diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..988724a
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  go:
+    name: go vet + test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+      - name: go vet
+        run: go vet ./...
+      - name: go test
+        run: go test ./...
+
+  compat:
+    name: compat (CONTRACT machine-attestation)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+      - name: resolve compat dependency
+        # The compat module lives at github.com/quantcli/common/compat
+        # under a subpath. `go mod tidy` materializes go.sum for it on
+        # first run; subsequent runs are cache-served.
+        run: go mod tidy
+      - name: build crono-export
+        run: go build -o /tmp/crono-export .
+      - name: run compat suite
+        env:
+          # Path the compat-tagged test reads from os.Getenv.
+          CRONO_EXPORT_BIN: /tmp/crono-export
+        run: go test -tags=compat -run TestContractDates ./...
diff --git a/compat_contract_test.go b/compat_contract_test.go
new file mode 100644
index 0000000..904afe1
--- /dev/null
+++ b/compat_contract_test.go
@@ -0,0 +1,41 @@
+//go:build compat
+
+// Compat-test entry point for crono-export-cli.
+//
+// This file is only compiled under the `compat` build tag, so it does
+// not affect the default `go test ./...` run. CI invokes it as
+// `go test -tags=compat ./...` after building the export binary and
+// exposing its path through CRONO_EXPORT_BIN.
+//
+// The actual assertions live in github.com/quantcli/common/compat.
+// Drift between this CLI and CONTRACT.md surfaces as a failure here.
+package main_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/quantcli/common/compat"
+	"github.com/quantcli/common/compat/dates"
+)
+
+func TestContractDates(t *testing.T) {
+	bin := os.Getenv("CRONO_EXPORT_BIN")
+	if bin == "" {
+		t.Skip("CRONO_EXPORT_BIN not set; skipping compat suite")
+	}
+	// crono is cobra-based: --since/--until live on each data-producing
+	// subcommand, not the root binary. The compat suite dispatches per
+	// subcommand under a `subcommand=NAME/...` subtree so any single
+	// regression surfaces as a named subtest failure.
+	dates.RunContract(t, compat.Runner{
+		Binary: bin,
+		Subcommands: []string{
+			"biometrics",
+			"exercises",
+			"nutrition",
+			"servings",
+			"notes",
+		},
+	})
+}
diff --git a/go.mod b/go.mod
index ac8d23a..e79155d 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.25.5
 
 require (
 	github.com/jrmycanady/gocronometer v1.5.1
+	github.com/quantcli/common/compat v0.0.0-20260510225630-4c588c19cd1b
 	github.com/spf13/cobra v1.10.2
 )
 
diff --git a/go.sum b/go.sum
index c9953fb..fd0f48f 100644
--- a/go.sum
+++ b/go.sum
@@ -3,6 +3,8 @@ github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/jrmycanady/gocronometer v1.5.1 h1:m2J31jEuLlL4RRdQLY33IFs4TAwmfevvJYl2SZxBSQ0=
 github.com/jrmycanady/gocronometer v1.5.1/go.mod h1:swnvYB6twU20LDzNpAz8JOX5mCHktTW06zlSXmmyZWc=
+github.com/quantcli/common/compat v0.0.0-20260510225630-4c588c19cd1b h1:fO7EfkEqzLRC8Ev22jIq05fPs+JwAB7bCDy6FA+GA5k=
+github.com/quantcli/common/compat v0.0.0-20260510225630-4c588c19cd1b/go.mod h1:VBC/zEphSZgCZS1rhWsR3A8EWYSbTkP/MwqWHL7266s=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/spf13/cobra v1.10.2 h1:DMTTonx5m65Ic0GOoRY2c16WCbHxOOw6xxezuLaBpcU=
 github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiTUUS4=