diff --git a/.github/workflows/python-app.yml b/.github/workflows/python-app.yml
index 26a596f..08bf87f 100644
--- a/.github/workflows/python-app.yml
+++ b/.github/workflows/python-app.yml
@@ -2,9 +2,9 @@ name: Python FastAPI CI
 
 on:
   push:
-    branches: [ main ]
+    branches: [ release ]
   pull_request:
-    branches: [ main ]
+    branches: [ release ]
 
 jobs:
   build:
diff --git a/main.py b/main.py
index a979a48..ea4123b 100644
--- a/main.py
+++ b/main.py
@@ -5,6 +5,9 @@
 import uvicorn
 from mongodb import users_collection
 from typing import Optional, List
+from rank_bm25 import BM25Okapi
+import re
+from string import punctuation
 
 app = FastAPI()
 
@@ -13,6 +16,20 @@ class InputData(BaseModel):
     user_ID: str
     context: Optional[List[str]] = None
 
+# Define a simple English stopword list
+STOPWORDS = set([
+    'i', 'me', 'my', 'myself', 'we', 'our', 'ours', 'ourselves', 'you', 'your', 'yours', 'yourself', 'yourselves',
+    'he', 'him', 'his', 'himself', 'she', 'her', 'hers', 'herself', 'it', 'its', 'itself', 'they', 'them', 'their',
+    'theirs', 'themselves', 'what', 'which', 'who', 'whom', 'this', 'that', 'these', 'those', 'am', 'is', 'are',
+    'was', 'were', 'be', 'been', 'being', 'have', 'has', 'had', 'having', 'do', 'does', 'did', 'doing', 'a', 'an',
+    'the', 'and', 'but', 'if', 'or', 'because', 'as', 'until', 'while', 'of', 'at', 'by', 'for', 'with', 'about',
+    'against', 'between', 'into', 'through', 'during', 'before', 'after', 'above', 'below', 'to', 'from', 'up',
+    'down', 'in', 'out', 'on', 'off', 'over', 'under', 'again', 'further', 'then', 'once', 'here', 'there', 'when',
+    'where', 'why', 'how', 'all', 'any', 'both', 'each', 'few', 'more', 'most', 'other', 'some', 'such', 'no',
+    'nor', 'not', 'only', 'own', 'same', 'so', 'than', 'too', 'very', 's', 't', 'can', 'will', 'just', 'don',
+    'should', 'now'
+])
+
 @app.get("/")
 def read_root():
     return {"message": "Hello, world!"}
@@ -32,18 +49,49 @@ def run_script():
     except Exception as e:
         return {"error": str(e)}
     
+# Enhanced regex-based tokenizer with stopword and punctuation removal
+def simple_tokenize(text, remove_stopwords=True):
+    tokens = re.findall(r"\b\w+\b", text.lower())
+    if remove_stopwords:
+        filtered = [t for t in tokens if t not in STOPWORDS and t not in punctuation]
+    else:
+        filtered = [t for t in tokens if t not in punctuation]
+    return filtered
+
 @app.post("/ask-ai")
 def ask_ai(data: InputData):
     try:
-        docs = list(users_collection.find({"user_id": data.user_ID}).sort("_id", -1).limit(5))
+        # Fetch a larger window of history
+        docs = list(users_collection.find({"user_id": data.user_ID}).sort("_id", -1).limit(50))
         if docs:
-            history = []
-            for doc in docs[::-1]:
-                history.append({
-                    "user_prompt": doc.get("user_promt", ""),
-                    "AI": doc.get("AI", "")
-                })
-            print("Last five history loaded from MongoDB:", history)
+            # Prepare documents for BM25
+            history_texts = [
+                f"{doc.get('user_promt', '')} {doc.get('AI', '')}" for doc in docs
+            ]
+            tokenized_corpus = [simple_tokenize(text, remove_stopwords=True) for text in history_texts]
+            tokenized_query = simple_tokenize(data.query, remove_stopwords=False)
+            print("Query:", data.query)
+            # print("Tokenized query:", tokenized_query)
+            # print("History texts:", history_texts)
+            # print("Tokenized corpus:", tokenized_corpus)
+            # Check for empty query or empty corpus
+            if not tokenized_query or not any(tokenized_corpus):
+                history = []
+                print("BM25 skipped: empty query or corpus.")
+            else:
+                bm25 = BM25Okapi(tokenized_corpus)
+                scores = bm25.get_scores(tokenized_query)
+                top_n = 5
+                top_indices = sorted(range(len(scores)), key=lambda i: scores[i], reverse=True)[:top_n]
+                # Select the most relevant history
+                relevant_docs = [docs[i] for i in top_indices]
+                history = []
+                for doc in relevant_docs:
+                    history.append({
+                        "user_prompt": doc.get("user_promt", ""),
+                        "AI": doc.get("AI", "")
+                    })
+                print("Top 5 relevant history loaded from MongoDB using BM25:", history)
         else:
             history = []
 
diff --git a/requirements.txt b/requirements.txt
index 5bc6a87..7985d6b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,4 +2,5 @@ fastapi
 uvicorn
 python-dotenv
 google-generativeai
-pymongo
\ No newline at end of file
+pymongo
+rank_bm25
\ No newline at end of file