diff --git a/.github/workflows/validate_hw_defs.yml b/.github/workflows/validate_hw_defs.yml
new file mode 100644
index 000000000..22c9f3d15
--- /dev/null
+++ b/.github/workflows/validate_hw_defs.yml
@@ -0,0 +1,41 @@
+name: Validate hw_defs
+on:
+  push:
+    branches:
+      - 'main'
+      - '[0-9]+.[0-9]+'
+    paths:
+      - 'radio/util/hw_defs/**'
+      - 'radio/src/boards/hw_defs/**'
+  pull_request:
+    paths:
+      - 'radio/util/hw_defs/**'
+      - 'radio/src/boards/hw_defs/**'
+  workflow_dispatch:
+
+jobs:
+  validate:
+    name: Validate hw_defs
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: radio/util/hw_defs
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v6
+
+      - name: Set up uv
+        uses: astral-sh/setup-uv@v7
+
+      - name: Install Python dependencies
+        working-directory: .
+        run: uv venv && uv pip install -r requirements.txt
+
+      - name: Check Python script syntax
+        run: uv run python3 -m py_compile *.py
+
+      - name: Validate JSON schemas
+        run: uv run python3 json_validator.py ../../src/boards/hw_defs
+
+      - name: Test template generation (all boards x all templates)
+        run: uv run python3 test_templates.py ../../src/boards/hw_defs
diff --git a/radio/util/hw_defs/test_templates.py b/radio/util/hw_defs/test_templates.py
new file mode 100644
index 000000000..ffbc3c7b3
--- /dev/null
+++ b/radio/util/hw_defs/test_templates.py
@@ -0,0 +1,67 @@
+"""Test that all templates render successfully for all board hw_defs.
+
+Runs all .jinja templates against all .json board definitions in a single
+process, accumulating failures rather than stopping at the first one.
+
+Usage:
+    python3 test_templates.py <hw_defs_dir>
+"""
+
+import argparse
+import contextlib
+import io
+import os
+import sys
+from pathlib import Path
+
+from generator import generate_from_template
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Test all templates x all boards")
+    parser.add_argument("hw_defs_dir", help="Directory containing board .json files")
+    args = parser.parse_args()
+
+    hw_defs_dir = Path(args.hw_defs_dir)
+    if not hw_defs_dir.is_dir():
+        print(f"ERROR: {hw_defs_dir} is not a directory", file=sys.stderr)
+        sys.exit(1)
+
+    script_dir = Path(os.path.dirname(os.path.abspath(__file__)))
+    templates = sorted(script_dir.glob("*.jinja"))
+    json_files = sorted(hw_defs_dir.glob("*.json"))
+
+    if not templates:
+        print("ERROR: no .jinja templates found", file=sys.stderr)
+        sys.exit(1)
+
+    if not json_files:
+        print(f"ERROR: no .json files found in {hw_defs_dir}", file=sys.stderr)
+        sys.exit(1)
+
+    print(f"Testing {len(json_files)} boards x {len(templates)} templates "
+          f"= {len(json_files) * len(templates)} combinations")
+
+    failures = []
+
+    for json_file in json_files:
+        board = json_file.stem
+        for tmpl in templates:
+            try:
+                with contextlib.redirect_stdout(io.StringIO()):
+                    generate_from_template(str(json_file), str(tmpl), board)
+            except SystemExit as e:
+                if e.code != 0:
+                    failures.append((board, tmpl.name))
+
+    if failures:
+        print(f"\nFAILED ({len(failures)}):", file=sys.stderr)
+        for board, tmpl in failures:
+            print(f"  board={board} template={tmpl}", file=sys.stderr)
+        sys.exit(1)
+
+    print(f"All combinations passed.")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/requirements.txt b/requirements.txt
index 92612f897..324d4d696 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,4 @@ jinja2
 pillow
 lz4
 pydantic
+typing_extensions