diff --git a/.gitea/workflows/validate.yml b/.gitea/workflows/validate.yml
new file mode 100644
index 0000000..decfce5
--- /dev/null
+++ b/.gitea/workflows/validate.yml
@@ -0,0 +1,37 @@
+name: validate
+
+# Catalog edits arrive as pull requests from mods, so validation has to run
+# before merge — a malformed season file would otherwise reach the bot's next
+# catalog reload.
+on:
+  pull_request:
+    paths:
+      - "seasons/**"
+      - "schema/**"
+      - "scripts/validate.py"
+      - ".gitea/workflows/validate.yml"
+  push:
+    branches: [main]
+    paths:
+      - "seasons/**"
+      - "schema/**"
+      - "scripts/validate.py"
+      - ".gitea/workflows/validate.yml"
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Install jsonschema
+        run: pip install --quiet jsonschema
+
+      - name: Validate season files
+        run: python scripts/validate.py