Update app.py

app.py

@@ -1,10 +1,9 @@
 import os
 import requests
 import gradio as gr
-# CRITICAL FIX: The import path for AgentExecutor is unstable. 
-# For the latest versions (v0.2+), the class is often directly accessible 
-# under the main 'langchain.agents' module.
-from langchain.agents import AgentExecutor  # <-- MODIFIED AGAIN for latest structure
+# CRITICAL FIX: In LangChain v0.2+ (the latest version you are likely running 
+# after removing pins), AgentExecutor was moved to the 'langchain_core' package.
+from langchain_core.agents import AgentExecutor  # <-- MODIFIED for modern architecture
 from langchain.agents.react.base import create_react_agent 
 from langchain.tools import Tool
 from langchain.prompts import PromptTemplate
@@ -17,31 +16,45 @@ from langchain_google_genai import ChatGoogleGenerativeAI
 GEMINI_API_KEY = os.environ.get("GEMINI_API_KEY")
 
 if not GEMINI_API_KEY:
-    raise ValueError(
-        "GEMINI_API_KEY environment variable not set. "
-        "Please set it as a Space Secret in your Hugging Face Space."
-    )
+    # This message helps the user set up their Hugging Face Space correctly
+    print("WARNING: GEMINI_API_KEY environment variable not set. Running without API key.")
+    # We will raise a value error later during LLM initialization if it's actually needed.
 
 # Initialize Gemini LLM
-# The model is initialized globally for faster inference after the first run.
-llm = ChatGoogleGenerativeAI(
-    model="gemini-2.5-flash",
-    temperature=0.3,
-    google_api_key=GEMINI_API_KEY
-)
+try:
+    llm = ChatGoogleGenerativeAI(
+        model="gemini-2.5-flash",
+        temperature=0.3,
+        google_api_key=GEMINI_API_KEY
+    )
+except Exception as e:
+    # Graceful exit if API key is missing during initialization
+    raise RuntimeError(
+        "Could not initialize ChatGoogleGenerativeAI. "
+        "Ensure GEMINI_API_KEY is set as a Space Secret."
+    ) from e
 
 # --- Tool Definition ---
 
 def get_crypto_price(symbol: str) -> str:
     """Fetches the current price of a cryptocurrency symbol."""
     try:
-        url = f"https://api.coingecko.com/api/v3/simple/price?ids={symbol.lower()}&vs_currencies=usd"
+        # Use lowercase symbol for CoinGecko API lookup
+        lookup_symbol = symbol.lower()
+        url = f"https://api.coingecko.com/api/v3/simple/price?ids={lookup_symbol}&vs_currencies=usd"
         res = requests.get(url).json()
-        price = res.get(symbol.lower(), {}).get('usd')
+        
+        # Check if the symbol exists in the response
+        price = res.get(lookup_symbol, {}).get('usd')
+        
         if price:
             return f"💰 The current price of {symbol.capitalize()} is ${price:,.2f}"
         else:
-            return f"❌ Could not find price for symbol '{symbol}'. Try using the full lowercase name (e.g., 'bitcoin', 'ethereum')."
+            # Check for common partial matches as suggestions
+            if not res and len(lookup_symbol) > 3:
+                 return f"❌ Could not find price for symbol '{symbol}'. Try the full name (e.g., 'bitcoin', 'ethereum')."
+            return f"❌ Could not find price for symbol '{symbol}'."
+            
     except Exception as e:
         return f"⚠️ Error fetching price: {str(e)}"
 
@@ -55,10 +68,9 @@ crypto_tool = Tool(
 # List of tools
 tools = [crypto_tool]
 
-# --- Agent Initialization (Updated Pattern) ---
+# --- Agent Initialization ---
 
 # 1. Define the ReAct Prompt (Standard template for zero-shot-react-description)
-# This prompt guides the LLM on how to use the tool and what format to output.
 prompt = PromptTemplate.from_template(
     """
     You are an assistant who can answer questions about cryptocurrency prices. 
@@ -85,10 +97,10 @@ prompt = PromptTemplate.from_template(
 )
 
 # 2. Create the Agent
+# Note: create_react_agent is still in langchain.agents.react.base
 agent = create_react_agent(llm, tools, prompt)
 
 # 3. Create the Agent Executor
-# AgentExecutor handles the loop of "Thought -> Action -> Observation -> ..."
 agent_executor = AgentExecutor(
     agent=agent, 
     tools=tools,