diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..1e61851
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,22 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+      - name: Set up Bun
+        uses: oven-sh/setup-bun@v2
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+      - name: Typecheck
+        run: bun run typecheck
+      - name: Test
+        run: bun test
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 287eae7..ec85728 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+- GitHub Actions CI for pull requests and pushes to `main`, running frozen dependency
+  installation, typechecking, and the full test suite.
+
 ## [0.2.0] - 2026-07-27
 
 ### Removed