internal: add bounded path registry to prevent cardinality explosion

"cardinality explosion" would make for an epic rock band name...

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I53cceb00ab9b17039b1fb1389977bf6b6a6a6964

internal/aggregate/registry_test.go

@@ -0,0 +1,98 @@
+package aggregate
+
+import (
+	"testing"
+)
+
+func TestPathRegistry_Add(t *testing.T) {
+	registry := NewPathRegistry(3)
+
+	// Add paths within limit
+	if !registry.Add("/api/users") {
+		t.Error("Expected first path to be accepted")
+	}
+	if !registry.Add("/api/posts") {
+		t.Error("Expected second path to be accepted")
+	}
+	if !registry.Add("/api/comments") {
+		t.Error("Expected third path to be accepted")
+	}
+
+	// Add duplicate path - should succeed
+	if !registry.Add("/api/users") {
+		t.Error("Expected duplicate path to be accepted")
+	}
+
+	// Verify count is still 3
+	if count := registry.Count(); count != 3 {
+		t.Errorf("Expected count 3, got %d", count)
+	}
+
+	// Exceed limit
+	if registry.Add("/api/photos") {
+		t.Error("Expected fourth unique path to be rejected")
+	}
+
+	// Verify overflow count
+	if overflow := registry.OverflowCount(); overflow != 1 {
+		t.Errorf("Expected overflow count 1, got %d", overflow)
+	}
+
+	// Add another path beyond limit
+	if registry.Add("/api/videos") {
+		t.Error("Expected fifth unique path to be rejected")
+	}
+
+	// Verify overflow count incremented
+	if overflow := registry.OverflowCount(); overflow != 2 {
+		t.Errorf("Expected overflow count 2, got %d", overflow)
+	}
+
+	// Verify count is still 3
+	if count := registry.Count(); count != 3 {
+		t.Errorf("Expected count 3, got %d", count)
+	}
+}
+
+func TestPathRegistry_Contains(t *testing.T) {
+	registry := NewPathRegistry(3)
+
+	registry.Add("/api/users")
+	registry.Add("/api/posts")
+
+	if !registry.Contains("/api/users") {
+		t.Error("Expected /api/users to be in registry")
+	}
+
+	if !registry.Contains("/api/posts") {
+		t.Error("Expected /api/posts to be in registry")
+	}
+
+	if registry.Contains("/api/comments") {
+		t.Error("Expected /api/comments to NOT be in registry")
+	}
+}
+
+func TestPathRegistry_Count(t *testing.T) {
+	registry := NewPathRegistry(5)
+
+	if count := registry.Count(); count != 0 {
+		t.Errorf("Expected initial count 0, got %d", count)
+	}
+
+	registry.Add("/api/users")
+	if count := registry.Count(); count != 1 {
+		t.Errorf("Expected count 1, got %d", count)
+	}
+
+	registry.Add("/api/posts")
+	if count := registry.Count(); count != 2 {
+		t.Errorf("Expected count 2, got %d", count)
+	}
+
+	// Add duplicate - count should not change
+	registry.Add("/api/users")
+	if count := registry.Count(); count != 2 {
+		t.Errorf("Expected count 2, got %d", count)
+	}
+}