diff --git a/main.py b/main.py
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--- /dev/null
+++ b/main.py
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+#!/usr/bin/env python3
+"""Deep agent that searches the web using Perplexity and writes results to a file.
+
+Usage:
+    python main.py "search query"
+
+The agent will:
+1. Query Perplexity via LangChain's Perplexity wrapper.
+2. Store the answer in a virtual file `output.txt`.
+3. Write the virtual file to the real filesystem.
+"""
+
+import argparse
+import os
+from pathlib import Path
+
+from langchain_community.utilities import Perplexity
+from langchain_core.prompts import ChatPromptTemplate
+from langchain_core.output_parsers import StrOutputParser
+
+# Configure Perplexity API key via environment variable
+# Users should set PERPLEXITY_API_KEY in their environment
+
+PERPLEXITY_API_KEY = os.getenv("PERPLEXITY_API_KEY")
+if not PERPLEXITY_API_KEY:
+    raise RuntimeError("PERPLEXITY_API_KEY environment variable not set")
+
+# Create a simple chain: prompt -> Perplexity -> output parser
+prompt = ChatPromptTemplate.from_messages([
+    ("system", "You are a helpful assistant that answers questions based on web search."),
+    ("human", "{question}")
+])
+
+llm = Perplexity(api_key=PERPLEXITY_API_KEY, temperature=0.7)
+chain = prompt | llm | StrOutputParser()
+
+
+def search_and_write(query: str, output_path: Path) -> None:
+    """Search the web for *query* and write the answer to *output_path*.
+
+    The function creates a virtual file in memory and then writes it to disk.
+    """
+    print(f"Searching for: {query}")
+    answer = chain.invoke({"question": query})
+    # Virtual file content
+    virtual_file_content = f"Query: {query}\n\nAnswer:\n{answer}\n"
+    # Write to real filesystem
+    output_path.write_text(virtual_file_content, encoding="utf-8")
+    print(f"Result written to {output_path.resolve()}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Deep agent search tool")
+    parser.add_argument("query", type=str, help="Search query")
+    parser.add_argument(
+        "--output",
+        type=str,
+        default="output.txt",
+        help="Path to write the result file (default: output.txt)",
+    )
+    args = parser.parse_args()
+
+    output_path = Path(args.output)
+    search_and_write(args.query, output_path)