG: ${{ github.ref_name }}
           VERSION: ${{ steps.ver.outputs.name }}
         run: |
-          RELEASE_ID=$(curl -sf \
-            "https://gitea.khodak.me/api/v1/repos/amir/SyncFlow/releases/tags/$TAG" \
-            -H "Authorization: token $TOKEN" \
-            | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
-          curl -sf -X POST \
-            "https://gitea.khodak.me/api/v1/repos/amir/SyncFlow/releases/$RELEASE_ID/assets" \
+          API="https://gitea.khodak.me/api/v1/repos/amir/SyncFlow"
+          # A pushed git tag does NOT create a Gitea release object — fetch it, create if missing.
+          RELEASE_ID=$(curl -s "$API/releases/tags/$TAG" -H "Authorization: token $TOKEN" \
+            | python3 -c "import sys,json;d=json.load(sys.stdin);print(d.get('id','') if isinstance(d,dict) else '')" 2>/dev/null)
+          if [ -z "$RELEASE_ID" ]; then
+            RELEASE_ID=$(curl -s -X POST "$API/releases" -H "Authorization: token $TOKEN" \
+              -H "Content-Type: application/json" -d "{\"tag_name\":\"$TAG\",\"name\":\"$TAG\"}" \
+              | python3 -c "import sys,json;print(json.load(sys.stdin).get('id',''))")
+            echo "created release object $RELEASE_ID for $TAG"
+          fi
+          curl -sf -X POST "$API/releases/$RELEASE_ID/assets?name=SyncFlow-v${VERSION}.apk" \
             -H "Authorization: token $TOKEN" \
             -F "attachment=@dist/SyncFlow-v${VERSION}.apk"
-          echo "APK uploaded to release $TAG"
+          echo "APK uploaded to release $TAG (id $RELEASE_ID)"

LICENSE

@@ -0,0 +1,40 @@
+SyncFlow Source-Available License
+Copyright (c) 2026 Amir Khodak. All rights reserved.
+
+This is NOT an OSI-approved open-source license. The source code is made
+publicly viewable ("source-available"), but the rights granted are limited as
+described below. Where this license is silent, all rights are reserved.
+
+1. DEFINITIONS
+   "Software" means the SyncFlow source code, assets, and documentation in this
+   repository. "You" means anyone other than the copyright holder.
+
+2. WHAT YOU MAY DO
+   a. View, read, and study the Software.
+   b. Clone or fork the repository for your own private, personal,
+      non-commercial use and experimentation.
+   c. Build the Software from source and run it on devices you personally own.
+   d. Submit contributions (pull requests) back to this repository; by doing so
+      you license your contribution to the copyright holder under these terms.
+
+3. WHAT YOU MAY NOT DO (without the copyright holder's prior written permission)
+   a. Redistribute, publish, or make available the Software or any derivative
+      work — in source or binary/APK form — to any third party or app store
+      (including but not limited to Google Play, F-Droid, Amazon Appstore,
+      Gitea/GitHub releases, or any website).
+   b. Use the Software, in whole or in part, for any commercial purpose.
+   c. Sell, sublicense, rent, or offer the Software as a service.
+   d. Use the names, app identity ("SyncFlow"), package identifier
+      ("com.syncflow"), logos, or signing keys of the original work.
+   e. Remove or alter this license or the copyright notice.
+
+4. RESERVED RIGHTS
+   All publishing and distribution rights are reserved exclusively to the
+   copyright holder. Only the copyright holder may publish official builds.
+
+5. NO WARRANTY
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM,
+   DAMAGES, OR OTHER LIABILITY ARISING FROM THE SOFTWARE OR ITS USE.
+
+To request permission for anything in section 3, contact the copyright holder.

README.md

@@ -40,3 +40,10 @@ Native Android file sync app — sync any folder to WebDAV, SFTP, Nextcloud, own
 
 - Android 8.0+ (API 26)
 - Storage permission (or SAF picker) for local folder access
+
+## License
+
+SyncFlow is **source-available, not open-source** — see [LICENSE](LICENSE).
+You may read, study, and fork it for personal, non-commercial use, but
+**redistributing or publishing the app (source or APK) is not permitted**.
+Only the copyright holder publishes official, signed builds.

app/build.gradle.kts

@@ -33,7 +33,10 @@ android {
         minSdk = 26
         targetSdk = 35
         versionCode = versionProps["VERSION_CODE"].toString().toInt()
-        versionName = versionProps["VERSION_NAME"].toString()
+        // Single source of truth: the human version always tracks the build number, so the
+        // git tag (v1.0.N), the APK filename, and the in-app "About" all read 1.0.N and
+        // can never drift apart again. Bump only VERSION_CODE in version.properties.
+        versionName = "1.0.${versionProps["VERSION_CODE"].toString().toInt()}"
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
 
         // Placeholder — replace with real keys before release

app/src/androidTest/kotlin/com/syncflow/FullSyncEngineTest.kt

@@ -7,7 +7,9 @@ import com.syncflow.data.db.SyncDatabase
 import com.syncflow.data.db.entities.CloudAccountEntity
 import com.syncflow.data.db.entities.SyncPairEntity
 import com.syncflow.data.db.entities.toDomain
+import com.syncflow.data.providers.CloudProvider
 import com.syncflow.data.providers.nextcloud.NextcloudProvider
+import com.syncflow.domain.sync.LocalAccessor
 import com.syncflow.domain.model.*
 import com.syncflow.domain.sync.SyncEngine
 import kotlinx.coroutines.runBlocking
@@ -73,8 +75,10 @@ class FullSyncEngineTest {
         conflict: ConflictStrategy = ConflictStrategy.KEEP_NEWEST,
         recursive: Boolean = true,
         excludeExtensions: String = "",
+        includeExtensions: String = "",
         excludePatterns: String = "",
         skipHidden: Boolean = false,
+        minKb: Long = 0L,
         maxKb: Long = 0L,
     ): Triple<SyncPair, File, String> {
         val local = File(ctx.cacheDir, "synctest_${name}_${System.currentTimeMillis()}").apply { mkdirs() }
@@ -86,8 +90,8 @@ class FullSyncEngineTest {
             syncDirection = dir, conflictStrategy = conflict, deleteBehavior = delete, recursive = recursive,
             scheduleType = ScheduleType.MANUAL, scheduleIntervalMinutes = 30, scheduleDailyTime = null, scheduleWeekdays = 0,
             wifiOnly = false, wifiSsid = "", chargingOnly = false, minBatteryPct = 0,
-            excludePatterns = excludePatterns, includeExtensions = "", excludeExtensions = excludeExtensions,
-            skipHiddenFiles = skipHidden, minFileSizeKb = 0, maxFileSizeKb = maxKb,
+            excludePatterns = excludePatterns, includeExtensions = includeExtensions, excludeExtensions = excludeExtensions,
+            skipHiddenFiles = skipHidden, minFileSizeKb = minKb, maxFileSizeKb = maxKb,
             notifyOnComplete = false, notifyOnError = false,
             isEnabled = true, lastSyncAt = null, lastSyncResult = SyncStatus.IDLE, pendingConflicts = 0,
         ))
@@ -236,11 +240,226 @@ class FullSyncEngineTest {
         assertEquals("newer local must win", "local-newer", remoteText("$remote/n.txt"))
     }
 
-    // ── 13. Content integrity: binary-ish bytes round-trip exactly ────────────
+    // ── 13b. Special & non-ASCII filenames upload (WebDAV URL/header encoding) ─
+    @Test fun specialAndNonAsciiNames_upload() = runBlocking {
+        val (pair, local, remote) = newPair("special", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        write(local, "naïve café.txt", "accents")   // non-ASCII (broke MOVE Destination header)
+        write(local, "a&b (1).txt", "ampersand")     // & ( ) space
+        write(local, "日本語.txt", "cjk")              // multibyte unicode
+        write(local, "my photo.txt", "space")
+        val r = sync(pair)
+        assertEquals("all special-name files must upload", 4, r.uploaded)
+        assertEquals(0, r.failedFiles)
+        val names = remoteNames(remote)
+        assertTrue("naïve café.txt" in names)
+        assertTrue("a&b (1).txt" in names)
+        assertTrue("日本語.txt" in names)
+        assertTrue("my photo.txt" in names)
+    }
+
+    // ── 13c. Volume: 100+ files (incl. subfolders & non-ASCII) upload, 0 fails ─
+    @Test fun volume_hundredFiles_allUploadNoFailures() = runBlocking {
+        val (pair, local, remote) = newPair("vol100", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        repeat(100) { i -> write(local, "f_%03d.txt".format(i), "payload $i ".repeat(30)) }
+        write(local, "sub/nested_a.txt", "n1")
+        write(local, "sub/deep/nested_b.txt", "n2")
+        write(local, "naïve café.txt", "accented")
+        val r = sync(pair)
+        assertEquals("no file may fail under volume", 0, r.failedFiles)
+        assertEquals("all 103 files upload", 103, r.uploaded)
+        assertEquals("100 flat files present on cloud", 100, remoteNames(remote).count { it.startsWith("f_") })
+        assertTrue("non-ASCII name present too", "naïve café.txt" in remoteNames(remote))
+        // re-sync is a clean no-op (no phantom re-uploads / loops at volume)
+        val r2 = sync(pair)
+        assertEquals(0, r2.uploaded); assertEquals(0, r2.deleted); assertEquals(0, r2.failedFiles)
+    }
+
+    // ── 14. Content integrity: binary-ish bytes round-trip exactly ────────────
     @Test fun contentIntegrity_roundTrip() = runBlocking {
         val (pair, local, remote) = newPair("integrity", SyncDirection.TWO_WAY)
         val payload = (0..5000).joinToString("") { "Ω$it·" }
         write(local, "big.txt", payload); sync(pair)
         assertEquals(payload, remoteText("$remote/big.txt"))
     }
+
+    // ══ EDGE CASES & STRESS ═══════════════════════════════════════════════════
+
+    private fun writeBytes(dir: File, rel: String, bytes: ByteArray) =
+        File(dir, rel).apply { parentFile?.mkdirs() }.writeBytes(bytes)
+
+    // 15. Empty (0-byte) file uploads correctly
+    @Test fun emptyFile_uploads() = runBlocking {
+        val (pair, local, remote) = newPair("empty", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        write(local, "zero.txt", "")
+        val r = sync(pair)
+        assertEquals(0, r.failedFiles); assertEquals(1, r.uploaded)
+        assertEquals(0L, provider.listFiles(remote).getOrThrow().first { it.name == "zero.txt" }.sizeBytes)
+    }
+
+    // 16. Large file (20 MB) uploads + downloads byte-intact (OOM / streaming guard)
+    @Test fun largeFile_intactRoundTrip() = runBlocking {
+        val (pair, local, remote) = newPair("large", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        val size = 20 * 1024 * 1024
+        val bytes = ByteArray(size).also { java.util.Random(42).nextBytes(it) }
+        writeBytes(local, "big.bin", bytes)
+        val r = sync(pair)
+        assertEquals(0, r.failedFiles); assertEquals(1, r.uploaded)
+        assertEquals(size.toLong(), provider.listFiles(remote).getOrThrow().first { it.name == "big.bin" }.sizeBytes)
+        val out = ByteArrayOutputStream(size); provider.downloadFile("$remote/big.bin", out).getOrThrow()
+        val dl = out.toByteArray()
+        assertEquals(size, dl.size)
+        assertArrayEquals(bytes.copyOfRange(0, 4096), dl.copyOfRange(0, 4096))
+        assertArrayEquals(bytes.copyOfRange(size - 4096, size), dl.copyOfRange(size - 4096, size))
+    }
+
+    // 17. Deeply nested path (8 levels) is created + uploaded
+    @Test fun deepNesting_uploads() = runBlocking {
+        val (pair, local, remote) = newPair("deep", SyncDirection.UPLOAD_ONLY, recursive = true)
+        write(local, "a/b/c/d/e/f/g/deep.txt", "deep")
+        assertEquals(0, sync(pair).failedFiles)
+        assertTrue("deep.txt" in remoteNames("$remote/a/b/c/d/e/f/g"))
+    }
+
+    // 18. Unicode FOLDER names (not just files) are created + encoded
+    @Test fun unicodeFolderNames_upload() = runBlocking {
+        val (pair, local, remote) = newPair("ufolder", SyncDirection.UPLOAD_ONLY, recursive = true)
+        write(local, "Фото/café/x.txt", "u")
+        assertEquals(0, sync(pair).failedFiles)
+        assertTrue("x.txt" in remoteNames("$remote/Фото/café"))
+    }
+
+    // 19. Very long filename (200 chars)
+    @Test fun veryLongFilename_uploads() = runBlocking {
+        val (pair, local, remote) = newPair("longname", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        val name = "L".repeat(200) + ".txt"
+        write(local, name, "x")
+        assertEquals(0, sync(pair).failedFiles)
+        assertTrue(name in remoteNames(remote))
+    }
+
+    // 20. File with no extension
+    @Test fun noExtensionFile_uploads() = runBlocking {
+        val (pair, local, remote) = newPair("noext", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        write(local, "README", "x")
+        assertEquals(1, sync(pair).uploaded)
+        assertTrue("README" in remoteNames(remote))
+    }
+
+    // 21. Idempotency / loop guard — repeated syncs do NOT re-upload anything
+    @Test fun idempotent_repeatedSyncsNoPhantomUploads() = runBlocking {
+        val (pair, local, remote) = newPair("idem", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        repeat(10) { i -> write(local, "x_$i.txt", "v$i") }
+        assertEquals(10, sync(pair).uploaded)
+        repeat(4) {
+            val r = sync(pair)
+            assertEquals("sync must be idempotent (no re-upload loop)", 0, r.uploaded)
+            assertEquals(0, r.deleted); assertEquals(0, r.failedFiles)
+        }
+    }
+
+    // 22. Bulk update — modifying many files re-uploads exactly those
+    @Test fun bulkUpdate_reuploadsChanged() = runBlocking {
+        val (pair, local, remote) = newPair("bulkupd", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        repeat(10) { i -> write(local, "u_$i.txt", "v1") }; sync(pair)
+        Thread.sleep(1100)
+        repeat(10) { i -> write(local, "u_$i.txt", "v2-updated-content") }
+        assertEquals(10, sync(pair).uploaded)
+        assertEquals("v2-updated-content", remoteText("$remote/u_0.txt"))
+    }
+
+    // 23. Bulk delete (MIRROR two-way) propagates all deletions
+    @Test fun mirror_bulkDeletePropagates() = runBlocking {
+        val (pair, local, remote) = newPair("bulkdel", SyncDirection.TWO_WAY, DeleteBehavior.MIRROR)
+        repeat(10) { i -> write(local, "d_$i.txt", "x") }; sync(pair)
+        repeat(10) { i -> File(local, "d_$i.txt").delete() }
+        assertEquals(10, sync(pair).deleted)
+        assertEquals(0, remoteNames(remote).count { it.startsWith("d_") })
+    }
+
+    // 24. Bulk download (download-only) pulls all remote files
+    @Test fun downloadOnly_bulkPull() = runBlocking {
+        val (pair, local, remote) = newPair("bulkdl", SyncDirection.DOWNLOAD_ONLY)
+        repeat(10) { i -> putRemote(remote, "r_$i.txt", "cloud$i") }
+        assertEquals(10, sync(pair).downloaded)
+        assertEquals(10, local.listFiles()!!.count { it.name.startsWith("r_") })
+    }
+
+    // 25. KEEP_BOTH conflict strategy records a conflict (no silent clobber)
+    @Test fun twoWay_keepBoth_recordsConflict() = runBlocking {
+        val (pair, local, remote) = newPair("keepboth", SyncDirection.TWO_WAY, conflict = ConflictStrategy.KEEP_BOTH)
+        write(local, "c.txt", "base"); sync(pair); sync(pair) // baseline + reconcile
+        Thread.sleep(1100)
+        write(local, "c.txt", "LOCAL"); putRemote(remote, "c.txt", "REMOTE")
+        assertEquals(1, sync(pair).conflicts)
+        assertEquals("LOCAL", File(local, "c.txt").readText())
+        assertEquals("REMOTE", remoteText("$remote/c.txt"))
+    }
+
+    // 26. Min-size filter skips tiny files
+    @Test fun filters_minSizeSkipsTiny() = runBlocking {
+        val (pair, local, remote) = newPair("minsize", SyncDirection.UPLOAD_ONLY, minKb = 1)
+        write(local, "tiny.txt", "x")                       // < 1 KB
+        write(local, "big.txt", "A".repeat(2048))           // ~2 KB
+        sync(pair)
+        val n = remoteNames(remote)
+        assertFalse("tiny.txt" in n); assertTrue("big.txt" in n)
+    }
+
+    // 27. Include-extension filter uploads only matching files
+    @Test fun filters_includeExtensionOnly() = runBlocking {
+        val (pair, local, remote) = newPair("incl", SyncDirection.UPLOAD_ONLY, includeExtensions = "jpg")
+        write(local, "keep.jpg", "x"); write(local, "skip.txt", "y")
+        sync(pair)
+        val n = remoteNames(remote)
+        assertTrue("keep.jpg" in n); assertFalse("skip.txt" in n)
+    }
+
+    // 28. Whole-folder wipe locally (MIRROR) removes all remote copies
+    @Test fun mirror_emptyLocalWipesRemote() = runBlocking {
+        val (pair, local, remote) = newPair("wipe", SyncDirection.TWO_WAY, DeleteBehavior.MIRROR)
+        repeat(5) { i -> write(local, "w_$i.txt", "x") }; sync(pair)
+        local.listFiles()!!.forEach { it.delete() }
+        assertEquals(5, sync(pair).deleted)
+        assertEquals(0, remoteNames(remote).count { it.startsWith("w_") })
+    }
+
+    // ══ INTERRUPTION / ATOMICITY ══════════════════════════════════════════════
+
+    // 29. A write that fails mid-stream must leave the existing file intact (no truncation)
+    @Test fun atomicWrite_failedWriteLeavesOriginalIntact() = runBlocking {
+        val dir = File(ctx.cacheDir, "atomic_${System.currentTimeMillis()}").apply { mkdirs() }
+        localDirs += dir
+        File(dir, "f.txt").writeText("ORIGINAL-GOOD-CONTENT")
+        val accessor = LocalAccessor.JavaFile(dir)
+        val outcome = runCatching {
+            accessor.writeAtomically("f.txt") { os ->
+                os.write("PARTIAL-GARBAGE".toByteArray()); os.flush()
+                throw java.io.IOException("simulated network drop mid-download")
+            }
+        }
+        assertTrue("the failed write must propagate", outcome.isFailure)
+        assertEquals("original must be untouched after a failed write", "ORIGINAL-GOOD-CONTENT", File(dir, "f.txt").readText())
+        assertTrue("no leftover .sfpart temp", dir.listFiles()!!.none { it.name.endsWith(".sfpart") })
+    }
+
+    // 30. A sync interrupted partway (provider fails after N files) loses nothing and the
+    //     next sync completes the rest with all content intact.
+    @Test fun interruptedSync_resumesCleanlyNoCorruption() = runBlocking {
+        val (pair, local, remote) = newPair("interrupt", SyncDirection.UPLOAD_ONLY, DeleteBehavior.KEEP)
+        repeat(10) { i -> write(local, "i_$i.txt", "content-$i-".repeat(50)) }
+        // Provider that simulates a connection drop after 4 successful uploads.
+        val flaky = object : CloudProvider by provider {
+            private val n = java.util.concurrent.atomic.AtomicInteger(0)
+            override suspend fun uploadFile(localStream: java.io.InputStream, remotePath: String, sizeBytes: Long, onProgress: (Long) -> Unit): Result<RemoteFile> =
+                if (n.incrementAndGet() > 4) Result.failure(java.io.IOException("connection dropped"))
+                else provider.uploadFile(localStream, remotePath, sizeBytes, onProgress)
+        }
+        val r1 = engine.sync(db.syncPairDao().getById(pair.id)!!.toDomain(), flaky)
+        assertTrue("some files should fail on the dropped sync", r1.failedFiles > 0)
+        // Re-sync with the healthy provider completes the rest.
+        val r2 = engine.sync(db.syncPairDao().getById(pair.id)!!.toDomain(), provider)
+        assertEquals("re-sync must complete with no failures", 0, r2.failedFiles)
+        assertEquals("all 10 files end up on the cloud", 10, remoteNames(remote).count { it.startsWith("i_") })
+        assertEquals("content intact (no truncation)", "content-0-".repeat(50), remoteText("$remote/i_0.txt"))
+    }
 }

app/src/androidTest/kotlin/com/syncflow/NextcloudIntegrationTest.kt

@@ -13,6 +13,7 @@ import com.syncflow.domain.sync.LocalFileInfo
 import com.syncflow.domain.sync.SyncDecision
 import com.syncflow.domain.sync.syncDecide
 import kotlinx.coroutines.runBlocking
+import org.junit.Assert.assertArrayEquals
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNotNull
 import org.junit.Assert.assertTrue
@@ -21,6 +22,9 @@ import org.junit.Test
 import org.junit.runner.RunWith
 import java.io.ByteArrayInputStream
 import java.io.ByteArrayOutputStream
+import java.io.File
+import java.io.FileInputStream
+import java.io.FileOutputStream
 import java.time.Instant
 
 /**
@@ -36,6 +40,7 @@ import java.time.Instant
 @RunWith(AndroidJUnit4::class)
 class NextcloudIntegrationTest {
 
+    private val ctx = InstrumentationRegistry.getInstrumentation().targetContext
     private val args = InstrumentationRegistry.getArguments()
     private val url = args.getString("ncUrl")
     private val user = args.getString("ncUser")
@@ -114,4 +119,67 @@ class NextcloudIntegrationTest {
             runCatching { p.deleteFile(dir) } // best-effort cleanup of the test folder
         }
     }
+
+    @Test
+    fun chunkedUpload_assemblesLargeFileByteExact() = runBlocking {
+        assumeTrue("ncUrl/ncUser/ncPass required", url != null && user != null && pass != null)
+        // Tiny chunk size exercises multi-chunk assembly without needing a multi-GB file.
+        val account = CloudAccount(
+            id = 1, displayName = "IT", email = user, providerType = ProviderType.NEXTCLOUD,
+            credentialJson = """{"username":"$user","password":"$pass"}""", serverUrl = url, port = null,
+        )
+        val p = NextcloudProvider(account, chunkSize = 1L * 1024 * 1024) // 1 MB chunks
+        val dir = "SyncFlowChunk_${System.currentTimeMillis()}"
+        try {
+            p.createDirectory(dir).getOrThrow()
+            val payload = ByteArray(5 * 1024 * 1024 + 7).also { java.util.Random(7).nextBytes(it) } // ~5 MB -> 6 chunks
+            val up = p.uploadFile(ByteArrayInputStream(payload), "$dir/big.bin", payload.size.toLong())
+            assertTrue("chunked upload failed: ${up.exceptionOrNull()}", up.isSuccess)
+            assertEquals(payload.size.toLong(), p.listFiles(dir).getOrThrow().first { it.name == "big.bin" }.sizeBytes)
+            val out = ByteArrayOutputStream(); p.downloadFile("$dir/big.bin", out).getOrThrow()
+            assertArrayEquals("chunk-assembled content must equal the original bytes", payload, out.toByteArray())
+        } finally {
+            runCatching { p.deleteFile(dir) }
+        }
+    }
+
+    /**
+     * Real-world large-file test: streams a multi-GB file FROM THE PHONE through the app's
+     * chunked-upload path to the external URL, verifies the full size landed, then cleans up.
+     * Opt-in (slow): pass -e bigFileMB=<size>, e.g. 1536 for 1.5 GB.
+     */
+    @Test
+    fun realWorld_largeFileChunkedUpload() = runBlocking {
+        assumeTrue("ncUrl/ncUser/ncPass required", url != null && user != null && pass != null)
+        val mb = args.getString("bigFileMB")?.toIntOrNull() ?: 0
+        assumeTrue("pass -e bigFileMB=<size> to run the big-file test", mb > 0)
+
+        val account = CloudAccount(
+            id = 1, displayName = "IT", email = user, providerType = ProviderType.NEXTCLOUD,
+            credentialJson = """{"username":"$user","password":"$pass"}""", serverUrl = url, port = null,
+        )
+        val p = NextcloudProvider(account) // default 100 MB chunks -> chunked path for >100 MB
+        val dir = "SyncFlowBig_${System.currentTimeMillis()}"
+        val tmp = File(ctx.cacheDir, "bigfile_${System.currentTimeMillis()}.bin")
+        try {
+            val total = mb.toLong() * 1024 * 1024
+            FileOutputStream(tmp).use { os ->
+                val buf = ByteArray(8 * 1024 * 1024)
+                var written = 0L
+                while (written < total) {
+                    val n = minOf(buf.size.toLong(), total - written).toInt()
+                    os.write(buf, 0, n); written += n
+                }
+            }
+            assertEquals(total, tmp.length())
+            p.createDirectory(dir).getOrThrow()
+            val up = p.uploadFile(FileInputStream(tmp), "$dir/big.bin", tmp.length())
+            assertTrue("large chunked upload failed: ${up.exceptionOrNull()}", up.isSuccess)
+            assertEquals("full file size must land on the server", total,
+                p.listFiles(dir).getOrThrow().first { it.name == "big.bin" }.sizeBytes)
+        } finally {
+            tmp.delete()
+            runCatching { p.deleteFile(dir) }
+        }
+    }
 }

app/src/androidTest/kotlin/com/syncflow/SchedulingTest.kt

@@ -0,0 +1,47 @@
+package com.syncflow
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.work.NetworkType
+import com.syncflow.worker.SyncWorker
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.util.concurrent.TimeUnit
+
+/**
+ * Scheduling/constraint mapping for WorkManager-backed syncs. Verifies the request builders
+ * translate pair settings into the right constraints (Wi-Fi-only, charging-only), interval, input
+ * data, and tags — the deterministic part of scheduling (without waiting for the OS to fire it).
+ */
+@RunWith(AndroidJUnit4::class)
+class SchedulingTest {
+
+    @Test fun periodic_wifiOnly_chargingOnly_intervalAndData() {
+        val req = SyncWorker.buildPeriodicRequest(pairId = 42L, intervalMinutes = 30, wifiOnly = true, chargingOnly = true)
+        val ws = req.workSpec
+        assertEquals(NetworkType.UNMETERED, ws.constraints.requiredNetworkType)
+        assertTrue("charging constraint", ws.constraints.requiresCharging())
+        assertEquals(TimeUnit.MINUTES.toMillis(30), ws.intervalDuration)
+        assertEquals(42L, ws.input.getLong(SyncWorker.KEY_PAIR_ID, -1))
+        assertTrue("sync_42" in req.tags)
+    }
+
+    @Test fun periodic_anyNetwork_noCharging() {
+        val req = SyncWorker.buildPeriodicRequest(pairId = 7L, intervalMinutes = 60, wifiOnly = false, chargingOnly = false)
+        val c = req.workSpec.constraints
+        assertEquals(NetworkType.CONNECTED, c.requiredNetworkType)
+        assertFalse(c.requiresCharging())
+    }
+
+    @Test fun oneTime_constraintsDataAndTag() {
+        val req = SyncWorker.buildOneTimeRequest(pairId = 9L, wifiOnly = true, chargingOnly = false, silent = true)
+        val ws = req.workSpec
+        assertEquals(NetworkType.UNMETERED, ws.constraints.requiredNetworkType)
+        assertFalse(ws.constraints.requiresCharging())
+        assertEquals(9L, ws.input.getLong(SyncWorker.KEY_PAIR_ID, -1))
+        assertTrue(ws.input.getBoolean(SyncWorker.KEY_SILENT, false))
+        assertTrue("sync_9" in req.tags)
+    }
+}

app/src/androidTest/kotlin/com/syncflow/SftpProviderTest.kt

@@ -0,0 +1,69 @@
+package com.syncflow
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.syncflow.data.providers.sftp.SftpProvider
+import com.syncflow.data.security.CredentialStore
+import com.syncflow.domain.model.CloudAccount
+import com.syncflow.domain.model.ProviderType
+import kotlinx.coroutines.runBlocking
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Assume.assumeTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.io.ByteArrayInputStream
+import java.io.ByteArrayOutputStream
+
+/**
+ * Live SFTP test (the other major provider code path: sshj). Runs against a throwaway SFTP
+ * server. Skips unless -e sftpHost/sftpPort/sftpUser/sftpPass are provided.
+ */
+@RunWith(AndroidJUnit4::class)
+class SftpProviderTest {
+
+    private val ctx = InstrumentationRegistry.getInstrumentation().targetContext
+    private val args = InstrumentationRegistry.getArguments()
+
+    private fun provider() = SftpProvider(
+        CloudAccount(
+            id = 1, displayName = "sftp", email = null, providerType = ProviderType.SFTP,
+            credentialJson = """{"username":"${args.getString("sftpUser")}","password":"${args.getString("sftpPass")}"}""",
+            serverUrl = args.getString("sftpHost"), port = args.getString("sftpPort")?.toInt(),
+        ),
+        CredentialStore(ctx),
+    )
+
+    @Test fun sftpFullRoundTrip() = runBlocking {
+        assumeTrue("sftp* args required", args.getString("sftpHost") != null)
+        val p = provider()
+        val dir = "upload/it_${System.currentTimeMillis()}"
+
+        // Skip (don't fail) if the endpoint isn't reachable from the test runner's network —
+        // e.g. a phone on an isolated VLAN that only reaches services via the reverse proxy.
+        assumeTrue("SFTP endpoint not reachable from this device's network", p.testConnection().isSuccess)
+        assertTrue("mkdir", p.createDirectory(dir).isSuccess)
+
+        // upload (atomic temp + rename), list, download
+        val body = "sftp round-trip ✓".toByteArray()
+        assertTrue("upload", p.uploadFile(ByteArrayInputStream(body), "$dir/f.txt", body.size.toLong()).isSuccess)
+        assertTrue("f.txt" in p.listFiles(dir).getOrThrow().map { it.name })
+        val out = ByteArrayOutputStream(); p.downloadFile("$dir/f.txt", out).getOrThrow()
+        assertEquals("sftp round-trip ✓", out.toString("UTF-8"))
+
+        // atomic overwrite (temp + rename over existing)
+        val v2 = "updated-content".toByteArray()
+        assertTrue(p.uploadFile(ByteArrayInputStream(v2), "$dir/f.txt", v2.size.toLong()).isSuccess)
+        val out2 = ByteArrayOutputStream(); p.downloadFile("$dir/f.txt", out2).getOrThrow()
+        assertEquals("updated-content", out2.toString("UTF-8"))
+
+        // special / non-ASCII name (SFTP handles UTF-8 natively, no URL encoding)
+        val special = "café & rapport (1).txt"
+        assertTrue(p.uploadFile(ByteArrayInputStream("x".toByteArray()), "$dir/$special", 1).isSuccess)
+        assertTrue(special in p.listFiles(dir).getOrThrow().map { it.name })
+
+        // delete
+        assertTrue(p.deleteFile("$dir/f.txt").isSuccess)
+        assertTrue("f.txt" !in p.listFiles(dir).getOrThrow().map { it.name })
+    }
+}

app/src/androidTest/kotlin/com/syncflow/SftpgoWebDavTest.kt

@@ -0,0 +1,68 @@
+package com.syncflow
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.syncflow.data.providers.webdav.WebDavProvider
+import com.syncflow.domain.model.CloudAccount
+import com.syncflow.domain.model.ProviderType
+import kotlinx.coroutines.runBlocking
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Assume.assumeTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.io.ByteArrayInputStream
+import java.io.ByteArrayOutputStream
+
+/**
+ * Live test of the app's SFTPGo provider (which is WebDavProvider) against a real SFTPGo
+ * server over its externally-exposed WebDAV URL. Validates the provider against a different
+ * WebDAV implementation than Nextcloud. Creds via -e davUrl/davUser/davPass; skips otherwise.
+ */
+@RunWith(AndroidJUnit4::class)
+class SftpgoWebDavTest {
+
+    private val args = InstrumentationRegistry.getArguments()
+
+    private fun provider() = WebDavProvider(
+        CloudAccount(
+            id = 1, displayName = "sftpgo", email = null, providerType = ProviderType.SFTPGO,
+            credentialJson = """{"username":"${args.getString("davUser")}","password":"${args.getString("davPass")}"}""",
+            serverUrl = args.getString("davUrl"), port = null,
+        ),
+    )
+
+    @Test fun sftpgoWebDavRoundTrip() = runBlocking {
+        assumeTrue("davUrl/davUser/davPass required", args.getString("davUrl") != null)
+        val p = provider()
+        val dir = "SyncFlowDav_${System.currentTimeMillis()}"
+        try {
+            assertTrue("testConnection", p.testConnection().isSuccess)
+            assertTrue("mkdir", p.createDirectory(dir).isSuccess)
+
+            // upload (atomic temp + MOVE), list, download — with a non-ASCII payload
+            val body = "sftpgo webdav round-trip ✓ café".toByteArray()
+            assertTrue("upload", p.uploadFile(ByteArrayInputStream(body), "$dir/f.txt", body.size.toLong()).isSuccess)
+            assertTrue("f.txt" in p.listFiles(dir).getOrThrow().map { it.name })
+            val out = ByteArrayOutputStream(); p.downloadFile("$dir/f.txt", out).getOrThrow()
+            assertEquals("sftpgo webdav round-trip ✓ café", out.toString("UTF-8"))
+
+            // overwrite via atomic temp+MOVE
+            val v2 = "updated-content".toByteArray()
+            assertTrue(p.uploadFile(ByteArrayInputStream(v2), "$dir/f.txt", v2.size.toLong()).isSuccess)
+            val out2 = ByteArrayOutputStream(); p.downloadFile("$dir/f.txt", out2).getOrThrow()
+            assertEquals("updated-content", out2.toString("UTF-8"))
+
+            // non-ASCII / special filename (the URL/MOVE-header encoding fix)
+            val special = "café & rapport (1).txt"
+            assertTrue(p.uploadFile(ByteArrayInputStream("x".toByteArray()), "$dir/$special", 1).isSuccess)
+            assertTrue(special in p.listFiles(dir).getOrThrow().map { it.name })
+
+            // delete
+            assertTrue(p.deleteFile("$dir/f.txt").isSuccess)
+            assertTrue("f.txt" !in p.listFiles(dir).getOrThrow().map { it.name })
+        } finally {
+            runCatching { p.deleteFile(dir) }
+        }
+    }
+}

app/src/main/kotlin/com/syncflow/data/providers/nextcloud/NextcloudProvider.kt

@@ -2,13 +2,111 @@ package com.syncflow.data.providers.nextcloud
 
 import com.syncflow.data.providers.webdav.WebDavProvider
 import com.syncflow.domain.model.CloudAccount
+import com.syncflow.domain.model.RemoteFile
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.Request
+import okhttp3.RequestBody
+import okio.BufferedSink
+import java.io.IOException
+import java.io.InputStream
+
+/**
+ * Nextcloud WebDAV provider. Endpoint is /remote.php/dav/files/<username>/.
+ *
+ * Large files are uploaded via Nextcloud's chunked-upload API (/remote.php/dav/uploads/<user>/)
+ * so they bypass per-request size caps (Apache LimitRequestBody, PHP post_max_size, proxy body
+ * limits) that otherwise 413 a single multi-GB PUT. The assembly MOVE is the atomic commit, so
+ * the destination only appears once every chunk is in — no temp-file dance needed for this path.
+ *
+ * @param chunkSize bytes per chunk; files at or below this use the parent's single-PUT path.
+ */
+class NextcloudProvider(
+    account: CloudAccount,
+    private val chunkSize: Long = 100L * 1024 * 1024,
+) : WebDavProvider(account) {
 
-class NextcloudProvider(account: CloudAccount) : WebDavProvider(account) {
-    // Nextcloud WebDAV endpoint is /remote.php/dav/files/<username>/
     override val baseUrl: String
         get() {
             val server = account.serverUrl?.trimEnd('/') ?: ""
             val email = account.email ?: "user"
             return "$server/remote.php/dav/files/$email"
         }
+
+    private val uploadsBase: String
+        get() {
+            val server = account.serverUrl?.trimEnd('/') ?: ""
+            val email = account.email ?: "user"
+            return "$server/remote.php/dav/uploads/$email"
+        }
+
+    override suspend fun uploadFile(
+        localStream: InputStream,
+        remotePath: String,
+        sizeBytes: Long,
+        onProgress: (Long) -> Unit,
+    ): Result<RemoteFile> {
+        if (sizeBytes <= chunkSize) {
+            return super.uploadFile(localStream, remotePath, sizeBytes, onProgress)
+        }
+        return runCatching {
+            withContext(Dispatchers.IO) {
+                val uploadId = "syncflow-${System.currentTimeMillis()}-${(0..999_999).random()}"
+                val dir = "$uploadsBase/$uploadId"
+                mkcol(dir)
+                try {
+                    var index = 1
+                    var sent = 0L
+                    while (sent < sizeBytes) {
+                        val len = minOf(chunkSize, sizeBytes - sent)
+                        putChunk("$dir/%05d".format(index), localStream, len)
+                        sent += len
+                        index++
+                        onProgress(sent)
+                    }
+                    // Assemble: MOVE the virtual .file onto the destination (atomic commit).
+                    val move = Request.Builder().url("$dir/.file")
+                        .method("MOVE", null)
+                        .header("Destination", url(remotePath))
+                        .header("Overwrite", "T")
+                        .header("OC-Total-Length", sizeBytes.toString())
+                        .build()
+                    client.newCall(move).execute().use { resp ->
+                        if (!resp.isSuccessful) throw IOException("Chunk assembly MOVE HTTP ${resp.code}")
+                    }
+                } catch (e: Throwable) {
+                    runCatching { client.newCall(Request.Builder().url(dir).delete().build()).execute().close() }
+                    throw e
+                }
+                getFileMetadata(remotePath).getOrThrow()
+            }
+        }
+    }
+
+    private fun mkcol(url: String) {
+        client.newCall(Request.Builder().url(url).method("MKCOL", null).build()).execute().use {
+            if (!it.isSuccessful && it.code != 405) throw IOException("MKCOL upload session HTTP ${it.code}")
+        }
+    }
+
+    private fun putChunk(url: String, stream: InputStream, len: Long) {
+        val body = object : RequestBody() {
+            override fun contentType() = "application/octet-stream".toMediaType()
+            override fun contentLength() = len
+            override fun writeTo(sink: BufferedSink) {
+                var remaining = len
+                val buf = ByteArray(64 * 1024)
+                while (remaining > 0) {
+                    val n = stream.read(buf, 0, minOf(buf.size.toLong(), remaining).toInt())
+                    if (n < 0) break
+                    sink.write(buf, 0, n)
+                    remaining -= n
+                }
+            }
+        }
+        client.newCall(Request.Builder().url(url).put(body).build()).execute().use {
+            if (!it.isSuccessful) throw IOException("Chunk PUT HTTP ${it.code}")
+        }
+    }
 }

app/src/main/kotlin/com/syncflow/data/providers/sftp/SftpProvider.kt

@@ -23,19 +23,36 @@ class SftpProvider(private val account: CloudAccount, private val credentialStor
     private val password = creds["password"]?.jsonPrimitive?.content
     private val privateKey = creds["private_key"]?.jsonPrimitive?.content
 
-    private fun <T> withSftp(block: (SFTPClient) -> T): T {
+    // Persistent SSH connection reused across all operations in the provider's lifetime.
+    // Each call to withSftp checks liveness and reconnects if the connection dropped.
+    // This eliminates the per-operation connect/auth/disconnect cycle that caused
+    // 100+ SSH handshakes during a recursive directory listing + file-transfer sync,
+    // leading to connection timeouts on large folder trees (e.g. 69 subdirectories).
+    private var sshClient: SSHClient? = null
+
+    private fun getOrCreateSsh(): SSHClient {
+        val existing = sshClient
+        if (existing != null && existing.isConnected && existing.isAuthenticated) return existing
         val ssh = SSHClient()
         ssh.addHostKeyVerifier(TofuHostKeyVerifier(credentialStore))
         ssh.connect(host, port)
-        try {
         if (!privateKey.isNullOrBlank()) {
             ssh.authPublickey(username, ssh.loadKeys(privateKey, null, null))
         } else {
             ssh.authPassword(username, password ?: "")
         }
-            return ssh.newSFTPClient().use(block)
-        } finally {
-            ssh.disconnect()
+        sshClient = ssh
+        return ssh
+    }
+
+    private fun <T> withSftp(block: (SFTPClient) -> T): T {
+        return try {
+            getOrCreateSsh().newSFTPClient().use(block)
+        } catch (e: Exception) {
+            // Connection may have gone stale — reset and retry once with a fresh connection.
+            runCatching { sshClient?.disconnect() }
+            sshClient = null
+            getOrCreateSsh().newSFTPClient().use(block)
         }
     }
 

app/src/main/kotlin/com/syncflow/data/providers/webdav/WebDavProvider.kt

@@ -35,7 +35,8 @@ open class WebDavProvider(protected val account: CloudAccount) : CloudProvider {
         val pass = creds["password"]?.jsonPrimitive?.content ?: ""
         OkHttpClient.Builder()
             .connectTimeout(15, TimeUnit.SECONDS)
-            .readTimeout(30, TimeUnit.SECONDS)
+            .readTimeout(5, TimeUnit.MINUTES)
+            .writeTimeout(5, TimeUnit.MINUTES)
             .addInterceptor { chain ->
                 val req = chain.request().newBuilder()
                     .header("Authorization", Credentials.basic(user, pass))
@@ -149,7 +150,12 @@ open class WebDavProvider(protected val account: CloudAccount) : CloudProvider {
         withContext(Dispatchers.IO) {
             val req = Request.Builder().url(url(remotePath)).method("MKCOL", null).build()
             client.newCall(req).execute().use { resp ->
-                if (!resp.isSuccessful && resp.code != 405) throw Exception("MKCOL HTTP ${resp.code}")
+                // 405 = directory already exists (most servers)
+                // 423 = Locked — SFTPGo returns this when the dir exists and has a lock;
+                //       treat as "already there", not a failure, so uploads inside it proceed.
+                if (!resp.isSuccessful && resp.code != 405 && resp.code != 423) {
+                    throw Exception("MKCOL HTTP ${resp.code}")
+                }
             }
         }
     }
@@ -181,7 +187,13 @@ open class WebDavProvider(protected val account: CloudAccount) : CloudProvider {
         }
     }
 
-    protected fun url(path: String) = "$baseUrl/${path.trimStart('/')}"
+    // Build a properly percent-encoded URL. addPathSegments encodes each segment (spaces,
+    // ampersands, and — critically — non-ASCII like "café"), which keeps OkHttp from rejecting
+    // non-ASCII in the WebDAV MOVE "Destination" header and avoids malformed request URLs.
+    protected fun url(path: String): String {
+        val base = baseUrl.toHttpUrlOrNull() ?: return "$baseUrl/${path.trimStart('/')}"
+        return base.newBuilder().addPathSegments(path.trimStart('/')).build().toString()
+    }
 
     private fun parsePropfind(xml: String, parentPath: String, dropFirst: Boolean = true): List<RemoteFile> {
         val results = mutableListOf<RemoteFile>()

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

@@ -68,6 +68,36 @@ class SyncEngine @Inject constructor(
         else
             LocalAccessor.JavaFile(File(localPath))
 
+    /**
+     * Recursively collect every FILE under [basePath] on the remote, descending into each
+     * subdirectory (one Depth:1 PROPFIND per directory). Directories are never returned as
+     * files — only their contents. The provider already drops the parent entry from each
+     * listing, so children-only is returned; the explicit self-path guard prevents any
+     * pathological infinite recursion. This MUST mirror the recursive local walk: otherwise
+     * files in remote subfolders appear absent and a TWO_WAY/MIRROR sync deletes them locally.
+     */
+    private suspend fun listRemoteFilesRecursive(
+        provider: CloudProvider,
+        basePath: String,
+        depth: Int = 0,
+    ): List<RemoteFile> {
+        if (depth > 64) {
+            Timber.w("SyncEngine: remote recursion depth limit hit at $basePath")
+            return emptyList()
+        }
+        val out = mutableListOf<RemoteFile>()
+        for (entry in provider.listFiles(basePath).getOrThrow()) {
+            if (entry.isDirectory) {
+                if (entry.path.trimEnd('/') != basePath.trimEnd('/')) {
+                    out += listRemoteFilesRecursive(provider, entry.path, depth + 1)
+                }
+            } else {
+                out += entry
+            }
+        }
+        return out
+    }
+
     private suspend fun performSync(
         pair: SyncPair,
         provider: CloudProvider,
@@ -76,8 +106,32 @@ class SyncEngine @Inject constructor(
     ): SyncResult {
         val accessor = makeAccessor(pair.localPath)
         var knownStates = fileStateDao.getForPair(pair.id).associateBy { it.relativePath }
-        val remoteFiles = provider.listFiles(pair.remotePath).getOrThrow()
+        // The local walk is RECURSIVE, so the remote listing must be too. Listing only the top
+        // level (Depth:1) made every file inside a remote subfolder look "missing from remote",
+        // which on a TWO_WAY/MIRROR pair triggered DELETE_LOCAL and wiped those files off the
+        // device (data loss). Walk the remote tree so subfolder files are matched, not deleted.
+        // Exclusions are filtered on BOTH sides. The local walk already drops excluded files,
+        // but the remote listing did not, so any excluded path that already existed on the
+        // server (e.g. a previously-uploaded ".thumbnails" entry) looked "local-missing" and
+        // 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 = try {
+            listRemoteFilesRecursive(provider, pair.remotePath)
                 .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
@@ -91,9 +145,14 @@ class SyncEngine @Inject constructor(
             return performSync(pair, provider, isRetry = true, onProgress = onProgress)
         }
 
-        val allPaths = (localFiles.keys + remoteFiles.keys + knownStates.keys).toSet()
+        // knownStates may still hold records for now-excluded paths (e.g. thumbnails uploaded
+        // by an older build). Drop them from the work set so they aren't acted on; their stale
+        // state rows are harmless and ignored.
+        val allPaths = (localFiles.keys + remoteFiles.keys + knownStates.keys)
+            .filter { !isExcludedPath(it, pair) }
+            .toSet()
         val hasPriorSyncState = knownStates.isNotEmpty()
-        val semaphore = Semaphore(4)
+        val semaphore = Semaphore(2)  // limit concurrency to be gentle on the server
         val uploadedAtomic = AtomicInteger(0)
         val downloadedAtomic = AtomicInteger(0)
         val deletedAtomic = AtomicInteger(0)
@@ -252,6 +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
@@ -375,6 +448,63 @@ 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
+ * subtree like "DCIM/.thumbnails/..." is ignored. Android continuously regenerates and evicts
+ * its thumbnail cache and shuffles files through .trashed-/.pending- staging dirs; syncing them
+ * produces an endless upload→evict→DELETE_REMOTE→regenerate loop. ".sfpart" is our own atomic-
+ * write temp suffix and must never be propagated either.
+ */
+private val ALWAYS_IGNORED_SEGMENTS = setOf(".thumbnails")
+private val ALWAYS_IGNORED_PREFIXES = listOf(".trashed-", ".pending-")
+private val ALWAYS_IGNORED_SUFFIXES = listOf(".sfpart")
+
+/**
+ * App-private storage trees. On Android 11+ (scoped storage) another app's SAF grant can LIST
+ * these directories but cannot OPEN the files inside, so every transfer fails and the pair is
+ * stuck reporting "Partial" forever (e.g. Android/media/com.whatsapp/...). They hold app-managed
+ * data, not user content worth syncing, so they are excluded entirely. Matched case-insensitively
+ * against the full relative path so the whole subtree is ignored on both sides.
+ */
+private val ALWAYS_IGNORED_PATH_PREFIXES = listOf("android/data/", "android/media/", "android/obb/")
+
+/**
+ * True if [rel] should be excluded from sync entirely. Applied symmetrically to the local walk,
+ * the remote listing, and known state so an excluded path is never uploaded, downloaded, or
+ * deleted. The always-ignored rules run on every segment; user-configured rules
+ * (skipHiddenFiles, excludePatterns, excludeExtensions) match the filename, mirroring the
+ * existing local-walk semantics in LocalAccessor.
+ */
+internal fun isExcludedPath(rel: String, pair: SyncPair): Boolean {
+    val normalized = rel.replace('\\', '/')
+    val lower = normalized.lowercase()
+    if (ALWAYS_IGNORED_PATH_PREFIXES.any { lower.startsWith(it) }) return true
+    val segments = normalized.split('/').filter { it.isNotEmpty() }
+    if (segments.isEmpty()) return false
+    for (seg in segments) {
+        if (seg in ALWAYS_IGNORED_SEGMENTS) return true
+        if (ALWAYS_IGNORED_PREFIXES.any { seg.startsWith(it) }) return true
+        if (ALWAYS_IGNORED_SUFFIXES.any { seg.endsWith(it) }) return true
+    }
+    val fileName = segments.last()
+    if (pair.skipHiddenFiles && fileName.startsWith('.')) return true
+    if (pair.excludePatterns.any { pat -> fileName.matches(globToRegex(pat)) }) return true
+    val ext = fileName.substringAfterLast('.', "").lowercase()
+    if (pair.excludeExtensions.any { ext == it.lowercase().trimStart('.') }) return true
+    return false
+}
+
 /**
  * True if a relative sync path is unsafe to act on — empty, absolute, or containing a ".."
  * segment that would let a hostile remote escape the sync root via path traversal. Applied to

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),
@@ -122,7 +122,40 @@ 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)
+                if (!s.isEditing) {
+                    ToggleRow(
+                        label = "Back up multiple folders",
+                        description = "Pick several folders; each is saved as its own subfolder under the remote base (no overwrites)",
+                        checked = s.multiFolder,
+                        onToggle = { vm.setMultiFolder(it) },
+                    )
+                    Spacer(Modifier.height(4.dp))
+                }
+
+                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 = {},
@@ -134,11 +167,12 @@ fun AddPairScreen(onDone: () -> Unit, vm: AddPairViewModel = hiltViewModel()) {
                         )
                         Box(modifier = Modifier.matchParentSize().clickable { showLocalBrowser = true })
                     }
+                }
 
-                // Remote folder
+                // 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

@@ -10,7 +10,10 @@ import com.syncflow.data.db.SyncPairDao
 import com.syncflow.data.db.entities.CloudAccountEntity
 import com.syncflow.data.db.entities.SyncPairEntity
 import com.syncflow.domain.model.*
+import androidx.work.ExistingPeriodicWorkPolicy
+import androidx.work.WorkManager
 import com.syncflow.worker.FileWatchService
+import com.syncflow.worker.SyncWorker
 import dagger.hilt.android.lifecycle.HiltViewModel
 import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.flow.*
@@ -22,6 +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(),
@@ -44,7 +51,7 @@ data class AddPairUiState(
     val chargingOnly: Boolean = false,
     val minBatteryPct: Int = 0,
     // ── File filters ─────────────────────────────────────────────────────────
-    val excludePatterns: String = ".DS_Store\n*.tmp\n.nomedia\nThumbs.db",
+    val excludePatterns: String = ".DS_Store\n*.tmp\n.nomedia\nThumbs.db\n.thumbnails",
     val includeExtensions: String = "",
     val excludeExtensions: String = "",
     val skipHiddenFiles: Boolean = true,
@@ -54,6 +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,
@@ -69,6 +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,
@@ -80,7 +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 {
@@ -99,6 +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,
@@ -145,12 +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.multiFolder) {
+                if (s.localPaths.isEmpty()) add("Add at least one folder")
+                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")
         }
@@ -159,9 +206,50 @@ class AddPairViewModel @Inject constructor(
         viewModelScope.launch {
             _state.update { it.copy(isSaving = true, error = null) }
             runCatching {
-                val entity = SyncPairEntity(
-                    id = editPairId ?: 0L,
-                    name = s.name, localPath = s.localPath, remotePath = s.remotePath,
+                if (s.multiFolder) {
+                    // One normal pair per folder, each into its OWN subfolder under the remote base.
+                    // Keeping each source in a distinct subfolder is what makes many-to-one safe —
+                    // flattening would let same-named files from different folders overwrite each other.
+                    val base = s.remotePath.trimEnd('/')
+                    val used = mutableSetOf<String>()
+                    s.localPaths.map { folder ->
+                        val sub = uniqueSubName(folderLeafName(folder), used)
+                        val pairName = if (s.name.isBlank()) sub else "${s.name} — $sub"
+                        val entity = buildEntity(s, name = pairName, localPath = folder, remotePath = "$base/$sub", id = 0L)
+                        entity.copy(id = syncPairDao.insert(entity))
+                    }
+                } 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))
+                }
+            }
+                .onSuccess { 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,
@@ -176,26 +264,29 @@ class AddPairViewModel @Inject constructor(
             notifyOnComplete = s.notifyOnComplete, notifyOnError = s.notifyOnError,
             isEnabled = true, lastSyncAt = null, lastSyncResult = SyncStatus.IDLE, pendingConflicts = 0,
         )
-                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)
+
+    /**
+     * 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
+     * background. Mirrors HomeViewModel.toggleEnabled / BootReceiver.
+     */
+    private fun applySchedule(pair: SyncPairEntity) {
+        val wm = WorkManager.getInstance(context)
+        when (pair.scheduleType) {
+            ScheduleType.ON_CHANGE -> {
+                wm.cancelUniqueWork("periodic_${pair.id}")
+                FileWatchService.start(context)
+            }
+            ScheduleType.MANUAL -> wm.cancelUniqueWork("periodic_${pair.id}")
+            else -> {
+                val req = SyncWorker.buildPeriodicRequest(
+                    pair.id,
+                    pair.scheduleIntervalMinutes.toLong().coerceAtLeast(15),
+                    pair.wifiOnly,
+                    pair.chargingOnly,
+                )
+                wm.enqueueUniquePeriodicWork("periodic_${pair.id}", ExistingPeriodicWorkPolicy.UPDATE, req)
             }
         }
     }
-                .onSuccess {
-                    if (s.scheduleType == ScheduleType.ON_CHANGE) FileWatchService.start(context)
-                    _state.update { it.copy(done = true) }
-                }
-                .onFailure { e -> _state.update { it.copy(isSaving = false, error = e.message) } }
-        }
-    }
 }

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

@@ -0,0 +1,106 @@
+package com.syncflow.domain.sync
+
+import com.syncflow.domain.model.ConflictStrategy
+import com.syncflow.domain.model.DeleteBehavior
+import com.syncflow.domain.model.ScheduleType
+import com.syncflow.domain.model.SyncDirection
+import com.syncflow.domain.model.SyncPair
+import com.syncflow.domain.model.SyncStatus
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * Exclusion symmetry: paths excluded from the local walk must also be excluded from the remote
+ * listing and the merged work set, so a previously-uploaded excluded file is never DELETE_REMOTE'd
+ * in an endless churn loop (the ".thumbnails" cache regression).
+ */
+class ExcludePathTest {
+
+    private fun pair(
+        excludePatterns: List<String> = emptyList(),
+        excludeExtensions: List<String> = emptyList(),
+        skipHiddenFiles: Boolean = false,
+    ) = SyncPair(
+        id = 1, name = "t", localPath = "/l", remotePath = "/r", accountId = 1,
+        syncDirection = SyncDirection.TWO_WAY,
+        conflictStrategy = ConflictStrategy.KEEP_NEWEST,
+        deleteBehavior = DeleteBehavior.MIRROR,
+        recursive = true,
+        scheduleType = ScheduleType.MANUAL, scheduleIntervalMinutes = 0,
+        scheduleDailyTime = null, scheduleWeekdays = 0,
+        wifiOnly = false, wifiSsid = "", chargingOnly = false, minBatteryPct = 0,
+        excludePatterns = excludePatterns, includeExtensions = emptyList(),
+        excludeExtensions = excludeExtensions, skipHiddenFiles = skipHiddenFiles,
+        minFileSizeKb = 0, maxFileSizeKb = 0,
+        notifyOnComplete = false, notifyOnError = false,
+        isEnabled = true, lastSyncAt = null, lastSyncResult = SyncStatus.IDLE,
+        pendingConflicts = 0,
+    )
+
+    @Test fun `thumbnails cache is always excluded regardless of config`() {
+        val p = pair()
+        assertTrue(isExcludedPath("DCIM/.thumbnails/123.jpg", p))
+        assertTrue(isExcludedPath("Pictures/.thumbnails/1000020397.jpg", p))
+        assertTrue(isExcludedPath(".thumbnails/x.jpg", p))
+    }
+
+    @Test fun `android trash and pending staging dirs are excluded`() {
+        val p = pair()
+        assertTrue(isExcludedPath("DCIM/Camera/.trashed-1700000000-IMG_0001.jpg", p))
+        assertTrue(isExcludedPath("DCIM/.pending-1700000000-VID_0001.mp4", p))
+    }
+
+    @Test fun `our own atomic-write temp files are excluded`() {
+        val p = pair()
+        assertTrue(isExcludedPath("Download/.movie.mp4.sfpart", p))
+        assertTrue(isExcludedPath("a/b/.photo.jpg.sfpart", p))
+    }
+
+    @Test fun `android app-private trees are excluded (scoped-storage unreadable)`() {
+        val p = pair()
+        assertTrue(isExcludedPath("Android/media/com.whatsapp/WhatsApp/Media/IMG.jpg", p))
+        assertTrue(isExcludedPath("Android/data/com.foo/files/x.bin", p))
+        assertTrue(isExcludedPath("Android/obb/com.game/main.obb", p))
+        assertTrue(isExcludedPath("android/MEDIA/com.x/y.jpg", p)) // case-insensitive
+    }
+
+    @Test fun `non-private Android paths are not excluded`() {
+        val p = pair()
+        // A user folder literally named "Android" at a deeper level is fine; only the
+        // top-level app-private trees are blocked.
+        assertFalse(isExcludedPath("DCIM/Android/holiday.jpg", p))
+        assertFalse(isExcludedPath("Pictures/android-wallpaper.png", p))
+    }
+
+    @Test fun `normal media files are not excluded`() {
+        val p = pair()
+        assertFalse(isExcludedPath("DCIM/Camera/IMG_0001.jpg", p))
+        assertFalse(isExcludedPath("Pictures/cat.png", p))
+        assertFalse(isExcludedPath("اصفهان/20171023.jpg", p)) // unicode folder, real data
+    }
+
+    @Test fun `user exclude patterns and extensions still apply on filename`() {
+        assertTrue(isExcludedPath("a/Thumbs.db", pair(excludePatterns = listOf("Thumbs.db"))))
+        assertTrue(isExcludedPath("a/note.tmp", pair(excludePatterns = listOf("*.tmp"))))
+        assertTrue(isExcludedPath("a/data.log", pair(excludeExtensions = listOf("log"))))
+        assertFalse(isExcludedPath("a/keep.jpg", pair(excludeExtensions = listOf("log"))))
+    }
+
+    @Test fun `skipHiddenFiles excludes dotfiles by filename only`() {
+        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=1.0.63
-VERSION_CODE=64
+VERSION_NAME=1.0.76
+VERSION_CODE=76