diff --git a/backend/package/yuxi/channels/infra/__init__.py b/backend/package/yuxi/channels/infra/__init__.py
index fe816ef3..bfbd3fdb 100644
--- a/backend/package/yuxi/channels/infra/__init__.py
+++ b/backend/package/yuxi/channels/infra/__init__.py
@@ -1,6 +1,6 @@
+from yuxi.channels.infra.broadcast import EventBroadcaster
 from yuxi.channels.infra.circuit_breaker import CircuitBreaker, CircuitBreakerOpenError, CircuitState
 from yuxi.channels.infra.config_watcher import ConfigWatcher
-from yuxi.channels.infra.broadcast import EventBroadcaster
 from yuxi.channels.infra.external_process import ExternalProcessManager
 from yuxi.channels.infra.text_chunker import ChunkMode, TextChunk, TextChunker
 
diff --git a/backend/package/yuxi/channels/infra/circuit_breaker.py b/backend/package/yuxi/channels/infra/circuit_breaker.py
index b01780b9..7b153b63 100644
--- a/backend/package/yuxi/channels/infra/circuit_breaker.py
+++ b/backend/package/yuxi/channels/infra/circuit_breaker.py
@@ -19,16 +19,27 @@ class CircuitBreakerOpenError(Exception):
     pass
 
 
+CircuitBreakerEventCallback = (
+    Callable[[str, str, dict[str, Any]], Awaitable[None]] | Callable[[str, str, dict[str, Any]], None] | None
+)
+
+
 class CircuitBreaker:
     def __init__(
         self,
         failure_threshold: int = 5,
         recovery_timeout: float = 60.0,
         half_open_max_calls: int = 3,
+        channel_id: str = "",
+        operation: str = "default",
+        on_event: CircuitBreakerEventCallback = None,
     ):
         self.failure_threshold = failure_threshold
         self.recovery_timeout = recovery_timeout
         self.half_open_max_calls = half_open_max_calls
+        self.channel_id = channel_id
+        self.operation = operation
+        self._on_event = on_event
 
         self.state = CircuitState.CLOSED
         self._failure_count = 0
@@ -44,6 +55,7 @@ class CircuitBreaker:
                     self.state = CircuitState.HALF_OPEN
                     self._half_open_calls = 0
                     logger.info("Circuit breaker transitioned to HALF_OPEN")
+                    await self._emit_event("on_half_open", {})
                 else:
                     raise CircuitBreakerOpenError(
                         f"Circuit breaker is OPEN, retry after {self.recovery_timeout - elapsed:.0f}s"
@@ -69,6 +81,7 @@ class CircuitBreaker:
                 self._failure_count = 0
                 self._half_open_calls = 0
                 logger.info("Circuit breaker closed after successful HALF_OPEN probe")
+                await self._emit_event("on_close", {})
             elif self.state == CircuitState.CLOSED and self._failure_count > 0:
                 self._failure_count = 0
 
@@ -82,6 +95,24 @@ class CircuitBreaker:
                 logger.warning(
                     f"Circuit breaker OPEN after {self._failure_count} failures (threshold={self.failure_threshold})"
                 )
+                await self._emit_event("on_open", {"failure_count": self._failure_count})
             elif self.state == CircuitState.HALF_OPEN:
                 self.state = CircuitState.OPEN
                 logger.warning("Circuit breaker re-OPENed after HALF_OPEN failure")
+                await self._emit_event("on_open", {"failure_count": self._failure_count, "from": "half_open"})
+
+    async def _emit_event(self, event: str, detail: dict[str, Any]) -> None:
+        if self._on_event is None:
+            return
+        payload = {
+            "channel_id": self.channel_id,
+            "operation": self.operation,
+            "state": self.state,
+            **detail,
+        }
+        try:
+            result = self._on_event(event, self.channel_id, payload)  # type: ignore[call-arg]
+            if asyncio.iscoroutine(result):
+                await result
+        except Exception:
+            logger.debug(f"CircuitBreaker event callback error: {event}", exc_info=True)
diff --git a/backend/package/yuxi/channels/infra/config_watcher.py b/backend/package/yuxi/channels/infra/config_watcher.py
index 58859602..8af12909 100644
--- a/backend/package/yuxi/channels/infra/config_watcher.py
+++ b/backend/package/yuxi/channels/infra/config_watcher.py
@@ -3,7 +3,7 @@ from __future__ import annotations
 import asyncio
 import hashlib
 import json
-from typing import Any, TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from yuxi.utils.logging_config import logger
 
diff --git a/backend/package/yuxi/channels/infra/text_chunker.py b/backend/package/yuxi/channels/infra/text_chunker.py
index 017b7ed3..25e7f508 100644
--- a/backend/package/yuxi/channels/infra/text_chunker.py
+++ b/backend/package/yuxi/channels/infra/text_chunker.py
@@ -2,8 +2,8 @@ from __future__ import annotations
 
 import re
 from collections.abc import Iterator
-from enum import StrEnum
 from dataclasses import dataclass
+from enum import StrEnum
 
 
 class ChunkMode(StrEnum):