diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 00000000..d0863fdd
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install dependencies
+        run: pip install -r requirements.txt
+
+      - name: Run tests
+        run: pytest -v
diff --git a/.github/workflows/pr-review.yml b/.github/workflows/pr-review.yml
new file mode 100644
index 00000000..1bbebca3
--- /dev/null
+++ b/.github/workflows/pr-review.yml
@@ -0,0 +1,56 @@
+name: AI Code Review
+
+on:
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  review:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install dependencies
+        run: pip install -r requirements.txt
+
+      - name: Get PR diff
+        run: |
+          git diff origin/main...HEAD > pr_diff.txt
+
+      - name: Run AI review
+        id: ai-review
+        env:
+          GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
+        run: |
+          REVIEW=$(python scripts/ai_review.py pr_diff.txt)
+          echo "review<<EOF" >> $GITHUB_OUTPUT
+          echo "$REVIEW" >> $GITHUB_OUTPUT
+          echo "EOF" >> $GITHUB_OUTPUT
+
+      - name: Post review comment
+        uses: actions/github-script@v7
+        env:
+          REVIEW: ${{ steps.ai-review.outputs.review }}
+        with:
+          script: |
+            const review = process.env.REVIEW;
+
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `## 🤖 AI Code Review\n\n${review}\n\n---\n*Powered by Gemini AI*`
+            });
diff --git a/app.py b/app.py
index 8f2f7ae1..86919caf 100644
--- a/app.py
+++ b/app.py
@@ -14,3 +14,7 @@ def is_even(n: int) -> bool:
 def reverse_string(s: str) -> str:
     """Reverse a string."""
     return s[::-1]
+
+def multiply(a: int, b: int) -> int:
+    """Multiply two numbers together."""
+    return a * b
\ No newline at end of file
diff --git a/dangerous.py b/dangerous.py
new file mode 100644
index 00000000..86d316f3
--- /dev/null
+++ b/dangerous.py
@@ -0,0 +1,10 @@
+import subprocess
+import shlex
+import os
+
+def run_command(user_input):
+    """Run a shell command safely."""
+    args = shlex.split(user_input)
+    subprocess.call(args, shell=False)
+
+API_KEY = os.environ.get("API_KEY")
diff --git a/requirements.txt b/requirements.txt
index 5f456517..389d026e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
 # Production dependencies (none for this simple app)
+google-genai>=1.0.0
 
 # Development/testing dependencies
 pytest>=7.0.0
diff --git a/scripts/ai_review.py b/scripts/ai_review.py
new file mode 100644
index 00000000..078a0fc5
--- /dev/null
+++ b/scripts/ai_review.py
@@ -0,0 +1,41 @@
+from google import genai
+import sys
+
+client = genai.Client()
+
+# Define a function that takes a code diff as input
+def review_code(diff_text):
+    prompt = f"""Act as a code reviewer. Here is a code diff:
+
+{diff_text}
+
+Review for:
+- Security issues
+- Bugs
+- Performance issues
+- Code style issues
+- Code readability issues
+- Code maintainability issues
+"""
+
+    response = client.models.generate_content(
+        model="gemini-2.5-flash",
+        contents=prompt,
+    )
+
+    return response.text
+
+# Only run this code when the script is executed directly
+if __name__ == "__main__":
+    # Check if a filename was passed as a command-line argument
+    if len(sys.argv) > 1:
+        diff_file = sys.argv[1]
+        with open(diff_file, "r", encoding="utf-8") as f:
+            diff_content = f.read()
+    else:
+        # If no filename was passed, read from standard input
+        diff_content = sys.stdin.read()
+
+    # Call the review function and print the result
+    review = review_code(diff_content)  # fixed name
+    print(review)
diff --git a/scripts/sample_diff.txt b/scripts/sample_diff.txt
new file mode 100644
index 00000000..d4b5984b
--- /dev/null
+++ b/scripts/sample_diff.txt
@@ -0,0 +1,17 @@
+diff --git a/app.py b/app.py
+index 1234567..abcdefg 100644
+--- a/app.py
++++ b/app.py
+@@ -1,5 +1,12 @@
+ """Simple utility functions"""
+
++import sqlite3
++
++def get_user(username):
++    conn = sqlite3.connect("users.db")
++    query = f"SELECT * FROM users WHERE name = '{username}'"
++    return conn.execute(query).fetchone()
++
+ def add(a: int, b: int) -> int:
+     """Add two numbers together."""
+     return a + b
diff --git a/tests/test_app.py b/tests/test_app.py
index 79c3e093..32cf991b 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -1,6 +1,6 @@
 """Tests for app.py - you'll add more!"""
 
-from app import add, is_even, reverse_string
+from app import add, is_even, reverse_string, multiply
 
 
 class TestMath:
@@ -22,3 +22,16 @@ def test_reverse(self):
     def test_is_even(self):
         assert is_even(4) is True
         assert is_even(3) is False
+
+class TestMultiply:
+    """Tests for multiply function."""
+
+    def test_multiply_positive(self):
+        assert multiply(2, 3) == 6
+    
+    def test_multiply_by_zero(self):
+        assert multiply(0, 10) == 0
+    
+    def test_multiply_by_negative(self):
+        assert multiply(-1, -1) == 1
+