diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..819365f
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,42 @@
+name: CI
+
+# Fast, deterministic checks on every PR and on main. The slow testnet integration
+# scripts (pool/scripts/*.mjs) are run manually, not here.
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  contracts:
+    name: contracts · cargo test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: contracts
+      - name: cargo test -p pool
+        working-directory: contracts
+        run: cargo test -p pool
+
+  app:
+    name: app · vitest + build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+          cache-dependency-path: app/package-lock.json
+      - name: install
+        working-directory: app
+        run: npm ci
+      - name: vitest
+        working-directory: app
+        run: npm test
+      - name: next build
+        working-directory: app
+        run: npm run build