Initial clean deploy of CppSensei

.gitignore

@@ -0,0 +1,4 @@
+vector.index
+__pycache__/
+*.pyc
+.env

Dockerfile

@@ -0,0 +1,13 @@
+FROM python:3.10-slim
+
+WORKDIR /app
+
+COPY requirements.txt .
+
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY . .
+
+EXPOSE 7860
+
+CMD ["gunicorn", "app:app", "--bind", "0.0.0.0:7860", "--workers", "1"]

app.py

@@ -0,0 +1,130 @@
+import os
+
+# Auto build FAISS index if not present
+if not os.path.exists("vector.index"):
+    print("vector.index not found. Building embeddings...")
+    os.system("python embeddings.py")
+
+import smtplib
+from email.mime.text import MIMEText
+from flask import Flask, request, jsonify, render_template
+
+from sentence_transformers import SentenceTransformer
+import faiss
+import numpy as np
+from transformers import pipeline
+
+from dotenv import load_dotenv
+import os
+
+app = Flask(__name__)
+load_dotenv()
+
+@app.route("/")
+def home():
+    return render_template("index.html")
+
+print("Loading embedding model...")
+embedder = SentenceTransformer("all-MiniLM-L6-v2")
+
+print("Loading vector database...")
+index = faiss.read_index("vector.index")
+
+with open("documents.txt", "r", encoding="utf-8") as f:
+    documents = [line.strip() for line in f.readlines()]
+
+print("Loading language model...")
+qa_model = pipeline(
+    "text2text-generation",
+    model="google/flan-t5-base",
+    max_new_tokens=120
+)
+
+def ask_bot(question, top_k=3, similarity_threshold=1.0):
+
+    greetings = [
+        "hi", "hello", "hey", "hii", "hola",
+        "good morning", "good evening", "good afternoon"
+    ]
+
+    if question.lower().strip() in greetings:
+        return "Hi 👋 I’m your C++ assistant. What’s on your mind today?"
+
+    # Normal RAG flow
+    q_embedding = embedder.encode([question])
+    distances, indices = index.search(np.array(q_embedding), top_k)
+
+    if distances[0][0] > similarity_threshold:
+        return "I don't know based on the given data."
+
+    context = "\n".join([documents[i] for i in indices[0]])
+
+    prompt = f"""
+Answer the question ONLY using the context below.
+If the answer is not present, reply exactly:
+I don't know based on the given data.
+
+Context:
+{context}
+
+Question:
+{question}
+
+Answer:
+"""
+
+    output = qa_model(prompt)[0]["generated_text"].strip()
+    return output
+
+
+@app.route("/ask", methods=["POST"])
+def ask():
+    data = request.json
+    question = data.get("question", "")
+
+    if not question:
+        return jsonify({"answer": "Please provide a question."})
+
+    answer = ask_bot(question)
+    return jsonify({"answer": answer})
+
+
+# -------------------------------
+@app.route("/feedback", methods=["POST"])
+def feedback():
+    data = request.json
+    message = data.get("feedback", "")
+    user_email = data.get("email", "Not provided")
+
+    YOUR_EMAIL = os.getenv("EMAIL")
+    YOUR_APP_PASSWORD = os.getenv("EMAIL_PASSWORD")
+
+    msg = MIMEText(f"""
+New Feedback Received from C++ Bot 🚀
+
+User Email: {user_email}
+
+Feedback:
+{message}
+""")
+
+    msg["Subject"] = "New Feedback from C++ Bot"
+    msg["From"] = YOUR_EMAIL
+    msg["To"] = YOUR_EMAIL
+
+    try:
+        server = smtplib.SMTP_SSL("smtp.gmail.com", 465)
+        server.login(YOUR_EMAIL, YOUR_APP_PASSWORD)
+        server.send_message(msg)
+        server.quit()
+        return jsonify({"status": "success"})
+    except Exception as e:
+        print("Email error:", e)
+        return jsonify({"status": "error"})
+
+
+import os
+
+if __name__ == "__main__":
+    port = int(os.environ.get("PORT", 7860))
+    app.run(host="0.0.0.0", port=port)

chatbot.py

@@ -0,0 +1,92 @@
+from sentence_transformers import SentenceTransformer
+import faiss
+import numpy as np
+from transformers import pipeline
+
+# -------------------------------
+# Load embedding model
+# -------------------------------
+print("Loading embedding model...")
+embedder = SentenceTransformer("all-MiniLM-L6-v2")
+
+# -------------------------------
+# Load vector database
+# -------------------------------
+print("Loading vector database...")
+index = faiss.read_index("vector.index")
+
+# -------------------------------
+# Load stored documents
+# -------------------------------
+with open("documents.txt", "r", encoding="utf-8") as f:
+    documents = [line.strip() for line in f.readlines()]
+
+# -------------------------------
+# Load language model (correct pipeline)
+# -------------------------------
+print("Loading language model...")
+qa_model = pipeline(
+    "text2text-generation",
+    model="google/flan-t5-base",
+    max_new_tokens=120
+)
+
+# -------------------------------
+# Core QA function (SAFE VERSION)
+# -------------------------------
+def ask_bot(question, top_k=3, similarity_threshold=1.0):
+    # Embed the question
+    q_embedding = embedder.encode([question])
+
+    # Search similar docs
+    distances, indices = index.search(np.array(q_embedding), top_k)
+
+    # If the closest result is too far → no relevant answer
+    if distances[0][0] > similarity_threshold:
+        return "I don't know based on the given data."
+
+    # Retrieve context
+    context = "\n".join([documents[i] for i in indices[0]])
+
+    # Build strict prompt
+    prompt = f"""
+You are a domain question answering assistant.
+Use ONLY the context below.
+If the answer is not clearly present in the context, reply exactly:
+I don't know based on the given data.
+
+Context:
+{context}
+
+Question:
+{question}
+
+Answer:
+"""
+
+    # Generate answer
+    output = qa_model(prompt)[0]["generated_text"].strip()
+
+    # Extra safety: if model still copies context, block it
+    if output.lower().startswith("flask") or output.lower().startswith("react") or output.lower().startswith("seo"):
+        # crude but effective safety fallback
+        if question.lower() not in context.lower():
+            return "I don't know based on the given data."
+
+    return output
+
+
+# -------------------------------
+# Chat loop
+# -------------------------------
+print("\nAI Agent ready. Type 'exit' to quit.\n")
+
+while True:
+    question = input("Ask: ")
+
+    if question.lower() in ["exit", "quit"]:
+        print("Goodbye!")
+        break
+
+    answer = ask_bot(question)
+    print("\nBot:", answer, "\n")

data/data.txt

@@ -0,0 +1,169 @@
+C++ is a general purpose programming language developed by Bjarne Stroustrup as an extension of the C language.
+C++ supports procedural programming, object oriented programming, and generic programming.
+C++ is widely used in system programming, game development, embedded systems, and competitive programming.
+
+A variable in C++ is a named memory location used to store data.
+Common data types in C++ include int, float, double, char, and bool.
+The size of an int is typically 4 bytes on most systems.
+
+The const keyword is used to declare variables whose values cannot be changed.
+The auto keyword allows the compiler to deduce the type of a variable automatically.
+
+Operators in C++ include arithmetic, relational, logical, bitwise, assignment, and conditional operators.
+Arithmetic operators perform addition, subtraction, multiplication, division, and modulus operations.
+
+Control statements include if, else, switch, for, while, and do while.
+The break statement terminates a loop or switch statement.
+The continue statement skips the current iteration of a loop.
+
+A function is a block of code that performs a specific task.
+The main function is the entry point of a C++ program.
+Function overloading allows multiple functions with the same name but different parameters.
+
+An array is a collection of elements of the same data type stored in contiguous memory locations.
+Array indexing in C++ starts from zero.
+A multidimensional array is an array of arrays.
+
+A pointer is a variable that stores the memory address of another variable.
+The address-of operator is represented by the ampersand symbol.
+The dereference operator is represented by the asterisk symbol.
+A null pointer does not point to any valid memory location.
+
+Dynamic memory allocation is performed using new and delete operators.
+The new operator allocates memory on the heap.
+The delete operator deallocates memory previously allocated with new.
+
+A reference is an alias for an existing variable and must be initialized at declaration.
+References cannot be reassigned after initialization.
+
+A structure is a user defined data type that groups variables of different data types.
+Members of a structure are accessed using the dot operator.
+
+A class is a blueprint for creating objects.
+An object is an instance of a class.
+Access specifiers include public, private, and protected.
+
+Encapsulation binds data and methods together and hides implementation details.
+Abstraction exposes only essential features and hides complex implementation.
+Inheritance allows a class to derive properties and methods from another class.
+Polymorphism allows the same function to behave differently in different contexts.
+
+A constructor is a special member function called when an object is created.
+A destructor is a special member function called when an object is destroyed.
+Constructors do not have a return type and have the same name as the class.
+
+The this pointer holds the address of the current object.
+Static data members are shared among all objects of a class.
+
+A virtual function supports runtime polymorphism.
+A base class pointer can point to a derived class object.
+
+The Standard Template Library provides containers, algorithms, and iterators.
+Common STL containers include vector, list, deque, stack, queue, priority_queue, set, map, and unordered_map.
+
+A vector is a dynamic array that resizes automatically.
+A list is a doubly linked list implementation.
+A deque allows insertion and deletion at both ends.
+
+A stack is a linear data structure that follows the Last In First Out principle.
+Common stack operations include push, pop, top, and isEmpty.
+A queue is a linear data structure that follows the First In First Out principle.
+Common queue operations include enqueue, dequeue, front, and rear.
+
+A priority queue stores elements such that the highest priority element is removed first.
+A circular queue connects the end of the queue back to the front.
+
+A linked list is a linear data structure where elements are connected using pointers.
+A singly linked list contains nodes with data and a pointer to the next node.
+A doubly linked list contains pointers to both next and previous nodes.
+A circular linked list connects the last node back to the first node.
+
+A tree is a hierarchical data structure consisting of nodes and edges.
+The root is the topmost node in a tree.
+A binary tree is a tree where each node has at most two children.
+A binary search tree stores elements such that left subtree values are smaller and right subtree values are larger.
+
+Tree traversal methods include inorder, preorder, and postorder traversal.
+A heap is a complete binary tree that satisfies the heap property.
+A max heap stores the largest element at the root.
+A min heap stores the smallest element at the root.
+
+A graph is a collection of vertices and edges.
+Graphs can be directed or undirected.
+Graph traversal methods include breadth first search and depth first search.
+
+Searching algorithms include linear search and binary search.
+Sorting algorithms include bubble sort, selection sort, insertion sort, merge sort, quick sort, and heap sort.
+
+The time complexity of binary search is O(log n).
+The time complexity of merge sort is O(n log n).
+
+An iterator is an object used to traverse elements of a container.
+The begin function returns an iterator to the first element.
+The end function returns an iterator to one past the last element.
+
+The string class stores sequences of characters.
+The length of a string can be obtained using size or length functions.
+
+Exception handling uses try, catch, and throw keywords.
+An exception represents an error condition during program execution.
+
+File handling is performed using ifstream, ofstream, and fstream classes.
+The ifstream class reads from files.
+The ofstream class writes to files.
+
+Templates allow writing generic functions and classes.
+A function template defines a generic function.
+A class template defines a generic class.
+
+Namespaces prevent name conflicts in large programs.
+The std namespace contains standard library identifiers.
+
+Inline functions reduce function call overhead by expanding code at the call site.
+The mutable keyword allows modification of class members in const functions.
+
+The sizeof operator returns the size of a variable or data type in bytes.
+The typedef keyword creates an alias for an existing data type.
+
+The volatile keyword indicates that a variable may change unexpectedly.
+The friend keyword allows access to private members of a class.
+
+Lambda expressions are anonymous functions introduced in C++11.
+Smart pointers include unique_ptr, shared_ptr, and weak_ptr.
+RAII ensures resource acquisition and release using object lifetime.
+
+Move semantics transfers resources efficiently using move constructors.
+The std::move function converts an lvalue into an rvalue reference.
+
+The constexpr keyword evaluates expressions at compile time.
+The nullptr keyword represents a null pointer constant.
+
+Enum class provides scoped and strongly typed enumerations.
+The using keyword creates type aliases and imports names.
+
+The iostream library provides input and output using cin and cout.
+The endl manipulator inserts a newline and flushes the output buffer.
+
+The compilation process includes preprocessing, compilation, linking, and execution.
+The linker combines object files and resolves references.
+
+Multiple inheritance allows a class to inherit from multiple base classes.
+Virtual inheritance avoids duplication in diamond inheritance problems.
+
+A pure virtual function makes a class abstract.
+An abstract class cannot be instantiated.
+
+The static_cast operator performs compile time type conversion.
+The dynamic_cast operator performs runtime type checking.
+
+Const correctness prevents modification of data using const qualifiers.
+
+The thread library provides multithreading support.
+A mutex protects shared data from concurrent access.
+The lock_guard class manages mutex locking automatically.
+
+The chrono library measures time and durations.
+The filesystem library performs file system operations.
+
+Fast input output techniques improve competitive programming performance.
+The ios_base::sync_with_stdio function disables synchronization with C IO for faster execution.

documents.txt

@@ -0,0 +1,122 @@
+C++ is a general purpose programming language developed by Bjarne Stroustrup as an extension of the C language.
+C++ supports procedural programming, object oriented programming, and generic programming.
+C++ is widely used in system programming, game development, embedded systems, and competitive programming.
+A variable in C++ is a named memory location used to store data.
+Common data types in C++ include int, float, double, char, and bool.
+The size of an int is typically 4 bytes on most systems.
+The const keyword is used to declare variables whose values cannot be changed.
+The auto keyword allows the compiler to deduce the type of a variable automatically.
+Operators in C++ include arithmetic, relational, logical, bitwise, assignment, and conditional operators.
+Arithmetic operators perform addition, subtraction, multiplication, division, and modulus operations.
+Control statements include if, else, switch, for, while, and do while.
+The break statement terminates a loop or switch statement.
+The continue statement skips the current iteration of a loop.
+A function is a block of code that performs a specific task.
+The main function is the entry point of a C++ program.
+Function overloading allows multiple functions with the same name but different parameters.
+An array is a collection of elements of the same data type stored in contiguous memory locations.
+Array indexing in C++ starts from zero.
+A multidimensional array is an array of arrays.
+A pointer is a variable that stores the memory address of another variable.
+The address-of operator is represented by the ampersand symbol.
+The dereference operator is represented by the asterisk symbol.
+A null pointer does not point to any valid memory location.
+Dynamic memory allocation is performed using new and delete operators.
+The new operator allocates memory on the heap.
+The delete operator deallocates memory previously allocated with new.
+A reference is an alias for an existing variable and must be initialized at declaration.
+References cannot be reassigned after initialization.
+A structure is a user defined data type that groups variables of different data types.
+Members of a structure are accessed using the dot operator.
+A class is a blueprint for creating objects.
+An object is an instance of a class.
+Access specifiers include public, private, and protected.
+Encapsulation binds data and methods together and hides implementation details.
+Abstraction exposes only essential features and hides complex implementation.
+Inheritance allows a class to derive properties and methods from another class.
+Polymorphism allows the same function to behave differently in different contexts.
+A constructor is a special member function called when an object is created.
+A destructor is a special member function called when an object is destroyed.
+Constructors do not have a return type and have the same name as the class.
+The this pointer holds the address of the current object.
+Static data members are shared among all objects of a class.
+A virtual function supports runtime polymorphism.
+A base class pointer can point to a derived class object.
+The Standard Template Library provides containers, algorithms, and iterators.
+Common STL containers include vector, list, deque, stack, queue, priority_queue, set, map, and unordered_map.
+A vector is a dynamic array that resizes automatically.
+A list is a doubly linked list implementation.
+A deque allows insertion and deletion at both ends.
+A stack is a linear data structure that follows the Last In First Out principle.
+Common stack operations include push, pop, top, and isEmpty.
+A queue is a linear data structure that follows the First In First Out principle.
+Common queue operations include enqueue, dequeue, front, and rear.
+A priority queue stores elements such that the highest priority element is removed first.
+A circular queue connects the end of the queue back to the front.
+A linked list is a linear data structure where elements are connected using pointers.
+A singly linked list contains nodes with data and a pointer to the next node.
+A doubly linked list contains pointers to both next and previous nodes.
+A circular linked list connects the last node back to the first node.
+A tree is a hierarchical data structure consisting of nodes and edges.
+The root is the topmost node in a tree.
+A binary tree is a tree where each node has at most two children.
+A binary search tree stores elements such that left subtree values are smaller and right subtree values are larger.
+Tree traversal methods include inorder, preorder, and postorder traversal.
+A heap is a complete binary tree that satisfies the heap property.
+A max heap stores the largest element at the root.
+A min heap stores the smallest element at the root.
+A graph is a collection of vertices and edges.
+Graphs can be directed or undirected.
+Graph traversal methods include breadth first search and depth first search.
+Searching algorithms include linear search and binary search.
+Sorting algorithms include bubble sort, selection sort, insertion sort, merge sort, quick sort, and heap sort.
+The time complexity of binary search is O(log n).
+The time complexity of merge sort is O(n log n).
+An iterator is an object used to traverse elements of a container.
+The begin function returns an iterator to the first element.
+The end function returns an iterator to one past the last element.
+The string class stores sequences of characters.
+The length of a string can be obtained using size or length functions.
+Exception handling uses try, catch, and throw keywords.
+An exception represents an error condition during program execution.
+File handling is performed using ifstream, ofstream, and fstream classes.
+The ifstream class reads from files.
+The ofstream class writes to files.
+Templates allow writing generic functions and classes.
+A function template defines a generic function.
+A class template defines a generic class.
+Namespaces prevent name conflicts in large programs.
+The std namespace contains standard library identifiers.
+Inline functions reduce function call overhead by expanding code at the call site.
+The mutable keyword allows modification of class members in const functions.
+The sizeof operator returns the size of a variable or data type in bytes.
+The typedef keyword creates an alias for an existing data type.
+The volatile keyword indicates that a variable may change unexpectedly.
+The friend keyword allows access to private members of a class.
+Lambda expressions are anonymous functions introduced in C++11.
+Smart pointers include unique_ptr, shared_ptr, and weak_ptr.
+RAII ensures resource acquisition and release using object lifetime.
+Move semantics transfers resources efficiently using move constructors.
+The std::move function converts an lvalue into an rvalue reference.
+The constexpr keyword evaluates expressions at compile time.
+The nullptr keyword represents a null pointer constant.
+Enum class provides scoped and strongly typed enumerations.
+The using keyword creates type aliases and imports names.
+The iostream library provides input and output using cin and cout.
+The endl manipulator inserts a newline and flushes the output buffer.
+The compilation process includes preprocessing, compilation, linking, and execution.
+The linker combines object files and resolves references.
+Multiple inheritance allows a class to inherit from multiple base classes.
+Virtual inheritance avoids duplication in diamond inheritance problems.
+A pure virtual function makes a class abstract.
+An abstract class cannot be instantiated.
+The static_cast operator performs compile time type conversion.
+The dynamic_cast operator performs runtime type checking.
+Const correctness prevents modification of data using const qualifiers.
+The thread library provides multithreading support.
+A mutex protects shared data from concurrent access.
+The lock_guard class manages mutex locking automatically.
+The chrono library measures time and durations.
+The filesystem library performs file system operations.
+Fast input output techniques improve competitive programming performance.
+The ios_base::sync_with_stdio function disables synchronization with C IO for faster execution.

embeddings.py

@@ -0,0 +1,34 @@
+from sentence_transformers import SentenceTransformer
+import faiss
+import numpy as np
+import os
+
+# Load embedding model
+print("Loading embedding model...")
+model = SentenceTransformer("all-MiniLM-L6-v2")
+
+# Load training data
+data_path = "data/data.txt"
+
+with open(data_path, "r", encoding="utf-8") as f:
+    documents = [line.strip() for line in f.readlines() if line.strip()]
+
+print(f"Loaded {len(documents)} documents")
+
+# Create embeddings
+print("Creating embeddings...")
+embeddings = model.encode(documents)
+
+# Create FAISS index
+dimension = embeddings.shape[1]
+index = faiss.IndexFlatL2(dimension)
+index.add(np.array(embeddings))
+
+# Save index and documents
+faiss.write_index(index, "vector.index")
+
+with open("documents.txt", "w", encoding="utf-8") as f:
+    for doc in documents:
+        f.write(doc + "\n")
+
+print("Vector database created successfully!")

requirements.txt

@@ -0,0 +1,6 @@
+sentence-transformers
+faiss-cpu
+python-dotenv
+transformers
+torch
+gunicorn

templates/index.html

@@ -0,0 +1,382 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  <title>CPP Bot</title>
+  <link rel="icon" type="image/svg+xml" href="{{ url_for('static', filename='favicon.svg') }}">
+<link rel="alternate icon" href="{{ url_for('static', filename='favicon.ico') }}">
+<link rel="apple-touch-icon" href="{{ url_for('static', filename='favicon.png') }}">
+
+  <link href="https://fonts.googleapis.com/css2?family=Inter:wght@300;400;600;700&display=swap" rel="stylesheet">
+
+  <style>
+    * { box-sizing: border-box; font-family: "Inter", sans-serif; }
+
+    body {
+      margin: 0;
+      height: 100vh;
+      background: radial-gradient(circle at top, #0f172a, #020617);
+      display: flex;
+      justify-content: center;
+      align-items: center;
+      overflow: hidden;
+      color: #e5e7eb;
+    }
+
+    .card {
+      width: 420px;
+      height: 620px;
+      background: rgba(2, 6, 23, 0.88);
+      border-radius: 20px;
+      box-shadow: 0 30px 80px rgba(0, 0, 0, 0.6);
+      display: flex;
+      flex-direction: column;
+      overflow: hidden;
+      border: 1px solid rgba(148, 163, 184, 0.15);
+      backdrop-filter: blur(12px);
+      position: relative;
+    }
+
+    /* Header */
+    .header {
+      padding: 16px 20px;
+      background: linear-gradient(135deg, #38bdf8, #818cf8);
+      color: #020617;
+      font-weight: 800;
+      font-size: 1.4rem;
+      letter-spacing: 0.5px;
+      display: flex;
+      justify-content: space-between;
+      align-items: center;
+    }
+
+    .subtitle {
+      font-size: 0.75rem;
+      font-weight: 500;
+      opacity: 0.8;
+      margin-top: 2px;
+    }
+
+    .clear-btn {
+      background: none;
+      border: none;
+      font-size: 1.3rem;
+      cursor: pointer;
+      color: #020617;
+    }
+
+    /* Chat area */
+    #messages {
+      flex: 1;
+      padding: 20px;
+      overflow-y: auto;
+      display: flex;
+      flex-direction: column;
+      gap: 12px;
+    }
+
+    /* Message bubbles */
+    .bubble {
+      max-width: 80%;
+      padding: 12px 14px;
+      border-radius: 14px;
+      line-height: 1.4;
+      animation: fadeIn 0.3s ease;
+    }
+
+    .user {
+      align-self: flex-end;
+      background: linear-gradient(135deg, #38bdf8, #60a5fa);
+      color: #020617;
+      border-bottom-right-radius: 4px;
+    }
+
+    .bot {
+      align-self: flex-start;
+      background: #0f172a;
+      color: #a7f3d0;
+      border: 1px solid rgba(148, 163, 184, 0.15);
+      border-bottom-left-radius: 4px;
+    }
+
+    /* Input bar */
+    .input-bar {
+      display: flex;
+      padding: 14px;
+      border-top: 1px solid rgba(148, 163, 184, 0.15);
+      background: rgba(2, 6, 23, 0.95);
+    }
+
+    .input-bar input {
+      flex: 1;
+      padding: 10px 12px;
+      border-radius: 10px;
+      border: none;
+      outline: none;
+      background: #020617;
+      color: white;
+      font-size: 0.95rem;
+    }
+
+    .input-bar button {
+      margin-left: 10px;
+      padding: 10px 16px;
+      border-radius: 10px;
+      border: none;
+      cursor: pointer;
+      background: linear-gradient(135deg, #38bdf8, #818cf8);
+      color: #020617;
+      font-weight: 600;
+      transition: transform 0.2s ease, box-shadow 0.2s ease;
+    }
+
+    .input-bar button:hover {
+      transform: translateY(-2px);
+      box-shadow: 0 6px 20px rgba(56, 189, 248, 0.5);
+    }
+
+    /* Footer */
+    .footer {
+      padding: 10px 14px;
+      display: flex;
+      justify-content: space-between;
+      align-items: center;
+      border-top: 1px solid rgba(148, 163, 184, 0.15);
+      background: rgba(2, 6, 23, 0.95);
+      font-size: 0.75rem;
+    }
+
+    .footer button {
+      background: none;
+      border: none;
+      color: #93c5fd;
+      cursor: pointer;
+      margin-right: 10px;
+    }
+
+    .footer button:hover { text-decoration: underline; }
+
+    /* Buy Me a Coffee */
+    .coffee {
+      position: fixed;
+      bottom: 20px;
+      right: 20px;
+      background: #facc15;
+      color: #020617;
+      padding: 12px 16px;
+      border-radius: 30px;
+      font-weight: 700;
+      text-decoration: none;
+      box-shadow: 0 10px 30px rgba(250, 204, 21, 0.5);
+      transition: transform 0.2s ease;
+      z-index: 999;
+    }
+
+    .coffee:hover { transform: translateY(-3px) scale(1.05); }
+
+    /* Modals */
+    .modal {
+      position: fixed;
+      inset: 0;
+      background: rgba(0, 0, 0, 0.6);
+      display: none;
+      justify-content: center;
+      align-items: center;
+      z-index: 1000;
+    }
+
+    .modal-content {
+      width: 360px;
+      background: #020617;
+      padding: 20px;
+      border-radius: 14px;
+      border: 1px solid rgba(148, 163, 184, 0.2);
+      position: relative;
+    }
+
+    .close-modal {
+      position: absolute;
+      top: 10px;
+      right: 12px;
+      background: none;
+      border: none;
+      font-size: 1.2rem;
+      cursor: pointer;
+      color: #93c5fd;
+    }
+
+    .modal-content h3 { margin-top: 0; color: #38bdf8; }
+
+    .modal-content textarea,
+    .modal-content input {
+      width: 100%;
+      margin-top: 10px;
+      padding: 8px;
+      border-radius: 6px;
+      border: none;
+      outline: none;
+      background: #0f172a;
+      color: white;
+    }
+
+    .modal-content button.submit-btn {
+      margin-top: 12px;
+      padding: 8px 14px;
+      border-radius: 8px;
+      border: none;
+      cursor: pointer;
+      background: linear-gradient(135deg, #38bdf8, #818cf8);
+      color: #020617;
+      font-weight: 600;
+    }
+
+    @keyframes fadeIn {
+      from { opacity: 0; transform: translateY(4px); }
+      to { opacity: 1; transform: translateY(0); }
+    }
+  </style>
+</head>
+<body>
+
+  <div class="card">
+
+    <div class="header">
+      <div>
+        C++ Bot
+        <div class="subtitle">Domain‑Trained C++ AI Assistant</div>
+      </div>
+      <button class="clear-btn" onclick="clearChat()" title="Clear chat">🗑️</button>
+    </div>
+
+    <div id="messages"></div>
+
+    <div class="input-bar">
+      <input id="question" placeholder="Ask a C++ question…" />
+      <button onclick="sendQuestion()">Send</button>
+    </div>
+
+    <div class="footer">
+      <div>
+        <button onclick="openAbout()">About</button>
+        <button onclick="openFeedback()">Feedback</button>
+      </div>
+      <div>© 2026 C++ Bot</div>
+    </div>
+
+  </div>
+
+  <!-- Buy Me a Coffee -->
+  <a class="coffee" href="https://buymeacoffee.com/siddharthmishra?status=1" target="_blank">☕ Buy me a coffee</a>
+
+  <!-- About Modal -->
+  <div class="modal" id="aboutModal" onclick="backdropClose(event, 'aboutModal')">
+    <div class="modal-content">
+      <button class="close-modal" onclick="closeAbout()">✖</button>
+      <h3>About C++ Bot</h3>
+      <p>This is a domain‑trained AI assistant built using Retrieval Augmented Generation with FAISS, Transformers, and Flask. It answers only from a curated C++ knowledge base.</p>
+    </div>
+  </div>
+
+  <!-- Feedback Modal -->
+  <div class="modal" id="feedbackModal" onclick="backdropClose(event, 'feedbackModal')">
+    <div class="modal-content">
+      <button class="close-modal" onclick="closeFeedback()">✖</button>
+      <h3>Send Feedback</h3>
+      <input id="email" placeholder="Your email (optional)" />
+      <textarea id="feedback" rows="5" placeholder="Your suggestion or feedback..."></textarea>
+      <button class="submit-btn" onclick="submitFeedback()">Submit</button>
+    </div>
+  </div>
+
+  <script>
+    const messages = document.getElementById("messages");
+    const input = document.getElementById("question");
+
+    input.addEventListener("keydown", function (e) {
+      if (e.key === "Enter") sendQuestion();
+    });
+
+    document.addEventListener("keydown", function (e) {
+      if (e.key === "Escape") {
+        closeAbout();
+        closeFeedback();
+      }
+    });
+
+    function addMessage(text, type) {
+      const div = document.createElement("div");
+      div.className = `bubble ${type}`;
+      div.textContent = text;
+      messages.appendChild(div);
+      messages.scrollTop = messages.scrollHeight;
+    }
+
+    function clearChat() {
+      if (confirm("Clear the chat?")) {
+        messages.innerHTML = "";
+      }
+    }
+
+    async function sendQuestion() {
+      const question = input.value.trim();
+      if (!question) return;
+
+      addMessage(question, "user");
+      input.value = "";
+
+      const typing = document.createElement("div");
+      typing.className = "bubble bot";
+      typing.textContent = "AI is thinking…";
+      messages.appendChild(typing);
+      messages.scrollTop = messages.scrollHeight;
+
+      try {
+        const response = await fetch("/ask", {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ question })
+        });
+
+        const data = await response.json();
+        messages.removeChild(typing);
+        addMessage(data.answer, "bot");
+
+      } catch (error) {
+        messages.removeChild(typing);
+        addMessage("Server error. Please try again.", "bot");
+      }
+    }
+
+    function openAbout() { document.getElementById("aboutModal").style.display = "flex"; }
+    function closeAbout() { document.getElementById("aboutModal").style.display = "none"; }
+    function openFeedback() { document.getElementById("feedbackModal").style.display = "flex"; }
+    function closeFeedback() { document.getElementById("feedbackModal").style.display = "none"; }
+
+    function backdropClose(event, modalId) {
+      if (event.target.id === modalId) {
+        document.getElementById(modalId).style.display = "none";
+      }
+    }
+
+    async function submitFeedback() {
+      const feedback = document.getElementById("feedback").value;
+      const email = document.getElementById("email").value;
+
+      if (!feedback) return alert("Please write some feedback first.");
+
+      await fetch("/feedback", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ feedback, email })
+      });
+
+      alert("Thank you for your feedback! 💙");
+      document.getElementById("feedback").value = "";
+      document.getElementById("email").value = "";
+      closeFeedback();
+    }
+  </script>
+
+</body>
+</html>