Use prek for pre-commit hooks

README.md

@@ -12,8 +12,21 @@ command-line tools.
     mise trust
     mise install
     npm install
+    prek install
     cp env-example .env.local
 
+## Scripts
+
+- `npm run start` - Start Expo development server on port 19001
+- `npm run android` - Run app in Android emulator
+- `npm run ios` - Run app in iOS simulator (requires macOS)
+- `npm run web` - Run app in web browser
+- `npm run lint` - Check code with ESLint
+- `npm run format` - Fix code formatting with ESLint
+- `npm run check-types` - Run TypeScript type checking
+- `npm test` - Run the test suite
+- `npm run test:watch` - Run the test suite in watch mode
+
 ## Development
 
 This app uses native functionality that isn't supported by [Expo Go](https://expo.dev/client),
@@ -54,17 +67,17 @@ Many packages (`expo-*`, `react-native`, and more) are versioned in lockstep wit
 Expo SDK. Check them with `npx expo install --check` and upgrade with
 `npx expo install --fix` instead of `npm update`.
 
-## Scripts
+## Pre-commit hooks
 
-- `npm run start` - Start Expo development server on port 19001
-- `npm run android` - Run app in Android emulator
-- `npm run ios` - Run app in iOS simulator (requires macOS)
-- `npm run web` - Run app in web browser
-- `npm run lint` - Check code with ESLint
-- `npm run format` - Fix code formatting with ESLint
-- `npm run check-types` - Run TypeScript type checking
-- `npm test` - Run the test suite
-- `npm run test:watch` - Run the test suite in watch mode
+Git hooks are managed with [prek](https://prek.j178.dev/) (installed by `mise install`)
+and configured in `prek.toml`. Enable them with:
+
+    prek install
+
+Commits then only succeed if linting, type checking and the related tests pass. Run all
+hooks against the whole repo with:
+
+    prek run --all-files
 
 ## History
 

mise.toml

@@ -2,3 +2,4 @@
 android-sdk = "latest"
 java = "temurin-17"
 node = "24"
+prek = "latest"

prek.toml

@@ -0,0 +1,42 @@
+#:schema https://www.schemastore.org/prek.json
+
+[[repos]]
+repo = "builtin"
+hooks = [
+    { id = "check-added-large-files" },
+    { id = "check-case-conflict" },
+    { id = "check-json", exclude = '^tsconfig\.json$' }, # tsconfig is JSONC, comments allowed
+    { id = "check-merge-conflict" },
+    { id = "check-yaml" },
+    { id = "detect-private-key" },
+    { id = "end-of-file-fixer" },
+    { id = "mixed-line-ending", args = ["--fix=lf"] },
+    { id = "trailing-whitespace", args = ["--markdown-linebreak-ext=md"] },
+]
+
+[[repos]]
+repo = "local"
+
+[[repos.hooks]]
+id = "eslint"
+name = "eslint"
+entry = "npx --no-install eslint --fix --no-warn-ignored"
+language = "system"
+types_or = ["javascript", "jsx", "ts", "tsx"]
+
+[[repos.hooks]]
+id = "check-types"
+name = "tsc"
+entry = "npx --no-install tsc"
+language = "system"
+files = '\.tsx?$|^tsconfig\.json$'
+pass_filenames = false
+
+[[repos.hooks]]
+id = "jest"
+name = "jest (tests related to staged files)"
+entry = "npx --no-install jest --bail --findRelatedTests --passWithNoTests"
+language = "system"
+types_or = ["javascript", "jsx", "ts", "tsx"]
+# One jest invocation for all files — parallel invocations contend and time out
+require_serial = true