diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e69d223..7a6399b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,3 +29,29 @@ jobs:
       - name: Run pytest
         # moto mocks DynamoDB — no AWS credentials required
         run: PYTHONPATH=. pytest tests/test_exclusao.py -v
+
+  synth:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          cache: pip
+          cache-dependency-path: cdk/requirements.txt
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+
+      - name: Install CDK Python deps
+        run: pip install -r cdk/requirements.txt
+
+      - name: CDK synth
+        # No deploy; placeholder account/region — no AWS credentials
+        env:
+          CDK_DEFAULT_ACCOUNT: "111111111111"
+          CDK_DEFAULT_REGION: us-east-1
+          AWS_DEFAULT_REGION: us-east-1
+        run: npx --yes aws-cdk@2 synth
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..bf4d751
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,11 @@
+.PHONY: check test synth
+
+# Same pytest command as CI job `test`
+test:
+	PYTHONPATH=. pytest tests/test_exclusao.py -v
+
+# Requires: pip install -r cdk/requirements.txt + Node (npx)
+synth:
+	npx --yes aws-cdk@2 synth
+
+check: test synth
diff --git a/README.md b/README.md
index 36c7617..793ed06 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,16 @@ PYTHONPATH=. pytest tests/test_exclusao.py -v
 
 Usa **moto** (sem AWS real). O pacote `lambda/` importa via `importlib` (nome reservado).
 
-CI (GitHub Actions): mesmo comando em Python 3.12 em todo PR/`push` na `main` — sem credenciais AWS no runner.
+CI (GitHub Actions): job `test` (pytest+moto, Python 3.12) e job `synth` (`npx aws-cdk@2 synth`, sem deploy) em todo PR/`push` na `main` — sem credenciais AWS no runner.
+
+### Check local
+
+```bash
+pip install -r requirements.txt -r cdk/requirements.txt
+make check   # pytest (igual ao CI) + npx aws-cdk@2 synth (sem deploy)
+```
+
+Requer Node (para `npx`). Só `make test` ou `make synth` se quiser isolar.
 
 ---