diff --git a/app/llm/__init__.py b/app/llm/__init__.py
index e69de29..cfcce48 100644
--- a/app/llm/__init__.py
+++ b/app/llm/__init__.py
@@ -0,0 +1,20 @@
+"""LLM module exports."""
+from .templates import PromptTemplate, TemplateRegistry, DEFAULT_TEMPLATES
+from .context import (
+    Context,
+    ContextConfig,
+    ContextManager,
+    DataAccessConfig,
+    Message,
+)
+
+__all__ = [
+    "Context",
+    "ContextConfig", 
+    "ContextManager",
+    "DataAccessConfig",
+    "Message",
+    "PromptTemplate",
+    "TemplateRegistry",
+    "DEFAULT_TEMPLATES",
+]
diff --git a/app/llm/context.py b/app/llm/context.py
index d05ab37..c75d19a 100644
--- a/app/llm/context.py
+++ b/app/llm/context.py
@@ -28,13 +28,13 @@ class DataAccessConfig:
             start_ts = time.strptime(start_date, "%Y%m%d")
             if end_date:
                 end_ts = time.strptime(end_date, "%Y%m%d")
-                days = (time.mktime(end_ts) - time.mktime(start_ts)) / (24 * 3600)
-                if days > self.max_history_days:
-                    errors.append(
-                        f"Date range exceeds max {self.max_history_days} days"
-                    )
-                if days < 0:
+                delta_days = (time.mktime(end_ts) - time.mktime(start_ts)) / (24 * 3600)
+                if delta_days < 0:
                     errors.append("End date before start date")
+                elif delta_days > self.max_history_days:
+                    errors.append(
+                        f"Date range ({int(delta_days)} days) exceeds max {self.max_history_days} days"
+                    )
         except ValueError:
             errors.append("Invalid date format (expected YYYYMMDD)")
 
diff --git a/app/llm/templates.py b/app/llm/templates.py
index 3a7940e..b4bb536 100644
--- a/app/llm/templates.py
+++ b/app/llm/templates.py
@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 import json
+import logging
 from dataclasses import dataclass
 from typing import Any, Dict, List, Optional
 
@@ -56,10 +57,14 @@ class PromptTemplate:
         except KeyError as e:
             raise ValueError(f"Missing template variable: {e}")
 
-        # Truncate if needed
+        # Truncate if needed, preserving exact number of characters
         if len(result) > self.max_length:
-            result = result[:self.max_length-3] + "..."
-
+            target = self.max_length - 3  # Reserve space for "..."
+            if target > 0:  # Only truncate if we have space for content
+                result = result[:target] + "..."
+            else:
+                result = "..."  # If max_length <= 3, just return "..."
+        
         return result
 
 
@@ -116,7 +121,7 @@ class TemplateRegistry:
         cls._templates.clear()
 
 
-# Register default templates
+# Default template definitions
 DEFAULT_TEMPLATES = {
     "department_base": {
         "name": "部门基础模板",
@@ -214,6 +219,25 @@ DEFAULT_TEMPLATES = {
     }
 }
 
-# Register default templates
-for template_id, cfg in DEFAULT_TEMPLATES.items():
-    TemplateRegistry.register(PromptTemplate(**{"id": template_id, **cfg}))
+
+def register_default_templates() -> None:
+    """Register all default templates from DEFAULT_TEMPLATES."""
+    for template_id, cfg in DEFAULT_TEMPLATES.items():
+        template_config = {
+            "id": template_id,
+            "name": cfg.get("name", template_id),
+            "description": cfg.get("description", ""),
+            "template": cfg.get("template", ""),
+            "variables": cfg.get("variables", []),
+            "max_length": cfg.get("max_length", 4000),
+            "required_context": cfg.get("required_context", []),
+            "validation_rules": cfg.get("validation_rules", [])
+        }
+        try:
+            TemplateRegistry.register(PromptTemplate(**template_config))
+        except ValueError as e:
+            logging.warning(f"Failed to register template {template_id}: {e}")
+
+
+# Auto-register default templates on module import
+register_default_templates()