diff --git a/.githooks/commit-msg b/.githooks/commit-msg
new file mode 100755
index 0000000..90978cd
--- /dev/null
+++ b/.githooks/commit-msg
@@ -0,0 +1,15 @@
+#!/bin/sh
+set -eu
+
+subject=$(head -n 1 "$1")
+pattern='^de\((python|sql|dsa|pyspark|kafka|databricks|system-design)\): \[(prep|project)\] ([^[:space:]].*[^[:space:]]|[^[:space:]])$'
+if ! printf '%s\n' "$subject" | grep -Eq "$pattern"; then
+  cat >&2 <<'EOF'
+Invalid commit subject. Use:
+  de(<python|sql|dsa|pyspark|kafka|databricks|system-design>): [<prep|project>] <short description>
+Example:
+  de(sql): [prep] solve rolling revenue query
+See https://github.com/minhazalam/data-engineering-interview-prep/blob/main/docs/commit-message-policy.md for setup and details.
+EOF
+  exit 1
+fi
diff --git a/.github/workflows/de-commit-policy.yml b/.github/workflows/de-commit-policy.yml
new file mode 100644
index 0000000..bbffa8f
--- /dev/null
+++ b/.github/workflows/de-commit-policy.yml
@@ -0,0 +1,14 @@
+name: Validate DE commit messages
+
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  validate:
+    uses: minhazalam/data-engineering-interview-prep/.github/workflows/validate-de-commit-messages.yml@1fe4838abed2fefeb5e118eb713e1439e9a328e9
+    with:
+      base: ${{ github.event.pull_request.base.sha }}
+      head: ${{ github.event.pull_request.head.sha }}