001/*
002 * Copyright 2022-2026 Revetware LLC.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.soklet;
018
019import org.jspecify.annotations.NonNull;
020
021import javax.annotation.concurrent.ThreadSafe;
022import java.util.Optional;
023
024/**
025 * Thread-safe, server-owned MCP trace-correlation control plane.
026 * <p>
027 * Correlation is disabled unless a key is supplied when the server is built.
028 * Rotation atomically replaces both active key ID and key material. Soklet
029 * retains no public history or historical-token derivation facility.
030 *
031 * @author <a href="https://www.revetkn.com">Mark Allen</a>
032 */
033@ThreadSafe
034public interface McpTraceCorrelationKeyManager {
035        /** @return whether trace correlation was enabled at server construction */
036        @NonNull
037        Boolean isEnabled();
038
039        /** @return active non-secret key ID, or empty when disabled */
040        @NonNull
041        Optional<@NonNull String> getActiveKeyId();
042
043        /** @return active configuration fingerprint, or empty when disabled */
044        @NonNull
045        Optional<@NonNull McpTraceCorrelationFingerprint>
046                        getFingerprint();
047
048        /**
049         * Atomically rotates both active key ID and material.
050         * <p>
051         * Re-supplying the byte-identical active entry is an idempotent no-op. Reuse
052         * of the active ID with different material is rejected so structured-log key
053         * IDs continue to identify one correlation-key version unambiguously.
054         *
055         * @param activeKey new active correlation key
056         * @throws IllegalArgumentException if its ID ambiguously reuses the active
057         *                                  ID or its material equals any protection
058         *                                  ring key material
059         * @throws IllegalStateException if correlation was not enabled when the
060         *                               server was built
061         */
062        void rotateActiveKey(@NonNull McpTraceCorrelationKey activeKey);
063}