diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1253db0..d094ad3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,39 +1,37 @@
-name: C++ Build
+name: C++ CI
 
 on:
   push:
+    branches: [main]
   pull_request:
+    branches: [main]
 
 jobs:
-  build:
+  build-and-run:
     runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        compiler: [g++]
-
+    env:
+      ASAN_OPTIONS: detect_leaks=1  # automatically detect memory leaks
     steps:
-      - name: Checkout repo
+      # 1. Checkout repo
+      - name: Checkout code
         uses: actions/checkout@v4
 
+      # 2. Install build tools
       - name: Install build tools
         run: |
           sudo apt-get update
-          sudo apt-get install -y build-essential
-
-      - name: Build all examples
-        run: |
-          make
+          sudo apt-get install -y build-essential g++ clang
 
-      - name: Run examples
+      # 3. Build and run all examples dynamically
+      - name: Build and Run
         run: |
-          for dir in */ ; do
-            if [ -f "$dir/Makefile" ]; then
-              echo "Running $dir"
-              (cd "$dir" && make run || true)
-            fi
+          for san in address thread undefined; do
+            echo "=== Building all examples with sanitizer $san ==="
+            make SANITIZE=$san
+            echo "=== Running all examples with sanitizer $san ==="
+            make run
           done
 
-      - name: Clean
+      - name: Clean up build artifacts
         run: |
           make clean
diff --git a/.gitignore b/.gitignore
index b8d81fd..5a0b7ba 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,17 @@
-.o
+# Object files
+*.o
+
+# Executable
+thread_safe_queue
+unique_ptr_basics
+*.out
+
+# Backup files
+*~
+*.swp
+
+# CMake / IDE files
+CMakeFiles/
+CMakeCache.txt
+*.idea/
+*.vscode/
diff --git a/Makefile b/Makefile
index abd5875..9ef44ba 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,37 @@
+# ======================================
+# Top-level Makefile for cpp-coding-exercise
+# ======================================
+
+# Auto-detect all subdirectories that contain a Makefile
 SUBDIRS := $(dir $(wildcard */Makefile))
 
-.PHONY: all clean $(SUBDIRS)
+# Default sanitizer (can be overridden)
+SANITIZE ?= address
+
+.PHONY: all clean run $(SUBDIRS)
 
+# --------------------------
+# Build all examples
+# --------------------------
 all: $(SUBDIRS)
 
 $(SUBDIRS):
-	$(MAKE) -C $@
+	@echo "=== Building $@ with SANITIZE=$(SANITIZE) ==="
+	$(MAKE) -C $@ SANITIZE=$(SANITIZE)
+
+# --------------------------
+# Run all examples (optional)
+# --------------------------
+run:
+	@for dir in $(SUBDIRS); do \
+		echo "=== Running $$dir ==="; \
+		(cd $$dir && $(MAKE) SANITIZE=$(SANITIZE) run) || exit 1; \
+	done
 
+# --------------------------
+# Clean all examples
+# --------------------------
 clean:
-	for dir in $(SUBDIRS); do \
+	@for dir in $(SUBDIRS); do \
 		$(MAKE) -C $$dir clean; \
 	done
diff --git a/README.md b/README.md
index bfa8645..644c8c0 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,7 @@ Runnable examples expose a `run` target:
 make run
 ```
 
-This keeps CI safe (build-only by default) while allowing local execution.
+`make run` on top level will run all built targets.
 
 ---
 
@@ -97,11 +97,11 @@ make clean
 
 ## Shared build configuration
 
-Common compiler settings live in `common.mk`:
+Common compiler settings live in [common.mk](./common.mk):
 
 ```make
 CXX      := g++
-CXXFLAGS := -std=c++20 -O2 -Wall -Wextra
+CXXFLAGS := -std=c++20 -Wall -Wextra
 ```
 
 Individual examples may extend this, e.g.:
@@ -112,6 +112,25 @@ CXXFLAGS += -pthread
 
 ---
 
+## Address Sanitizer Check
+The Address Sanitizer is enabled by default to ensure there is no memory leaks or other memory problems.
+
+```make
+# Builds with AddressSanitizer automatically
+make
+
+# ThreadSanitizer
+make SANITIZE=thread
+
+# UndefinedBehaviorSanitizer
+make SANITIZE=undefined
+
+# No sanitizers
+make SANITIZE=
+```
+
+---
+
 ## Continuous Integration
 
 GitHub Actions automatically builds all examples on:
diff --git a/common.mk b/common.mk
index 79f1337..e1b2520 100644
--- a/common.mk
+++ b/common.mk
@@ -1,2 +1,48 @@
+# ======================================
+# common.mk - shared compiler flags
+# ======================================
+
 CXX      := g++
-CXXFLAGS := -std=c++20 -O2 -Wall -Wextra
+OPTFLAGS ?= -O1 -g           # Safe for ASAN/TSAN (default)
+
+# --------------------------
+# Sanitizer selection
+# --------------------------
+# Default: AddressSanitizer
+SANITIZE ?= address
+
+ifeq ($(SANITIZE),address)
+    SAN_FLAGS := -fsanitize=address
+else ifeq ($(SANITIZE),thread)
+    SAN_FLAGS := -fsanitize=thread
+else ifeq ($(SANITIZE),undefined)
+    SAN_FLAGS := -fsanitize=undefined
+else ifeq ($(SANITIZE),)
+    SAN_FLAGS :=
+else
+    $(error Unknown SANITIZE=$(SANITIZE))
+endif
+
+# --------------------------
+# Compiler / Linker flags
+# --------------------------
+CXXFLAGS := -std=c++20 -Wall -Wextra $(OPTFLAGS) $(SAN_FLAGS)
+LDFLAGS  := $(SAN_FLAGS)
+
+# --------------------------
+# Usage notes
+# --------------------------
+# Local build (default): ASAN enabled
+#   $ make
+#
+# Override for ThreadSanitizer:
+#   $ make SANITIZE=thread
+#
+# Override for UBSAN:
+#   $ make SANITIZE=undefined
+#
+# Disable sanitizers (rare):
+#   $ make SANITIZE=
+#
+# LDFLAGS are automatically applied in example Makefiles:
+#   $(CXX) $(CXXFLAGS) -o $(TARGET) $(OBJS) $(LDFLAGS)