diff --git a/agent/error_classifier.py b/agent/error_classifier.py
index 9fcd18ca098e..396d922fb44c 100644
--- a/agent/error_classifier.py
+++ b/agent/error_classifier.py
@@ -775,6 +775,14 @@ def classify_api_error(
         if classified is not None:
             return classified
 
+    # Local MoA config drift is deterministic: a persisted session can retain
+    # a preset name that was later renamed/deleted. Retrying the same lookup
+    # cannot recover and makes a clear config error look like an API outage.
+    from agent.errors import MoAPresetNotFoundError
+
+    if isinstance(error, MoAPresetNotFoundError):
+        return _result(FailoverReason.model_not_found, retryable=False)
+
     # ── 3. Error code classification ────────────────────────────────
 
     if error_code:
diff --git a/agent/errors.py b/agent/errors.py
index 89afcd3b4c8a..8b3db5a3589c 100644
--- a/agent/errors.py
+++ b/agent/errors.py
@@ -7,3 +7,7 @@ class EmptyStreamError(RuntimeError):
     """Raised when a provider closes a stream without yielding a response."""
 
     pass
+
+
+class MoAPresetNotFoundError(ValueError):
+    """Raised when a persisted MoA preset no longer exists in config."""
diff --git a/hermes_cli/moa_config.py b/hermes_cli/moa_config.py
index 39594ee399eb..a5401c525892 100644
--- a/hermes_cli/moa_config.py
+++ b/hermes_cli/moa_config.py
@@ -295,7 +295,13 @@ def resolve_moa_preset(config: Any, name: str | None = None) -> dict[str, Any]:
     preset_name = str(name or cfg.get("default_preset") or DEFAULT_MOA_PRESET_NAME).strip()
     preset = cfg["presets"].get(preset_name)
     if preset is None:
-        raise KeyError(preset_name)
+        from agent.errors import MoAPresetNotFoundError
+
+        available = ", ".join(cfg["presets"]) or "(none)"
+        raise MoAPresetNotFoundError(
+            f"MoA preset '{preset_name}' was not found. Available presets: "
+            f"{available}. Run `hermes moa list`."
+        )
     return deepcopy(preset)
 
 
diff --git a/tests/hermes_cli/test_moa_config.py b/tests/hermes_cli/test_moa_config.py
index c78631f5e24c..e6b4714e2256 100644
--- a/tests/hermes_cli/test_moa_config.py
+++ b/tests/hermes_cli/test_moa_config.py
@@ -1,3 +1,6 @@
+import pytest
+
+from agent.errors import MoAPresetNotFoundError
 from hermes_cli.moa_config import (
     DEFAULT_MOA_AGGREGATOR,
     DEFAULT_MOA_PRESET_NAME,
@@ -205,6 +208,46 @@ def test_resolve_moa_preset_returns_requested_model_set():
     ]
 
 
+def test_resolve_missing_moa_preset_has_actionable_error():
+    cfg = {
+        "default_preset": "日常对话-高峰",
+        "presets": {"日常对话-高峰": {}, "日常对话-非高峰": {}},
+    }
+
+    with pytest.raises(MoAPresetNotFoundError) as exc_info:
+        resolve_moa_preset(cfg, "日常对话-高峰期")
+
+    message = str(exc_info.value)
+    assert "日常对话-高峰期" in message
+    assert "日常对话-高峰" in message
+    assert "日常对话-非高峰" in message
+    assert "hermes moa list" in message
+
+
+def test_resolve_missing_moa_preset_does_not_silently_fallback():
+    cfg = {
+        "default_preset": "日常对话-高峰",
+        "presets": {"日常对话-高峰": {}},
+    }
+
+    with pytest.raises(MoAPresetNotFoundError):
+        resolve_moa_preset(cfg, "renamed-preset")
+
+
+def test_missing_moa_preset_is_non_retryable():
+    from agent.error_classifier import FailoverReason, classify_api_error
+
+    result = classify_api_error(
+        MoAPresetNotFoundError("MoA preset 'old' was not found"),
+        provider="moa",
+        model="old",
+    )
+
+    assert result.reason == FailoverReason.model_not_found
+    assert result.retryable is False
+    assert result.should_fallback is False
+
+
 def test_build_moa_turn_prompt_encodes_one_shot_default_preset():
     prompt = build_moa_turn_prompt("write a file then inspect it")