fix: harden dashboard auth and terminal flows

Tighten terminal websocket auth and proxy trust handling while making file-backed auth/RBAC writes atomic to reduce high-impact security and persistence risks.

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

dashboard/backend/auth.py

@@ -1,6 +1,8 @@
 from datetime import datetime, timedelta, timezone
 from typing import Optional
 import time
+import threading
+import tempfile
 import jwt
 from passlib.context import CryptContext
 import pyotp
@@ -78,6 +80,30 @@ import base64
 import hashlib
 from cryptography.fernet import Fernet
 
+_auth_lock = threading.RLock()
+
+
+def _atomic_json_write(path: str, data: dict):
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    fd, temp_path = tempfile.mkstemp(dir=os.path.dirname(path), prefix=".tmp-auth-", suffix=".json")
+    try:
+        with os.fdopen(fd, "w") as f:
+            json.dump(data, f)
+            f.flush()
+            os.fsync(f.fileno())
+        os.replace(temp_path, path)
+    finally:
+        if os.path.exists(temp_path):
+            os.unlink(temp_path)
+
+
+def _update_auth_data(mutator):
+    with _auth_lock:
+        data = _load_auth_data()
+        result = mutator(data)
+        _atomic_json_write(AUTH_FILE, data)
+        return result
+
 def _get_fernet():
     from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
     from cryptography.hazmat.primitives import hashes
@@ -108,6 +134,7 @@ def _decrypt(ciphertext: str) -> str:
         return ciphertext  # fallback for unencrypted legacy values
 
 def _load_auth_data():
+    with _auth_lock:
         try:
             if os.path.exists(AUTH_FILE):
                 with open(AUTH_FILE, "r") as f:
@@ -117,9 +144,7 @@ def _load_auth_data():
         return {}
 
 def _save_auth_data(data):
-    os.makedirs(os.path.dirname(AUTH_FILE), exist_ok=True)
-    with open(AUTH_FILE, "w") as f:
-        json.dump(data, f)
+    _atomic_json_write(AUTH_FILE, data)
 
 def load_totp_secret():
     encrypted = _load_auth_data().get("totp_secret", "")
@@ -128,17 +153,17 @@ def load_totp_secret():
     return _decrypt(encrypted)
 
 def save_totp_secret(secret: str):
-    data = _load_auth_data()
+    def mutator(data):
         data["totp_secret"] = _encrypt(secret) if secret else ""
-    _save_auth_data(data)
+    _update_auth_data(mutator)
 
 def load_password_hash():
     return _load_auth_data().get("password_hash", "") or config.ADMIN_PASSWORD_HASH
 
 def save_password_hash(hashed: str):
-    data = _load_auth_data()
+    def mutator(data):
         data["password_hash"] = hashed
-    _save_auth_data(data)
+    _update_auth_data(mutator)
         
 def verify_totp(token: str, secret: str = None):
     if secret is None:
@@ -148,41 +173,42 @@ def verify_totp(token: str, secret: str = None):
     totp = pyotp.TOTP(secret)
     if not totp.verify(token):
         return False
-    # Replay protection: reject reuse within same 30s window
+
+    def mutator(data):
         current_ts = int(time.time()) // 30
-    data = _load_auth_data()
         if data.get("last_totp_ts") == current_ts:
             return False
         data["last_totp_ts"] = current_ts
-    _save_auth_data(data)
         return True
 
+    return _update_auth_data(mutator)
+
 # Passkey credentials
 def load_passkey_credentials():
     return _load_auth_data().get("passkey_credentials", [])
 
 def save_passkey_credential(cred):
-    data = _load_auth_data()
+    def mutator(data):
         creds = data.get("passkey_credentials", [])
         creds.append(cred)
         data["passkey_credentials"] = creds
-    _save_auth_data(data)
+    _update_auth_data(mutator)
 
 def clear_passkey_credentials():
-    data = _load_auth_data()
+    def mutator(data):
         data["passkey_credentials"] = []
-    _save_auth_data(data)
+    _update_auth_data(mutator)
 
 # Token version for refresh token rotation
 def _load_token_version() -> int:
     return _load_auth_data().get("token_version", 0)
 
 def increment_token_version() -> int:
-    data = _load_auth_data()
+    def mutator(data):
         v = data.get("token_version", 0) + 1
         data["token_version"] = v
-    _save_auth_data(data)
         return v
+    return _update_auth_data(mutator)
 
 def verify_token_version(tv: int) -> bool:
     return tv == _load_token_version()

dashboard/backend/config.py

@@ -1,4 +1,6 @@
 import os
+import ipaddress
+from fastapi import Request
 # Dashboard v1.3 — Runner DNS fix applied
 
 GITEA_URL = os.environ.get("GITEA_URL", "http://gitea:3000")
@@ -63,43 +65,59 @@ OPENCLAW_GATEWAY_TOKEN = os.environ.get("OPENCLAW_GATEWAY_TOKEN", "")
 
 # Networking configs
 LAN_IP_RANGES = os.environ.get("LAN_IP_RANGES", "192.168.31.0/24").split(",")
+TRUSTED_PROXIES = os.environ.get("TRUSTED_PROXIES", "127.0.0.1,::1,172.21.0.1").split(",")
+
+
+def _parse_ip(ip_str: str):
+    try:
+        return ipaddress.ip_address((ip_str or "").strip())
+    except ValueError:
+        return None
+
+
+def _ip_matches_ranges(ip_str: str, ranges: list[str]) -> bool:
+    ip_obj = _parse_ip(ip_str)
+    if ip_obj is None:
+        return False
+
+    for subnet_str in ranges:
+        subnet_str = subnet_str.strip()
+        if not subnet_str:
+            continue
+        try:
+            if "/" in subnet_str:
+                if ip_obj in ipaddress.ip_network(subnet_str, strict=False):
+                    return True
+            elif ip_obj == ipaddress.ip_address(subnet_str):
+                return True
+        except ValueError:
+            continue
+    return False
+
 
 def is_lan_ip(ip_str: str) -> bool:
     """Check if IP is in local LAN (not Tailscale)"""
-    import ipaddress
-    try:
-        ip_obj = ipaddress.ip_address(ip_str)
-        for subnet_str in LAN_IP_RANGES:
-            if ip_obj in ipaddress.ip_network(subnet_str.strip()):
-                return True
-        return False
-    except ValueError:
-        return False
+    return _ip_matches_ranges(ip_str, LAN_IP_RANGES)
+
 
 def is_tailscale_ip(ip_str: str) -> bool:
     """Check if IP is in Tailscale CGNAT range (100.64.0.0/10)"""
-    import ipaddress
-    try:
-        ip_obj = ipaddress.ip_address(ip_str)
-        return ip_obj in ipaddress.ip_network("100.64.0.0/10")
-    except ValueError:
-        return False
+    return _ip_matches_ranges(ip_str, ["100.64.0.0/10"])
 
-TRUSTED_PROXIES = os.environ.get("TRUSTED_PROXIES", "127.0.0.1,::1,172.16.0.0/12").split(",")
 
 def is_trusted_proxy(ip_str: str) -> bool:
-    import ipaddress
-    try:
-        ip_obj = ipaddress.ip_address(ip_str)
-        for subnet_str in TRUSTED_PROXIES:
-            subnet_str = subnet_str.strip()
-            if "/" in subnet_str:
-                if ip_obj in ipaddress.ip_network(subnet_str):
-                    return True
-            else:
-                if ip_obj == ipaddress.ip_address(subnet_str):
-                    return True
-        return False
-    except ValueError:
-        return False
+    return _ip_matches_ranges(ip_str, TRUSTED_PROXIES)
 
+
+def get_forwarded_client_ip(request: Request) -> str | None:
+    source_ip = request.client.host if request.client else ""
+    if not is_trusted_proxy(source_ip):
+        return None
+
+    forwarded_for = request.headers.get("x-forwarded-for", "")
+    forwarded_ip = forwarded_for.split(",", 1)[0].strip()
+    return forwarded_ip or None
+
+
+def get_client_ip(request: Request) -> str:
+    return get_forwarded_client_ip(request) or (request.client.host if request.client else "")

dashboard/backend/main.py

@@ -8,6 +8,7 @@ from slowapi.util import get_remote_address
 from slowapi.errors import RateLimitExceeded
 from routers import docker_router, gitea, files, terminal, system, auth, chat_summary, security, passkey, totp, litellm, cc_connect, info_engine
 import auth as auth_module
+import config
 from rbac import require_page, require_write
 
 import asyncio
@@ -16,7 +17,7 @@ import logging
 import time
 import jwt
 from datetime import datetime, timezone, timedelta
-from config import TELEGRAM_BOT_TOKEN, TELEGRAM_CHAT_ID, CORS_ORIGINS, SECRET_KEY, ALGORITHM, VOLUME_ROOT
+from config import TELEGRAM_BOT_TOKEN, TELEGRAM_CHAT_ID, CORS_ORIGINS, SECRET_KEY, ALGORITHM, VOLUME_ROOT, get_client_ip
 
 _tz_cst = timezone(timedelta(hours=8))
 
@@ -70,19 +71,11 @@ async def audit_log(request: Request, call_next):
     start = time.time()
     response = await call_next(request)
     duration = int((time.time() - start) * 1000)
-    user = "-"
-    try:
-        auth_header = request.headers.get("authorization", "")
-        if auth_header.startswith("Bearer "):
-            payload = jwt.decode(auth_header[7:], SECRET_KEY, algorithms=[ALGORITHM])
-            user = payload.get("sub", "-")
-    except jwt.PyJWTError:
-        user = "Invalid/Malformed Token"
-    except Exception:
-        pass
+    user = getattr(request.state, "user", None)
+    username = user.username if user else "-"
     _audit_logger.info(
         "%s %s %s %s %s %d %dms",
-        datetime.now(_tz_cst).strftime("%Y-%m-%dT%H:%M:%S"), request.client.host, user,
+        datetime.now(_tz_cst).strftime("%Y-%m-%dT%H:%M:%S"), get_client_ip(request), username,
         request.method, request.url.path, response.status_code, duration,
     )
     return response
@@ -128,12 +121,7 @@ async def health():
 
 @app.get("/api/client-ip")
 async def client_ip(request: Request):
-    ip = request.client.host
-    import config
-    if config.is_trusted_proxy(ip):
-        forwarded = request.headers.get("x-forwarded-for", "").split(",")[0].strip()
-        if forwarded:
-            ip = forwarded
+    ip = get_client_ip(request)
 
     # LAN detection logic:
     # - True LAN IP (192.168.31.x) → lan=True

dashboard/backend/rbac.py

@@ -1,5 +1,7 @@
 import json
 import os
+import threading
+import tempfile
 from typing import Optional
 from pydantic import BaseModel
 from fastapi import HTTPException, Request, status
@@ -7,6 +9,7 @@ from fastapi import HTTPException, Request, status
 import config
 
 RBAC_FILE = os.path.join(config.VOLUME_ROOT, "docker/nas-dashboard/rbac.json")
+_rbac_lock = threading.RLock()
 
 ROLE_GROUP_MAP = {
     "dashboard_admin": "admin",
@@ -41,10 +44,30 @@ def load_rbac() -> dict:
     return DEFAULT_RBAC.copy()
 
 
-def save_rbac(data: dict):
-    os.makedirs(os.path.dirname(RBAC_FILE), exist_ok=True)
-    with open(RBAC_FILE, "w") as f:
+def _atomic_json_write(path: str, data: dict):
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    fd, temp_path = tempfile.mkstemp(dir=os.path.dirname(path), prefix=".tmp-rbac-", suffix=".json")
+    try:
+        with os.fdopen(fd, "w") as f:
             json.dump(data, f, indent=2)
+            f.flush()
+            os.fsync(f.fileno())
+        os.replace(temp_path, path)
+    finally:
+        if os.path.exists(temp_path):
+            os.unlink(temp_path)
+
+
+def update_rbac(mutator):
+    with _rbac_lock:
+        data = load_rbac()
+        result = mutator(data)
+        _atomic_json_write(RBAC_FILE, data)
+        return result
+
+
+def save_rbac(data: dict):
+    _atomic_json_write(RBAC_FILE, data)
 
 
 def resolve_role(groups: list[str]) -> Optional[str]:
@@ -77,9 +100,9 @@ def get_sidebar_order(username: str) -> dict | None:
 
 
 def save_sidebar_order(username: str, order: dict):
-    rbac = load_rbac()
+    def mutator(rbac):
         rbac.setdefault("user_overrides", {}).setdefault(username, {})["sidebar_order"] = order
-    save_rbac(rbac)
+    update_rbac(mutator)
 
 
 def has_page_access(user: User, page: str) -> bool:

dashboard/backend/routers/auth.py

@@ -102,7 +102,6 @@ async def login(creds: LoginRequest, request: Request):
 async def proxy_auth(request: Request):
     """Auto-login when Authelia has already authenticated the user via forward-auth.
     Caddy sets Remote-User and Remote-Groups headers after successful Authelia verification."""
-    import config
     from rbac import resolve_role
     if not config.is_trusted_proxy(request.client.host):
         logger.warning(f"Rejected proxy auth attempt from unauthorized IP: {request.client.host}")
@@ -195,16 +194,18 @@ async def rbac_config(current_user = Depends(auth.get_current_user)):
 async def rbac_set_override(username: str, request: Request, current_user = Depends(auth.get_current_user)):
     if current_user.role != "admin":
         raise HTTPException(status_code=403, detail="Admin only")
-    from rbac import load_rbac, save_rbac
+    from rbac import update_rbac
     body = await request.json()
     pages = body.get("pages")
     if pages is None:
         raise HTTPException(status_code=400, detail="Missing pages field")
-    rbac = load_rbac()
+
+    def mutator(rbac):
         existing = rbac.setdefault("user_overrides", {}).get(username, {})
         existing["pages"] = pages
         rbac["user_overrides"][username] = existing
-    save_rbac(rbac)
+
+    update_rbac(mutator)
     return {"ok": True}
 
 @router.get("/preferences")
@@ -235,17 +236,19 @@ async def save_preferences(request: Request, current_user = Depends(auth.get_cur
 async def rbac_delete_override(username: str, current_user = Depends(auth.get_current_user)):
     if current_user.role != "admin":
         raise HTTPException(status_code=403, detail="Admin only")
-    from rbac import load_rbac, save_rbac
-    rbac = load_rbac()
+    from rbac import update_rbac
+
+    def mutator(rbac):
         rbac.get("user_overrides", {}).pop(username, None)
-    save_rbac(rbac)
+
+    update_rbac(mutator)
     return {"ok": True}
 
 @router.put("/rbac/roles/{role}")
 async def rbac_update_role(role: str, request: Request, current_user = Depends(auth.get_current_user)):
     if current_user.role != "admin":
         raise HTTPException(status_code=403, detail="Admin only")
-    from rbac import load_rbac, save_rbac
+    from rbac import update_rbac
     body = await request.json()
     pages = body.get("pages")
     sidebar_links = body.get("sidebar_links")
@@ -255,10 +258,12 @@ async def rbac_update_role(role: str, request: Request, current_user = Depends(a
         raise HTTPException(status_code=400, detail="pages must be '*' or a list")
     if sidebar_links is not None and sidebar_links != "*" and not isinstance(sidebar_links, list):
         raise HTTPException(status_code=400, detail="sidebar_links must be '*' or a list")
-    rbac = load_rbac()
+
+    def mutator(rbac):
         role_config = {"pages": pages}
         if sidebar_links is not None:
             role_config["sidebar_links"] = sidebar_links
         rbac.setdefault("role_defaults", {})[role] = role_config
-    save_rbac(rbac)
+
+    update_rbac(mutator)
     return {"ok": True}

dashboard/backend/routers/files.py

@@ -100,13 +100,28 @@ async def upload(path: str, file: UploadFile = File(...)):
 
 
 @router.delete("/delete")
-def delete(path: str):
+def delete(path: str, recursive: bool = False):
     try:
         target = _safe_path(path)
     except ValueError:
         raise HTTPException(status_code=403, detail="Access denied")
+
+    if target == BASE.resolve():
+        raise HTTPException(status_code=403, detail="Cannot delete base root")
+
+    try:
         if target.is_dir():
+            if not recursive:
+                raise HTTPException(status_code=400, detail="Directory deletion requires recursive=true")
             shutil.rmtree(target)
         else:
             target.unlink()
+    except HTTPException:
+        raise
+    except FileNotFoundError:
+        raise HTTPException(status_code=404, detail="Path not found")
+    except PermissionError:
+        raise HTTPException(status_code=403, detail="Permission denied")
+    except OSError as exc:
+        raise HTTPException(status_code=400, detail=str(exc))
     return {"ok": True}

dashboard/backend/routers/system.py

@@ -5,6 +5,7 @@ import platform
 import time
 import httpx
 from fastapi import APIRouter, Query, Request, HTTPException
+import config
 from config import TELEGRAM_BOT_TOKEN, TELEGRAM_CHAT_ID, VOLUME_ROOT, OPENCLAW_GATEWAY_TOKEN
 
 router = APIRouter()
@@ -116,13 +117,11 @@ def _classify(method, path, status, user):
 
 @router.get("/openclaw-token")
 def openclaw_token(request: Request):
-    ip = request.client.host
-    import config
-    if config.is_trusted_proxy(ip):
-        forwarded = request.headers.get("x-forwarded-for", "").split(",")[0].strip()
-        if forwarded:
-            ip = forwarded
-    import config
+    user = request.state.user
+    if user.role != "admin":
+        raise HTTPException(status_code=403, detail="Admin only")
+
+    ip = config.get_client_ip(request)
     if not config.is_lan_ip(ip):
         raise HTTPException(status_code=403, detail="Access denied")
     return {"token": OPENCLAW_GATEWAY_TOKEN}

dashboard/backend/routers/terminal.py

@@ -1,16 +1,18 @@
 import asyncio
 import struct
 import logging
-import time
-from fastapi import WebSocket, WebSocketDisconnect, Query
+from collections import Counter
+from fastapi import WebSocket, Query
 import asyncssh
-import jwt
 import config
+from auth import get_current_user_ws
 
 logger = logging.getLogger(__name__)
 
 MAX_SESSIONS = 5
-_active_sessions: set = set()
+MAX_SESSIONS_PER_USER = 2
+_session_lock = asyncio.Lock()
+_active_sessions: dict[int, str] = {}
 
 HOSTS = {
     "nas": {"host": config.SSH_HOST, "user": config.SSH_USER, "key": config.SSH_KEY_PATH},
@@ -31,43 +33,57 @@ except Exception:
     logger.error("SSH known_hosts file not found at %s — terminal connections will be refused", config.SSH_KNOWN_HOSTS)
 
 
-async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
-    await websocket.accept()
+async def _reserve_session(session_id: int, username: str) -> tuple[bool, str | None, int | None]:
+    async with _session_lock:
+        if len(_active_sessions) >= MAX_SESSIONS:
+            return False, "Too many sessions", 1013
+        user_sessions = Counter(_active_sessions.values())
+        if user_sessions[username] >= MAX_SESSIONS_PER_USER:
+            return False, "Too many sessions for user", 1013
+        _active_sessions[session_id] = username
+        return True, None, session_id
+
+
+async def _release_session(session_id: int | None):
+    if session_id is None:
+        return
+    async with _session_lock:
+        _active_sessions.pop(session_id, None)
+
+
+async def ws_endpoint(websocket: WebSocket, host: str = Query("nas"), token: str | None = Query(None)):
+    if host not in HOSTS:
+        await websocket.close(code=1008, reason="Unknown host")
+        return
+
+    if not token:
+        await websocket.close(code=1008, reason="Unauthorized")
+        return
 
-    # Auth: expect token as first text message
     try:
-        first_msg = await asyncio.wait_for(websocket.receive_text(), timeout=5)
-        payload = jwt.decode(first_msg, config.SECRET_KEY, algorithms=[config.ALGORITHM])
-        if payload.get("type") != "access":
-            await websocket.close(code=1008, reason="Unauthorized")
-            return
-        username = payload.get("sub")
-        role = payload.get("role", "admin")
-        if username is None:
-            await websocket.close(code=1008, reason="Unauthorized")
-            return
-        # RBAC: check terminal page access
-        from rbac import get_pages
-        pages = get_pages(username, role)
-        if pages != "*" and "terminal" not in pages:
-            await websocket.close(code=1008, reason="Access denied")
-            return
+        user = await get_current_user_ws(token)
     except Exception:
         await websocket.close(code=1008, reason="Unauthorized")
         return
 
+    if user.pages != "*" and "terminal" not in user.pages:
+        await websocket.close(code=1008, reason="Access denied")
+        return
+
     if not _known_hosts_available:
         await websocket.close(code=1011, reason="SSH host verification unavailable")
         return
 
-    if len(_active_sessions) >= MAX_SESSIONS:
-        await websocket.close(code=1013, reason="Too many sessions")
-        return
-
     session_id = id(websocket)
-    _active_sessions.add(session_id)
+    reserved, reason, session_or_code = await _reserve_session(session_id, user.username)
+    if not reserved:
+        await websocket.close(code=session_or_code, reason=reason)
+        return
+    session_id = session_or_code
 
-    h = HOSTS.get(host, HOSTS["nas"])
+    await websocket.accept()
+
+    h = HOSTS[host]
     try:
         conn = await asyncssh.connect(
             h["host"], username=h["user"],
@@ -76,7 +92,7 @@ async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
             keepalive_count_max=3,
         )
     except Exception:
-        _active_sessions.discard(session_id)
+        await _release_session(session_id)
         await websocket.close(code=1011, reason="SSH connection failed")
         return
 
@@ -93,7 +109,7 @@ async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
                     if not data:
                         break
                     await websocket.send_bytes(data)
-            except (asyncssh.Error, WebSocketDisconnect, asyncio.CancelledError):
+            except (asyncssh.Error, asyncio.CancelledError):
                 pass
 
         read_task = asyncio.create_task(read_ssh())
@@ -113,11 +129,11 @@ async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
                     if msg["text"] == "__ping__":
                         continue
                     process.stdin.write(msg["text"].encode())
-        except WebSocketDisconnect:
+        except Exception:
             pass
         finally:
             read_task.cancel()
             process.close()
     finally:
         conn.close()
-        _active_sessions.discard(session_id)
+        await _release_session(session_id)

dashboard/frontend/src/routes/Terminal.svelte

@@ -120,6 +120,8 @@
   function closeTab(id) {
     const d = tabData.get(id);
     if (d) {
+      d.closedManually = true;
+      if (d.reconnectTimer) clearTimeout(d.reconnectTimer);
       d.voice?.destroy();
       d.ro?.disconnect();
       if (d.heartbeat) clearInterval(d.heartbeat);
@@ -157,11 +159,30 @@
 
       const proto = location.protocol === "https:" ? "wss:" : "ws:";
       const token = localStorage.getItem("token") || "";
-      const ws = new WebSocket(
-        `${proto}//${location.host}/ws/terminal?host=${tab.hostId}`
-      );
-      ws.binaryType = "arraybuffer";
-      function sendSize() {
+      let heartbeat = null;
+      let reconnectTimer = null;
+      let closedManually = false;
+
+      function clearHeartbeat() {
+        if (heartbeat) {
+          clearInterval(heartbeat);
+          heartbeat = null;
+        }
+      }
+
+      function scheduleReconnect(reason) {
+        clearHeartbeat();
+        if (closedManually || reconnectTimer) return;
+        updateTab(tabId, { connected: false, error: `${reason} — reconnecting...` });
+        term.write(`\r\n\x1b[90m[${reason} — reconnecting...]\x1b[0m`);
+        reconnectTimer = setTimeout(() => {
+          reconnectTimer = null;
+          if (!tabData.has(tabId) || closedManually) return;
+          connect();
+        }, 2000);
+      }
+
+      function sendSize(ws) {
         if (ws.readyState === 1) {
           const buf = new Uint8Array(5);
           buf[0] = 0x01;
@@ -171,19 +192,62 @@
         }
       }
 
-      ws.onopen = () => { ws.send(token); updateTab(tabId, { connected: true, error: "" }); sendSize(); };
+      function connect() {
+        const ws = new WebSocket(
+          `${proto}//${location.host}/ws/terminal?host=${encodeURIComponent(tab.hostId)}&token=${encodeURIComponent(token)}`
+        );
+        ws.binaryType = "arraybuffer";
+
+        ws.onopen = () => {
+          updateTab(tabId, { connected: true, error: "" });
+          sendSize(ws);
+          clearHeartbeat();
+          heartbeat = setInterval(() => {
+            if (ws.readyState === 1) ws.send("__ping__");
+          }, 25000);
+          const d = tabData.get(tabId);
+          if (d) {
+            d.ws = ws;
+            d.heartbeat = heartbeat;
+            d.reconnectTimer = reconnectTimer;
+            d.closedManually = closedManually;
+            d.voice?.attach(term, ws);
+          }
+        };
         ws.onmessage = (e) => term.write(new Uint8Array(e.data));
         ws.onclose = (e) => {
           const reason = e.reason || `Connection closed (code ${e.code})`;
+          const d = tabData.get(tabId);
+          if (d) d.ws = null;
+          if (!closedManually) scheduleReconnect(reason);
+          else {
+            clearHeartbeat();
             updateTab(tabId, { connected: false, error: reason });
             term.write(`\r\n\x1b[90m[${reason}]\x1b[0m`);
+          }
+        };
+        ws.onerror = () => {
+          const d = tabData.get(tabId);
+          if (d) d.ws = null;
+          if (!closedManually) scheduleReconnect("Connection failed");
+          else updateTab(tabId, { connected: false, error: "Connection failed" });
         };
-      ws.onerror = () => updateTab(tabId, { connected: false, error: "Connection failed" });
-      term.onData((data) => ws.readyState === 1 && ws.send(new TextEncoder().encode(data)));
 
-      const heartbeat = setInterval(() => {
-        if (ws.readyState === 1) ws.send("__ping__");
-      }, 25000);
+        const d = tabData.get(tabId);
+        if (d) {
+          d.ws = ws;
+          d.heartbeat = heartbeat;
+          d.reconnectTimer = reconnectTimer;
+          d.closedManually = closedManually;
+        }
+        return ws;
+      }
+
+      let ws = connect();
+      term.onData((data) => {
+        const currentWs = tabData.get(tabId)?.ws;
+        if (currentWs?.readyState === 1) currentWs.send(new TextEncoder().encode(data));
+      });
 
       const handleDragOver = (e) => {
         e.preventDefault();
@@ -192,19 +256,21 @@
       const handleDrop = async (e) => {
         e.preventDefault();
         if (activeTab !== tabId) return;
+        const currentWs = tabData.get(tabId)?.ws;
         const files = [...(e.dataTransfer?.files || [])].filter((f) => f.type?.startsWith("image/"));
         for (const file of files) {
-          await sendDroppedImage(term, ws, file);
+          await sendDroppedImage(term, currentWs, file);
         }
       };
 
       const handlePaste = async (e) => {
         if (activeTab !== tabId) return;
+        const currentWs = tabData.get(tabId)?.ws;
         const items = [...(e.clipboardData?.items || [])]
           .filter((it) => it.kind === "file" && it.type?.startsWith("image/"));
         for (const item of items) {
           const file = item.getAsFile();
-          if (file) await sendDroppedImage(term, ws, file);
+          if (file) await sendDroppedImage(term, currentWs, file);
         }
       };
 
@@ -212,11 +278,15 @@
       term.element?.addEventListener("drop", handleDrop);
       term.textarea?.addEventListener("paste", handlePaste);
 
-      const ro = new ResizeObserver(() => { fit.fit(); sendSize(); });
+      const ro = new ResizeObserver(() => {
+        fit.fit();
+        const currentWs = tabData.get(tabId)?.ws;
+        if (currentWs) sendSize(currentWs);
+      });
       ro.observe(el);
       const voice = new VoiceSession(() => { voiceTick++; });
       voice.attach(term, ws);
-      tabData.set(tabId, { ws, term, ro, el, voice, heartbeat, handleDragOver, handleDrop, handlePaste });
+      tabData.set(tabId, { ws, term, ro, el, voice, heartbeat, reconnectTimer, closedManually, handleDragOver, handleDrop, handlePaste });
     })();
   }
 
@@ -225,6 +295,8 @@
   onDestroy(() => {
     themeObserver.disconnect();
     tabData.forEach((d) => {
+      d.closedManually = true;
+      if (d.reconnectTimer) clearTimeout(d.reconnectTimer);
       d.voice?.destroy();
       d.ro?.disconnect();
       if (d.heartbeat) clearInterval(d.heartbeat);