diff --git a/Cargo.lock b/Cargo.lock
index 8d50945..bb7e87a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -231,7 +231,7 @@ dependencies = [
 
 [[package]]
 name = "codemp"
-version = "0.7.2"
+version = "0.7.3"
 dependencies = [
  "async-trait",
  "codemp-proto",
diff --git a/src/api/controller.rs b/src/api/controller.rs
index 0f19d70..853f1e5 100644
--- a/src/api/controller.rs
+++ b/src/api/controller.rs
@@ -37,7 +37,7 @@ where
 /// See [`Controller`]'s documentation for details.
 ///
 /// Details about the receiving end are left to the implementor.
-pub trait AsyncSender<T : Sized + Send + Sync> : Sized + Send + Sync {
+pub trait AsyncSender<T: Sized + Send + Sync>: Sized + Send + Sync {
 	/// Enqueue a new value to be sent to all other users without blocking
 	fn send(&self, x: T) -> ControllerResult<()>;
 }
diff --git a/src/buffer/controller.rs b/src/buffer/controller.rs
index d52b472..efb5a7d 100644
--- a/src/buffer/controller.rs
+++ b/src/buffer/controller.rs
@@ -22,7 +22,8 @@ pub(crate) struct BufferAck {
 
 impl Acknowledgeable for BufferAck {
 	fn send(&mut self) {
-		self.tx.send(self.version.clone())
+		self.tx
+			.send(self.version.clone())
 			.unwrap_or_warn("no worker to receive sent ack");
 	}
 }
diff --git a/src/buffer/worker.rs b/src/buffer/worker.rs
index ba1a318..01826b8 100644
--- a/src/buffer/worker.rs
+++ b/src/buffer/worker.rs
@@ -75,7 +75,8 @@ impl BufferController {
 			path: path.to_string(),
 			latest_version: latest_version_tx,
 			local_version: my_version_tx,
-			ack_tx, ack_rx,
+			ack_tx,
+			ack_rx,
 			ops_in: opin_rx,
 			poller: poller_rx,
 			pollers: Vec::new(),
@@ -185,7 +186,8 @@ impl BufferWorker {
 			self.latest_version
 				.send(self.oplog.local_version())
 				.unwrap_or_warn("failed to update latest version!");
-			self.local_version.send(self.branch.local_version())
+			self.local_version
+				.send(self.branch.local_version())
 				.unwrap_or_warn("failed to update local version!");
 		}
 	}
@@ -261,10 +263,14 @@ impl BufferWorker {
 					version: step_ver,
 				},
 			};
-			self.local_version.send(new_local_v).unwrap_or_warn("could not update local version");
-			tx.send(Some(delta)).unwrap_or_warn("could not update ops channel -- is controller dead?");
+			self.local_version
+				.send(new_local_v)
+				.unwrap_or_warn("could not update local version");
+			tx.send(Some(delta))
+				.unwrap_or_warn("could not update ops channel -- is controller dead?");
 		} else {
-			tx.send(None).unwrap_or_warn("could not update ops channel -- is controller dead?");
+			tx.send(None)
+				.unwrap_or_warn("could not update ops channel -- is controller dead?");
 		}
 	}
 }
diff --git a/src/cursor/controller.rs b/src/cursor/controller.rs
index bac20cf..63a5483 100644
--- a/src/cursor/controller.rs
+++ b/src/cursor/controller.rs
@@ -42,22 +42,19 @@ impl AsyncSender<Cursor> for CursorController {
 		if cursor.start > cursor.end {
 			std::mem::swap(&mut cursor.start, &mut cursor.end);
 		}
-		Ok(self
-			.0
-			.op
-			.send(CursorPosition {
-				buffer: BufferNode {
-					path: cursor.buffer,
-				},
-				start: RowCol {
-					row: cursor.start.0,
-					col: cursor.start.1,
-				},
-				end: RowCol {
-					row: cursor.end.0,
-					col: cursor.end.1,
-				},
-			})?)
+		Ok(self.0.op.send(CursorPosition {
+			buffer: BufferNode {
+				path: cursor.buffer,
+			},
+			start: RowCol {
+				row: cursor.start.0,
+				col: cursor.start.1,
+			},
+			end: RowCol {
+				row: cursor.end.0,
+				col: cursor.end.1,
+			},
+		})?)
 	}
 }
 
diff --git a/src/ffi/java/buffer.rs b/src/ffi/java/buffer.rs
index 639c187..1a5e2d8 100644
--- a/src/ffi/java/buffer.rs
+++ b/src/ffi/java/buffer.rs
@@ -3,9 +3,11 @@ use jni_toolbox::jni;
 
 use crate::{
 	api::{
+		change::Delta,
 		controller::{AsyncReceiver, AsyncSender},
 		TextChange,
 	},
+	buffer::controller::BufferAck,
 	errors::ControllerError,
 };
 
@@ -27,13 +29,13 @@ fn get_content(controller: &mut crate::buffer::Controller) -> Result<String, Con
 #[jni(package = "mp.code", class = "BufferController")]
 fn try_recv(
 	controller: &mut crate::buffer::Controller,
-) -> Result<Option<TextChange>, ControllerError> {
+) -> Result<Option<Delta<BufferAck>>, ControllerError> {
 	super::tokio().block_on(controller.try_recv())
 }
 
 /// Block until it receives a [TextChange].
 #[jni(package = "mp.code", class = "BufferController")]
-fn recv(controller: &mut crate::buffer::Controller) -> Result<TextChange, ControllerError> {
+fn recv(controller: &mut crate::buffer::Controller) -> Result<Delta<BufferAck>, ControllerError> {
 	super::tokio().block_on(controller.recv())
 }
 
@@ -43,7 +45,7 @@ fn send(
 	controller: &mut crate::buffer::Controller,
 	change: TextChange,
 ) -> Result<(), ControllerError> {
-	super::tokio().block_on(controller.send(change))
+	controller.send(change)
 }
 
 /// Register a callback for buffer changes.
diff --git a/src/ffi/java/cursor.rs b/src/ffi/java/cursor.rs
index 65cb0c4..60f2810 100644
--- a/src/ffi/java/cursor.rs
+++ b/src/ffi/java/cursor.rs
@@ -5,6 +5,10 @@ use crate::{
 	},
 	errors::ControllerError,
 };
+use crate::{
+	api::{Controller, Cursor},
+	errors::ControllerError,
+};
 use jni::{objects::JObject, JNIEnv};
 use jni_toolbox::jni;
 
@@ -25,7 +29,7 @@ fn recv(controller: &mut crate::cursor::Controller) -> Result<Cursor, Controller
 /// Receive from Java, converts and sends a [Cursor].
 #[jni(package = "mp.code", class = "CursorController")]
 fn send(controller: &mut crate::cursor::Controller, cursor: Cursor) -> Result<(), ControllerError> {
-	super::tokio().block_on(controller.send(cursor))
+	controller.send(cursor)
 }
 
 /// Register a callback for cursor changes.
diff --git a/src/ffi/js/buffer.rs b/src/ffi/js/buffer.rs
index df89f06..945b25c 100644
--- a/src/ffi/js/buffer.rs
+++ b/src/ffi/js/buffer.rs
@@ -1,9 +1,14 @@
+use crate::api::change::Delta;
 use crate::api::controller::{AsyncReceiver, AsyncSender};
 use crate::api::TextChange;
 use crate::buffer::controller::BufferController;
 use napi::threadsafe_function::{
 	ErrorStrategy::Fatal, ThreadSafeCallContext, ThreadsafeFunction, ThreadsafeFunctionCallMode,
 };
+use napi::threadsafe_function::{
+	ErrorStrategy::Fatal, ThreadSafeCallContext, ThreadsafeFunction, ThreadsafeFunctionCallMode,
+};
+use napi_derive::napi;
 use napi_derive::napi;
 
 #[napi]
@@ -51,20 +56,20 @@ impl BufferController {
 
 	/// Return next buffer event if present
 	#[napi(js_name = "try_recv")]
-	pub async fn js_try_recv(&self) -> napi::Result<Option<TextChange>> {
+	pub async fn js_try_recv(&self) -> napi::Result<Option<Delta<BufferAck>>> {
 		Ok(self.try_recv().await?)
 	}
 
 	/// Wait for next buffer event and return it
 	#[napi(js_name = "recv")]
-	pub async fn js_recv(&self) -> napi::Result<TextChange> {
+	pub async fn js_recv(&self) -> napi::Result<Delta<BufferAck>> {
 		Ok(self.recv().await?)
 	}
 
 	/// Send a buffer update to workspace
 	#[napi(js_name = "send")]
-	pub async fn js_send(&self, op: TextChange) -> napi::Result<()> {
-		Ok(self.send(op).await?)
+	pub fn js_send(&self, op: TextChange) -> napi::Result<()> {
+		Ok(self.send(op)?)
 	}
 
 	/// Return buffer whole content
diff --git a/src/ffi/js/cursor.rs b/src/ffi/js/cursor.rs
index 2bb09e5..f7fbf4f 100644
--- a/src/ffi/js/cursor.rs
+++ b/src/ffi/js/cursor.rs
@@ -1,9 +1,14 @@
 use crate::api::controller::{AsyncReceiver, AsyncSender};
 use crate::cursor::controller::CursorController;
 use napi::threadsafe_function::ErrorStrategy::Fatal;
+use napi::threadsafe_function::ErrorStrategy::Fatal;
 use napi::threadsafe_function::{
 	ThreadSafeCallContext, ThreadsafeFunction, ThreadsafeFunctionCallMode,
 };
+use napi::threadsafe_function::{
+	ThreadSafeCallContext, ThreadsafeFunction, ThreadsafeFunctionCallMode,
+};
+use napi_derive::napi;
 use napi_derive::napi;
 
 #[napi(object, js_name = "Cursor")]
@@ -74,8 +79,8 @@ impl CursorController {
 
 	/// Send a new cursor event to remote
 	#[napi(js_name = "send")]
-	pub async fn js_send(&self, pos: JsCursor) -> napi::Result<()> {
-		Ok(self.send(crate::api::Cursor::from(pos)).await?)
+	pub fn js_send(&self, pos: JsCursor) -> napi::Result<()> {
+		Ok(self.send(crate::api::Cursor::from(pos))?)
 	}
 
 	/// Get next cursor event if available without blocking
diff --git a/src/ffi/js/workspace.rs b/src/ffi/js/workspace.rs
index e44fe81..294dd98 100644
--- a/src/ffi/js/workspace.rs
+++ b/src/ffi/js/workspace.rs
@@ -8,8 +8,6 @@ use napi::threadsafe_function::{
 };
 use napi_derive::napi;
 
-use super::client::JsUser;
-
 #[napi(object, js_name = "Event")]
 pub struct JsEvent {
 	pub r#type: String,
diff --git a/src/ffi/lua/buffer.rs b/src/ffi/lua/buffer.rs
index 76c89cd..2a46dc6 100644
--- a/src/ffi/lua/buffer.rs
+++ b/src/ffi/lua/buffer.rs
@@ -11,10 +11,10 @@ impl LuaUserData for CodempBufferController {
 			Ok(format!("{:?}", this))
 		});
 
-		methods.add_method(
-			"send",
-			|_, this, (change,): (CodempTextChange,)| a_sync! { this => this.send(change).await? },
-		);
+		methods.add_method("send", |_, this, (change,): (CodempTextChange,)| {
+			this.send(change)?;
+			Ok(())
+		});
 
 		methods.add_method(
 			"try_recv",
diff --git a/src/ffi/lua/cursor.rs b/src/ffi/lua/cursor.rs
index 3deea7c..2e93fc8 100644
--- a/src/ffi/lua/cursor.rs
+++ b/src/ffi/lua/cursor.rs
@@ -12,10 +12,10 @@ impl LuaUserData for CodempCursorController {
 			Ok(format!("{:?}", this))
 		});
 
-		methods.add_method(
-			"send",
-			|_, this, (cursor,): (CodempCursor,)| a_sync! { this => this.send(cursor).await? },
-		);
+		methods.add_method("send", |_, this, (cursor,): (CodempCursor,)| {
+			this.send(cursor)?;
+			Ok(())
+		});
 		methods.add_method(
 			"try_recv",
 			|_, this, ()| a_sync! { this => this.try_recv().await? },
diff --git a/src/ffi/python/controllers.rs b/src/ffi/python/controllers.rs
index 6ee1e27..5b0381c 100644
--- a/src/ffi/python/controllers.rs
+++ b/src/ffi/python/controllers.rs
@@ -15,11 +15,11 @@ impl CursorController {
 	#[pyo3(name = "send")]
 	fn pysend(
 		&self,
-		py: Python,
+		_py: Python,
 		path: String,
 		start: (i32, i32),
 		end: (i32, i32),
-	) -> PyResult<Promise> {
+	) -> PyResult<()> {
 		let pos = Cursor {
 			start,
 			end,
@@ -27,7 +27,8 @@ impl CursorController {
 			user: None,
 		};
 		let this = self.clone();
-		a_sync_allow_threads!(py, this.send(pos).await)
+		this.send(pos)?;
+		Ok(())
 	}
 
 	#[pyo3(name = "try_recv")]
@@ -84,7 +85,7 @@ impl BufferController {
 	}
 
 	#[pyo3(name = "send")]
-	fn pysend(&self, py: Python, start: u32, end: u32, txt: String) -> PyResult<Promise> {
+	fn pysend(&self, _py: Python, start: u32, end: u32, txt: String) -> PyResult<()> {
 		let op = TextChange {
 			start,
 			end,
@@ -92,7 +93,8 @@ impl BufferController {
 			hash: None,
 		};
 		let this = self.clone();
-		a_sync_allow_threads!(py, this.send(op).await)
+		this.send(op)?;
+		Ok(())
 	}
 
 	#[pyo3(name = "try_recv")]