fix: MCP sees live sessions — wrap DashMap in Arc for shared state

DashMap::clone() deep-copies all entries into a new map. The MCP
server's cloned SshService/SftpService/RdpService/ScrollbackRegistry
were snapshots from startup that never saw new sessions.

Fix: wrap all DashMap fields in Arc<DashMap<...>> so clones share
the same underlying map. Sessions added after MCP startup are now
visible to MCP tools.

Affected: SshService, SftpService, RdpService, ScrollbackRegistry.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/mcp/mod.rs

@@ -19,12 +19,12 @@ use crate::mcp::scrollback::ScrollbackBuffer;
 /// Shared between SSH/PTY output loops (writers) and MCP tools (readers).
 #[derive(Clone)]
 pub struct ScrollbackRegistry {
-    buffers: DashMap<String, Arc<ScrollbackBuffer>>,
+    buffers: Arc<DashMap<String, Arc<ScrollbackBuffer>>>,
 }
 
 impl ScrollbackRegistry {
     pub fn new() -> Self {
-        Self { buffers: DashMap::new() }
+        Self { buffers: Arc::new(DashMap::new()) }
     }
 
     /// Create and register a new scrollback buffer for a session.

src-tauri/src/rdp/mod.rs

@@ -76,13 +76,13 @@ struct RdpSessionHandle {
 }
 
 pub struct RdpService {
-    sessions: DashMap<String, Arc<RdpSessionHandle>>,
+    sessions: Arc<DashMap<String, Arc<RdpSessionHandle>>>,
 }
 
 impl RdpService {
     pub fn new() -> Self {
         Self {
-            sessions: DashMap::new(),
+            sessions: Arc::new(DashMap::new()),
         }
     }
 

src-tauri/src/sftp/mod.rs

@@ -99,13 +99,13 @@ pub struct SftpService {
     /// One `SftpSession` per SSH session, behind a mutex so async commands can
     /// take a shared reference to the `SftpService` and still mutably borrow
     /// individual sessions.
-    clients: DashMap<String, Arc<TokioMutex<SftpSession>>>,
+    clients: Arc<DashMap<String, Arc<TokioMutex<SftpSession>>>>,
 }
 
 impl SftpService {
     pub fn new() -> Self {
         Self {
-            clients: DashMap::new(),
+            clients: Arc::new(DashMap::new()),
         }
     }
 

src-tauri/src/ssh/session.rs

@@ -76,13 +76,13 @@ impl client::Handler for SshClient {
 
 #[derive(Clone)]
 pub struct SshService {
-    sessions: DashMap<String, Arc<SshSession>>,
+    sessions: Arc<DashMap<String, Arc<SshSession>>>,
     db: Database,
 }
 
 impl SshService {
     pub fn new(db: Database) -> Self {
-        Self { sessions: DashMap::new(), db }
+        Self { sessions: Arc::new(DashMap::new()), db }
     }
 
     pub async fn connect(&self, app_handle: AppHandle, hostname: &str, port: u16, username: &str, auth: AuthMethod, cols: u32, rows: u32, sftp_service: &SftpService, scrollback: &ScrollbackRegistry, error_watcher: &ErrorWatcher) -> Result<String, String> {