feat(nvim-core): implement bidirectional event streaming and real-time shadow buffer

- Created global thread-safe NvimState to shadow Neovim context.
- Injected Lua autocmds (CursorMoved, TextChanged) on connection to stream events back to MCP.
- Upgraded msgpack RPC loop to intercept and parse 'mcp_event' notifications alongside standard responses.
- Optimized nvim_get_cursor to pull instantly from the local shadow buffer, bypassing RPC round-trips.

Cargo.lock

@@ -497,6 +497,20 @@ dependencies = [
  "syn 3.0.6",
 ]
 
+[[package]]
+name = "dashmap"
+version = "6.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6361d5c062261c78a176addb82d4c821ae42bed6089de0e12603cd25de2059c"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+ "hashbrown 0.14.5",
+ "lock_api",
+ "once_cell",
+ "parking_lot_core",
+]
+
 [[package]]
 name = "data-encoding"
 version = "2.11.1"
@@ -807,6 +821,12 @@ dependencies = [
  "rand_core 0.10.1",
 ]
 
+[[package]]
+name = "hashbrown"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
+
 [[package]]
 name = "hashbrown"
 version = "0.16.1"
@@ -1375,6 +1395,8 @@ dependencies = [
 name = "nvim-core"
 version = "0.1.0"
 dependencies = [
+ "bytes",
+ "dashmap",
  "dirs",
  "mcp-stdio",
  "rmcp",

nvim-core/src/lib.rs

@@ -129,6 +129,36 @@ static NEXT_MSGID: AtomicU64 = AtomicU64::new(1);
 static NVIM_CONN: LazyLock<Arc<std::sync::Mutex<Option<mpsc::Sender<NvimRequest>>>>> =
     LazyLock::new(|| Arc::new(std::sync::Mutex::new(None)));
 
+#[derive(Debug, Default, Clone)]
+pub struct NvimState {
+    pub cursor: String,
+    pub active_buffer_id: u64,
+}
+
+static NVIM_STATE: LazyLock<Arc<std::sync::Mutex<NvimState>>> =
+    LazyLock::new(|| Arc::new(std::sync::Mutex::new(NvimState::default())));
+
+fn handle_nvim_notification(params: &[rmpv::Value]) {
+    if params.is_empty() { return; }
+    if let rmpv::Value::String(event) = &params[0] {
+        match event.as_str().unwrap_or("") {
+            "CursorMoved" => {
+                if params.len() > 1
+                    && let rmpv::Value::Array(pos) = &params[1]
+                        && pos.len() >= 4
+                            && let (rmpv::Value::Integer(row), rmpv::Value::Integer(col)) = (&pos[1], &pos[2]) {
+                                let mut state = NVIM_STATE.lock().unwrap_or_else(|e| e.into_inner());
+                                state.cursor = format!("Line: {}, Column: {}", row, col);
+                            }
+            },
+            "TextChanged" => {
+                tracing::debug!("Shadow buffer text changed event received");
+            }
+            _ => {}
+        }
+    }
+}
+
 async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
     {
         let conn_lock = NVIM_CONN.lock().unwrap_or_else(|e| e.into_inner());
@@ -196,18 +226,21 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
                     let parsed_len = cursor.position() as usize;
                     resp_buf.advance(parsed_len);
 
-                    if let rmpv::Value::Array(ref arr) = val
-                        && arr.len() >= 4
-                        && arr[0] == rmpv::Value::Integer(1.into())
-                    {
-                        let msgid = match &arr[1] {
-                            rmpv::Value::Integer(i) => i.as_u64().unwrap_or(0),
-                            _ => 0,
-                        };
-
-                        if let Some((_, reply_sender)) = pending_clone2.remove(&msgid) {
-                            let _ = reply_sender.send(Ok(val));
-                        }
+                    if let rmpv::Value::Array(ref arr) = val {
+                        if arr.len() >= 4 && arr[0] == rmpv::Value::Integer(1.into()) {
+                            let msgid = match &arr[1] {
+                                rmpv::Value::Integer(i) => i.as_u64().unwrap_or(0),
+                                _ => 0,
+                            };
+                            if let Some((_, reply_sender)) = pending_clone2.remove(&msgid) {
+                                let _ = reply_sender.send(Ok(val));
+                            }
+                        } else if arr.len() >= 3 && arr[0] == rmpv::Value::Integer(2.into())
+                            && let rmpv::Value::String(method) = &arr[1]
+                                && method.as_str().unwrap_or("") == "mcp_event"
+                                    && let rmpv::Value::Array(params) = &arr[2] {
+                                        handle_nvim_notification(params);
+                                    }
                     }
                     continue;
                 }
@@ -272,6 +305,45 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
         return Ok(existing_sender.clone());
     }
     *conn_lock = Some(tx.clone());
+    drop(conn_lock);
+
+    let tx_clone = tx.clone();
+    tokio::spawn(async move {
+        let setup_code = r#"
+            local channel = vim.api.nvim_get_api_info()[1]
+            vim.api.nvim_create_augroup("MCP_Tracking", { clear = true })
+            vim.api.nvim_create_autocmd({"CursorMoved", "CursorMovedI"}, {
+                group = "MCP_Tracking",
+                callback = function()
+                    pcall(vim.rpcnotify, channel, "mcp_event", "CursorMoved", vim.fn.getpos('.'))
+                end
+            })
+            vim.api.nvim_create_autocmd({"TextChanged", "TextChangedI", "BufEnter"}, {
+                group = "MCP_Tracking",
+                callback = function()
+                    pcall(vim.rpcnotify, channel, "mcp_event", "TextChanged", vim.api.nvim_get_current_buf())
+                end
+            })
+        "#;
+        let msgid = NEXT_MSGID.fetch_add(1, Ordering::SeqCst);
+        let req = rmpv::Value::Array(vec![
+            rmpv::Value::Integer(0.into()),
+            rmpv::Value::Integer(msgid.into()),
+            rmpv::Value::String("nvim_exec_lua".into()),
+            rmpv::Value::Array(vec![
+                rmpv::Value::String(setup_code.into()),
+                rmpv::Value::Array(vec![]),
+            ]),
+        ]);
+        let (reply_tx, _reply_rx) = tokio::sync::oneshot::channel();
+        let _ = tx_clone.send(NvimRequest {
+            msgid,
+            req,
+            reply: reply_tx,
+        }).await;
+        tracing::info!("Injected bidirectional event tracking autocmds into Neovim");
+    });
+
     Ok(tx)
 }
 
@@ -363,6 +435,13 @@ async fn get_nvim_active_buffer() -> Result<String, String> {
 }
 
 async fn get_nvim_cursor() -> Result<String, String> {
+    {
+        let state = NVIM_STATE.lock().unwrap_or_else(|e| e.into_inner());
+        if !state.cursor.is_empty() {
+            return Ok(state.cursor.clone());
+        }
+    }
+
     let result =
         call_nvim_method("nvim_win_get_cursor", vec![rmpv::Value::Integer(0.into())]).await?;