diff --git a/.github/workflows/pr-checks.yml b/.github/workflows/pr-checks.yml
new file mode 100644
index 0000000..6f45626
--- /dev/null
+++ b/.github/workflows/pr-checks.yml
@@ -0,0 +1,43 @@
+name: PR checks
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7.0.1
+
+      - name: Install ruff
+        run: python3 -m pip install ruff
+
+      - name: Lint scripts
+        run: ruff check scripts/
+
+  validate-data:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7.0.1
+
+      - name: Install catalog tools
+        run: python3 -m pip install -r requirements.txt
+
+      - name: Validate chemistry catalog
+        run: |
+          python3 scripts/validate_chemistry_catalog.py \
+            --catalog data/chemistry-catalog.json
+
+      - name: Validate equipment catalog
+        run: |
+          python3 scripts/validate_equipment_catalog.py \
+            --catalog data/equipment-catalog.json \
+            --index data/equipment-index.json \
+            --config config/equipment-sources.yml \
+            --sprites data/equipment-sprites
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7a60b85
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+__pycache__/
+*.pyc
diff --git a/ruff.toml b/ruff.toml
new file mode 100644
index 0000000..0b46ce0
--- /dev/null
+++ b/ruff.toml
@@ -0,0 +1,6 @@
+target-version = "py311"
+
+[lint]
+# Только реальные ошибки (неопределённые имена, неиспользуемые импорты/переменные и т.п.),
+# без стилистических правил — они не про баги, а про вкус.
+select = ["F"]
diff --git a/scripts/build_equipment_catalog.py b/scripts/build_equipment_catalog.py
index e853fba..db7a41e 100644
--- a/scripts/build_equipment_catalog.py
+++ b/scripts/build_equipment_catalog.py
@@ -2365,7 +2365,8 @@ def build_public_catalog(
         if item_id in visited:
             continue
         visited.add(item_id)
-        item = items[item_id]
+        if item_id not in items:
+            raise RuntimeError(f"Unknown item id reachable from public roots: {item_id}")
         public_candidates.add(item_id)
         # Every configured product and every reachable content item is public.
         # Boxes/crates are no longer silently replaced with their contents.