Add initial actions for linting, formatting, and typechecking

Author: jathoms

.github/workflows/ci-lint-typecheck.yml

@@ -0,0 +1,58 @@
+name: CI - Lint & Typecheck
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - "**/*.py"
+      - "pyproject.toml"
+      - "uv.lock"
+      - ".github/workflows/ci-lint-typecheck.yml"
+  pull_request:
+    paths:
+      - "**/*.py"
+      - "pyproject.toml"
+      - "uv.lock"
+      - ".github/workflows/ci-lint-typecheck.yml"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  ruff:
+    name: Ruff (lint + format)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Ruff check
+        uses: astral-sh/ruff-action@v3
+        with:
+          args: "check"
+
+      - name: Ruff format (check)
+        uses: astral-sh/ruff-action@v3
+        with:
+          args: "format --check"
+
+  typecheck:
+    name: Typecheck (pyrefly)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.13"
+          cache: "pip"
+
+      - name: Install uv
+        run: python -m pip install -U uv
+
+      - name: Sync typecheck deps (locked)
+        run: uv sync --dev --frozen
+
+      - name: Run pyrefly
+        run: uv run pyrefly check