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Fix perpetual sync loop and wrong delete decisions

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Three bugs fixed:

1. catchupScan used raw dir.walk() with no filters, causing hidden/excluded
   files to appear as "new" every startup and trigger a catchup sync.
   Fixed by using LocalAccessor.walkFiles(pair) which applies the same
   filters and uses the same mtime source (SAF cursor) as SyncEngine.

2. catchupScan compared localModifiedAt.toEpochMilli() vs File.lastModified()
   (millisecond precision) while SyncEngine uses second precision. Every file
   appeared "modified" after a successful sync. Fixed by using epochSecond.

3. syncDecide() treated !localExists && remoteExists && known==null as
   "user deleted local copy → delete remote" even on files that were never
   synced. Fixed to treat unknown remote files as new (download them), which
   is safe because a genuinely-deleted file will always have a known state
   record from the previous sync.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Amir Khodak
2026-05-25 15:13:43 +00:00
parent 4b20697bb1
commit 897b685c70
4 changed files with 24 additions and 22 deletions
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app/src/main/kotlin/com/syncflow/domain/sync/SyncEngine.kt
+9 -13
View File
@@ -146,13 +146,15 @@ class SyncEngine @Inject constructor(
storeLocalMtime = false))
}
SyncDecision.DELETE_LOCAL -> {
accessor.delete(rel)
val deleted = accessor.delete(rel)
if (!deleted) Timber.w("SyncEngine: DELETE_LOCAL failed (silent) for $rel")
fileStateDao.delete(pair.id, rel)
logEvent(pair.id, SyncEventType.FILE_DELETED, rel, "local", 0)
FileOutcome(deleted = 1)
}
SyncDecision.DELETE_REMOTE -> {
provider.deleteFile("${pair.remotePath}/$rel")
runCatching { provider.deleteFile("${pair.remotePath}/$rel") }
.onFailure { e -> Timber.e(e, "SyncEngine: DELETE_REMOTE failed for $rel") }
fileStateDao.delete(pair.id, rel)
logEvent(pair.id, SyncEventType.FILE_DELETED, rel, "remote", 0)
FileOutcome(deleted = 1)
@@ -283,21 +285,15 @@ internal fun syncDecide(
}
!localExists && remoteExists -> when {
known == null -> if (!hasPriorSyncState) {
// Initial sync: no history at all — remote files are new, download them.
known == null -> {
// No state record: could be a new remote file OR a file whose state was lost.
// Downloading is always safer than deleting — if the user deleted the local
// copy intentionally, the state record will still exist (known != null) and
// the else-branch below correctly deletes the remote copy.
when (direction) {
SyncDirection.DOWNLOAD_ONLY, SyncDirection.TWO_WAY -> SyncDecision.DOWNLOAD
else -> SyncDecision.SKIP
}
} else {
// Pair has been synced before but this file has no state record
// (e.g. uploaded before state-tracking was fixed). Treat the same
// as a known remote-deletion: apply mirror/keep behavior.
when {
deleteBehavior == DeleteBehavior.KEEP -> SyncDecision.SKIP
direction == SyncDirection.UPLOAD_ONLY || direction == SyncDirection.TWO_WAY -> SyncDecision.DELETE_REMOTE
else -> SyncDecision.SKIP
}
}
else -> when {
deleteBehavior == DeleteBehavior.KEEP -> SyncDecision.SKIP