diff --git a/services/ai_call_logger.py b/services/ai_call_logger.py
index 9def60a..805475e 100644
--- a/services/ai_call_logger.py
+++ b/services/ai_call_logger.py
@@ -138,7 +138,11 @@ class _CallState:
             from services.llm_caller_registry import assert_known_caller
             assert_known_caller(caller, strict=False)
         except ImportError:
-            pass  # registry 不可用時不阻擋（向下相容）
+            logger.warning(
+                "[AICallLogger] caller registry import failed; skipping caller validation (caller=%s)",
+                caller,
+                exc_info=True,
+            )
 
         self.caller = caller
         self.provider = provider
diff --git a/tests/test_ai_call_logger.py b/tests/test_ai_call_logger.py
index 193e8d7..595cd13 100644
--- a/tests/test_ai_call_logger.py
+++ b/tests/test_ai_call_logger.py
@@ -18,6 +18,8 @@ ai_call_logger 單元測試 (Operation Ollama-First v5.0 — Phase 1)
 import os
 import sys
 import time
+import builtins
+import logging
 
 import pytest
 
@@ -120,6 +122,24 @@ def test_context_manager_exception_path(reset_state):
     assert 'boom' in rec['error']
 
 
+def test_context_manager_logs_registry_import_failure(monkeypatch, caplog):
+    """caller registry 匯入失敗時不阻擋 LLM 遙測，但要留下診斷 log。"""
+    real_import = builtins.__import__
+
+    def _import_with_missing_registry(name, globals=None, locals=None, fromlist=(), level=0):
+        if name == "services.llm_caller_registry":
+            raise ImportError("registry unavailable")
+        return real_import(name, globals, locals, fromlist, level)
+
+    monkeypatch.setattr(builtins, "__import__", _import_with_missing_registry)
+    caplog.set_level(logging.WARNING, logger="services.ai_call_logger")
+
+    with log_ai_call('hermes_analyst', 'gcp_ollama', 'hermes3:latest') as ctx:
+        ctx.set_tokens(input=10, output=5)
+
+    assert "caller registry import failed" in caplog.text
+
+
 def test_context_manager_explicit_fallback(reset_state):
     captured = reset_state
     with log_ai_call('openclaw_qa', 'gemini', 'gemini-2.5-flash') as ctx: