feat: add pre-commit hooks with lint-staged

.husky/pre-commit

@@ -0,0 +1 @@
+lint-staged

README.md

@@ -2,13 +2,28 @@
 
 This repo is the home of BitGo's WASM libraries.
 
-
 # Dependencies
 
 - [Rust](https://www.rust-lang.org/) nightly
 - [wasm-pack](https://rustwasm.github.io/wasm-pack/) (install with `cargo install wasm-pack`)
 - [Node.js](https://nodejs.org/en/)
 
+# Developer Setup
+
+```bash
+npm install
+```
+
+This will:
+
+- Install all dependencies
+- Set up pre-commit hooks via Husky
+
+Pre-commit hooks automatically run on staged files:
+
+- **JS/TS**: Prettier formatting + ESLint
+- **Rust**: `cargo fmt` + `cargo clippy`
+
 # Package Management
 
 This monorepo uses [Lerna](https://lerna.js.org/) for managing package versions and publishing to npm.
@@ -44,7 +59,6 @@ npx lerna changed
 
 # Packages
 
-
 ## wasm-utxo
 
 This is a wrapper around the
@@ -56,5 +70,4 @@ compiled to WebAssembly.
 
 A live playground for the wasm-utxo crate.
 
-Go to https://bitgo.github.io/wasm-utxo to see a live demo of the wasm-utxo library in action. *WIP*
-
+Go to https://bitgo.github.io/wasm-utxo to see a live demo of the wasm-utxo library in action. _WIP_

lint-staged.config.mjs

@@ -0,0 +1,73 @@
+import { existsSync } from "fs";
+
+const IGNORED_PATTERNS = [
+  "node_modules",
+  "/dist/",
+  "/target/",
+  "/pkg/",
+  "/js/wasm/",
+  "/bundler-test/",
+];
+
+function filterIgnored(filenames) {
+  return filenames.filter((f) => !IGNORED_PATTERNS.some((p) => f.includes(p)));
+}
+
+/** Extract package name from a file path like packages/wasm-utxo/src/foo.rs */
+function getPackageName(filepath) {
+  const match = filepath.match(/packages\/([^/]+)\//);
+  return match?.[1];
+}
+
+/** Group files by their package name */
+function groupByPackage(filenames) {
+  const groups = new Map();
+  for (const f of filenames) {
+    const pkg = getPackageName(f);
+    if (!pkg) continue;
+    if (!groups.has(pkg)) groups.set(pkg, []);
+    groups.get(pkg).push(f);
+  }
+  return groups;
+}
+
+export default {
+  "*.{js,ts,tsx,mjs,cjs}": (filenames) => {
+    const filtered = filterIgnored(filenames);
+    if (filtered.length === 0) return [];
+
+    const commands = [`prettier --write ${filtered.join(" ")}`];
+
+    for (const [pkg, files] of groupByPackage(filtered)) {
+      const configPath = `packages/${pkg}/eslint.config.js`;
+      if (existsSync(configPath)) {
+        commands.push(`npx eslint -c ${configPath} --fix ${files.join(" ")}`);
+      }
+    }
+
+    return commands;
+  },
+
+  "*.{json,yaml,yml,md}": (filenames) => {
+    const filtered = filterIgnored(filenames);
+    if (filtered.length === 0) return [];
+    return [`prettier --write ${filtered.join(" ")}`];
+  },
+
+  "*.rs": (filenames) => {
+    const filtered = filterIgnored(filenames);
+    if (filtered.length === 0) return [];
+
+    const commands = [];
+    for (const pkg of new Set(filtered.map(getPackageName).filter(Boolean))) {
+      const manifest = `packages/${pkg}/Cargo.toml`;
+      if (existsSync(manifest)) {
+        commands.push(`cargo fmt --manifest-path ${manifest}`);
+        commands.push(
+          `cargo clippy --manifest-path ${manifest} --all-targets --all-features -- -D warnings`,
+        );
+      }
+    }
+    return commands;
+  },
+};