feat(embedding,vision): candle embeddings with offline fallback, on-demand clipboard vision capture, and concurrency audit

stub/src/main.rs

@@ -1,6 +1,5 @@
 use clap::Parser;
 use futures_util::{SinkExt, StreamExt};
-use tokio::sync::mpsc;
 
 #[derive(Parser)]
 #[command(name = "mcp-memory-stub", author, version = env!("APP_VERSION"), about = "Antigravity MCP Memory Stub / Proxy", long_about = None)]
@@ -35,14 +34,14 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let rt = tokio::runtime::Runtime::new()?;
     rt.block_on(async {
         let (msg_tx, msg_rx) = async_channel::bounded::<String>(100);
-        let (shutdown_tx, mut shutdown_rx) = mpsc::channel::<()>(1);
+        let (shutdown_tx, mut shutdown_rx) = tokio::sync::watch::channel(false);
 
         tokio::spawn(async move {
             let mut stdin = tokio::io::BufReader::new(tokio::io::stdin());
             while let Some(msg) = mcp_stdio::read_mcp_message(&mut stdin).await {
                 let _ = msg_tx.send(msg).await;
             }
-            let _ = shutdown_tx.send(()).await;
+            let _ = shutdown_tx.send(true);
         });
 
         let target_url = if cli.target == "http://localhost:3000" {
@@ -58,7 +57,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
         let mut retry_count = 0;
         loop {
-            if shutdown_rx.try_recv().is_ok() {
+            if *shutdown_rx.borrow() {
                 tracing::info!("Stub shutdown requested");
                 break;
             }
@@ -76,7 +75,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             };
 
             let connect_result = tokio::select! {
-                _ = shutdown_rx.recv() => {
+                _ = shutdown_rx.wait_for(|&is_shutdown| is_shutdown) => {
                     tracing::info!("Shutdown received during connect");
                     break;
                 }
@@ -126,11 +125,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                                     if text.len() > 1000 { "..." } else { "" }
                                 );
                                 use tokio::io::AsyncWriteExt;
-                                let mut payload = Vec::with_capacity(text.len() + 1);
-                                payload.extend_from_slice(text.as_bytes());
-                                payload.push(b'\n');
                                 let mut stdout = tokio::io::stdout();
-                                let _ = stdout.write_all(&payload).await;
+                                let _ = stdout.write_all(text.as_bytes()).await;
+                                let _ = stdout.write_all(b"\n").await;
                                 let _ = stdout.flush().await;
                             }
                         }
@@ -138,7 +135,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                     });
 
                     tokio::select! {
-                        _ = shutdown_rx.recv() => {
+                _ = shutdown_rx.wait_for(|&is_shutdown| is_shutdown) => {
                             tracing::info!("Shutdown received while connected");
                             break;
                         }