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 * https://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 */
016package com.soklet;
017
018import org.jspecify.annotations.NonNull;
019
020import javax.annotation.concurrent.ThreadSafe;
021import java.util.Optional;
022
023/**
024 * Concurrently callable selector for one explicit Skills variant group.
025 *
026 * <p>Only accessible, discoverable registrations are supplied. Return one exact
027 * supplied registration instance, not an equal copy, or omit the group with
028 * {@link Optional#empty()}. A foreign registration, null result, or callback
029 * failure fails listing without publishing a partial result. Selection grants
030 * no access; direct URI lookup bypasses it and independently rechecks access.
031 *
032 * <p>A configured selector runs for every nonempty filtered group, including a
033 * singleton. Empty filtered groups do not invoke it. Declared multivariant
034 * groups require an explicit selector, even if filtering leaves one candidate.
035 * The application owns fallback selection and must respect the supplied bounded
036 * language preferences, including zero-weight exclusions. The existing
037 * localization context is available through invocation features rather than a
038 * separate negotiation; Soklet does not replace a custom selector's policy
039 * with automatic regional matching.
040 *
041 * @author <a href="https://www.revetkn.com">Mark Allen</a>
042 */
043@ThreadSafe
044@FunctionalInterface
045public interface McpSkillVariantSelector {
046        /**
047         * Selects at most one of the supplied canonical registrations for listing.
048         *
049         * @param requestContext admitted request context
050         * @param skillVariantSelectionContext group key, filtered candidates, and bounded client preferences
051         * @param invocationFeatures invocation-scoped optional features
052         * @return one supplied registration instance, or empty to omit the group; never null
053         * @throws Exception if variant selection fails
054         */
055        @NonNull
056        Optional<@NonNull McpSkillRegistration> select(@NonNull McpRequestContext requestContext,
057                        @NonNull McpSkillVariantSelectionContext skillVariantSelectionContext,
058                        @NonNull McpInvocationFeatures invocationFeatures) throws Exception;
059}