fix: WebSSH terminal disconnect after connect + stale pool retry

- Fix shell creation failure on stale pooled SSH connections:
  force-close and retry with fresh connection
- Fix empty error message in logs: use {type(e).__name__}: {e!r}
- Fix double WebSocket.close() causing RuntimeError in finally block:
  track ws_closed flag to avoid closing twice
- Fix Alpine undefined error in terminal.html: $d() now returns
  default object when Alpine hasn't initialized yet
- All websocket.close() calls now wrapped in try/except

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

server/api/webssh.py

@@ -156,22 +156,56 @@ async def terminal_ws(
 
     logger.info(f"WebSSH: admin={admin.username} connecting to server={server.name} ({server.domain})")
 
-    # ── Establish SSH connection ──
+    # ── Establish SSH connection (with stale-connection retry) ──
+    conn = None
     try:
         conn = await ssh_pool.acquire(server)
     except Exception as e:
         logger.error(f"WebSSH connection failed: {e}")
-        await websocket.send_json({"type": MSG_ERROR, "message": f"SSH连接失败: {str(e)}"})
-        await websocket.close(code=4003, reason="SSH connection failed")
+        try:
+            await websocket.send_json({"type": MSG_ERROR, "message": f"SSH连接失败: {str(e)}"})
+        except Exception:
+            pass
+        try:
+            await websocket.close(code=4003, reason="SSH connection failed")
+        except Exception:
+            pass
         await _close_ssh_session(session_id)
         return
 
-    # ── Create SSH shell ──
+    # ── Create SSH shell (retry once if stale pooled connection) ──
+    ws_closed = False  # Track whether we've closed the WebSocket
     try:
-        async with conn.create_process(
-            term_type="xterm-256color",
-            term_size=(24, 80),
-        ) as shell:
+        try:
+            shell_proc = conn.create_process(
+                term_type="xterm-256color",
+                term_size=(24, 80),
+            )
+        except Exception as e:
+            # Stale pooled connection — force-close and retry with fresh connection
+            logger.warning(f"WebSSH shell creation failed on pooled connection (server={server.id}): {type(e).__name__}: {e!r}")
+            await ssh_pool.close_connection(server.id)
+            try:
+                conn = await ssh_pool.acquire(server)
+                shell_proc = conn.create_process(
+                    term_type="xterm-256color",
+                    term_size=(24, 80),
+                )
+            except Exception as e2:
+                logger.error(f"WebSSH shell creation failed on fresh connection (server={server.id}): {type(e2).__name__}: {e2!r}")
+                try:
+                    await websocket.send_json({"type": MSG_ERROR, "message": f"Shell创建失败: {type(e2).__name__}"})
+                except Exception:
+                    pass
+                try:
+                    await websocket.close(code=4003, reason="Shell creation failed")
+                except Exception:
+                    pass
+                ws_closed = True
+                await _close_ssh_session(session_id)
+                return
+
+        async with shell_proc as shell:
             # Send TERMINAL_INIT to client
             await websocket.send_json({
                 "type": MSG_TERMINAL_INIT,
@@ -267,25 +301,27 @@ async def terminal_ws(
                 logger.warning(f"WebSSH relay error: {e}")
 
     except Exception as e:
-        logger.error(f"WebSSH shell creation failed: {e}")
-        try:
-            await websocket.send_json({"type": MSG_ERROR, "message": f"Shell创建失败: {str(e)}"})
-        except Exception:
-            pass
+        logger.error(f"WebSSH shell creation failed: {type(e).__name__}: {e!r}")
+        if not ws_closed:
+            try:
+                await websocket.send_json({"type": MSG_ERROR, "message": f"Shell创建失败: {type(e).__name__}"})
+            except Exception:
+                pass
     finally:
         # ── Cleanup ──
         await ssh_pool.release(server.id)
         await _close_ssh_session(session_id)
 
-        try:
-            await websocket.send_json({"type": MSG_CLOSE, "session_id": session_id})
-        except Exception:
-            pass
+        if not ws_closed:
+            try:
+                await websocket.send_json({"type": MSG_CLOSE, "session_id": session_id})
+            except Exception:
+                pass
 
-        try:
-            await websocket.close()
-        except Exception:
-            pass
+            try:
+                await websocket.close()
+            except Exception:
+                pass
 
         logger.info(f"WebSSH session closed: admin={admin.username}, server={server.name}, session={session_id}")