feat(nvim): implement auto-spawning headless instance and interactive preemption

nvim-core/src/headless.rs

@@ -0,0 +1,42 @@
+use std::sync::Arc;
+use std::sync::LazyLock;
+
+pub static ACTIVE_SOCKET: LazyLock<Arc<std::sync::Mutex<Option<String>>>> =
+    LazyLock::new(|| Arc::new(std::sync::Mutex::new(None)));
+
+pub static HEADLESS_PROC: LazyLock<Arc<std::sync::Mutex<Option<tokio::process::Child>>>> =
+    LazyLock::new(|| Arc::new(std::sync::Mutex::new(None)));
+
+pub async fn spawn_headless_nvim() -> Result<String, String> {
+    if std::process::Command::new("nvim").arg("--version").output().is_err() {
+        return Err("Error: Neovim is not installed or not in PATH. Cannot execute nvim tool. Fallback to basic terminal tools.".to_string());
+    }
+
+    #[cfg(windows)]
+    let socket_name = format!(r"\\.\pipe\agy-headless-nvim-{}", std::process::id());
+    #[cfg(unix)]
+    let socket_name = format!("/tmp/agy-headless-nvim-{}.sock", std::process::id());
+
+    let child = tokio::process::Command::new("nvim")
+        .arg("--headless")
+        .arg("--listen")
+        .arg(&socket_name)
+        .kill_on_drop(true)
+        .spawn()
+        .map_err(|e| format!("Failed to spawn headless Neovim: {}", e))?;
+
+    tokio::time::sleep(tokio::time::Duration::from_millis(1000)).await;
+
+    let mut old_child = {
+        let mut lock = HEADLESS_PROC.lock().unwrap_or_else(|e| e.into_inner());
+        let old = lock.take();
+        *lock = Some(child);
+        old
+    };
+
+    if let Some(mut old) = old_child {
+        let _ = old.kill().await;
+    }
+
+    Ok(socket_name)
+}

nvim-core/src/lib.rs

@@ -1,3 +1,5 @@
+mod headless;
+use headless::*;
 use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
@@ -160,17 +162,55 @@ fn handle_nvim_notification(params: &[rmpv::Value]) {
 }
 
 async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
+    let interactive_socket = get_socket_path().await.ok();
+    let mut should_kill_headless = false;
+
     {
-        let conn_lock = NVIM_CONN.lock().unwrap_or_else(|e| e.into_inner());
-        if let Some(sender) = conn_lock.as_ref()
-            && !sender.is_closed()
-        {
-            return Ok(sender.clone());
+        let mut conn_lock = NVIM_CONN.lock().unwrap_or_else(|e| e.into_inner());
+        if let Some(sender) = conn_lock.as_ref() {
+            if !sender.is_closed() {
+                let current_socket = {
+                    let active_lock = ACTIVE_SOCKET.lock().unwrap_or_else(|e| e.into_inner());
+                    active_lock.clone()
+                };
+
+                if let Some(ref interactive) = interactive_socket {
+                    if Some(interactive.clone()) != current_socket {
+                        tracing::info!("Interactive Preemption: New Neovim instance detected at {}. Disconnecting from current.", interactive);
+                        should_kill_headless = true;
+                        *conn_lock = None;
+                        {
+                            let mut active_lock2 = ACTIVE_SOCKET.lock().unwrap_or_else(|e| e.into_inner());
+                            *active_lock2 = None;
+                        }
+                    } else {
+                        return Ok(sender.clone());
+                    }
+                } else {
+                    return Ok(sender.clone());
+                }
+            }
         }
     }
 
-    tracing::info!("Establishing new persistent connection to Neovim");
-    let socket_path = get_socket_path().await?;
+    if should_kill_headless {
+        let mut child_to_kill = {
+            let mut proc_lock = HEADLESS_PROC.lock().unwrap_or_else(|e| e.into_inner());
+            proc_lock.take()
+        };
+        if let Some(mut child) = child_to_kill {
+            let _ = child.kill().await;
+        }
+    }
+
+    let socket_path = if let Some(p) = interactive_socket {
+        p
+    } else {
+        tracing::info!("No interactive Neovim detected. Spawning headless instance.");
+        spawn_headless_nvim().await?
+    };
+
+    tracing::info!("Establishing new persistent connection to Neovim at {}", socket_path);
 
     #[cfg(windows)]
     let stream = {
@@ -183,11 +223,16 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
     #[cfg(unix)]
     let stream = {
         use tokio::net::UnixStream;
-        UnixStream::connect(socket_path)
+        UnixStream::connect(&socket_path)
             .await
             .map_err(|e| e.to_string())?
     };
 
+    {
+        let mut active_lock = ACTIVE_SOCKET.lock().unwrap_or_else(|e| e.into_inner());
+        *active_lock = Some(socket_path.clone());
+    }
+
     let (mut read_half, mut write_half) = tokio::io::split(stream);
     let (tx, mut rx) = mpsc::channel::<NvimRequest>(32);
     type PendingRequestsMap =