diff --git a/README.md b/README.md
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+++ b/README.md
@@ -58,9 +58,9 @@ This repository was created to:
 
 ## 🚀 Phase 3 — CI/CD
 
-- [ ] GitHub Actions
-- [ ] Automated Testing
-- [ ] Continuous Integration
+- [x] GitHub Actions
+- [x] Automated Testing
+- [x] Continuous Integration
 - [ ] Continuous Deployment
 - [ ] Deployment Pipelines
 
diff --git a/checkpoints/checkpoint-10-github-actions-automated-testing-and-ci.md b/checkpoints/checkpoint-10-github-actions-automated-testing-and-ci.md
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@@ -0,0 +1,391 @@
+Checkpoint 09 — GitHub Actions, Automated Testing & Continuous Integration
+Objective
+
+Understand how GitHub Actions automates software validation by creating temporary runners that install dependencies, execute tests, and build applications whenever code is pushed.
+
+This checkpoint introduces the foundations of Continuous Integration (CI).
+
+Why this checkpoint matters
+
+Before this checkpoint, software development looked like this:
+
+Write code
+↓
+Run project manually
+↓
+Hope nothing broke
+
+After this checkpoint:
+
+Write code
+↓
+git push
+↓
+GitHub automatically verifies everything
+↓
+Pass / Fail
+
+This is the foundation of:
+
+CI/CD
+DevOps
+Cloud deployment
+Team collaboration
+Production pipelines
+Main Questions
+
+We asked:
+
+How does GitHub automatically run commands?
+What is a workflow?
+What is a runner?
+How does GitHub know if code is broken?
+How do tests stop deployments?
+How can GitHub build Docker images?
+Step 1 — Create the Workflow Directory
+
+GitHub only scans workflows inside:
+
+.github/workflows/
+
+Repository structure:
+
+DevSecOps-Learning-Lab/
+
+├── .github/
+│ └── workflows/
+│ └── hello.yml
+│
+├── checkpoints/
+├── labs/
+└── README.md
+Step 2 — Create the First Workflow
+
+File:
+
+.github/workflows/hello.yml
+
+Code:
+
+name: My First Workflow
+
+on: push
+
+jobs:
+hello:
+runs-on: ubuntu-latest
+
+    steps:
+      - name: Say hello
+        run: echo "Hello from GitHub Actions!"
+
+What happens internally?
+
+When running:
+
+git push
+
+GitHub performs:
+
+git push
+↓
+GitHub receives new code
+↓
+Checks .github/workflows/
+↓
+Creates an Ubuntu runner
+↓
+Runs workflow steps
+↓
+Destroys the runner
+GitHub Runner Mental Model
+
+A runner is:
+
+Temporary machine
+
+GitHub provides:
+
+Ubuntu
+Windows
+macOS
+
+Example:
+
+runs-on: ubuntu-latest
+Step 3 — Install Node.js
+
+Workflow:
+
+- uses: actions/setup-node@v4
+
+  with:
+  node-version: 24
+
+This prepares Node.js inside the GitHub runner.
+
+Connection to Docker:
+
+Docker GitHub Actions
+FROM node:24 node-version: 24
+Step 4 — Understanding uses
+
+Example:
+
+- uses: actions/checkout@v4
+
+This action:
+
+Clones the repository
+
+inside the runner.
+
+Without checkout:
+
+GitHub runner has no access to project files.
+Step 5 — Create the Testing Lab
+
+Structure:
+
+labs/github-actions/testing-lab/
+
+├── math.js
+├── math.test.js
+└── package.json
+math.js
+function sum(a, b) {
+return a + b;
+}
+
+module.exports = sum;
+math.test.js
+const sum = require("./math");
+
+if (sum(2, 3) !== 5) {
+throw new Error("❌ Test failed!");
+}
+
+console.log("✅ Test passed!");
+package.json
+
+Original:
+
+"test": "echo \"Error: no test specified\" && exit 1"
+
+Updated:
+
+"scripts": {
+"test": "node math.test.js"
+}
+
+Run:
+
+npm test
+
+Output:
+
+✅ Test passed!
+Step 6 — Add Automated Testing to GitHub Actions
+
+Workflow:
+
+name: Node CI
+
+on: push
+
+jobs:
+test:
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+
+      - name: Install dependencies
+        run: npm install
+        working-directory: labs/github-actions/testing-lab
+
+      - name: Run tests
+        run: npm test
+        working-directory: labs/github-actions/testing-lab
+
+CI Pipeline
+git push
+↓
+GitHub runner starts
+↓
+Checkout repository
+↓
+Setup Node.js
+↓
+npm install
+↓
+npm test
+↓
+Success / Failure
+Step 7 — Break the Code
+
+Modified:
+
+function sum(a, b) {
+return a - b;
+}
+
+Workflow output:
+
+Error: ❌ Test failed!
+
+Process completed with exit code 1.
+Exit Codes
+
+Linux programs communicate using exit codes.
+
+Exit Code Meaning
+0 Success
+1 Failure
+
+Connection to Docker:
+
+Exited (0)
+
+Exited (1)
+
+GitHub uses the same mechanism:
+
+Exit code 0 → Workflow succeeds
+
+Exit code 1 → Workflow fails
+Continuous Integration (CI)
+
+CI means:
+
+Code changes are automatically verified.
+
+Pipeline:
+
+Developer pushes code
+↓
+GitHub runs tests
+↓
+Tests pass?
+↓
+YES → Continue
+
+NO → Stop
+Step 8 — Build Docker Images in GitHub
+
+Workflow:
+
+- name: Build Docker image
+  run: |
+  docker build \
+   -t my-first-image \
+   labs/docker/dockerfile-lab
+
+GitHub automatically executed:
+
+docker build -t my-first-image labs/docker/dockerfile-lab
+
+inside the Ubuntu runner.
+
+Full CI Pipeline
+git push
+↓
+GitHub receives code
+↓
+Create Ubuntu runner
+↓
+Checkout repository
+↓
+Setup Node.js
+↓
+npm install
+↓
+npm test
+↓
+docker build
+↓
+Workflow result
+Mental Models Built
+Concept Mental Model
+Workflow Recipe
+Runner Temporary machine
+Job Mission
+Step Task
+Test Safety check
+Exit code Pass / Fail signal
+CI Pipeline Quality-control assembly line
+Commands Learned
+
+Create workflow:
+
+mkdir -p .github/workflows
+
+Run tests:
+
+npm test
+
+Initialize Node:
+
+npm init -y
+
+Push code:
+
+git add .
+
+git commit -m "test(ci): add automated Node.js tests"
+
+git push
+Biggest Lesson
+
+Continuous Integration is not magic.
+
+GitHub automatically:
+
+Creates machines
+Downloads code
+Installs dependencies
+Runs tests
+Builds applications
+Builds Docker images
+
+and blocks broken code from moving forward.
+
+Connection to Future Topics
+
+This checkpoint bridges:
+
+GitHub Actions
+↓
+Continuous Integration
+↓
+Docker
+↓
+Continuous Deployment
+↓
+Cloud Platforms
+↓
+Kubernetes
+Questions Asked During the Lab
+What is a runner?
+What does uses: mean?
+Why does GitHub create Ubuntu machines?
+How does GitHub know if code is broken?
+Why do tests stop the workflow?
+What are exit codes?
+How does GitHub build Docker images?
+How does CI protect deployments?
+Biggest Discovery
+
+GitHub Actions is not just automation.
+
+It is a system that continuously proves:
+
+"This code works."
+
+before software reaches production. 🚀