diff --git a/nanobot/agent/tools/cron.py b/nanobot/agent/tools/cron.py
index ec0d2cd..9f1ecdb 100644
--- a/nanobot/agent/tools/cron.py
+++ b/nanobot/agent/tools/cron.py
@@ -50,6 +50,10 @@ class CronTool(Tool):
                     "type": "string",
                     "description": "Cron expression like '0 9 * * *' (for scheduled tasks)"
                 },
+                "at": {
+                    "type": "string",
+                    "description": "ISO datetime for one-time execution (e.g. '2026-02-12T10:30:00')"
+                },
                 "job_id": {
                     "type": "string",
                     "description": "Job ID (for remove)"
@@ -64,30 +68,38 @@ class CronTool(Tool):
         message: str = "",
         every_seconds: int | None = None,
         cron_expr: str | None = None,
+        at: str | None = None,
         job_id: str | None = None,
         **kwargs: Any
     ) -> str:
         if action == "add":
-            return self._add_job(message, every_seconds, cron_expr)
+            return self._add_job(message, every_seconds, cron_expr, at)
         elif action == "list":
             return self._list_jobs()
         elif action == "remove":
             return self._remove_job(job_id)
         return f"Unknown action: {action}"
     
-    def _add_job(self, message: str, every_seconds: int | None, cron_expr: str | None) -> str:
+    def _add_job(self, message: str, every_seconds: int | None, cron_expr: str | None, at: str | None) -> str:
         if not message:
             return "Error: message is required for add"
         if not self._channel or not self._chat_id:
             return "Error: no session context (channel/chat_id)"
         
         # Build schedule
+        delete_after = False
         if every_seconds:
             schedule = CronSchedule(kind="every", every_ms=every_seconds * 1000)
         elif cron_expr:
             schedule = CronSchedule(kind="cron", expr=cron_expr)
+        elif at:
+            from datetime import datetime
+            dt = datetime.fromisoformat(at)
+            at_ms = int(dt.timestamp() * 1000)
+            schedule = CronSchedule(kind="at", at_ms=at_ms)
+            delete_after = True
         else:
-            return "Error: either every_seconds or cron_expr is required"
+            return "Error: either every_seconds, cron_expr, or at is required"
         
         job = self._cron.add_job(
             name=message[:30],
@@ -96,6 +108,7 @@ class CronTool(Tool):
             deliver=True,
             channel=self._channel,
             to=self._chat_id,
+            delete_after_run=delete_after,
         )
         return f"Created job '{job.name}' (id: {job.id})"
     
diff --git a/nanobot/channels/dingtalk.py b/nanobot/channels/dingtalk.py
index 72d3afd..4a8cdd9 100644
--- a/nanobot/channels/dingtalk.py
+++ b/nanobot/channels/dingtalk.py
@@ -137,8 +137,15 @@ class DingTalkChannel(BaseChannel):
 
             logger.info("DingTalk bot started with Stream Mode")
 
-            # client.start() is an async infinite loop handling the websocket connection
-            await self._client.start()
+            # Reconnect loop: restart stream if SDK exits or crashes
+            while self._running:
+                try:
+                    await self._client.start()
+                except Exception as e:
+                    logger.warning(f"DingTalk stream error: {e}")
+                if self._running:
+                    logger.info("Reconnecting DingTalk stream in 5 seconds...")
+                    await asyncio.sleep(5)
 
         except Exception as e:
             logger.exception(f"Failed to start DingTalk channel: {e}")
diff --git a/nanobot/channels/feishu.py b/nanobot/channels/feishu.py
index 1c176a2..23d1415 100644
--- a/nanobot/channels/feishu.py
+++ b/nanobot/channels/feishu.py
@@ -98,12 +98,15 @@ class FeishuChannel(BaseChannel):
             log_level=lark.LogLevel.INFO
         )
         
-        # Start WebSocket client in a separate thread
+        # Start WebSocket client in a separate thread with reconnect loop
         def run_ws():
-            try:
-                self._ws_client.start()
-            except Exception as e:
-                logger.error(f"Feishu WebSocket error: {e}")
+            while self._running:
+                try:
+                    self._ws_client.start()
+                except Exception as e:
+                    logger.warning(f"Feishu WebSocket error: {e}")
+                if self._running:
+                    import time; time.sleep(5)
         
         self._ws_thread = threading.Thread(target=run_ws, daemon=True)
         self._ws_thread.start()
diff --git a/nanobot/channels/qq.py b/nanobot/channels/qq.py
index 5964d30..0e8fe66 100644
--- a/nanobot/channels/qq.py
+++ b/nanobot/channels/qq.py
@@ -75,12 +75,15 @@ class QQChannel(BaseChannel):
         logger.info("QQ bot started (C2C private message)")
 
     async def _run_bot(self) -> None:
-        """Run the bot connection."""
-        try:
-            await self._client.start(appid=self.config.app_id, secret=self.config.secret)
-        except Exception as e:
-            logger.error(f"QQ auth failed, check AppID/Secret at q.qq.com: {e}")
-            self._running = False
+        """Run the bot connection with auto-reconnect."""
+        while self._running:
+            try:
+                await self._client.start(appid=self.config.app_id, secret=self.config.secret)
+            except Exception as e:
+                logger.warning(f"QQ bot error: {e}")
+            if self._running:
+                logger.info("Reconnecting QQ bot in 5 seconds...")
+                await asyncio.sleep(5)
 
     async def stop(self) -> None:
         """Stop the QQ bot."""
diff --git a/nanobot/channels/telegram.py b/nanobot/channels/telegram.py
index ff46c86..1abd600 100644
--- a/nanobot/channels/telegram.py
+++ b/nanobot/channels/telegram.py
@@ -9,6 +9,7 @@ from typing import TYPE_CHECKING
 from loguru import logger
 from telegram import BotCommand, Update
 from telegram.ext import Application, CommandHandler, MessageHandler, filters, ContextTypes
+from telegram.request import HTTPXRequest
 
 from nanobot.bus.events import OutboundMessage
 from nanobot.bus.queue import MessageBus
@@ -121,11 +122,13 @@ class TelegramChannel(BaseChannel):
         
         self._running = True
         
-        # Build the application
-        builder = Application.builder().token(self.config.token)
+        # Build the application with larger connection pool to avoid pool-timeout on long runs
+        req = HTTPXRequest(connection_pool_size=16, pool_timeout=5.0, connect_timeout=30.0, read_timeout=30.0)
+        builder = Application.builder().token(self.config.token).request(req).get_updates_request(req)
         if self.config.proxy:
             builder = builder.proxy(self.config.proxy).get_updates_proxy(self.config.proxy)
         self._app = builder.build()
+        self._app.add_error_handler(self._on_error)
         
         # Add command handlers
         self._app.add_handler(CommandHandler("start", self._on_start))
@@ -386,6 +389,10 @@ class TelegramChannel(BaseChannel):
         except Exception as e:
             logger.debug(f"Typing indicator stopped for {chat_id}: {e}")
     
+    async def _on_error(self, update: object, context: ContextTypes.DEFAULT_TYPE) -> None:
+        """Log polling / handler errors instead of silently swallowing them."""
+        logger.error(f"Telegram error: {context.error}")
+
     def _get_extension(self, media_type: str, mime_type: str | None) -> str:
         """Get file extension based on media type."""
         if mime_type:
diff --git a/nanobot/skills/cron/SKILL.md b/nanobot/skills/cron/SKILL.md
index c8beecb..7db25d8 100644
--- a/nanobot/skills/cron/SKILL.md
+++ b/nanobot/skills/cron/SKILL.md
@@ -7,10 +7,11 @@ description: Schedule reminders and recurring tasks.
 
 Use the `cron` tool to schedule reminders or recurring tasks.
 
-## Two Modes
+## Three Modes
 
 1. **Reminder** - message is sent directly to user
 2. **Task** - message is a task description, agent executes and sends result
+3. **One-time** - runs once at a specific time, then auto-deletes
 
 ## Examples
 
@@ -24,6 +25,11 @@ Dynamic task (agent executes each time):
 cron(action="add", message="Check HKUDS/nanobot GitHub stars and report", every_seconds=600)
 ```
 
+One-time scheduled task (compute ISO datetime from current time):
+```
+cron(action="add", message="Remind me about the meeting", at="<ISO datetime>")
+```
+
 List/remove:
 ```
 cron(action="list")
@@ -38,3 +44,4 @@ cron(action="remove", job_id="abc123")
 | every hour | every_seconds: 3600 |
 | every day at 8am | cron_expr: "0 8 * * *" |
 | weekdays at 5pm | cron_expr: "0 17 * * 1-5" |
+| at a specific time | at: ISO datetime string (compute from current time) |