1 files changed, 50 insertions, 0 deletions
diff --git a/internal/providerhealth/tracker_test.go b/internal/providerhealth/tracker_test.go
new file mode 100644
index 0000000..73bd6d5
--- /dev/null
+++ b/internal/providerhealth/tracker_test.go
@@ -0,0 +1,50 @@
+package providerhealth
+
+import (
+	"sync"
+	"testing"
+	"time"
+)
+
+func TestTrackerOpensAndRecoversCircuit(t *testing.T) {
+	now := time.Date(2026, time.August, 6, 0, 0, 0, 0, time.UTC)
+	tracker := New(Options{FailureThreshold: 3, OpenDuration: 30 * time.Second, Now: func() time.Time { return now }})
+	key := RouteKey{ModelID: "openai/test", ProviderID: "primary", WireAPI: "responses"}
+	for _, status := range []int{503, 429, 504} {
+		tracker.Observe(key, Observation{StatusCode: status, Latency: 100 * time.Millisecond, Failed: true})
+	}
+	if !tracker.CircuitOpen(key) {
+		t.Fatal("circuit did not open after consecutive retryable failures")
+	}
+	snapshot := tracker.Snapshot()
+	if len(snapshot) != 1 || snapshot[0].State != "open" || snapshot[0].AvailabilityPercent != 0 || snapshot[0].CircuitOpenUntil == nil {
+		t.Fatalf("unexpected open snapshot: %+v", snapshot)
+	}
+	now = now.Add(31 * time.Second)
+	if tracker.CircuitOpen(key) {
+		t.Fatal("circuit did not permit a recovery attempt after cooldown")
+	}
+	tracker.Observe(key, Observation{StatusCode: 200, Latency: 50 * time.Millisecond})
+	snapshot = tracker.Snapshot()
+	if snapshot[0].State != "healthy" || snapshot[0].ConsecutiveFailures != 0 || snapshot[0].LastHealthyAt == nil || snapshot[0].HeaderLatencyEWMA < 50 {
+		t.Fatalf("unexpected recovered snapshot: %+v", snapshot[0])
+	}
+}
+
+func TestTrackerConcurrentObservations(t *testing.T) {
+	tracker := New(Options{FailureThreshold: 1000})
+	key := RouteKey{ModelID: "model", ProviderID: "provider", WireAPI: "chat_completions"}
+	var group sync.WaitGroup
+	for index := range 200 {
+		group.Add(1)
+		go func(failed bool) {
+			defer group.Done()
+			tracker.Observe(key, Observation{StatusCode: 200, Latency: time.Millisecond, Failed: failed})
+		}(index%2 == 0)
+	}
+	group.Wait()
+	snapshot := tracker.Snapshot()
+	if len(snapshot) != 1 || snapshot[0].Attempts != 200 || snapshot[0].RecentSamples != recentWindow || snapshot[0].AvailabilityPercent < 0 || snapshot[0].AvailabilityPercent > 100 {
+		t.Fatalf("unexpected concurrent snapshot: %+v", snapshot)
+	}
+}