diff --git a/.github/workflows/reusable-quality.yml b/.github/workflows/reusable-quality.yml
index 8566a01..bb832c8 100644
--- a/.github/workflows/reusable-quality.yml
+++ b/.github/workflows/reusable-quality.yml
@@ -8,6 +8,11 @@ on:
         required: false
         default: 0
         type: number
+      run-hygiene-check:
+        description: Run generic repository hygiene checks.
+        required: false
+        default: true
+        type: boolean
       setup-node:
         description: Enable Node.js setup.
         required: false
@@ -60,6 +65,11 @@ jobs:
         with:
           fetch-depth: ${{ inputs.checkout-fetch-depth }}
 
+      - name: Repository hygiene
+        if: ${{ inputs.run-hygiene-check }}
+        shell: bash
+        run: bash scripts/hygiene.sh
+
       - name: Set up Node.js
         if: ${{ inputs.setup-node }}
         uses: actions/setup-node@v4
diff --git a/docs/DEVEX.md b/docs/DEVEX.md
index 9e1f1a6..fea815b 100644
--- a/docs/DEVEX.md
+++ b/docs/DEVEX.md
@@ -44,6 +44,21 @@ Template repositories should support these task names when applicable:
 - `lint` for static analysis
 - `test` for automated tests
 
+Generic validation is always available through:
+
+```bash
+bash scripts/hygiene.sh
+```
+
+The hygiene check is stack-agnostic and currently verifies:
+
+- required template files are present
+- shell scripts parse successfully
+- unresolved merge markers are not present
+- Markdown files start with a top-level heading
+
+`bash scripts/validate.sh` runs the generic hygiene checks first, then runs project-specific package commands when a supported project setup is present.
+
 The reusable GitHub Actions workflow can call custom commands for each project. Local validation should stay simple and safe to run repeatedly.
 
 ## Debugging workflow
diff --git a/scripts/hygiene.sh b/scripts/hygiene.sh
new file mode 100644
index 0000000..21909fb
--- /dev/null
+++ b/scripts/hygiene.sh
@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+failures=0
+
+report_failure() {
+  echo "hygiene: $1" >&2
+  failures=$((failures + 1))
+}
+
+check_required_files() {
+  local required_files=(
+    README.md
+    LICENSE
+    CONTRIBUTING.md
+    SECURITY.md
+    CODE_OF_CONDUCT.md
+    CHANGELOG.md
+    .editorconfig
+    .gitattributes
+    .gitignore
+    docs/ARCHITECTURE.md
+    docs/DEVEX.md
+    docs/REPOSITORY_STANDARDS.md
+    config/.env.example
+  )
+
+  for file in "${required_files[@]}"; do
+    if [[ ! -f "$file" ]]; then
+      report_failure "missing required file: $file"
+    fi
+  done
+}
+
+check_shell_syntax() {
+  local script
+  while IFS= read -r -d '' script; do
+    bash -n "$script" || report_failure "shell syntax failed: $script"
+  done < <(find . -type f -name '*.sh' -not -path './.git/*' -print0)
+}
+
+check_merge_markers() {
+  local left middle right
+  left="$(printf '<%.0s' {1..7})"
+  middle="$(printf '=%.0s' {1..7})"
+  right="$(printf '>%.0s' {1..7})"
+
+  if git grep -n -e "$left" -e "$middle" -e "$right" -- . ':!.git' >/tmp/hygiene-markers.txt; then
+    cat /tmp/hygiene-markers.txt >&2
+    report_failure "possible unresolved merge markers found"
+  fi
+}
+
+check_markdown_headings() {
+  local file first_line
+  while IFS= read -r -d '' file; do
+    first_line="$(head -n 1 "$file")"
+    if [[ "$first_line" != '#'* && "$first_line" != '---' ]]; then
+      report_failure "markdown file should start with a heading or front matter: $file"
+    fi
+  done < <(find . -type f -name '*.md' -not -path './.git/*' -print0)
+}
+
+check_required_files
+check_shell_syntax
+check_merge_markers
+check_markdown_headings
+
+if [[ "$failures" -gt 0 ]]; then
+  echo "Repository hygiene checks failed: $failures issue(s)." >&2
+  exit 1
+fi
+
+echo "Repository hygiene checks passed."
diff --git a/scripts/validate.sh b/scripts/validate.sh
index ff38f62..05189b0 100644
--- a/scripts/validate.sh
+++ b/scripts/validate.sh
@@ -1,6 +1,8 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+bash scripts/hygiene.sh
+
 if [[ -f package.json ]]; then
   if command -v npm >/dev/null 2>&1; then
     npm run format:check --if-present