Merge pull request #16 from CodePandaaAI/jvm-impl

Improve multi-file TCP batching and clean up local tooling files

Author: CodePandaaAI

.gitignore

@@ -43,6 +43,7 @@ guide/
 _CODEX_CONTEXT_DO_NOT_DELETE/
 recover.py
 skills-main/
+skills-lock.json
 
 # JavaScript
 node_modules/

CHANGELOG.md

@@ -15,7 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - Text offers, receiver Accept/Decline, text transfer, Copy, and Clear.
 - Android and Desktop multiple-file selection and metadata offers.
 - Raw TCP file transfer using one persistent connection per accepted batch.
-- Sequential file framing with index/size validation and per-file save acknowledgements.
+- Sequential file framing with index/size validation and one final batch result containing receiver success and the completed-file count.
 - Android Downloads writing through pending `MediaStore` entries.
 - Desktop Downloads writing through temporary `.part` files and collision-safe final names.
 - Unified send operation states and best-effort cancellation.
@@ -29,6 +29,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - Replaced the old generated sync implementation with a smaller, manually understood flow.
 - Separated Ktor HTTP offer/control messages from raw TCP file bytes.
 - Reused one TCP connection for the complete accepted multi-file batch instead of opening one connection per file.
+- Removed per-file flush-and-acknowledgement waits so an accepted batch can stream continuously before one final receiver result.
 - Positioned the project around direct local-network nearby sharing rather than chat or cloud sync.
 
 ### Known limitations

README.md

@@ -55,7 +55,7 @@ Sync360 has a working Android-to-Android MVP for text and multiple-file transfer
 - Stream file bytes directly over raw TCP without loading an entire file into memory.
 - Save received files into public Android Downloads through `MediaStore`, preserving the extension when duplicate names are resolved.
 - Delete the incomplete current file if its receive operation fails or is cancelled.
-- Send files sequentially with a save acknowledgement after each file.
+- Stream each accepted file batch continuously, then confirm the batch with one final receiver result.
 - Cancel a pending send or active file transfer on a best-effort basis.
 - Show batch-wide byte percentage while files are being sent and received.
 - Show clear offer, transfer, success, failure, and cancelled states on the sender, with incoming, receiving, and received states on the receiver.
@@ -122,10 +122,10 @@ Platform file picker
   -> platform FileTransferSender opens an InputStream
   -> one raw TCP connection streams the accepted file batch
   -> platform DownloadsWriter saves each file
-  -> receiver acknowledges that the file was saved
+  -> receiver returns final success and completed-file count
 ```
 
-One TCP socket is opened for the complete accepted batch. Each file begins with its index and promised byte count, followed by exactly that many bytes. The receiver checks the index and size against the accepted offer before saving the file, then sends one save acknowledgement before the sender continues. The current shared payload buffer is 512 KiB; TCP correctness does not depend on sender and receiver reads using identical chunk boundaries.
+One TCP socket is opened for the complete accepted batch. Each file begins with its index and promised byte count, followed by exactly that many bytes. The receiver checks the index and size against the accepted offer before saving each file. The sender writes every file sequentially, flushes once after the complete batch, then reads one final success flag and completed-file count from the receiver. The count increases only after the platform Downloads writer successfully returns. The current shared payload buffer is 512 KiB; exact byte counts define file boundaries, so correctness does not depend on `flush()` calls or matching sender and receiver read chunks.
 
 Files are sent sequentially. If a later file fails, files that were already completed stay in Downloads; the incomplete current file is cleaned up. Android uses a pending `MediaStore` entry and resolves its MIME type from the filename extension so duplicate names remain in the form `file (1).ext`. Desktop writes a temporary `.part` file before moving a completed file into place without overwriting an existing name.
 

context.md

@@ -51,11 +51,12 @@ Raw TCP is the file data plane:
 
 ```text
 one connection per accepted batch
-  -> file index
-  -> promised byte count
-  -> exact file bytes
-  -> save acknowledgement
-  -> next file
+  -> repeat for each file:
+       -> file index
+       -> promised byte count
+       -> exact file bytes
+  -> sender flushes once
+  -> receiver returns final success and completed-file count
 ```
 
 Current shared transfer constants use a 512 KiB payload buffer, 5-second connect timeout, 60-second connected-socket timeout, and 10-second wait for the first file connection after acceptance.

docs/ARCHITECTURE.md

@@ -101,14 +101,16 @@ Accepted file bytes use a separate raw TCP connection:
 
 ```text
 one connection for the accepted batch
-  -> file index: Int
-  -> promised file size: Long
-  -> exactly promised-size bytes
-  -> receiver save acknowledgement: Boolean
-  -> repeat for the next file
+  -> repeat for each accepted file:
+       -> file index: Int
+       -> promised file size: Long
+       -> exactly promised-size bytes
+  -> sender flushes after the complete batch
+  -> receiver result: Boolean
+  -> completed-file count: Int
 ```
 
-Files remain sequential. The receiver verifies each index and size against the accepted offer before saving. It acknowledges a file only after the platform Downloads writer completes it.
+Files remain sequential. The receiver verifies each index and size directly against the matching file in the accepted offer before saving. It increments the completed-file count only after the platform Downloads writer returns successfully. After every file has been processed, the receiver sends one final success flag and completed count. If processing fails, it attempts to send `false` with the number of files that were fully saved.
 
 `FileTransferConstants` currently provides:
 
@@ -117,7 +119,7 @@ Files remain sequential. The receiver verifies each index and size against the a
 - 60-second connected-socket timeout
 - 10-second wait for the first file connection after acceptance
 
-The sender and receiver do not need matching read boundaries because TCP is a byte stream; exact file sizes define the protocol framing.
+The sender and receiver do not need matching read boundaries because TCP is a byte stream; exact file sizes define the protocol framing. Flushing once after the batch makes any remaining buffered bytes available before the sender waits for the final result, but the flush does not define file boundaries.
 
 ## Platform storage
 

docs/ROADMAP.md

@@ -11,7 +11,7 @@ Sync360 is an active Android-first rebuild. The current MVP can discover nearby
 - Android and Desktop multiple-file selection.
 - File metadata offer before any file bytes are sent.
 - One persistent raw TCP connection per accepted file batch.
-- Sequential file framing, index/size validation, and per-file save acknowledgements.
+- Sequential file framing, index/size validation, and one final success/completed-count result per batch.
 - Android public Downloads writing with incomplete-entry cleanup.
 - Desktop Downloads writing through temporary `.part` files and collision-safe final names.
 - Best-effort sender cancellation.

shared/src/androidMain/kotlin/com/liftley/sync360/data/network/tcp/AndroidFileTransferReceiver.kt

@@ -32,7 +32,6 @@ class AndroidFileTransferReceiver(
     @Volatile
     private var expectedFileOffer: FileOfferRequest? = null
 
-    private var nextExpectedFileIndex: Int = 0
     private var onFileSaved: ((completedFileCount: Int) -> Unit)? = null
     private var onProgress: ((FileTransferProgress) -> Unit)? = null
     private var onTransferFinished: ((wasSuccessful: Boolean) -> Unit)? = null
@@ -75,7 +74,6 @@ class AndroidFileTransferReceiver(
         onTransferFinished: (wasSuccessful: Boolean) -> Unit
     ) {
         expectedFileOffer = fileOffer
-        nextExpectedFileIndex = 0
         this.onFileSaved = onFileSaved
         this.onProgress = onProgress
         this.onTransferFinished = onTransferFinished
@@ -86,7 +84,6 @@ class AndroidFileTransferReceiver(
     override fun clearExpectedTransfer() {
         waitingForSenderTimeout?.cancel()
         expectedFileOffer = null
-        nextExpectedFileIndex = 0
         onFileSaved = null
         onProgress = null
         onTransferFinished = null
@@ -107,6 +104,8 @@ class AndroidFileTransferReceiver(
 
             val socketOutput = DataOutputStream(socket.getOutputStream())
 
+            var completedFileCount = 0
+
             try {
                 val fileOffer = expectedFileOffer
                     ?: error("No accepted file offer is waiting")
@@ -119,20 +118,16 @@ class AndroidFileTransferReceiver(
                     val receivedFileIndex = socketInput.readInt()
                     val receivedFileSize = socketInput.readLong()
 
-                    if (receivedFileIndex != nextExpectedFileIndex) {
+                    if (receivedFileIndex != expectedFile.index) {
                         error(
-                            "Expected file index $nextExpectedFileIndex " +
-                                "but received $receivedFileIndex"
+                            "Expected file index ${expectedFile.index}, " +
+                                    "but received $receivedFileIndex"
                         )
                     }
 
-                    if (expectedFile.index != receivedFileIndex) {
-                        error("File index does not match the accepted offer")
-                    }
-
                     val expectedFileSize = expectedFile.fileSizeBytes
 
-                    if (receivedFileSize != expectedFileSize) {
+                    if (expectedFileSize != receivedFileSize) {
                         error("File size does not match the accepted offer")
                     }
 
@@ -144,47 +139,35 @@ class AndroidFileTransferReceiver(
                         onBytesWritten = progressTracker::addBytes
                     )
 
-                    markCurrentFileComplete(
-                        completedFileIndex = receivedFileIndex
-                    )
+                    completedFileCount++
 
-                    sendSaveResult(socketOutput, wasSaved = true)
+                    onFileSaved?.invoke(completedFileCount)
                 }
+                socketOutput.writeBoolean(true)
+                socketOutput.writeInt(completedFileCount)
+                socketOutput.flush()
 
                 finishTransfer(wasSuccessful = true)
             } catch (exception: Exception) {
                 exception.printStackTrace()
 
-                try {
-                    sendSaveResult(socketOutput, wasSaved = false)
-                } catch (_: Exception) {
-                    // The sender may already have closed the socket.
+                runCatching {
+                    socketOutput.writeBoolean(false)
+                    socketOutput.writeInt(completedFileCount)
+                    socketOutput.flush()
                 }
 
                 finishTransfer(wasSuccessful = false)
             }
         }
     }
 
-    @Synchronized
-    private fun markCurrentFileComplete(
-        completedFileIndex: Int
-    ) {
-        if (completedFileIndex != nextExpectedFileIndex) {
-            return
-        }
-
-        nextExpectedFileIndex++
-        onFileSaved?.invoke(nextExpectedFileIndex)
-    }
-
     @Synchronized
     private fun finishTransfer(wasSuccessful: Boolean) {
         val completionCallback = onTransferFinished
 
         waitingForSenderTimeout?.cancel()
         expectedFileOffer = null
-        nextExpectedFileIndex = 0
         onFileSaved = null
         onProgress = null
         onTransferFinished = null
@@ -202,12 +185,4 @@ class AndroidFileTransferReceiver(
             finishTransfer(wasSuccessful = false)
         }
     }
-
-    private fun sendSaveResult(
-        output: DataOutputStream,
-        wasSaved: Boolean
-    ) {
-        output.writeBoolean(wasSaved)
-        output.flush()
-    }
 }

shared/src/androidMain/kotlin/com/liftley/sync360/data/network/tcp/AndroidFileTransferSender.kt

@@ -66,11 +66,20 @@ class AndroidFileTransferSender(
                             fileIndex = fileIndex,
                             file = file,
                             socketOutput = socketOutput,
-                            socketInput = socketInput,
                             buffer = buffer,
                             progressTracker = progressTracker
                         )
                     }
+
+                    // Ensure every remaining buffered byte reaches the receiver.
+                    socketOutput.flush()
+
+                    val receiverSavedTransferSuccessfully = socketInput.readBoolean()
+                    val completedFileCount = socketInput.readInt()
+
+                    check(receiverSavedTransferSuccessfully && completedFileCount == files.size) {
+                        "Receiver saved $completedFileCount of ${files.size} files"
+                    }
                 } finally {
                     activeSocket.compareAndSet(socket, null)
                 }
@@ -89,7 +98,6 @@ class AndroidFileTransferSender(
         fileIndex: Int,
         file: SelectedFile,
         socketOutput: DataOutputStream,
-        socketInput: DataInputStream,
         buffer: ByteArray,
         progressTracker: FileTransferProgressTracker
     ) {
@@ -132,14 +140,6 @@ class AndroidFileTransferSender(
                 bytesRemaining -= bytesRead
                 progressTracker.addBytes(bytesRead)
             }
-
-            socketOutput.flush()
-
-            val receiverSavedFile = socketInput.readBoolean()
-
-            if (!receiverSavedFile) {
-                error("Receiver could not save ${file.displayName}")
-            }
         }
     }
 
@@ -166,5 +166,4 @@ class AndroidFileTransferSender(
 
         throw lastFailure ?: error("No address is available for ${device.deviceName}")
     }
-
 }