diff --git a/.githooks/commit-msg b/.githooks/commit-msg
new file mode 100755
index 0000000..0679578
--- /dev/null
+++ b/.githooks/commit-msg
@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# .githooks/commit-msg — enforces conventional commit format
+# Format: type: description  OR  type(scope): description
+set -euo pipefail
+
+RED='\033[0;31m'; YELLOW='\033[1;33m'; NC='\033[0m'
+
+VALID_TYPES="feat|fix|docs|chore|test|refactor|perf|ci|build"
+MSG_FILE="$1"
+MSG=$(head -1 "$MSG_FILE")
+
+if [[ -z "${MSG// }" ]]; then
+    echo -e "${RED}Commit rejected:${NC} Commit message is empty."
+    exit 1
+fi
+
+if ! echo "$MSG" | grep -qE "^($VALID_TYPES)(\(.+\))?: .+"; then
+    echo -e "${RED}Commit rejected:${NC} Message does not follow conventional commit format."
+    echo ""
+    echo -e "  Required: ${YELLOW}type: description${NC}  or  ${YELLOW}type(scope): description${NC}"
+    echo -e "  Valid types: ${YELLOW}$VALID_TYPES${NC}"
+    echo ""
+    echo -e "  Your message: ${YELLOW}$MSG${NC}"
+    echo ""
+    echo -e "  Examples:"
+    echo -e "    ${YELLOW}feat: add cover letter refinement${NC}"
+    echo -e "    ${YELLOW}fix(wizard): handle missing user.yaml gracefully${NC}"
+    echo -e "    ${YELLOW}docs: update tier system reference${NC}"
+    exit 1
+fi
+
+exit 0
diff --git a/tests/test_hooks.sh b/tests/test_hooks.sh
index b48358c..7683fce 100755
--- a/tests/test_hooks.sh
+++ b/tests/test_hooks.sh
@@ -48,3 +48,30 @@ run_hook_with "app/app.py" "import streamlit" && pass "allowed safe file" || \
     fail "should have allowed safe file"
 
 echo "All pre-commit hook tests passed."
+
+# ── commit-msg hook tests ────────────────────────────────────────────────────
+COMMIT_HOOK=".githooks/commit-msg"
+tmpfile=$(mktemp)
+
+echo "Test 5: accepts valid feat message"
+echo "feat: add thing" > "$tmpfile"
+bash "$COMMIT_HOOK" "$tmpfile" && pass "accepted feat" || fail "rejected valid feat"
+
+echo "Test 6: accepts valid fix with scope"
+echo "fix(auth): handle token expiry" > "$tmpfile"
+bash "$COMMIT_HOOK" "$tmpfile" && pass "accepted fix(scope)" || fail "rejected valid fix(scope)"
+
+echo "Test 7: rejects empty message"
+echo "" > "$tmpfile"
+bash "$COMMIT_HOOK" "$tmpfile" && fail "should reject empty" || pass "rejected empty"
+
+echo "Test 8: rejects non-conventional message"
+echo "updated the thing" > "$tmpfile"
+bash "$COMMIT_HOOK" "$tmpfile" && fail "should reject non-conventional" || pass "rejected non-conventional"
+
+echo "Test 9: rejects invalid type"
+echo "yolo: ship it" > "$tmpfile"
+bash "$COMMIT_HOOK" "$tmpfile" && fail "should reject invalid type" || pass "rejected invalid type"
+
+rm -f "$tmpfile"
+echo "All commit-msg hook tests passed."