diff --git a/scripts/regen_metric_signatures.py b/scripts/regen_metric_signatures.py
index 9c27e69e..dcc6721a 100644
--- a/scripts/regen_metric_signatures.py
+++ b/scripts/regen_metric_signatures.py
@@ -11,9 +11,81 @@
 """
 
 import json
+import sys
+from importlib.abc import Loader, MetaPathFinder
+from importlib.machinery import ModuleSpec
 from pathlib import Path
+from types import ModuleType
+from typing import TypedDict
 
-from eva.metrics.signatures import compute_all_metric_signatures
+
+def _stub_heavy_imports() -> None:
+    """Install a meta-path finder that stubs heavy packages before any eva imports.
+
+    litellm and pipecat together account for ~4 s of import time, but
+    regen_metric_signatures only needs class definitions and source hashes —
+    it never calls into these libraries at runtime.
+
+    Using a MetaPathFinder means every submodule import (no matter how deep)
+    is automatically intercepted and given a lightweight stub, with no manual
+    per-submodule registration required.
+
+    The one exception is DeploymentTypedDict, which is used as a base class in
+    eva.models.config and must be an actual type, not a stub object.
+    """
+    _STUB_PACKAGES = frozenset({"litellm"})
+
+    class _AutoStub(ModuleType):
+        """A module stub that satisfies arbitrary attribute and submodule access."""
+
+        def __getattr__(self, name: str) -> "_AutoStub":
+            child = _AutoStub(f"{self.__name__}.{name}")
+            object.__setattr__(self, name, child)
+            sys.modules[child.__name__] = child
+            return child
+
+        def __call__(self, *args: object, **kwargs: object) -> "_AutoStub":
+            return self
+
+        def __iter__(self):  # type: ignore[override]
+            return iter([])
+
+        # Allow use in type union expressions at module level, e.g. `Router | None`
+        def __or__(self, other: object) -> object:
+            return object
+
+        def __ror__(self, other: object) -> object:
+            return object
+
+    class _StubLoader(Loader):
+        def create_module(self, spec: ModuleSpec) -> _AutoStub:
+            return _AutoStub(spec.name)
+
+        def exec_module(self, module: ModuleType) -> None:
+            pass  # _AutoStub handles everything via __getattr__
+
+    class _StubFinder(MetaPathFinder):
+        def find_spec(self, fullname: str, path: object, target: object = None) -> ModuleSpec | None:
+            if fullname.split(".")[0] in _STUB_PACKAGES:
+                return ModuleSpec(fullname, _StubLoader())
+            return None
+
+    sys.meta_path.insert(0, _StubFinder())
+
+    # DeploymentTypedDict is inherited by ModelDeployment in eva.models.config,
+    # so it must be a real class. Trigger the import so the stub is registered in
+    # sys.modules, then replace the attribute with a proper TypedDict.
+    import litellm.types.router  # noqa: PLC0415, F401
+
+    class DeploymentTypedDict(TypedDict, total=False):
+        pass
+
+    sys.modules["litellm.types.router"].DeploymentTypedDict = DeploymentTypedDict  # type: ignore[attr-defined]
+
+
+_stub_heavy_imports()
+
+from eva.metrics.signatures import compute_all_metric_signatures  # noqa: E402
 
 REPO_ROOT = Path(__file__).resolve().parent.parent
 FIXTURE_PATH = REPO_ROOT / "tests" / "fixtures" / "metric_signatures.json"
diff --git a/src/eva/assistant/agentic/system.py b/src/eva/assistant/agentic/system.py
index 7be55472..12575b45 100644
--- a/src/eva/assistant/agentic/system.py
+++ b/src/eva/assistant/agentic/system.py
@@ -17,6 +17,7 @@
 )
 from eva.assistant.tools.tool_executor import ToolExecutor
 from eva.models.agents import AgentConfig
+from eva.utils.conversation_checks import LLM_GENERIC_ERROR_MESSAGE as GENERIC_ERROR
 from eva.utils.error_handler import categorize_error
 from eva.utils.log_processing import truncate_data_uris
 from eva.utils.logging import get_logger
@@ -27,9 +28,6 @@
 # Suppress LiteLLM's Pydantic serialization warnings (harmless internal warnings)
 warnings.filterwarnings("ignore", category=UserWarning, message=".*Pydantic serializer warnings.*")
 
-# Response messages
-GENERIC_ERROR = "I'm sorry, I encountered an error processing your request."
-
 
 def _clean_tool_name(name: str) -> str:
     """Strip Harmony special tokens that leak into tool names due to a known vLLM bug.
diff --git a/src/eva/metrics/processor.py b/src/eva/metrics/processor.py
index aa4a34b9..2a6f83db 100644
--- a/src/eva/metrics/processor.py
+++ b/src/eva/metrics/processor.py
@@ -5,9 +5,9 @@
 from dataclasses import dataclass, field
 from pathlib import Path
 
-from eva.assistant.agentic.system import GENERIC_ERROR
 from eva.models.config import PipelineType
 from eva.models.results import ConversationResult
+from eva.utils.conversation_checks import LLM_GENERIC_ERROR_MESSAGE as GENERIC_ERROR
 from eva.utils.log_processing import (
     AnnotationLabel,
     aggregate_pipecat_logs_by_type,