diff --git a/examples/golang/codex.go b/examples/golang/codex.go
index 19a44357..5c04a9f1 100644
--- a/examples/golang/codex.go
+++ b/examples/golang/codex.go
@@ -124,6 +124,10 @@ package main
 		return codex_upload_file(codexCtx, sessionId, (CodexCallback) callback, resp);
 	}
 
+	static int cGoCodexUploadSubscribe(void* codexCtx, char* sessionId, void* resp) {
+		return codex_upload_subscribe(codexCtx, sessionId, (CodexCallback) callback, resp);
+	}
+
 	static int cGoCodexStart(void* codexCtx, void* resp) {
 		return codex_start(codexCtx, (CodexCallback) callback, resp);
 	}
@@ -255,10 +259,12 @@ type CodexNode struct {
 
 const defaultBlockSize = 1024 * 64
 
+type OnProgressFunc func(read, total int, percent float64)
+
 type CodexUploadOptions struct {
 	filepath   string
 	chunkSize  int
-	onProgress func(read, total int, percent float64)
+	onProgress OnProgressFunc
 }
 
 type bridgeCtx struct {
@@ -273,22 +279,25 @@ type bridgeCtx struct {
 }
 
 func newBridgeCtx() *bridgeCtx {
-	var wg sync.WaitGroup
-	wg.Add(1)
+	bridge := &bridgeCtx{}
+	bridge.wg = &sync.WaitGroup{}
+	bridge.wg.Add(1)
 
-	bridge := &bridgeCtx{wg: &wg}
 	bridge.h = cgo.NewHandle(bridge)
 	bridge.resp = C.allocResp(C.uintptr_t(uintptr(bridge.h)))
-
 	return bridge
 }
 
 func (b *bridgeCtx) free() {
-	b.h.Delete()
-	b.h = 0
+	if b.h > 0 {
+		b.h.Delete()
+		b.h = 0
+	}
 
-	C.freeResp(b.resp)
-	b.resp = nil
+	if b.resp != nil {
+		C.freeResp(b.resp)
+		b.resp = nil
+	}
 }
 
 func (b *bridgeCtx) CallError(name string) error {
@@ -298,7 +307,12 @@ func (b *bridgeCtx) CallError(name string) error {
 func (b *bridgeCtx) wait() (string, error) {
 	b.wg.Wait()
 
-	return b.result, b.err
+	result := b.result
+	err := b.err
+
+	b.free()
+
+	return result, err
 }
 
 func getReaderSize(r io.Reader) int64 {
@@ -327,16 +341,6 @@ func callback(ret C.int, msg *C.char, len C.size_t, resp unsafe.Pointer) {
 	m.msg = msg
 	m.len = len
 
-	if ret == C.RET_PROGRESS {
-		if m.h != 0 {
-			h := cgo.Handle(m.h)
-			if v, ok := h.Value().(*bridgeCtx); ok && v.onProgress != nil {
-				v.onProgress(int(len))
-			}
-		}
-		return
-	}
-
 	if m.h == 0 {
 		return
 	}
@@ -348,15 +352,22 @@ func callback(ret C.int, msg *C.char, len C.size_t, resp unsafe.Pointer) {
 	}
 
 	if v, ok := h.Value().(*bridgeCtx); ok {
-		if ret == C.RET_OK || ret == C.RET_ERR {
-			retMsg := C.GoStringN(msg, C.int(len))
-
-			if ret == C.RET_OK {
-				v.result = retMsg
-				v.err = nil
-			} else {
-				v.err = errors.New(retMsg)
+		switch ret {
+		case C.RET_PROGRESS:
+			if v.onProgress != nil {
+				v.onProgress(int(C.int(len)))
 			}
+		case C.RET_OK:
+			retMsg := C.GoStringN(msg, C.int(len))
+			v.result = retMsg
+			v.err = nil
+
+			if v.wg != nil {
+				v.wg.Done()
+			}
+		case C.RET_ERR:
+			retMsg := C.GoStringN(msg, C.int(len))
+			v.err = errors.New(retMsg)
 
 			if v.wg != nil {
 				v.wg.Done()
@@ -367,7 +378,6 @@ func callback(ret C.int, msg *C.char, len C.size_t, resp unsafe.Pointer) {
 
 func CodexNew(config CodexConfig) (*CodexNode, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	jsonConfig, err := json.Marshal(config)
 	if err != nil {
@@ -386,9 +396,8 @@ func CodexNew(config CodexConfig) (*CodexNode, error) {
 	return &CodexNode{ctx: ctx}, bridge.err
 }
 
-func (self *CodexNode) CodexVersion() (string, error) {
+func (self CodexNode) CodexVersion() (string, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	if C.cGoCodexVersion(self.ctx, bridge.resp) != C.RET_OK {
 		return "", bridge.CallError("cGoCodexVersion")
@@ -397,9 +406,8 @@ func (self *CodexNode) CodexVersion() (string, error) {
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexRevision() (string, error) {
+func (self CodexNode) CodexRevision() (string, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	if C.cGoCodexRevision(self.ctx, bridge.resp) != C.RET_OK {
 		return "", bridge.CallError("cGoCodexRevision")
@@ -408,9 +416,8 @@ func (self *CodexNode) CodexRevision() (string, error) {
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexRepo() (string, error) {
+func (self CodexNode) CodexRepo() (string, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	if C.cGoCodexRepo(self.ctx, bridge.resp) != C.RET_OK {
 		return "", bridge.CallError("cGoCodexRepo")
@@ -419,11 +426,10 @@ func (self *CodexNode) CodexRepo() (string, error) {
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexDebug() (CodexDebugInfo, error) {
+func (self CodexNode) CodexDebug() (CodexDebugInfo, error) {
 	var info CodexDebugInfo
 
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	if C.cGoCodexDebug(self.ctx, bridge.resp) != C.RET_OK {
 		return info, bridge.CallError("cGoCodexDebug")
@@ -439,9 +445,8 @@ func (self *CodexNode) CodexDebug() (CodexDebugInfo, error) {
 	return info, err
 }
 
-func (self *CodexNode) CodexSpr() (string, error) {
+func (self CodexNode) CodexSpr() (string, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	if C.cGoCodexSpr(self.ctx, bridge.resp) != C.RET_OK {
 		return "", bridge.CallError("cGoCodexSpr")
@@ -450,9 +455,8 @@ func (self *CodexNode) CodexSpr() (string, error) {
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexPeerId() (string, error) {
+func (self CodexNode) CodexPeerId() (string, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	if C.cGoCodexPeerId(self.ctx, bridge.resp) != C.RET_OK {
 		return "", bridge.CallError("cGoCodexPeerId")
@@ -461,9 +465,8 @@ func (self *CodexNode) CodexPeerId() (string, error) {
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexLogLevel(logLevel LogLevel) error {
+func (self CodexNode) CodexLogLevel(logLevel LogLevel) error {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	var cLogLevel = C.CString(fmt.Sprintf("%s", logLevel))
 	defer C.free(unsafe.Pointer(cLogLevel))
@@ -476,9 +479,8 @@ func (self *CodexNode) CodexLogLevel(logLevel LogLevel) error {
 	return err
 }
 
-func (self *CodexNode) CodexConnect(peerId string, peerAddresses []string) error {
+func (self CodexNode) CodexConnect(peerId string, peerAddresses []string) error {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	var cPeerId = C.CString(peerId)
 	defer C.free(unsafe.Pointer(cPeerId))
@@ -503,11 +505,10 @@ func (self *CodexNode) CodexConnect(peerId string, peerAddresses []string) error
 	return err
 }
 
-func (self *CodexNode) CodexPeerDebug(peerId string) (RestPeerRecord, error) {
+func (self CodexNode) CodexPeerDebug(peerId string) (RestPeerRecord, error) {
 	var record RestPeerRecord
 
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	var cPeerId = C.CString(peerId)
 	defer C.free(unsafe.Pointer(cPeerId))
@@ -526,21 +527,8 @@ func (self *CodexNode) CodexPeerDebug(peerId string) (RestPeerRecord, error) {
 	return record, err
 }
 
-func (self *CodexNode) CodexUploadInit(options *CodexUploadOptions) (string, error) {
+func (self CodexNode) CodexUploadInit(options *CodexUploadOptions) (string, error) {
 	bridge := newBridgeCtx()
-	totalRead := 0
-
-	bridge.onProgress = func(bytes int) {
-		if bytes == -1 {
-			bridge.free()
-		} else {
-			totalRead += bytes
-
-			if options.onProgress != nil {
-				options.onProgress(bytes, totalRead, 0)
-			}
-		}
-	}
 
 	var cFilename = C.CString(options.filepath)
 	defer C.free(unsafe.Pointer(cFilename))
@@ -558,9 +546,8 @@ func (self *CodexNode) CodexUploadInit(options *CodexUploadOptions) (string, err
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexUploadChunk(sessionId string, chunk []byte) error {
+func (self CodexNode) CodexUploadChunk(sessionId string, chunk []byte) error {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	var cSessionId = C.CString(sessionId)
 	defer C.free(unsafe.Pointer(cSessionId))
@@ -578,9 +565,8 @@ func (self *CodexNode) CodexUploadChunk(sessionId string, chunk []byte) error {
 	return err
 }
 
-func (self *CodexNode) CodexUploadFinalize(sessionId string) (string, error) {
+func (self CodexNode) CodexUploadFinalize(sessionId string) (string, error) {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	var cSessionId = C.CString(sessionId)
 	defer C.free(unsafe.Pointer(cSessionId))
@@ -592,9 +578,8 @@ func (self *CodexNode) CodexUploadFinalize(sessionId string) (string, error) {
 	return bridge.wait()
 }
 
-func (self *CodexNode) CodexUploadCancel(sessionId string) error {
+func (self CodexNode) CodexUploadCancel(sessionId string) error {
 	bridge := newBridgeCtx()
-	defer bridge.free()
 
 	var cSessionId = C.CString(sessionId)
 	defer C.free(unsafe.Pointer(cSessionId))
@@ -607,28 +592,46 @@ func (self *CodexNode) CodexUploadCancel(sessionId string) error {
 	return err
 }
 
-func (self *CodexNode) CodexUploadReader(options CodexUploadOptions, r io.Reader) (string, error) {
+func (self CodexNode) CodexUploadReader(options CodexUploadOptions, r io.Reader) (string, error) {
+	sessionId, err := self.CodexUploadInit(&options)
+	if err != nil {
+		return "", err
+	}
+
 	if options.onProgress != nil {
 		size := getReaderSize(r)
+		total := 0
 
 		if size > 0 {
-			fn := options.onProgress
+			onProgress := func(read int) {
+				if read == 0 {
+					return
+				}
+
+				total += read
 
-			options.onProgress = func(read, total int, _ float64) {
 				percent := float64(total) / float64(size) * 100.0
 				// The last block could be a bit over the size due to padding
 				// on the chunk size.
 				if percent > 100.0 {
 					percent = 100.0
 				}
-				fn(read, total, percent)
+
+				options.onProgress(read, int(size), percent)
+			}
+
+			if err := self.CodexUploadSubscribe(sessionId, onProgress); err != nil {
+				if err := self.CodexUploadCancel(sessionId); err != nil {
+					log.Println("Error cancelling upload after subscribe failure:", err)
+				}
+
+				return "", err
 			}
 		}
 	}
 
-	sessionId, err := self.CodexUploadInit(&options)
-	if err != nil {
-		return "", err
+	if options.chunkSize == 0 {
+		options.chunkSize = defaultBlockSize
 	}
 
 	buf := make([]byte, options.chunkSize)
@@ -649,19 +652,25 @@ func (self *CodexNode) CodexUploadReader(options CodexUploadOptions, r io.Reader
 
 			return "", err
 		}
+
+		if n == 0 {
+			break
+		}
 	}
 
 	return self.CodexUploadFinalize(sessionId)
 }
 
-func (self *CodexNode) CodexUploadReaderAsync(options CodexUploadOptions, r io.Reader, onDone func(cid string, err error)) {
+func (self CodexNode) CodexUploadReaderAsync(options CodexUploadOptions, r io.Reader, onDone func(cid string, err error)) {
 	go func() {
 		cid, err := self.CodexUploadReader(options, r)
 		onDone(cid, err)
 	}()
 }
 
-func (self *CodexNode) CodexUploadFile(options CodexUploadOptions) (string, error) {
+func (self CodexNode) CodexUploadFile(options CodexUploadOptions) (string, error) {
+	bridge := newBridgeCtx()
+
 	if options.onProgress != nil {
 		stat, err := os.Stat(options.filepath)
 		if err != nil {
@@ -669,24 +678,28 @@ func (self *CodexNode) CodexUploadFile(options CodexUploadOptions) (string, erro
 		}
 
 		size := stat.Size()
-		if size > 0 {
-			fn := options.onProgress
+		total := 0
+
+		if size > 0 {
+			bridge.onProgress = func(read int) {
+				if read == 0 {
+					return
+				}
+
+				total += read
 
-			options.onProgress = func(read, total int, _ float64) {
 				percent := float64(total) / float64(size) * 100.0
 				// The last block could be a bit over the size due to padding
 				// on the chunk size.
 				if percent > 100.0 {
 					percent = 100.0
 				}
-				fn(read, total, percent)
+
+				options.onProgress(read, int(size), percent)
 			}
 		}
 	}
 
-	bridge := newBridgeCtx()
-	defer bridge.free()
-
 	var cFilePath = C.CString(options.filepath)
 	defer C.free(unsafe.Pointer(cFilePath))
 
@@ -702,18 +715,40 @@ func (self *CodexNode) CodexUploadFile(options CodexUploadOptions) (string, erro
 		return "", bridge.CallError("cGoCodexUploadFile")
 	}
 
-	cid, err := bridge.wait()
-	return cid, err
+	return bridge.wait()
 }
 
-func (self *CodexNode) CodexUploadFileAsync(options CodexUploadOptions, onDone func(cid string, err error)) {
+func (self CodexNode) CodexUploadFileAsync(options CodexUploadOptions, onDone func(cid string, err error)) {
 	go func() {
 		cid, err := self.CodexUploadFile(options)
 		onDone(cid, err)
 	}()
 }
 
-func (self *CodexNode) CodexStart() error {
+func (self CodexNode) CodexUploadSubscribe(sessionId string, onProgress func(read int)) error {
+	bridge := newBridgeCtx()
+
+	bridge.onProgress = onProgress
+
+	var cSessionId = C.CString(sessionId)
+	defer C.free(unsafe.Pointer(cSessionId))
+
+	log.Println("Subscribing to upload progress...")
+
+	if C.cGoCodexUploadSubscribe(self.ctx, cSessionId, bridge.resp) != C.RET_OK {
+		return bridge.CallError("cGoCodexUploadSubscribe")
+	}
+
+	go func() {
+		if _, err := bridge.wait(); err != nil {
+			log.Println("Error in CodexUploadSubscribe:", err)
+		}
+	}()
+
+	return nil
+}
+
+func (self CodexNode) CodexStart() error {
 	bridge := newBridgeCtx()
 	defer bridge.free()
 
@@ -725,14 +760,14 @@ func (self *CodexNode) CodexStart() error {
 	return err
 }
 
-func (self *CodexNode) CodexStartAsync(onDone func(error)) {
+func (self CodexNode) CodexStartAsync(onDone func(error)) {
 	go func() {
 		err := self.CodexStart()
 		onDone(err)
 	}()
 }
 
-func (self *CodexNode) CodexStop() error {
+func (self CodexNode) CodexStop() error {
 	bridge := newBridgeCtx()
 	defer bridge.free()
 
@@ -744,7 +779,7 @@ func (self *CodexNode) CodexStop() error {
 	return err
 }
 
-func (self *CodexNode) CodexDestroy() error {
+func (self CodexNode) CodexDestroy() error {
 	bridge := newBridgeCtx()
 	defer bridge.free()
 
@@ -764,11 +799,11 @@ func globalEventCallback(callerRet C.int, msg *C.char, len C.size_t, userData un
 	self.MyEventCallback(callerRet, msg, len)
 }
 
-func (self *CodexNode) MyEventCallback(callerRet C.int, msg *C.char, len C.size_t) {
+func (self CodexNode) MyEventCallback(callerRet C.int, msg *C.char, len C.size_t) {
 	log.Println("Event received:", C.GoStringN(msg, C.int(len)))
 }
 
-func (self *CodexNode) CodexSetEventCallback() {
+func (self CodexNode) CodexSetEventCallback() {
 	// Notice that the events for self node are handled by the 'MyEventCallback' method
 	C.cGoCodexSetEventCallback(self.ctx)
 }
@@ -853,7 +888,6 @@ func main() {
 	if err != nil {
 		log.Fatal("Error happened:", err.Error())
 	}
-
 	log.Println("Codex Upload Init sessionId:", sessionId)
 
 	err = node.CodexUploadChunk(sessionId, []byte("Hello "))
@@ -874,7 +908,9 @@ func main() {
 	log.Println("Codex Upload Finalized, cid:", cid)
 
 	buf := bytes.NewBuffer([]byte("Hello World!"))
-	cid, err = node.CodexUploadReader(CodexUploadOptions{filepath: "hello.txt"}, buf)
+	cid, err = node.CodexUploadReader(CodexUploadOptions{filepath: "hello.txt", onProgress: func(read, total int, percent float64) {
+		log.Printf("Uploaded %d bytes, total %d bytes (%.2f%%)\n", read, total, percent)
+	}}, buf)
 	if err != nil {
 		log.Fatal("Error happened:", err.Error())
 	}
@@ -888,10 +924,12 @@ func main() {
 
 	// Choose a big file to see the progress logs
 	filepath := path.Join(current, "examples", "golang", "hello.txt")
-	// filepath := path.Join(current, "examples", "golang", "discord-0.0.109.deb")
+	//filepath := path.Join(current, "examples", "golang", "discord-0.0.109.deb")
+
 	options := CodexUploadOptions{filepath: filepath, onProgress: func(read, total int, percent float64) {
 		log.Printf("Uploaded %d bytes, total %d bytes (%.2f%%)\n", read, total, percent)
 	}}
+
 	cid, err = node.CodexUploadFile(options)
 
 	if err != nil {
diff --git a/library/codex_context.nim b/library/codex_context.nim
index fb69aad5..e983cd52 100644
--- a/library/codex_context.nim
+++ b/library/codex_context.nim
@@ -18,6 +18,9 @@ import ./codex_thread_requests/[codex_thread_request]
 
 from ../codex/codex import CodexServer
 
+logScope:
+  topics = "codexlib"
+
 type CodexContext* = object
   thread: Thread[(ptr CodexContext)]
 
diff --git a/library/codex_thread_requests/requests/node_debug_request.nim b/library/codex_thread_requests/requests/node_debug_request.nim
index 855db904..2f492505 100644
--- a/library/codex_thread_requests/requests/node_debug_request.nim
+++ b/library/codex_thread_requests/requests/node_debug_request.nim
@@ -16,6 +16,9 @@ import ../../../codex/node
 
 from ../../../codex/codex import CodexServer, node
 
+logScope:
+  topics = "codexlib codexlibdebug"
+
 type NodeDebugMsgType* = enum
   DEBUG
   PEER
diff --git a/library/codex_thread_requests/requests/node_info_request.nim b/library/codex_thread_requests/requests/node_info_request.nim
index 37a3499a..167a3094 100644
--- a/library/codex_thread_requests/requests/node_info_request.nim
+++ b/library/codex_thread_requests/requests/node_info_request.nim
@@ -11,6 +11,9 @@ import ../../../codex/node
 
 from ../../../codex/codex import CodexServer, config, node
 
+logScope:
+  topics = "codexlib codexlibinfo"
+
 type NodeInfoMsgType* = enum
   REPO
   SPR
diff --git a/library/codex_thread_requests/requests/node_lifecycle_request.nim b/library/codex_thread_requests/requests/node_lifecycle_request.nim
index d5431867..c6d06f48 100644
--- a/library/codex_thread_requests/requests/node_lifecycle_request.nim
+++ b/library/codex_thread_requests/requests/node_lifecycle_request.nim
@@ -24,6 +24,9 @@ import ../../../codex/units
 
 from ../../../codex/codex import CodexServer, new, start, stop
 
+logScope:
+  topics = "codexlib codexliblifecycle"
+
 type NodeLifecycleMsgType* = enum
   CREATE_NODE
   START_NODE
diff --git a/library/codex_thread_requests/requests/node_p2p_request.nim b/library/codex_thread_requests/requests/node_p2p_request.nim
index 3b840702..46790070 100644
--- a/library/codex_thread_requests/requests/node_p2p_request.nim
+++ b/library/codex_thread_requests/requests/node_p2p_request.nim
@@ -12,6 +12,9 @@ import ../../../codex/node
 
 from ../../../codex/codex import CodexServer, node
 
+logScope:
+  topics = "codexlib codexlibp2p"
+
 type NodeP2PMsgType* = enum
   CONNECT
 
diff --git a/library/codex_thread_requests/requests/node_upload_request.nim b/library/codex_thread_requests/requests/node_upload_request.nim
index e7b2a64a..b83d6aeb 100644
--- a/library/codex_thread_requests/requests/node_upload_request.nim
+++ b/library/codex_thread_requests/requests/node_upload_request.nim
@@ -10,6 +10,7 @@
 ##  - CHUNK: sends a chunk of data to the upload session.
 ##  - FINALIZE: finalizes the upload and returns the CID of the uploaded file.
 ##  - CANCEL: cancels the upload session.
+##  - SUBSCRIBE: subscribes to progress updates for the upload session.
 ##
 ## 2. Directly from a file path: the filepath has to be absolute.
 ##  - INIT: creates a new upload session and returns its ID
@@ -32,12 +33,16 @@ from ../../../codex/codex import CodexServer, node
 from ../../../codex/node import store
 from libp2p import Cid
 
+logScope:
+  topics = "codexlib codexlibupload"
+
 type NodeUploadMsgType* = enum
   INIT
   CHUNK
   FINALIZE
   CANCEL
   FILE
+  SUBSCRIBE
 
 type OnProgressHandler =
   proc(bytes: int): Future[void] {.gcsafe, async: (raises: [CancelledError]).}
@@ -57,6 +62,8 @@ type
     stream: BufferStream
     fut: Future[?!Cid]
     filepath: string
+    chunkSize: int
+    onProgress: OnProgressHandler
 
 var uploadSessions {.threadvar.}: Table[UploadSessionId, UploadSession]
 var nexUploadSessionCount {.threadvar.}: UploadSessionCount
@@ -85,10 +92,7 @@ proc destroyShared(self: ptr NodeUploadRequest) =
   deallocShared(self)
 
 proc init(
-    codex: ptr CodexServer,
-    filepath: cstring = "",
-    chunkSize: csize_t = 0,
-    onProgress: OnProgressHandler,
+    codex: ptr CodexServer, filepath: cstring = "", chunkSize: csize_t = 0
 ): Future[Result[string, string]] {.async: (raises: []).} =
   ## Init a new session upload and return its ID.
   ## The session contains the future corresponding to the
@@ -100,18 +104,19 @@ proc init(
   ##
   ## The chunkSize matches by default the block size used to store the file.
   ##
-  ## An onProgress handler can be provided to get upload progress.
-  ## The handler is called with the size of the block stored in the node
-  ## when a new block is put in the node.
-  ## After the `node.store` future is completed, whether successfully or not,
-  ## the onProgress handler is called with -1 to signal the end of the upload.
-  ## This allows to clean up the cGo states.
+  ## When a session contains an onProgress handler, it is called
+  ## with the number of bytes received each time a block is stored thanks to
+  ## `onBlockStore` callback.
+  ## After the `node.store` future is done, the onProgress handler
+  ## is called one last time with 0 bytes to signal the end of the upload.
 
   var filenameOpt, mimetypeOpt = string.none
 
   if isAbsolute($filepath):
     if not fileExists($filepath):
-      return err("File does not exist")
+      return err(
+        "Failed to create an upload session, the filepath does not exist: " & $filepath
+      )
 
   if filepath != "":
     let (_, name, ext) = splitFile($filepath)
@@ -139,20 +144,32 @@ proc init(
   let onBlockStore = proc(
       chunk: seq[byte]
   ): Future[void] {.gcsafe, async: (raises: [CancelledError]).} =
-    discard onProgress(chunk.len)
+    try:
+      let session = uploadSessions[$sessionId]
+      if session.onProgress != nil:
+        await session.onProgress(chunk.len)
+    except KeyError:
+      error "Failed to push progress update, session is not found: ",
+        sessionId = $sessionId
 
   let blockSize =
     if chunkSize.NBytes > 0.NBytes: chunkSize.NBytes else: DefaultBlockSize
   let fut = node.store(lpStream, filenameOpt, mimetypeOpt, blockSize, onBlockStore)
 
   proc cb(_: pointer) {.raises: [].} =
-    # Signal end of upload
-    discard onProgress(-1)
+    try:
+      let session = uploadSessions[$sessionId]
+      if session.onProgress != nil:
+        discard session.onProgress(0)
+    except KeyError:
+      error "Failed to push the progress final state, session is not found.",
+        sessionId = $sessionId
 
   fut.addCallback(cb)
 
-  uploadSessions[sessionId] =
-    UploadSession(stream: stream, fut: fut, filepath: $filepath)
+  uploadSessions[sessionId] = UploadSession(
+    stream: stream, fut: fut, filepath: $filepath, chunkSize: blockSize.int
+  )
 
   return ok(sessionId)
 
@@ -163,17 +180,17 @@ proc chunk(
   ## The chunk is pushed to the BufferStream of the session.
 
   if not uploadSessions.contains($sessionId):
-    return err("Invalid session ID")
+    return err("Failed to upload the chunk, the session is not found: " & $sessionId)
 
   try:
     let session = uploadSessions[$sessionId]
     await session.stream.pushData(chunk)
   except KeyError as e:
-    return err("Invalid session ID")
+    return err("Failed to upload the chunk, the session is not found: " & $sessionId)
   except LPError as e:
-    return err("Stream error: " & $e.msg)
+    return err("Failed to upload the chunk, stream error: " & $e.msg)
   except CancelledError as e:
-    return err("Operation cancelled")
+    return err("Failed to upload the chunk, operation cancelled.")
 
   return ok("")
 
@@ -189,7 +206,8 @@ proc finalize(
   ## case of errors).
 
   if not uploadSessions.contains($sessionId):
-    return err("Invalid session ID")
+    return
+      err("Failed to finalize the upload session, session not found: " & $sessionId)
 
   var session: UploadSession
   try:
@@ -198,17 +216,18 @@ proc finalize(
 
     let res = await session.fut
     if res.isErr:
-      return err("Upload failed: " & res.error().msg)
+      return err("Failed to finalize the upload session: " & res.error().msg)
 
     return ok($res.get())
   except KeyError as e:
-    return err("Invalid session ID")
+    return
+      err("Failed to finalize the upload session, invalid session ID: " & $sessionId)
   except LPStreamError as e:
-    return err("Stream error: " & $e.msg)
+    return err("Failed to finalize the upload session, stream error: " & $e.msg)
   except CancelledError as e:
-    return err("Operation cancelled")
+    return err("Failed to finalize the upload session, operation cancelled")
   except CatchableError as e:
-    return err("Upload failed: " & $e.msg)
+    return err("Failed to finalize the upload session: " & $e.msg)
   finally:
     if uploadSessions.contains($sessionId):
       uploadSessions.del($sessionId)
@@ -224,20 +243,20 @@ proc cancel(
   ## from the table.
 
   if not uploadSessions.contains($sessionId):
-    return err("Invalid session ID")
+    return err("Failed to cancel the upload session, session not found: " & $sessionId)
 
   try:
     let session = uploadSessions[$sessionId]
     session.fut.cancelSoon()
   except KeyError as e:
-    return err("Invalid session ID")
+    return err("Failed to cancel the upload session, invalid session ID: " & $sessionId)
 
   uploadSessions.del($sessionId)
 
   return ok("")
 
 proc streamFile(
-    filepath: string, stream: BufferStream
+    filepath: string, stream: BufferStream, chunkSize: int
 ): Future[Result[void, string]] {.async: (raises: [CancelledError]).} =
   ## Streams a file from the given filepath using faststream.
   ## fsMultiSync cannot be used with chronos because of this warning:
@@ -252,43 +271,54 @@ proc streamFile(
     let inputStreamHandle = filePath.fileInput()
     let inputStream = inputStreamHandle.implicitDeref
 
+    var buf = newSeq[byte](chunkSize)
     while inputStream.readable:
-      let byt = inputStream.read
-      await stream.pushData(@[byt])
+      let read = inputStream.readIntoEx(buf)
+      if read == 0:
+        break
+      await stream.pushData(buf[0 ..< read])
+      # let byt = inputStream.read
+      # await stream.pushData(@[byt])
     return ok()
   except IOError, OSError, LPStreamError:
     let e = getCurrentException()
-    return err("Stream error: " & $e.msg)
+    return err("Failed to stream the file: " & $e.msg)
 
 proc file(
-    codex: ptr CodexServer, sessionId: cstring
+    codex: ptr CodexServer, sessionId: cstring, onProgress: OnProgressHandler
 ): Future[Result[string, string]] {.raises: [], async: (raises: []).} =
   ## Starts the file upload for the session identified by sessionId.
   ## Will call finalize when done and return the CID of the uploaded file.
   ## In the finally block, the cleanup section removes the session
   ## from the table and cancels the future if it is not complete (in
   ## case of errors).
+  ##
+  ## If `onProgress` is provided, it is called with the number of bytes
+  ## received each time a block is stored thanks to `onBlockStore` callback.
+
   if not uploadSessions.contains($sessionId):
-    return err("Invalid session ID")
+    return err("Failed to upload the file, invalid session ID: " & $sessionId)
 
   var session: UploadSession
 
   try:
     session = uploadSessions[$sessionId]
-    let res = await streamFile(session.filepath, session.stream)
+    if onProgress != nil:
+      uploadSessions[$sessionId].onProgress = onProgress
+    let res = await streamFile(session.filepath, session.stream, session.chunkSize)
     if res.isErr:
-      return err("Failed to stream file: " & res.error)
+      return err("Failed to upload the file: " & res.error)
 
     return await codex.finalize(sessionId)
   except KeyError as e:
-    return err("Invalid session ID")
+    return err("Failed to upload the file, the session is not found: " & $sessionId)
   except LPStreamError, IOError:
     let e = getCurrentException()
-    return err("Stream error: " & $e.msg)
+    return err("Failed to upload the file: " & $e.msg)
   except CancelledError as e:
-    return err("Operation cancelled")
+    return err("Failed to upload the file, the operation is cancelled.")
   except CatchableError as e:
-    return err("Upload failed: " & $e.msg)
+    return err("Failed to upload the file: " & $e.msg)
   finally:
     if uploadSessions.contains($sessionId):
       uploadSessions.del($sessionId)
@@ -296,6 +326,46 @@ proc file(
     if session.fut != nil and not session.fut.finished():
       session.fut.cancelSoon()
 
+proc subscribe(
+    codex: ptr CodexServer, sessionId: cstring, onProgress: OnProgressHandler
+): Future[Result[string, string]] {.raises: [], async: (raises: []).} =
+  ## Subscribes to progress updates for the upload session identified by sessionId.
+  ## The onProgress handler is called with the number of bytes received
+  ## each time a block is stored thanks to `onBlockStore` callback.
+
+  if not uploadSessions.contains($sessionId):
+    return err(
+      "Failed to subscribe to the upload session, invalid session ID: " & $sessionId
+    )
+
+  let fut = newFuture[void]()
+
+  proc onBlockReceived(bytes: int): Future[void] {.async: (raises: [CancelledError]).} =
+    try:
+      let session = uploadSessions[$sessionId]
+      await onProgress(bytes)
+
+      if bytes == 0:
+        fut.complete()
+    except KeyError:
+      fut.cancelSoon()
+      error "Failed to push progress update, session is not found: ",
+        sessionId = $sessionId
+
+  try:
+    uploadSessions[$sessionId].onProgress = onBlockReceived
+  except KeyError:
+    return err(
+      "Failed to subscribe to the upload session, session is not found: " & $sessionId
+    )
+
+  try:
+    await fut
+  except CatchableError as e:
+    return err("Failed to subscribe to the upload session: " & $e.msg)
+
+  return ok("")
+
 proc process*(
     self: ptr NodeUploadRequest, codex: ptr CodexServer
 ): Future[Result[string, string]] {.async: (raises: []).} =
@@ -304,7 +374,7 @@ proc process*(
 
   case self.operation
   of NodeUploadMsgType.INIT:
-    let res = (await init(codex, self.filepath, self.chunkSize, self.onProgress))
+    let res = (await init(codex, self.filepath, self.chunkSize))
     if res.isErr:
       error "INIT failed", error = res.error
       return err($res.error)
@@ -328,10 +398,16 @@ proc process*(
       return err($res.error)
     return res
   of NodeUploadMsgType.FILE:
-    let res = (await file(codex, self.sessionId))
+    let res = (await file(codex, self.sessionId, self.onProgress))
     if res.isErr:
       error "FILE failed", error = res.error
       return err($res.error)
     return res
+  of NodeUploadMsgType.SUBSCRIBE:
+    let res = (await subscribe(codex, self.sessionId, self.onProgress))
+    if res.isErr:
+      error "SUBSCRIBE failed", error = res.error
+      return err($res.error)
+    return res
 
   return ok("")
diff --git a/library/libcodex.h b/library/libcodex.h
index cd0d2fae..8523e86a 100644
--- a/library/libcodex.h
+++ b/library/libcodex.h
@@ -115,6 +115,12 @@ int codex_upload_file(
                 CodexCallback callback,
                 void* userData);
 
+int codex_upload_subscribe(
+                void* ctx,
+                const char* sessionId,
+                CodexCallback callback,
+                void* userData);
+
 int codex_start(void* ctx,
                CodexCallback callback,
                void* userData);
diff --git a/library/libcodex.nim b/library/libcodex.nim
index 3c3f3efe..b537707e 100644
--- a/library/libcodex.nim
+++ b/library/libcodex.nim
@@ -38,6 +38,9 @@ import ./ffi_types
 
 from ../codex/conf import codexVersion, updateLogLevel
 
+logScope:
+  topics = "codexlib"
+
 template checkLibcodexParams*(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ) =
@@ -76,10 +79,6 @@ proc initializeLibrary() {.exported.} =
     locals = addr(locals)
     nimGC_setStackBottom(locals)
 
-template init(ctx, callback, userData) =
-  initializeLibrary()
-  checkLibcodexParams(ctx, callback, userData)
-
 proc codex_new(
     configJson: cstring, callback: CodexCallback, userData: pointer
 ): pointer {.dynlib, exported.} =
@@ -111,7 +110,8 @@ proc codex_new(
 proc codex_version(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   callback(
     RET_OK,
@@ -125,7 +125,8 @@ proc codex_version(
 proc codex_revision(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   callback(
     RET_OK,
@@ -139,7 +140,8 @@ proc codex_revision(
 proc codex_repo(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent = NodeInfoRequest.createShared(NodeInfoMsgType.REPO)
   let res = codex_context.sendRequestToCodexThread(
@@ -151,7 +153,8 @@ proc codex_repo(
 proc codex_debug(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent = NodeDebugRequest.createShared(NodeDebugMsgType.DEBUG)
   let res = codex_context.sendRequestToCodexThread(
@@ -163,7 +166,8 @@ proc codex_debug(
 proc codex_spr(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent = NodeInfoRequest.createShared(NodeInfoMsgType.SPR)
   let res = codex_context.sendRequestToCodexThread(
@@ -175,7 +179,8 @@ proc codex_spr(
 proc codex_peer_id(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent = NodeInfoRequest.createShared(NodeInfoMsgType.PEERID)
   let res = codex_context.sendRequestToCodexThread(
@@ -190,7 +195,8 @@ proc codex_peer_id(
 proc codex_log_level(
     ctx: ptr CodexContext, logLevel: cstring, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   try:
     updateLogLevel($logLevel)
@@ -207,7 +213,8 @@ proc codex_connect(
     callback: CodexCallback,
     userData: pointer,
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   var peerAddresses = newSeq[cstring](peerAddressesLength)
   let peers = cast[ptr UncheckedArray[cstring]](peerAddressesPtr)
@@ -226,7 +233,8 @@ proc codex_connect(
 proc codex_peer_debug(
     ctx: ptr CodexContext, peerId: cstring, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent = NodeDebugRequest.createShared(NodeDebugMsgType.PEER, peerId = peerId)
   let res = codex_context.sendRequestToCodexThread(
@@ -238,7 +246,8 @@ proc codex_peer_debug(
 proc codex_destroy(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let res = codex_context.destroyCodexContext(ctx)
   if res.isErr:
@@ -253,19 +262,13 @@ proc codex_upload_init(
     callback: CodexCallback,
     userData: pointer,
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
-
-  let onProgress = proc(
-      bytes: int
-  ): Future[void] {.gcsafe, async: (raises: [CancelledError]).} =
-    callback(RET_PROGRESS, nil, bytes.csize_t, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent = NodeUploadRequest.createShared(
-    NodeUploadMsgType.INIT,
-    filepath = filepath,
-    chunkSize = chunkSize,
-    onProgress = onProgress,
+    NodeUploadMsgType.INIT, filepath = filepath, chunkSize = chunkSize
   )
+
   let res = codex_context.sendRequestToCodexThread(
     ctx, RequestType.UPLOAD, reqContent, callback, userData
   )
@@ -280,7 +283,8 @@ proc codex_upload_chunk(
     callback: CodexCallback,
     userData: pointer,
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let chunk = newSeq[byte](len)
   copyMem(addr chunk[0], data, len)
@@ -300,7 +304,8 @@ proc codex_upload_finalize(
     callback: CodexCallback,
     userData: pointer,
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent =
     NodeUploadRequest.createShared(NodeUploadMsgType.FINALIZE, sessionId = sessionId)
@@ -316,7 +321,8 @@ proc codex_upload_cancel(
     callback: CodexCallback,
     userData: pointer,
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent =
     NodeUploadRequest.createShared(NodeUploadMsgType.CANCEL, sessionId = sessionId)
@@ -333,10 +339,43 @@ proc codex_upload_file(
     callback: CodexCallback,
     userData: pointer,
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
-  let reqContent =
-    NodeUploadRequest.createShared(NodeUploadMsgType.FILE, sessionId = sessionId)
+  let onProgress = proc(
+      bytes: int
+  ): Future[void] {.async: (raises: [CancelledError]).} =
+    if userData != nil:
+      callback(RET_PROGRESS, nil, cast[csize_t](bytes), userData)
+
+  let reqContent = NodeUploadRequest.createShared(
+    NodeUploadMsgType.FILE, sessionId = sessionId, onProgress = onProgress
+  )
+
+  let res = codex_context.sendRequestToCodexThread(
+    ctx, RequestType.UPLOAD, reqContent, callback, userData
+  )
+
+  return callback.okOrError(res, userData)
+
+proc codex_upload_subscribe(
+    ctx: ptr CodexContext,
+    sessionId: cstring,
+    callback: CodexCallback,
+    userData: pointer,
+): cint {.dynlib, exportc.} =
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
+
+  let onProgress = proc(
+      bytes: int
+  ): Future[void] {.async: (raises: [CancelledError]).} =
+    if userData != nil:
+      callback(RET_PROGRESS, nil, cast[csize_t](bytes), userData)
+
+  let reqContent = NodeUploadRequest.createShared(
+    NodeUploadMsgType.SUBSCRIBE, sessionId = sessionId, onProgress = onProgress
+  )
 
   let res = codex_context.sendRequestToCodexThread(
     ctx, RequestType.UPLOAD, reqContent, callback, userData
@@ -347,7 +386,8 @@ proc codex_upload_file(
 proc codex_start(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent: ptr NodeLifecycleRequest =
     NodeLifecycleRequest.createShared(NodeLifecycleMsgType.START_NODE)
@@ -360,7 +400,8 @@ proc codex_start(
 proc codex_stop(
     ctx: ptr CodexContext, callback: CodexCallback, userData: pointer
 ): cint {.dynlib, exportc.} =
-  init(ctx, callback, userData)
+  initializeLibrary()
+  checkLibcodexParams(ctx, callback, userData)
 
   let reqContent: ptr NodeLifecycleRequest =
     NodeLifecycleRequest.createShared(NodeLifecycleMsgType.STOP_NODE)