p2.7: prometheus /metrics

Default GET /metrics is Prometheus text; JSON stays at /metrics.json
and ?format=json. :8443 needs the metrics caller bearer; loopback
stays open. Restricted callers have no per-caller series and no
tavily:restricted gauge.

vendor/google.golang.org/protobuf/internal/filedesc/presence.go

@@ -0,0 +1,33 @@
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filedesc
+
+import "google.golang.org/protobuf/reflect/protoreflect"
+
+// UsePresenceForField reports whether the presence bitmap should be used for
+// the specified field.
+func UsePresenceForField(fd protoreflect.FieldDescriptor) (usePresence, canBeLazy bool) {
+	switch {
+	case fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic():
+		// Oneof fields never use the presence bitmap.
+		//
+		// Synthetic oneofs are an exception: Those are used to implement proto3
+		// optional fields and hence should follow non-oneof field semantics.
+		return false, false
+
+	case fd.IsMap():
+		// Map-typed fields never use the presence bitmap.
+		return false, false
+
+	case fd.Kind() == protoreflect.MessageKind || fd.Kind() == protoreflect.GroupKind:
+		// Lazy fields always use the presence bitmap (only messages can be lazy).
+		isLazy := fd.(interface{ IsLazy() bool }).IsLazy()
+		return isLazy, isLazy
+
+	default:
+		// If the field has presence, use the presence bitmap.
+		return fd.HasPresence(), false
+	}
+}