add presubmit workflow for skills

Author: twishabansal

.github/workflows/skills-validate.yml

@@ -0,0 +1,64 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Validate Skills
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "skills/**"
+  pull_request:
+    branches:
+      - main
+    paths:
+      - "skills/**"
+  workflow_dispatch:
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Checkout agentskills/agentskills
+        uses: actions/checkout@v4
+        with:
+          repository: agentskills/agentskills
+          path: agentskills
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install skills-ref
+        run: |
+          cd agentskills/skills-ref
+          pip install .
+
+      - name: Validate Skills
+        run: |
+          failed=0
+          for skill_dir in skills/*/; do
+            if [ -d "$skill_dir" ]; then
+              echo "Validating $skill_dir..."
+              if ! skills-ref validate "$skill_dir"; then
+                echo "Validation failed for $skill_dir"
+                failed=1
+              fi
+            fi
+          done
+          exit $failed