Merge branch 'main' into main

core

@@ -1 +1 @@
-Subproject commit 5f977636531d1b978b762a615d720097baa37830
+Subproject commit fb2e5022e5c1d125e45227b49076c2b200763986

lib/bld/bld-wrapper.properties

@@ -9,4 +9,4 @@ bld.javaOptions=
 bld.javacOptions=
 bld.repositories=MAVEN_CENTRAL,RIFE2_RELEASES,RIFE2_SNAPSHOTS
 bld.sourceDirectories=core/src/bld/java
-bld.version=2.3.1-SNAPSHOT
+bld.version=2.4.0-SNAPSHOT

src/main/java/rife/bld/BaseProject.java

@@ -31,7 +31,7 @@ public class BaseProject extends BuildExecutor {
     /**
      * The CLI option to trigger automatic dependency download and purge.
      *
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public static final String AUTO_DOWNLOAD_PURGE_OPTION = "--auto-download-purge";
 
@@ -395,6 +395,7 @@ public class BaseProject extends BuildExecutor {
     private final CompileOperation compileOperation_ = new CompileOperation();
     private final DependencyTreeOperation dependencyTreeOperation_ = new DependencyTreeOperation();
     private final DownloadOperation downloadOperation_ = new DownloadOperation();
+    private final McpOperation mcpOperation_ = new McpOperation();
     private final PurgeOperation purgeOperation_ = new PurgeOperation();
     private final PublishOperation publishOperation_ = new PublishOperation();
     private final RunOperation runOperation_ = new RunOperation();
@@ -442,6 +443,16 @@ public class BaseProject extends BuildExecutor {
         return downloadOperation_;
     }
 
+    /**
+     * Retrieves the project's default MCP operation.
+     *
+     * @return the default MCP operation instance
+     * @since 2.4.0
+     */
+    public McpOperation mcpOperation() {
+        return mcpOperation_;
+    }
+
     /**
      * Retrieves the project's default publish operation.
      *
@@ -546,6 +557,18 @@ public class BaseProject extends BuildExecutor {
         downloadOperation().executeOnce(() -> downloadOperation().fromProject(this));
     }
 
+    /**
+     * Standard build command, starts an MCP server that exposes the build
+     * commands as tools.
+     *
+     * @since 2.4.0
+     */
+    @BuildCommand(help = McpHelp.class)
+    public void mcp()
+    throws Exception {
+        mcpOperation().executeOnce(() -> mcpOperation().fromProject(this));
+    }
+
     /**
      * Standard build command, purges all unused artifacts from the project.
      *
@@ -910,8 +933,7 @@ public class BaseProject extends BuildExecutor {
      */
     public LocalDependency local(String path) {
         return new LocalDependency(path);
-    } /**
+    }
-
 
      /**
      * Creates a local dependency instance.
@@ -920,8 +942,9 @@ public class BaseProject extends BuildExecutor {
      *
      * @param path the file system path (absolute or relative to the {@link #workDirectory})
      *             of the local dependency
-     * @since 2.3.1
+     * @since 2.4.0
      */
+
     public LocalDependency local(Path path) {
         return new LocalDependency(path.toString());
     }
@@ -931,7 +954,7 @@ public class BaseProject extends BuildExecutor {
      * If the local dependency points to a directory, it will be scanned for jar files.
      *
      * @param path the file system path of the local dependency
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public LocalDependency local(File path) {
         return new LocalDependency(path.getAbsolutePath());
@@ -1019,6 +1042,62 @@ public class BaseProject extends BuildExecutor {
         return Module.parse(description);
     }
 
+    /**
+     * Creates a new bill of materials instance.
+     *
+     * @param groupId    the BOM group identifier
+     * @param artifactId the BOM artifact identifier
+     * @return a newly created {@code Bom} instance
+     * @since 2.4.0
+     */
+    public Bom bom(String groupId, String artifactId) {
+        return new Bom(groupId, artifactId);
+    }
+
+    /**
+     * Creates a new bill of materials instance.
+     *
+     * @param groupId    the BOM group identifier
+     * @param artifactId the BOM artifact identifier
+     * @param version    the BOM version
+     * @return a newly created {@code Bom} instance
+     * @since 2.4.0
+     */
+    public Bom bom(String groupId, String artifactId, String version) {
+        return new Bom(groupId, artifactId, version(version));
+    }
+
+    /**
+     * Creates a new bill of materials instance.
+     *
+     * @param groupId    the BOM group identifier
+     * @param artifactId the BOM artifact identifier
+     * @param version    the BOM version
+     * @return a newly created {@code Bom} instance
+     * @since 2.4.0
+     */
+    public Bom bom(String groupId, String artifactId, Version version) {
+        return new Bom(groupId, artifactId, version);
+    }
+
+    /**
+     * Creates a new bill of materials instance from a string representation.
+     * The format is {@code groupId:artifactId:version}.
+     * The {@code version} is optional, and an optional {@code @bom} or
+     * {@code @pom} type suffix is accepted. BOMs can't have classifiers,
+     * strings that contain one are rejected.
+     * <p>
+     * If the string can't be successfully parsed, {@code null} will be returned.
+     *
+     * @param description the BOM string to parse
+     * @return a parsed instance of {@code Bom}; or
+     * {@code null} when the string couldn't be parsed
+     * @since 2.4.0
+     */
+    public Bom bom(String description) {
+        return Bom.parse(description);
+    }
+
     /**
      * Creates a local module instance.
      * <p>
@@ -1039,7 +1118,7 @@ public class BaseProject extends BuildExecutor {
      *
      * @param path the file system path (absolute or relative to the {@link #workDirectory})
      *             of the local module
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public LocalModule localModule(Path path) {
         return new LocalModule(path.toString());
@@ -1051,7 +1130,7 @@ public class BaseProject extends BuildExecutor {
      * If the local module points to a directory, it will be scanned for jar files.
      *
      * @param path the file system path of the local module
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public LocalModule localModule(File path) {
         return new LocalModule(path.getAbsolutePath());
@@ -2062,6 +2141,22 @@ public class BaseProject extends BuildExecutor {
         purge();
     }
 
+    /**
+     * Performs the automatic download and purge of the project
+     * dependencies when it's enabled through {@link #autoDownloadPurge()}
+     * and the project isn't offline.
+     * <p>
+     * The dependencies are only refreshed when the dependency cache is
+     * stale, so that repeated invocations are cheap.
+     *
+     * @since 2.4.0
+     */
+    public void performAutoDownloadPurgeIfEnabled() {
+        if (!offline() && autoDownloadPurge()) {
+            performAutoDownloadPurge();
+        }
+    }
+
     private void performAutoDownloadPurge() {
         var resolution = new VersionResolution(properties());
         var cache = new BldCache(libBldDirectory(), resolution);
@@ -2085,6 +2180,12 @@ public class BaseProject extends BuildExecutor {
         var remainingArguments = new ArrayList<>(List.of(arguments));
         var auto = remainingArguments.remove(AUTO_DOWNLOAD_PURGE_OPTION);
 
+        if (remainingArguments.contains(BuildExecutor.ARG_USE_STDERR)) {
+            // the build output is sent to standard error so that standard
+            // output stays free for the MCP protocol, done before the
+            // automatic download and purge produces any output
+            System.setOut(System.err);
+        }
         if (!offline() &&
             (autoDownloadPurge() || auto)) {
             performAutoDownloadPurge();

src/main/java/rife/bld/BldCache.java

@@ -271,6 +271,10 @@ public class BldCache {
             finger_print.append(entry.getKey());
             finger_print.append('\n');
             if (entry.getValue() != null) {
+                for (var bom : entry.getValue().boms()) {
+                    finger_print.append(bom.toString());
+                    finger_print.append('\n');
+                }
                 for (var dependency : entry.getValue()) {
                     finger_print.append(dependency.toString());
                     finger_print.append('\n');

src/main/java/rife/bld/BuildExecutor.java

@@ -32,6 +32,8 @@ public class BuildExecutor {
     public static final String LOCAL_PROPERTIES = "local.properties";
 
     private static final String ARG_OFFLINE = "--offline";
+    static final String ARG_USE_STDERR = "--use-stderr";
+
     private static final String ARG_HELP1 = "--help";
     private static final String ARG_HELP2 = "-h";
     private static final String ARG_HELP3 = "-?";
@@ -41,7 +43,7 @@ public class BuildExecutor {
     private static final String ARG_VERBOSE2 = "-v";
 
     private final HierarchicalProperties properties_;
-    private List<String> arguments_ = Collections.emptyList();
+    private List<String> arguments_ = new ArrayList<>();
     private boolean offline_ = false;
     private boolean verbose_ = false;
     private Map<String, CommandDefinition> buildCommands_ = null;
@@ -138,18 +140,65 @@ public class BuildExecutor {
         return offline_;
     }
 
+    /**
+     * Changes whether the bld execution is intended to be offline.
+     *
+     * @param offline {@code true} if the execution is intended to be offline;
+     *                or {@code false} otherwise
+     * @since 2.4.0
+     */
+    public void offline(boolean offline) {
+        offline_ = offline;
+    }
+
     /**
      * Returns whether the bld execution should output detailed information
      * about the operations it performs.
      *
      * @return {@code true} if the execution is verbose;
      *         or {@code false} otherwise
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public boolean verbose() {
         return verbose_;
     }
 
+    /**
+     * Changes whether the bld execution should output detailed information
+     * about the operations it performs.
+     *
+     * @param verbose {@code true} if the execution is verbose;
+     *                or {@code false} otherwise
+     * @since 2.4.0
+     */
+    public void verbose(boolean verbose) {
+        verbose_ = verbose;
+    }
+
+    /**
+     * Returns whether the bld execution prints out the stacktrace for
+     * exceptions.
+     *
+     * @return {@code true} if the stacktrace is printed;
+     *         or {@code false} otherwise
+     * @since 2.4.0
+     */
+    public boolean showStacktrace() {
+        return showStacktrace;
+    }
+
+    /**
+     * Changes whether the bld execution prints out the stacktrace for
+     * exceptions.
+     *
+     * @param showStacktrace {@code true} if the stacktrace is printed;
+     *                       or {@code false} otherwise
+     * @since 2.4.0
+     */
+    public void showStacktrace(boolean showStacktrace) {
+        this.showStacktrace = showStacktrace;
+    }
+
     /**
      * Returns the properties uses for bld execution.
      *
@@ -243,12 +292,19 @@ public class BuildExecutor {
         show_help |= arguments_.removeAll(List.of(ARG_HELP1, ARG_HELP2, ARG_HELP3));
         showStacktrace = arguments_.removeAll(List.of(ARG_STACKTRACE1, ARG_STACKTRACE2));
         verbose_ = arguments_.removeAll(List.of(ARG_VERBOSE1, ARG_VERBOSE2));
+        if (arguments_.removeAll(List.of(ARG_USE_STDERR))) {
+            // the build output is sent to standard error so that standard
+            // output stays free for the MCP protocol, which the MCP server
+            // relies on to keep its protocol stream clean
+            System.setOut(System.err);
+        }
 
         if (show_help) {
             new HelpOperation(this, Collections.emptyList()).execute();
             return exitStatus_;
         }
-        else if (arguments_.isEmpty()) {
+
+        if (arguments_.isEmpty()) {
             showBldHelp();
             return exitStatus_;
         }
@@ -441,47 +497,14 @@ public class BuildExecutor {
      */
     public boolean executeCommand(String command)
     throws Throwable {
-        var matched_command = command;
+        var matched_command = resolveCommand(command);
-        var definition = buildCommands().get(command);
+        CommandDefinition definition = null;
-
+        if (matched_command != null) {
-        // try to find an alias
+            if (!matched_command.equals(command) &&
-        if (definition == null) {
+                !matched_command.equals(buildAliases().get(command))) {
-            var aliased_command = buildAliases().get(command);
-            if (aliased_command != null) {
-                matched_command = aliased_command;
-                definition = buildCommands().get(aliased_command);
-            }
-        }
-
-        // try to find a match for the provided command amongst
-        // the ones that are known
-        if (definition == null) {
-            // try to find starting matching options
-            var matches = new ArrayList<>(buildCommands().keySet().stream()
-                .filter(c -> c.toLowerCase().startsWith(command.toLowerCase()))
-                .toList());
-
-            if (matches.isEmpty()) {
-                // try to find fuzzy matching options
-                var fuzzy_regexp = new StringBuilder("^.*");
-                for (var ch : command.toCharArray()) {
-                    fuzzy_regexp.append("\\Q");
-                    fuzzy_regexp.append(ch);
-                    fuzzy_regexp.append("\\E.*");
-                }
-                fuzzy_regexp.append('$');
-                var fuzzy_pattern = Pattern.compile(fuzzy_regexp.toString());
-                matches.addAll(buildCommands().keySet().stream()
-                    .filter(c -> fuzzy_pattern.matcher(c.toLowerCase()).matches())
-                    .toList());
-            }
-
-            // only proceed if exactly one match was found
-            if (matches.size() == 1) {
-                matched_command = matches.get(0);
                 System.out.println("Executing matched command: " + matched_command);
-                definition = buildCommands().get(matched_command);
             }
+            definition = buildCommands().get(matched_command);
         }
 
         // execute the command if we found one
@@ -507,6 +530,54 @@ public class BuildExecutor {
         return true;
     }
 
+    /**
+     * Resolves a command name to the name of the build command that would
+     * be executed for it, taking the command aliases, unique name prefixes
+     * and unique fuzzy matches into account.
+     *
+     * @param command the command name to resolve
+     * @return the name of the build command that would be executed; or
+     * {@code null} when the name couldn't be resolved
+     * @since 2.4.0
+     */
+    public String resolveCommand(String command) {
+        if (buildCommands().containsKey(command)) {
+            return command;
+        }
+
+        // try to find an alias
+        var aliased_command = buildAliases().get(command);
+        if (aliased_command != null) {
+            return aliased_command;
+        }
+
+        // try to find starting matching options
+        var matches = new ArrayList<>(buildCommands().keySet().stream()
+            .filter(c -> c.toLowerCase().startsWith(command.toLowerCase()))
+            .toList());
+
+        if (matches.isEmpty()) {
+            // try to find fuzzy matching options
+            var fuzzy_regexp = new StringBuilder("^.*");
+            for (var ch : command.toCharArray()) {
+                fuzzy_regexp.append("\\Q");
+                fuzzy_regexp.append(ch);
+                fuzzy_regexp.append("\\E.*");
+            }
+            fuzzy_regexp.append('$');
+            var fuzzy_pattern = Pattern.compile(fuzzy_regexp.toString());
+            matches.addAll(buildCommands().keySet().stream()
+                .filter(c -> fuzzy_pattern.matcher(c.toLowerCase()).matches())
+                .toList());
+        }
+
+        // only resolve if exactly one match was found
+        if (matches.size() == 1) {
+            return matches.get(0);
+        }
+        return null;
+    }
+
     private void showBldHelp() {
         var help = new HelpOperation(this, arguments());
         help.executePrintWelcome();

src/main/java/rife/bld/dependencies/ArtifactRetriever.java

@@ -19,6 +19,7 @@ import java.net.URLConnection;
 import java.nio.channels.Channels;
 import java.security.MessageDigest;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
 import static rife.tools.HttpUtils.HEADER_AUTHORIZATION;
 import static rife.tools.HttpUtils.basicAuthorizationHeader;
@@ -35,6 +36,8 @@ import static rife.tools.StringUtils.encodeHexLower;
  * @since 1.5.18
  */
 public abstract class ArtifactRetriever {
+    private static final int TRANSFER_CHUNK_SIZE = 128 * 1024;
+
     private final static ArtifactRetriever UNCACHED = new ArtifactRetriever() {
         String getCached(RepositoryArtifact artifact) {
             return null;
@@ -42,6 +45,10 @@ public abstract class ArtifactRetriever {
 
         void cache(RepositoryArtifact artifact, String content) {
         }
+
+        boolean isCaching() {
+            return false;
+        }
     };
 
     /**
@@ -63,7 +70,7 @@ public abstract class ArtifactRetriever {
      */
     public static ArtifactRetriever cachingInstance() {
         return new ArtifactRetriever() {
-            private final Map<RepositoryArtifact, String> artifactCache = new HashMap<>();
+            private final Map<RepositoryArtifact, String> artifactCache = new ConcurrentHashMap<>();
 
             String getCached(RepositoryArtifact artifact) {
                 return artifactCache.get(artifact);
@@ -73,6 +80,9 @@ public abstract class ArtifactRetriever {
                 artifactCache.put(artifact, content);
             }
 
+            boolean isCaching() {
+                return true;
+            }
         };
     }
 
@@ -83,6 +93,8 @@ public abstract class ArtifactRetriever {
 
     abstract void cache(RepositoryArtifact artifact, String content);
 
+    abstract boolean isCaching();
+
     /**
      * Reads the contents of an artifact as a string.
      *
@@ -141,17 +153,17 @@ public abstract class ArtifactRetriever {
 
         var download_filename = artifact.location().substring(artifact.location().lastIndexOf("/") + 1);
         var download_file = new File(directory, download_filename);
-        System.out.print("Downloading: " + artifact.location() + " ... ");
+        var transfer = TransferOutput.instance().start(artifact.location());
-        System.out.flush();
+        var status = "";
         try {
             if (artifact.repository().isLocal()) {
                 var source = new File(artifact.location());
                 if (source.exists()) {
                     FileUtils.copy(source, download_file);
-                    System.out.print("done");
+                    status = "done";
                     return true;
                 } else {
-                    System.out.print("not found");
+                    status = "not found";
                     return false;
                 }
             } else {
@@ -159,7 +171,7 @@ public abstract class ArtifactRetriever {
                     if (download_file.exists() && download_file.canRead()) {
                         if (checkHash(artifact, download_file, ".sha256", "SHA-256") ||
                             checkHash(artifact, download_file, ".md5", "MD5")) {
-                            System.out.print("exists");
+                            status = "exists";
                             return true;
                         }
                     }
@@ -170,23 +182,29 @@ public abstract class ArtifactRetriever {
                             HEADER_AUTHORIZATION,
                             basicAuthorizationHeader(artifact.repository().username(), artifact.repository().password()));
                     }
+                    var content_length = connection.getContentLengthLong();
                     try (var input_stream = connection.getInputStream()) {
                         var readableByteChannel = Channels.newChannel(input_stream);
                         try (var fileOutputStream = new FileOutputStream(download_file)) {
                             var fileChannel = fileOutputStream.getChannel();
-                            fileChannel.transferFrom(readableByteChannel, 0, Long.MAX_VALUE);
+                            var position = 0L;
+                            long transferred;
+                            while ((transferred = fileChannel.transferFrom(readableByteChannel, position, TRANSFER_CHUNK_SIZE)) > 0) {
+                                position += transferred;
+                                transfer.progress(position, content_length);
+                            }
 
-                            System.out.print("done");
+                            status = "done";
                             return true;
                         }
                     }
                 } catch (FileNotFoundException e) {
-                    System.out.print("not found");
+                    status = "not found";
                     return false;
                 }
             }
         } finally {
-            System.out.println();
+            transfer.finish(status);
         }
     }
 

src/main/java/rife/bld/dependencies/Bom.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import java.util.regex.Pattern;
+
+/**
+ * Contains the information required to describe a bill of materials (BOM)
+ * in the build system.
+ * <p>
+ * A BOM is a POM whose dependency management section supplies versions
+ * during dependency resolution: dependencies that are declared without a
+ * version take the BOM's version, and transitive dependencies that match a
+ * BOM entry are pinned to the BOM's version. Versions that are explicitly
+ * declared in the build file, and versions provided through the
+ * {@code bld.override} property, always take precedence over a BOM.
+ * <p>
+ * BOMs don't transfer any artifacts, they only participate in resolution.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+public class Bom extends Dependency {
+    public Bom(String groupId, String artifactId) {
+        this(groupId, artifactId, null);
+    }
+
+    public Bom(String groupId, String artifactId, Version version) {
+        super(groupId, artifactId, version, null, TYPE_BOM);
+    }
+
+    private static final Pattern BOM_PATTERN = Pattern.compile("^(?<groupId>[^:@]+):(?<artifactId>[^:@]+)(?::(?<version>[^:@]+))?(?:@(?:bom|pom))?$");
+
+    /**
+     * Parses a BOM from a string representation.
+     * The format is {@code groupId:artifactId:version}.
+     * The {@code version} is optional, and an optional {@code @bom} or
+     * {@code @pom} type suffix is accepted. BOMs can't have classifiers,
+     * strings that contain one are rejected.
+     * <p>
+     * If the string can't be successfully parsed, {@code null} will be returned.
+     *
+     * @param bom the BOM string to parse
+     * @return a parsed instance of {@code Bom}; or
+     * {@code null} when the string couldn't be parsed
+     * @since 2.4.0
+     */
+    public static Bom parse(String bom) {
+        if (bom == null || bom.isEmpty()) {
+            return null;
+        }
+
+        var matcher = BOM_PATTERN.matcher(bom);
+        if (!matcher.matches()) {
+            return null;
+        }
+
+        var groupId = matcher.group("groupId");
+        var artifactId = matcher.group("artifactId");
+        var version = Version.parse(matcher.group("version"));
+
+        return new Bom(groupId, artifactId, version);
+    }
+}

src/main/java/rife/bld/dependencies/Dependency.java

@@ -40,6 +40,14 @@ public class Dependency {
     // see https://github.com/apache/maven/blob/maven-4.0.0-beta-3/api/maven-api-core/src/main/java/org/apache/maven/api/Type.java
     public static final String TYPE_MODULAR_JAR = "modular-jar";
 
+    /**
+     * The dependency type name for a bill of materials POM whose
+     * dependency management supplies versions during resolution.
+     *
+     * @since 2.4.0
+     */
+    public static final String TYPE_BOM = "bom";
+
     private final String groupId_;
     private final String artifactId_;
     private final Version version_;

src/main/java/rife/bld/dependencies/DependencyResolver.java

@@ -102,7 +102,7 @@ public class DependencyResolver {
         var pom_dependencies = getMavenPom(dependency_).getDependencies(scopes);
         var result = new DependencySet();
         for (var dependency : pom_dependencies) {
-            result.add(resolution_.overrideDependency(dependency.convertToDependency()));
+            result.add(resolution_.overrideTransitiveDependency(dependency.convertToDependency()));
         }
         return result;
     }
@@ -121,8 +121,17 @@ public class DependencyResolver {
      * @since 1.5
      */
     public DependencySet getAllDependencies(Scope... scopes) {
+        var prefetcher = new PomPrefetcher(resolution_, retriever_, repositories_);
+        try {
+            return getAllDependencies(prefetcher, scopes);
+        } finally {
+            prefetcher.shutdown();
+        }
+    }
+
+    DependencySet getAllDependencies(PomPrefetcher prefetcher, Scope... scopes) {
         var result = new DependencySet();
-        var overridden = resolution_.overrideDependency(dependency_);
+        var overridden = resolution_.overrideDeclaredDependency(dependency_);
         result.add(overridden);
 
         var dependency_queue = new ArrayList<PomDependency>();
@@ -138,8 +147,11 @@ public class DependencyResolver {
             next_dependencies.removeIf(it -> matchesExclusions(exclusion_context, it));
             // add all next dependencies to the queue
             dependency_queue.addAll(next_dependencies);
+            // speculatively retrieve the POMs of the queued dependencies in
+            // parallel so that they are cached when they're processed in order
+            prefetcher.prefetch(next_dependencies);
 
-            // unless we find a next set of dependencies to add, stop resolving
+            // unless we find the next set of dependencies to add, stop resolving
             parent = null;
             next_dependencies = null;
 
@@ -147,7 +159,7 @@ public class DependencyResolver {
             // part of the results yet
             while (!dependency_queue.isEmpty()) {
                 var candidate = dependency_queue.remove(0);
-                var dependency = resolution_.overrideDependency(candidate.convertToDependency());
+                var dependency = resolution_.overrideTransitiveDependency(candidate.convertToDependency());
                 if (!result.contains(dependency)) {
                     result.add(dependency);
 

src/main/java/rife/bld/dependencies/DependencyScopes.java

@@ -6,6 +6,8 @@ package rife.bld.dependencies;
 
 import rife.ioc.HierarchicalProperties;
 
+import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
 
@@ -37,7 +39,8 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
     }
 
     /**
-     * Includes all the dependencies from another dependency scope map.
+     * Includes all the dependencies, local dependencies, local modules and
+     * BOMs from another dependency scope map.
      *
      * @param other the other map to include dependencies from
      * @since 1.5
@@ -49,7 +52,7 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
                 dependencies = new DependencySet();
                 put(entry.getKey(), dependencies);
             }
-            dependencies.addAll(entry.getValue());
+            dependencies.include(entry.getValue());
         }
     }
 
@@ -65,6 +68,150 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
         return computeIfAbsent(scope, k -> new DependencySet());
     }
 
+    /**
+     * Returns the BOMs that apply to the version resolution of a particular
+     * scope.
+     * <p>
+     * BOMs follow the same scope composition as the classpaths: the
+     * {@code compile} scope BOMs also apply to the {@code provided},
+     * {@code runtime} and {@code test} scopes, and the {@code runtime} and
+     * {@code provided} scope BOMs also apply to the {@code test} scope.
+     * The BOMs are returned with the scope's own BOMs first, followed by
+     * the inherited ones in the standard scope order, for the {@code test}
+     * scope that is {@code test}, {@code compile}, {@code provided},
+     * {@code runtime}. This order determines their precedence when several
+     * manage the same dependency: a BOM declared in the scope where a
+     * dependency is used takes precedence over a BOM that is inherited from
+     * another scope, and among the inherited BOMs the more fundamental
+     * scope wins.
+     * <p>
+     * The {@code standalone} scope only uses its own BOMs, and its BOMs
+     * deliberately never apply to any other scope.
+     *
+     * @param scope the scope to retrieve the applicable BOMs for
+     * @return the BOMs that apply to the scope's version resolution
+     * @since 2.4.0
+     */
+    public List<Bom> effectiveBoms(Scope scope) {
+        var boms = new ArrayList<Bom>();
+        for (var bom_scope : bomScopes(scope)) {
+            var scoped_dependencies = get(bom_scope);
+            if (scoped_dependencies != null) {
+                boms.addAll(scoped_dependencies.boms());
+            }
+        }
+        return boms;
+    }
+
+    private static Scope[] bomScopes(Scope scope) {
+        return switch (scope) {
+            case provided -> new Scope[]{Scope.provided, Scope.compile};
+            case runtime -> new Scope[]{Scope.runtime, Scope.compile};
+            case test -> new Scope[]{Scope.test, Scope.compile, Scope.provided, Scope.runtime};
+            default -> new Scope[]{scope};
+        };
+    }
+
+    /**
+     * Returns the version-less dependencies that are not covered by the
+     * BOMs that apply to their scope.
+     * <p>
+     * Scopes that no BOMs apply to are not considered, their
+     * version-less dependencies simply resolve to the latest version.
+     * Dependencies whose version is supplied by a {@code bld.override}
+     * property are not reported either.
+     *
+     * @param properties   the properties to use to get artifacts
+     * @param retriever    the retriever to use to get artifacts
+     * @param repositories the repositories to use for the BOM resolution
+     * @return the version-less dependencies that no applicable BOM covers
+     * @since 2.4.0
+     */
+    public List<Dependency> versionlessDependenciesWithoutBom(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
+        var result = new ArrayList<Dependency>();
+        for (var entry : entrySet()) {
+            var effective_boms = effectiveBoms(entry.getKey());
+            if (effective_boms.isEmpty()) {
+                continue;
+            }
+            var resolution = new VersionResolution(properties, retriever, repositories, effective_boms);
+            for (var dependency : entry.getValue()) {
+                if (dependency.version().equals(VersionNumber.UNKNOWN) &&
+                    !resolution.coversDependency(dependency) &&
+                    !resolution.versionOverrides().containsKey(dependency.toArtifactString()) &&
+                    !result.contains(dependency)) {
+                    result.add(dependency);
+                }
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Returns the version conflicts between the BOMs that apply to the
+     * scopes, where more than one applicable BOM manages the same
+     * dependency at a different version.
+     * <p>
+     * Each conflict is reported once, the versions are keyed by their BOM
+     * in precedence order so that the first is the version that is used.
+     *
+     * @param properties   the properties to use to get artifacts
+     * @param retriever    the retriever to use to get artifacts
+     * @param repositories the repositories to use for the BOM resolution
+     * @return the version conflicts between the applicable BOMs
+     * @since 2.4.0
+     */
+    public List<VersionResolution.BomVersionConflict> bomVersionConflicts(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
+        var result = new ArrayList<VersionResolution.BomVersionConflict>();
+        var seen = new HashSet<String>();
+        for (var scope : keySet()) {
+            var effective_boms = effectiveBoms(scope);
+            if (effective_boms.size() < 2) {
+                continue;
+            }
+            for (var conflict : VersionResolution.resolveBomVersionConflicts(properties, retriever, repositories, effective_boms)) {
+                if (seen.add(conflict.dependency() + conflict.bomVersions())) {
+                    result.add(conflict);
+                }
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Returns the declared dependencies whose explicit version differs
+     * from the version that a BOM applying to their scope manages them at.
+     * <p>
+     * The declared version is used for the dependency itself, its
+     * transitive dependencies still resolve to the versions that the BOMs
+     * manage. Dependencies whose version is supplied by a
+     * {@code bld.override} property are not reported. Each difference is
+     * reported once.
+     *
+     * @param properties   the properties to use to get artifacts
+     * @param retriever    the retriever to use to get artifacts
+     * @param repositories the repositories to use for the BOM resolution
+     * @return the version differences between the declared dependencies
+     * and the applicable BOMs
+     * @since 2.4.0
+     */
+    public List<VersionResolution.DeclaredVersionConflict> declaredVersionConflicts(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
+        var result = new ArrayList<VersionResolution.DeclaredVersionConflict>();
+        var seen = new HashSet<String>();
+        for (var entry : entrySet()) {
+            var effective_boms = effectiveBoms(entry.getKey());
+            if (effective_boms.isEmpty()) {
+                continue;
+            }
+            for (var conflict : VersionResolution.resolveDeclaredVersionConflicts(properties, retriever, repositories, effective_boms, entry.getValue())) {
+                if (seen.add(conflict.dependency() + conflict.declaredVersion() + conflict.bom() + conflict.bomVersion())) {
+                    result.add(conflict);
+                }
+            }
+        }
+        return result;
+    }
+
     /**
      * Returns the transitive set of dependencies that would be used for the compile scope in a project.
      *
@@ -76,6 +223,7 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
      */
     public DependencySet resolveCompileDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
         return resolveScopedDependencies(properties, retriever, repositories,
+            Scope.compile,
             new Scope[]{Scope.compile},
             new Scope[]{Scope.compile},
             null);
@@ -92,6 +240,7 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
      */
     public DependencySet resolveProvidedDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
         return resolveScopedDependencies(properties, retriever, repositories,
+            Scope.provided,
             new Scope[]{Scope.provided},
             new Scope[]{Scope.compile, Scope.runtime},
             null);
@@ -108,6 +257,7 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
      */
     public DependencySet resolveRuntimeDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
         return resolveScopedDependencies(properties, retriever, repositories,
+            Scope.runtime,
             new Scope[]{Scope.compile, Scope.runtime},
             new Scope[]{Scope.compile, Scope.runtime},
             resolveCompileDependencies(properties, retriever, repositories));
@@ -124,6 +274,7 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
      */
     public DependencySet resolveStandaloneDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
         return resolveScopedDependencies(properties, retriever, repositories,
+            Scope.standalone,
             new Scope[]{Scope.standalone},
             new Scope[]{Scope.compile, Scope.runtime},
             null);
@@ -140,22 +291,22 @@ public class DependencyScopes extends LinkedHashMap<Scope, DependencySet> {
      */
     public DependencySet resolveTestDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories) {
         return resolveScopedDependencies(properties, retriever, repositories,
+            Scope.test,
             new Scope[]{Scope.test},
             new Scope[]{Scope.compile, Scope.runtime},
             null);
     }
 
-    private DependencySet resolveScopedDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories, Scope[] resolvedScopes, Scope[] transitiveScopes, DependencySet excluded) {
+    private DependencySet resolveScopedDependencies(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories, Scope scope, Scope[] resolvedScopes, Scope[] transitiveScopes, DependencySet excluded) {
-        var resolution = new VersionResolution(properties);
+        var roots = new ArrayList<Dependency>();
-        var dependencies = new DependencySet();
+        for (var resolved_scope : resolvedScopes) {
-        for (var scope : resolvedScopes) {
+            var scoped_dependencies = get(resolved_scope);
-            var scoped_dependencies = get(scope);
             if (scoped_dependencies != null) {
-                for (var dependency : scoped_dependencies) {
+                roots.addAll(scoped_dependencies);
-                    dependencies.addAll(new DependencyResolver(resolution, retriever, repositories, dependency).getAllDependencies(transitiveScopes));
-                }
             }
         }
+        var resolution = new VersionResolution(properties, retriever, repositories, effectiveBoms(scope));
+        var dependencies = new ParallelDependencyResolver(resolution, retriever, repositories).resolveAllDependencies(roots, transitiveScopes);
         if (excluded != null) {
             dependencies.removeAll(excluded);
         }

src/main/java/rife/bld/dependencies/DependencySet.java

@@ -24,6 +24,7 @@ public class DependencySet extends AbstractSet<Dependency> implements Set<Depend
     private final Map<Dependency, Dependency> dependencies_ = new LinkedHashMap<>();
     private final Set<LocalDependency> localDependencies_ = new LinkedHashSet<>();
     private final Set<LocalModule> localModules_ = new LinkedHashSet<>();
+    private final Set<Bom> boms_ = new LinkedHashSet<>();
 
     /**
      * Creates an empty dependency set.
@@ -40,7 +41,23 @@ public class DependencySet extends AbstractSet<Dependency> implements Set<Depend
      * @since 1.5
      */
     public DependencySet(DependencySet other) {
+        include(other);
+    }
+
+    /**
+     * Includes all the dependencies, local dependencies, local modules and
+     * BOMs from another dependency set.
+     *
+     * @param other the other set to include
+     * @return this dependency set instance
+     * @since 2.4.0
+     */
+    public DependencySet include(DependencySet other) {
         addAll(other);
+        localDependencies_.addAll(other.localDependencies_);
+        localModules_.addAll(other.localModules_);
+        boms_.addAll(other.boms_);
+        return this;
     }
 
     /**
@@ -81,7 +98,32 @@ public class DependencySet extends AbstractSet<Dependency> implements Set<Depend
     }
 
     /**
-     * Includes a local module into the dependency set.
+     * Includes a bill of materials in the dependency set.
+     * <p>
+     * BOMs aren't transferred, their dependency management sections supply
+     * versions during the resolution of this dependency set.
+     *
+     * @param bom the BOM to include
+     * @return this dependency set instance
+     * @since 2.4.0
+     */
+    public DependencySet include(Bom bom) {
+        boms_.add(bom);
+        return this;
+    }
+
+    /**
+     * Retrieves the bills of materials.
+     *
+     * @return the set of BOMs
+     * @since 2.4.0
+     */
+    public Set<Bom> boms() {
+        return boms_;
+    }
+
+    /**
+     * Includes a local module in the dependency set.
      * <p>
      * Local modules aren't resolved and point to a location on
      * the file system.
@@ -128,6 +170,11 @@ public class DependencySet extends AbstractSet<Dependency> implements Set<Depend
      * including other classifiers.
      * <p>
      * The destination directory must exist and be writable.
+     * <p>
+     * The artifacts of different dependencies are transferred in parallel,
+     * the {@value VersionResolution#PROPERTY_TRANSFER_PARALLELISM} property
+     * can be used to change the number of simultaneous transfers, setting it
+     * to {@code 1} makes the transfers sequential.
      *
      * @param resolution        the version resolution state that can be cached
      * @param retriever         the retriever to use to get artifacts
@@ -140,48 +187,15 @@ public class DependencySet extends AbstractSet<Dependency> implements Set<Depend
      * @since 2.1
      */
     public List<RepositoryArtifact> transferIntoDirectory(VersionResolution resolution, ArtifactRetriever retriever, List<Repository> repositories, File directory, File modulesDirectory, String... classifiers) {
-        var result = new ArrayList<RepositoryArtifact>();
+        return new DependencyTransferBatch()
-        for (var dependency : this) {
+            .add(this, directory, modulesDirectory, classifiers)
-            var transfer_directory = directory;
+            .transfer(resolution, retriever, repositories);
-            if (dependency.isModularJar()) {
-                if (modulesDirectory == null) {
-                    throw new DependencyTransferException(dependency, "modules directory is not provided");
-                }
-                transfer_directory = modulesDirectory;
-            }
-            else if (directory == null) {
-                throw new DependencyTransferException(dependency, "artifacts directory is not provided");
-            }
-
-            if (!transfer_directory.exists()) {
-                if (!transfer_directory.mkdirs()) {
-                    throw new DependencyTransferException(dependency, transfer_directory, "couldn't create directory");
-                }
-            }
-
-            var artifact = new DependencyResolver(resolution, retriever, repositories, dependency).transferIntoDirectory(transfer_directory);
-            if (artifact != null) {
-                result.add(artifact);
-            }
-
-            if (classifiers != null) {
-                for (var classifier : classifiers) {
-                    if (classifier != null && !dependency.excludedClassifiers().contains(classifier)) {
-                        var classifier_artifact = new DependencyResolver(resolution, retriever, repositories, dependency.withClassifier(classifier)).transferIntoDirectory(transfer_directory);
-                        if (classifier_artifact != null) {
-                            result.add(classifier_artifact);
-                        }
-                    }
-                }
-            }
-        }
-        return result;
     }
 
     /**
      * Returns the dependency that was stored in the set.
      * <p>
-     * The version can be different from the dependency passed in and this
+     * The version can be different from the dependency passed in, and this
      * method can be used to look up the actual version of the dependency in the set.
      *
      * @param dependency the dependency to look for
@@ -206,11 +220,8 @@ public class DependencySet extends AbstractSet<Dependency> implements Set<Depend
      * @since 2.0
      */
     public String generateTransitiveDependencyTree(VersionResolution resolution, ArtifactRetriever retriever, List<Repository> repositories, Scope... scopes) {
-        var compile_dependencies = new DependencySet();
+        resolution = resolution.withBoms(retriever, repositories, boms_);
-        for (var dependency : this) {
+        return new ParallelDependencyResolver(resolution, retriever, repositories).resolveAllDependencies(this, scopes).generateDependencyTree();
-            compile_dependencies.addAll(new DependencyResolver(resolution, retriever, repositories, dependency).getAllDependencies(scopes));
-        }
-        return compile_dependencies.generateDependencyTree();
     }
 
     /**

src/main/java/rife/bld/dependencies/DependencyTransferBatch.java

@@ -0,0 +1,129 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import rife.bld.dependencies.exceptions.DependencyTransferException;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Supplier;
+
+/**
+ * Collects the artifact transfers of one or more dependency sets so that
+ * they can be transferred together in a single parallel batch, instead of
+ * separate consecutive batches per dependency set.
+ * <p>
+ * The batch itself is a passive collector, the resolution context is only
+ * provided when the transfers are {@linkplain #transfer performed}. The
+ * parallelism is determined by {@link VersionResolution#transferParallelism()},
+ * setting it to {@code 1} makes the transfers sequential. Identical
+ * transfers into the same directory are only performed once.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+public class DependencyTransferBatch {
+    private record TransferRequest(Dependency dependency, File directory, String[] classifiers) {
+    }
+
+    private final List<TransferRequest> requests_ = new ArrayList<>();
+    private final Set<String> transferTargets_ = new HashSet<>();
+
+    /**
+     * Adds the artifact transfers for a dependency set to this batch.
+     * <p>
+     * The destination directory must exist and be writable.
+     *
+     * @param dependencies     the dependencies whose artifacts to transfer
+     * @param directory        the directory to transfer the artifacts into
+     * @param modulesDirectory the directory to download the modules into
+     * @param classifiers      the additional classifiers to transfer
+     * @return this batch instance
+     * @throws DependencyTransferException when the transfer couldn't be prepared
+     * @since 2.4.0
+     */
+    public DependencyTransferBatch add(DependencySet dependencies, File directory, File modulesDirectory, String... classifiers) {
+        for (var dependency : dependencies) {
+            var transfer_directory = directory;
+            if (dependency.isModularJar()) {
+                if (modulesDirectory == null) {
+                    throw new DependencyTransferException(dependency, "modules directory is not provided");
+                }
+                transfer_directory = modulesDirectory;
+            }
+            else if (directory == null) {
+                throw new DependencyTransferException(dependency, "artifacts directory is not provided");
+            }
+
+            if (!transfer_directory.exists()) {
+                if (!transfer_directory.mkdirs()) {
+                    throw new DependencyTransferException(dependency, transfer_directory, "couldn't create directory");
+                }
+            }
+
+            // skip transfers that are already batched for the same directory
+            if (!transferTargets_.add(dependency + " -> " + transfer_directory.getAbsolutePath())) {
+                continue;
+            }
+
+            requests_.add(new TransferRequest(dependency, transfer_directory, classifiers));
+        }
+        return this;
+    }
+
+    /**
+     * Performs all the collected artifact transfers in a single parallel
+     * batch, in the order they were added.
+     * <p>
+     * This empties the batch, transfers can be collected and transferred
+     * again with the same instance.
+     *
+     * @param resolution   the version resolution state that can be cached
+     * @param retriever    the retriever to use to get artifacts
+     * @param repositories the repositories to use for the transfer
+     * @return the list of artifacts that were transferred successfully
+     * @throws DependencyTransferException when an error occurred during the transfer
+     * @since 2.4.0
+     */
+    public List<RepositoryArtifact> transfer(VersionResolution resolution, ArtifactRetriever retriever, List<Repository> repositories) {
+        final var repos = (repositories == null ? List.<Repository>of() : repositories);
+        try {
+            var transfers = new ArrayList<Supplier<List<RepositoryArtifact>>>(requests_.size());
+            for (var request : requests_) {
+                transfers.add(() -> {
+                    var artifacts = new ArrayList<RepositoryArtifact>();
+                    var artifact = new DependencyResolver(resolution, retriever, repos, request.dependency()).transferIntoDirectory(request.directory());
+                    if (artifact != null) {
+                        artifacts.add(artifact);
+                    }
+
+                    if (request.classifiers() != null) {
+                        for (var classifier : request.classifiers()) {
+                            if (classifier != null && !request.dependency().excludedClassifiers().contains(classifier)) {
+                                var classifier_artifact = new DependencyResolver(resolution, retriever, repos, request.dependency().withClassifier(classifier)).transferIntoDirectory(request.directory());
+                                if (classifier_artifact != null) {
+                                    artifacts.add(classifier_artifact);
+                                }
+                            }
+                        }
+                    }
+                    return artifacts;
+                });
+            }
+
+            var result = new ArrayList<RepositoryArtifact>();
+            for (var artifacts : ParallelExecution.execute(transfers, resolution.transferParallelism())) {
+                result.addAll(artifacts);
+            }
+            return result;
+        } finally {
+            requests_.clear();
+            transferTargets_.clear();
+        }
+    }
+}

src/main/java/rife/bld/dependencies/ParallelDependencyResolver.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * Resolves multiple dependencies in parallel within a list of
+ * Maven-compatible repositories.
+ * <p>
+ * The parallelism is determined by {@link VersionResolution#resolutionParallelism()},
+ * setting it to {@code 1} makes the resolution sequential. The results are
+ * always identical to resolving each dependency sequentially with a
+ * {@link DependencyResolver}, in the same order.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+public class ParallelDependencyResolver {
+    private final VersionResolution resolution_;
+    private final ArtifactRetriever retriever_;
+    private final List<Repository> repositories_;
+
+    /**
+     * Creates a new parallel resolver.
+     * <p>
+     * The repositories will be checked in the order they're listed.
+     *
+     * @param resolution   the version resolution state that can be cached
+     * @param retriever    the retriever to use to get artifacts
+     * @param repositories the repositories to use for the resolution
+     * @since 2.4.0
+     */
+    public ParallelDependencyResolver(VersionResolution resolution, ArtifactRetriever retriever, List<Repository> repositories) {
+        resolution_ = resolution;
+        retriever_ = retriever;
+        if (repositories == null) {
+            repositories = List.of();
+        }
+        repositories_ = repositories;
+    }
+
+    /**
+     * Resolves the transitive dependencies of multiple root dependencies,
+     * merging the results in the order of the provided roots.
+     * <p>
+     * The roots are resolved in parallel while a shared prefetcher
+     * speculatively warms the retriever cache across all of them.
+     *
+     * @param roots  the root dependencies to resolve
+     * @param scopes the scopes to return the transitive dependencies for
+     * @return the merged transitive dependencies of all the roots
+     * @since 2.4.0
+     */
+    public DependencySet resolveAllDependencies(Collection<Dependency> roots, Scope... scopes) {
+        var result = new DependencySet();
+        if (roots.isEmpty()) {
+            return result;
+        }
+
+        var prefetcher = new PomPrefetcher(resolution_, retriever_, repositories_);
+        try {
+            var resolutions = new ArrayList<Supplier<DependencySet>>(roots.size());
+            for (var root : roots) {
+                resolutions.add(() -> new DependencyResolver(resolution_, retriever_, repositories_, root).getAllDependencies(prefetcher, scopes));
+            }
+            for (var dependencies : ParallelExecution.execute(resolutions, resolution_.resolutionParallelism())) {
+                result.addAll(dependencies);
+            }
+        } finally {
+            prefetcher.shutdown();
+        }
+        return result;
+    }
+
+    /**
+     * Resolves the latest versions of multiple dependencies, returning them
+     * in the same order as the provided dependencies.
+     *
+     * @param dependencies the dependencies to resolve the latest versions of
+     * @return the latest versions in the order of the provided dependencies
+     * @since 2.4.0
+     */
+    public List<Version> resolveLatestVersions(List<Dependency> dependencies) {
+        var resolutions = new ArrayList<Supplier<Version>>(dependencies.size());
+        for (var dependency : dependencies) {
+            resolutions.add(() -> new DependencyResolver(resolution_, retriever_, repositories_, dependency).latestVersion());
+        }
+        return ParallelExecution.execute(resolutions, resolution_.resolutionParallelism());
+    }
+
+    /**
+     * Returns the version resolution state that can be cached.
+     *
+     * @return the version resolution state
+     * @since 2.4.0
+     */
+    public VersionResolution resolution() {
+        return resolution_;
+    }
+
+    /**
+     * Retrieve the repositories that are used by this resolver.
+     *
+     * @return the resolver's repositories
+     * @since 2.4.0
+     */
+    public List<Repository> repositories() {
+        return repositories_;
+    }
+}

src/main/java/rife/bld/dependencies/ParallelExecution.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.function.Supplier;
+
+/**
+ * Executes tasks in parallel while preserving the order of their results
+ * and the sequential semantics of failures: the first task that fails in
+ * order will have its exception rethrown.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+final class ParallelExecution {
+    private ParallelExecution() {
+    }
+
+    static <T> List<T> execute(List<Supplier<T>> tasks, int parallelism) {
+        var result = new ArrayList<T>(tasks.size());
+
+        parallelism = Math.min(tasks.size(), parallelism);
+        if (parallelism <= 1) {
+            for (var task : tasks) {
+                result.add(task.get());
+            }
+            return result;
+        }
+
+        var executor = Executors.newFixedThreadPool(parallelism);
+        try {
+            var futures = new ArrayList<Future<T>>(tasks.size());
+            for (var task : tasks) {
+                futures.add(executor.submit(task::get));
+            }
+            for (var future : futures) {
+                try {
+                    result.add(future.get());
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    throw new IllegalStateException("Parallel execution was interrupted", e);
+                } catch (ExecutionException e) {
+                    if (e.getCause() instanceof RuntimeException runtime) {
+                        throw runtime;
+                    }
+                    if (e.getCause() instanceof Error error) {
+                        throw error;
+                    }
+                    throw new IllegalStateException(e.getCause());
+                }
+            }
+        } finally {
+            executor.shutdownNow();
+        }
+        return result;
+    }
+}

src/main/java/rife/bld/dependencies/PomPrefetcher.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+/**
+ * Speculatively retrieves POMs in parallel so that they are already cached
+ * by the artifact retriever when the sequential dependency resolution
+ * processes them, without influencing the resolution semantics.
+ * <p>
+ * A single instance can be shared by multiple concurrent resolutions, the
+ * POM of each unique dependency will only be prefetched once.
+ * <p>
+ * Prefetching only has benefits when the retrieved POMs are cached for the
+ * sequential resolution that follows, the prefetcher is inert when the
+ * retriever doesn't cache or when the resolution parallelism disables it.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+class PomPrefetcher {
+    private final VersionResolution resolution_;
+    private final ArtifactRetriever retriever_;
+    private final List<Repository> repositories_;
+    private final ExecutorService executor_;
+    private final Set<Dependency> submitted_ = ConcurrentHashMap.newKeySet();
+
+    PomPrefetcher(VersionResolution resolution, ArtifactRetriever retriever, List<Repository> repositories) {
+        resolution_ = resolution;
+        retriever_ = retriever;
+        repositories_ = repositories;
+        if (retriever.isCaching() && resolution.resolutionParallelism() > 1) {
+            executor_ = Executors.newFixedThreadPool(resolution.resolutionParallelism());
+        } else {
+            executor_ = null;
+        }
+    }
+
+    void prefetch(Collection<PomDependency> candidates) {
+        if (executor_ == null) {
+            return;
+        }
+        for (var candidate : candidates) {
+            var dependency = resolution_.overrideTransitiveDependency(candidate.convertToDependency());
+            if (submitted_.add(dependency)) {
+                executor_.submit(() -> {
+                    try {
+                        new DependencyResolver(resolution_, retriever_, repositories_, dependency).getMavenPom(dependency);
+                    } catch (Throwable e) {
+                        // failures are ignored since they will resurface
+                        // with the proper context when the dependency is
+                        // resolved in order
+                    }
+                });
+            }
+        }
+    }
+
+    void shutdown() {
+        if (executor_ != null) {
+            executor_.shutdownNow();
+        }
+    }
+}

src/main/java/rife/bld/dependencies/TransferOutput.java

@@ -0,0 +1,185 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Outputs the status of artifact transfers to the console.
+ * <p>
+ * When the console is an interactive terminal, the transfers that are in
+ * progress are displayed in a live updating block at the bottom of the
+ * output, with each transfer reporting its progress as it happens.
+ * Otherwise, a single line is printed when each transfer finishes, keeping
+ * the output stable for CI logs, pipes and IDE consoles, while still never
+ * interleaving the lines of parallel transfers.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+abstract class TransferOutput {
+    private static final TransferOutput INSTANCE = create();
+
+    static TransferOutput instance() {
+        return INSTANCE;
+    }
+
+    private static TransferOutput create() {
+        if (System.console() != null && !"dumb".equals(System.getenv("TERM"))) {
+            return new AnsiTransferOutput();
+        }
+        return new PlainTransferOutput();
+    }
+
+    /**
+     * Starts tracking a single artifact transfer.
+     *
+     * @param location the location of the artifact that is being transferred
+     * @return the transfer to report progress and completion on
+     * @since 2.4.0
+     */
+    abstract Transfer start(String location);
+
+    /**
+     * A single artifact transfer whose progress is being tracked.
+     *
+     * @since 2.4.0
+     */
+    abstract static class Transfer {
+        protected final String location_;
+
+        protected Transfer(String location) {
+            location_ = location;
+        }
+
+        /**
+         * Reports transfer progress.
+         *
+         * @param transferred the number of bytes transferred so far
+         * @param total       the total number of bytes; or {@code -1} when unknown
+         * @since 2.4.0
+         */
+        abstract void progress(long transferred, long total);
+
+        /**
+         * Reports that the transfer finished.
+         *
+         * @param status the final status of the transfer, like
+         *               {@code done}, {@code exists} or {@code not found}
+         * @since 2.4.0
+         */
+        abstract void finish(String status);
+    }
+
+    static String describe(String location, String status) {
+        return "Downloading: " + location + " ... " + status;
+    }
+
+    private static class PlainTransferOutput extends TransferOutput {
+        Transfer start(String location) {
+            return new Transfer(location) {
+                void progress(long transferred, long total) {
+                    // no-op, only the finished state is printed
+                }
+
+                void finish(String status) {
+                    System.out.println(describe(location_, status));
+                }
+            };
+        }
+    }
+
+    private static class AnsiTransferOutput extends TransferOutput {
+        private static final long REPAINT_INTERVAL_MS = 100;
+        private static final int MAX_LINE_WIDTH = 79;
+
+        private final List<AnsiTransfer> active_ = new ArrayList<>();
+        private int paintedLines_ = 0;
+        private long lastRepaint_ = 0;
+
+        synchronized Transfer start(String location) {
+            var transfer = new AnsiTransfer(location);
+            active_.add(transfer);
+            repaint(null);
+            return transfer;
+        }
+
+        private synchronized void reportProgress() {
+            if (System.currentTimeMillis() - lastRepaint_ >= REPAINT_INTERVAL_MS) {
+                repaint(null);
+            }
+        }
+
+        private synchronized void reportFinished(AnsiTransfer transfer, String status) {
+            active_.remove(transfer);
+            repaint(describe(transfer.location_, status));
+        }
+
+        private void repaint(String finishedLine) {
+            var output = new StringBuilder();
+            if (paintedLines_ > 0) {
+                // move the cursor to the beginning of the live block
+                // and clear everything below it
+                output.append("\u001B[").append(paintedLines_).append("F\u001B[0J");
+            }
+            if (finishedLine != null) {
+                output.append(finishedLine).append('\n');
+            }
+            for (var transfer : active_) {
+                output.append(transfer.statusLine()).append('\n');
+            }
+            paintedLines_ = active_.size();
+            lastRepaint_ = System.currentTimeMillis();
+            System.out.print(output);
+            System.out.flush();
+        }
+
+        private class AnsiTransfer extends Transfer {
+            private volatile long transferred_ = 0;
+            private volatile long total_ = -1;
+
+            AnsiTransfer(String location) {
+                super(location);
+            }
+
+            void progress(long transferred, long total) {
+                transferred_ = transferred;
+                total_ = total;
+                reportProgress();
+            }
+
+            void finish(String status) {
+                reportFinished(this, status);
+            }
+
+            String statusLine() {
+                var filename = location_.substring(location_.lastIndexOf('/') + 1);
+                var line = new StringBuilder("Downloading: ").append(filename).append(" ... ");
+                if (total_ > 0) {
+                    line.append(transferred_ * 100 / total_).append('%');
+                } else if (transferred_ > 0) {
+                    line.append(humanBytes(transferred_));
+                }
+                // prevent lines from wrapping since that would break
+                // the cursor repositioning of the repaints
+                if (line.length() > MAX_LINE_WIDTH) {
+                    line.setLength(MAX_LINE_WIDTH);
+                }
+                return line.toString();
+            }
+
+            private String humanBytes(long bytes) {
+                if (bytes >= 1024 * 1024) {
+                    return (bytes / (1024 * 1024)) + " MB";
+                }
+                if (bytes >= 1024) {
+                    return (bytes / 1024) + " KB";
+                }
+                return bytes + " B";
+            }
+        }
+    }
+}

src/main/java/rife/bld/dependencies/VersionResolution.java

@@ -6,13 +6,19 @@ package rife.bld.dependencies;
 
 import rife.ioc.HierarchicalProperties;
 
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
+import java.util.logging.Logger;
 
 /**
- * This class is responsible for managing version overrides for dependencies.
+ * This class is responsible for managing the versions that are applied
+ * during dependency resolution.
  * <p>
- * It allows users to specify a property keys with the prefix "{@code bld.override}" where the values will be parsed as
+ * It allows users to specify a property key with the prefix "{@code bld.override}" where the values will be parsed as
  * a comma-separated list of dependencies with the versions that should override any other versions that are encountered.
  * <p>
  * For instance:
@@ -27,6 +33,20 @@ import java.util.Map;
  * bld.override-tests=com.uwyn.rife2:bld-tests-badge:1.4.7
  * bld.override-h2=com.h2database:h2:2.2.222
  * </pre>
+ * <p>
+ * It can also import versions from the dependency management sections of
+ * bills of materials (BOMs). When resolving versions, the
+ * following precedence applies: a version from a "{@code bld.override}"
+ * property always wins, followed by a version explicitly declared
+ * in the build file, followed by a version from a BOM. Dependencies that
+ * are declared without a version and that are not covered by a BOM,
+ * resolve to their latest version.
+ * <p>
+ * It also captures other dependency resolution preferences, like the number
+ * of parallel artifact transfers through the "{@code bld.transferParallelism}"
+ * property and the number of parallel POM retrievals during transitive
+ * dependency resolution through the "{@code bld.resolutionParallelism}"
+ * property.
  * @since 2.0
  */
 public class VersionResolution {
@@ -36,7 +56,27 @@ public class VersionResolution {
      */
     public static final String PROPERTY_OVERRIDE_PREFIX = "bld.override";
 
+    /**
+     * The property key that determines how many artifact transfers are
+     * performed in parallel, {@code 1} makes them sequential.
+     * @since 2.4.0
+     */
+    public static final String PROPERTY_TRANSFER_PARALLELISM = "bld.transferParallelism";
+    private static final int DEFAULT_TRANSFER_PARALLELISM = 6;
+
+    /**
+     * The property key that determines how many POMs are speculatively
+     * retrieved in parallel during transitive dependency resolution,
+     * {@code 1} disables the parallel retrieval.
+     * @since 2.4.0
+     */
+    public static final String PROPERTY_RESOLUTION_PARALLELISM = "bld.resolutionParallelism";
+    private static final int DEFAULT_RESOLUTION_PARALLELISM = 6;
+
     private final Map<String, Version> versionOverrides_ = new HashMap<>();
+    private final Map<String, Version> bomVersions_;
+    private final int transferParallelism_;
+    private final int resolutionParallelism_;
 
     /**
      * Returns a dummy {@code VersionResolution} instance that doesn't override anything.
@@ -74,6 +114,223 @@ public class VersionResolution {
                 }
             }
         }
+        transferParallelism_ = parseParallelism(properties, PROPERTY_TRANSFER_PARALLELISM, DEFAULT_TRANSFER_PARALLELISM);
+        resolutionParallelism_ = parseParallelism(properties, PROPERTY_RESOLUTION_PARALLELISM, DEFAULT_RESOLUTION_PARALLELISM);
+        bomVersions_ = Map.of();
+    }
+
+    private VersionResolution(VersionResolution base, Map<String, Version> bomVersions) {
+        versionOverrides_.putAll(base.versionOverrides_);
+        transferParallelism_ = base.transferParallelism_;
+        resolutionParallelism_ = base.resolutionParallelism_;
+        bomVersions_ = Map.copyOf(bomVersions);
+    }
+
+    /**
+     * Creates a new instance of the {@code VersionResolution} class from
+     * hierarchical properties and bills of materials whose dependency
+     * management sections supply versions during resolution.
+     * <p>
+     * The BOMs are imported in the order they're provided, the first BOM
+     * that manages a particular dependency determines its version. The
+     * version overrides of the properties take precedence over any BOM
+     * version, they also apply when resolving the BOMs themselves.
+     *
+     * @param properties   the hierarchical properties that will be used to determine the version overrides
+     * @param retriever    the retriever to use to get the BOMs
+     * @param repositories the repositories to resolve the BOMs in
+     * @param boms         the BOMs to import
+     * @since 2.4.0
+     */
+    public VersionResolution(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories, Collection<Bom> boms) {
+        this(new VersionResolution(properties), retriever, repositories, boms);
+    }
+
+    private VersionResolution(VersionResolution base, ArtifactRetriever retriever, List<Repository> repositories, Collection<Bom> boms) {
+        this(base, resolveBomVersions(base, retriever, repositories, boms));
+    }
+
+    // returns a resolution that additionally imports the provided BOMs,
+    // versions that are already imported take precedence over the new ones
+    VersionResolution withBoms(ArtifactRetriever retriever, List<Repository> repositories, Collection<Bom> boms) {
+        if (boms == null || boms.isEmpty()) {
+            return this;
+        }
+        var merged = new HashMap<>(resolveBomVersions(this, retriever, repositories, boms));
+        merged.putAll(bomVersions_);
+        return new VersionResolution(this, merged);
+    }
+
+    private static Map<String, Version> resolveBomVersions(VersionResolution resolution, ArtifactRetriever retriever, List<Repository> repositories, Collection<Bom> boms) {
+        var bom_versions = new HashMap<String, Version>();
+        if (boms != null) {
+            for (var bom : boms) {
+                var pom = new DependencyResolver(resolution, retriever, repositories, bom).getMavenPom(bom);
+                for (var managed : pom.getManagedDependencies()) {
+                    if (managed.version() != null && !managed.version().isBlank()) {
+                        var dependency = managed.convertToDependency();
+                        bom_versions.putIfAbsent(managedKey(dependency), dependency.version());
+                    }
+                }
+            }
+        }
+        return bom_versions;
+    }
+
+    /**
+     * Describes a version conflict between bills of materials, where more
+     * than one applicable BOM manages the same dependency at a different
+     * version.
+     *
+     * @param dependency  the group and artifact identifiers of the
+     *                    dependency that is managed at conflicting versions
+     * @param bomVersions the versions that the BOMs manage the dependency
+     *                    at, keyed by the BOM, in precedence order so that
+     *                    the first entry is the version that is used
+     * @since 2.4.0
+     */
+    public record BomVersionConflict(String dependency, Map<String, Version> bomVersions) {
+    }
+
+    /**
+     * Resolves the version conflicts between the provided bills of
+     * materials, where more than one of them manages the same dependency
+     * at a different version.
+     *
+     * @param properties   the properties to use to get artifacts
+     * @param retriever    the retriever to use to get the BOMs
+     * @param repositories the repositories to resolve the BOMs in
+     * @param boms         the BOMs to check, in precedence order
+     * @return the version conflicts between the BOMs
+     * @since 2.4.0
+     */
+    public static List<BomVersionConflict> resolveBomVersionConflicts(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories, Collection<Bom> boms) {
+        var base = new VersionResolution(properties);
+        var versions_by_key = new LinkedHashMap<String, LinkedHashMap<String, Version>>();
+        var dependency_by_key = new LinkedHashMap<String, String>();
+        if (boms != null) {
+            for (var bom : boms) {
+                var pom = new DependencyResolver(base, retriever, repositories, bom).getMavenPom(bom);
+                for (var managed : pom.getManagedDependencies()) {
+                    if (managed.version() != null && !managed.version().isBlank()) {
+                        var dependency = managed.convertToDependency();
+                        var key = managedKey(dependency);
+                        versions_by_key.computeIfAbsent(key, k -> new LinkedHashMap<>())
+                            .putIfAbsent(bom.toArtifactString(), dependency.version());
+                        dependency_by_key.putIfAbsent(key, dependency.toArtifactString());
+                    }
+                }
+            }
+        }
+
+        var conflicts = new ArrayList<BomVersionConflict>();
+        for (var entry : versions_by_key.entrySet()) {
+            var bom_versions = entry.getValue();
+            if (bom_versions.values().stream().distinct().count() > 1) {
+                conflicts.add(new BomVersionConflict(dependency_by_key.get(entry.getKey()), new LinkedHashMap<>(bom_versions)));
+            }
+        }
+        return conflicts;
+    }
+
+    /**
+     * Describes a declared dependency whose explicit version differs from
+     * the version that an applicable bill of materials manages it at.
+     * <p>
+     * The declared version is used for the dependency itself, its
+     * transitive dependencies still resolve to the versions that the BOM
+     * manages.
+     *
+     * @param dependency      the group and artifact identifiers of the
+     *                        declared dependency
+     * @param declaredVersion the version the dependency is declared with
+     * @param bom             the BOM that manages the dependency, the one
+     *                        with the highest precedence when several do
+     * @param bomVersion      the version the BOM manages the dependency at
+     * @since 2.4.0
+     */
+    public record DeclaredVersionConflict(String dependency, Version declaredVersion, String bom, Version bomVersion) {
+    }
+
+    /**
+     * Finds the declared dependencies whose explicit version differs from
+     * the version that the provided bills of materials manage them at.
+     * <p>
+     * Dependencies that are declared without a version or whose version is
+     * supplied by a {@code bld.override} property are not reported.
+     *
+     * @param properties   the properties to use to get artifacts
+     * @param retriever    the retriever to use to get the BOMs
+     * @param repositories the repositories to resolve the BOMs in
+     * @param boms         the BOMs to check, in precedence order
+     * @param declared     the declared dependencies to check
+     * @return the version differences between the declared dependencies and the BOMs
+     * @since 2.4.0
+     */
+    public static List<DeclaredVersionConflict> resolveDeclaredVersionConflicts(HierarchicalProperties properties, ArtifactRetriever retriever, List<Repository> repositories, Collection<Bom> boms, Collection<Dependency> declared) {
+        var base = new VersionResolution(properties);
+        var managed_versions = new LinkedHashMap<String, Version>();
+        var managed_boms = new LinkedHashMap<String, String>();
+        if (boms != null) {
+            for (var bom : boms) {
+                var pom = new DependencyResolver(base, retriever, repositories, bom).getMavenPom(bom);
+                for (var managed : pom.getManagedDependencies()) {
+                    if (managed.version() != null && !managed.version().isBlank()) {
+                        var dependency = managed.convertToDependency();
+                        var key = managedKey(dependency);
+                        // the first BOM that manages a dependency determines
+                        // its version, mirroring the resolution precedence
+                        if (managed_versions.putIfAbsent(key, dependency.version()) == null) {
+                            managed_boms.put(key, bom.toArtifactString());
+                        }
+                    }
+                }
+            }
+        }
+
+        var conflicts = new ArrayList<DeclaredVersionConflict>();
+        if (declared != null) {
+            for (var dependency : declared) {
+                if (VersionNumber.UNKNOWN.equals(dependency.version()) ||
+                    base.versionOverrides_.containsKey(dependency.toArtifactString())) {
+                    continue;
+                }
+                var key = managedKey(dependency);
+                var managed_version = managed_versions.get(key);
+                if (managed_version != null && !managed_version.equals(dependency.version())) {
+                    conflicts.add(new DeclaredVersionConflict(dependency.toArtifactString(), dependency.version(), managed_boms.get(key), managed_version));
+                }
+            }
+        }
+        return conflicts;
+    }
+
+    // builds the identity that dependency management entries are matched
+    // on, mirroring Maven this includes the type and the classifier, the
+    // modular and forced-classpath JAR types match the plain jar entries
+    // that BOMs manage
+    private static String managedKey(Dependency dependency) {
+        var type = dependency.type();
+        if (type == null || type.isBlank() ||
+            Dependency.TYPE_MODULAR_JAR.equals(type) ||
+            Dependency.TYPE_CLASSPATH_JAR.equals(type)) {
+            type = Dependency.TYPE_JAR;
+        }
+        return dependency.toArtifactString() + ":" + type + ":" + dependency.classifier();
+    }
+
+    private static int parseParallelism(HierarchicalProperties properties, String property, int defaultValue) {
+        if (properties != null) {
+            var parallelism = properties.getValueString(property);
+            if (parallelism != null && !parallelism.isBlank()) {
+                try {
+                    return Math.max(1, Integer.parseInt(parallelism.trim()));
+                } catch (NumberFormatException e) {
+                    Logger.getLogger("rife.bld").warning("Unable to parse the " + property + " property as an integer: '" + parallelism + "', using " + defaultValue + " instead");
+                }
+            }
+        }
+        return defaultValue;
     }
 
     /**
@@ -85,11 +342,17 @@ public class VersionResolution {
      */
     public Version overrideVersion(Dependency original) {
         var overridden = versionOverrides_.get(original.toArtifactString());
-        if (overridden == null) {
+        if (overridden != null) {
-            return original.version();
-        }
             return overridden;
         }
+        if (VersionNumber.UNKNOWN.equals(original.version())) {
+            var bom_version = bomVersions_.get(managedKey(original));
+            if (bom_version != null) {
+                return bom_version;
+            }
+        }
+        return original.version();
+    }
 
     /**
      * Overrides the version of a given dependency with the corresponding overridden version and
@@ -104,9 +367,63 @@ public class VersionResolution {
         if (overridden == null) {
             return original;
         }
+        return withVersion(original, overridden);
+    }
+
+    /**
+     * Applies version overrides to a dependency that was explicitly declared
+     * in the build file.
+     * <p>
+     * A version from the {@code bld.override} property always takes
+     * precedence. A bill of materials version is only applied when the
+     * dependency was declared without a version, an explicitly declared
+     * version is never rewritten by a BOM.
+     *
+     * @param declared the declared dependency to apply overrides to
+     * @return the dependency with the overridden version if one applies; or
+     * the original dependency otherwise
+     * @since 2.4.0
+     */
+    public Dependency overrideDeclaredDependency(Dependency declared) {
+        var overridden = versionOverrides_.get(declared.toArtifactString());
+        if (overridden == null && VersionNumber.UNKNOWN.equals(declared.version())) {
+            overridden = bomVersions_.get(managedKey(declared));
+        }
+        if (overridden == null) {
+            return declared;
+        }
+        return withVersion(declared, overridden);
+    }
+
+    /**
+     * Applies version overrides to a transitive dependency that was
+     * encountered during resolution.
+     * <p>
+     * A version from the {@code bld.override} property always takes
+     * precedence, followed by a matching bill of materials version that
+     * pins the transitive dependency regardless of the version its parent
+     * POM declared.
+     *
+     * @param transitive the transitive dependency to apply overrides to
+     * @return the dependency with the overridden version if one applies; or
+     * the original dependency otherwise
+     * @since 2.4.0
+     */
+    public Dependency overrideTransitiveDependency(Dependency transitive) {
+        var overridden = versionOverrides_.get(transitive.toArtifactString());
+        if (overridden == null) {
+            overridden = bomVersions_.get(managedKey(transitive));
+        }
+        if (overridden == null) {
+            return transitive;
+        }
+        return withVersion(transitive, overridden);
+    }
+
+    private static Dependency withVersion(Dependency original, Version version) {
         return new Dependency(original.groupId(),
             original.artifactId(),
-            overridden,
+            version,
             original.classifier(),
             original.type(),
             original.exclusions(),
@@ -122,4 +439,56 @@ public class VersionResolution {
     public Map<String, Version> versionOverrides() {
         return versionOverrides_;
     }
+
+    /**
+     * Indicates whether a bill of materials supplies the version of a
+     * particular dependency.
+     * <p>
+     * The dependency identity takes the group, artifact, type and
+     * classifier into account, mirroring Maven's dependency management.
+     *
+     * @param dependency the dependency to check
+     * @return {@code true} when a BOM manages the dependency's version;
+     * {@code false} otherwise
+     * @since 2.4.0
+     */
+    public boolean coversDependency(Dependency dependency) {
+        return bomVersions_.containsKey(managedKey(dependency));
+    }
+
+    /**
+     * Returns the map of versions that were imported from bills of
+     * materials, where the key is the dependency identity composed of the
+     * group, artifact, type and classifier, and the value is the managed
+     * version.
+     *
+     * @return the map of BOM versions
+     * @since 2.4.0
+     */
+    public Map<String, Version> bomVersions() {
+        return bomVersions_;
+    }
+
+    /**
+     * Returns the number of artifact transfers that are performed in parallel,
+     * {@code 1} means transfers are sequential.
+     *
+     * @return the number of parallel artifact transfers
+     * @since 2.4.0
+     */
+    public int transferParallelism() {
+        return transferParallelism_;
+    }
+
+    /**
+     * Returns the number of POMs that are speculatively retrieved in parallel
+     * during transitive dependency resolution, {@code 1} means the parallel
+     * retrieval is disabled.
+     *
+     * @return the number of parallel POM retrievals
+     * @since 2.4.0
+     */
+    public int resolutionParallelism() {
+        return resolutionParallelism_;
+    }
 }

src/main/java/rife/bld/dependencies/Xml2MavenPom.java

@@ -129,6 +129,17 @@ class Xml2MavenPom extends Xml2Data {
         return result;
     }
 
+    Set<PomDependency> getManagedDependencies() {
+        var result = new LinkedHashSet<PomDependency>();
+        // iterate the values since putting an entry with an equal key
+        // preserves the original key instance while the value reflects
+        // the actual managed dependency
+        for (var managed : dependencyManagement_.values()) {
+            result.add(resolveDependency(managed));
+        }
+        return result;
+    }
+
     PomDependency resolveDependency(PomDependency dependency) {
         return new PomDependency(
             resolveMavenProperties(dependency.groupId()),

src/main/java/rife/bld/help/McpHelp.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.help;
+
+import rife.bld.CommandHelp;
+import rife.tools.StringUtils;
+
+/**
+ * Provides help for the MCP command.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+public class McpHelp implements CommandHelp {
+    public String getSummary() {
+        return "Starts an MCP server that exposes the build commands";
+    }
+
+    public String getDescription(String topic) {
+        return StringUtils.replace("""
+            Starts a Model Context Protocol (MCP) server that exposes the
+            build commands as tools, so that AI agents can drive the build.
+            This is an experimental feature and may still change.
+
+            The server communicates over standard input and output with the
+            MCP stdio transport and runs until its input stream ends. Launch
+            bld with the --use-stderr option to keep standard output free
+            for the protocol while the build starts up.
+
+            The install argument doesn't start the server, it registers the
+            project with an MCP client by writing the standard configuration
+            file inside the project directory:
+
+            install          writes .mcp.json (Claude Code and compatible)
+            install cursor   writes .cursor/mcp.json
+            install vscode   writes .vscode/mcp.json
+            install --print  prints the configuration instead of writing it
+
+            Existing configuration files are merged with, other servers are
+            preserved. The registered command launches the wrapper directly
+            through java, so that the same file works on every platform.
+
+            Usage : ${topic} [install [claude | cursor | vscode] [--print]]""", "${topic}", topic);
+    }
+}

src/main/java/rife/bld/operations/AbstractCreateOperation.java

@@ -179,7 +179,7 @@ public abstract class AbstractCreateOperation<T extends AbstractCreateOperation<
      * parents, outputting the location when the operation is {@link #verbose()}.
      *
      * @param directory the directory to create
-     * @since 2.3.1
+     * @since 2.4.0
      */
     protected void executeCreateDirectory(File directory) {
         if (verbose()) {
@@ -194,7 +194,7 @@ public abstract class AbstractCreateOperation<T extends AbstractCreateOperation<
      *
      * @param content the content to write
      * @param file    the file to write the content into
-     * @since 2.3.1
+     * @since 2.4.0
      */
     protected void executeWriteProjectFile(String content, File file)
     throws FileUtilsErrorException {

src/main/java/rife/bld/operations/AbstractOperation.java

@@ -55,7 +55,7 @@ public abstract class AbstractOperation<T extends AbstractOperation<T>> {
      * @param verbose {@code true} if the operation should be verbose;
      *                {@code false} otherwise
      * @return this operation instance
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public T verbose(boolean verbose) {
         verbose_ = verbose;
@@ -68,7 +68,7 @@ public abstract class AbstractOperation<T extends AbstractOperation<T>> {
      *
      * @return {@code true} if the operation should be verbose;
      * {@code false} otherwise
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public boolean verbose() {
         return verbose_;

src/main/java/rife/bld/operations/AbstractProcessOperation.java

@@ -241,7 +241,7 @@ public abstract class AbstractProcessOperation<T extends AbstractProcessOperatio
      *
      * @param classpath classpath entries for the operation
      * @return this operation instance
-     * @since 2.3.1
+     * @since 2.4.0
      *
      */
     public T classpath(File... classpath) {
@@ -269,7 +269,7 @@ public abstract class AbstractProcessOperation<T extends AbstractProcessOperatio
      *
      * @param classpath a list of classpath entries for the operation
      * @return this operation instance
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public T classpath(Collection<File> classpath) {
         classpath_.addAll(classpath.stream().map(File::getAbsolutePath).toList());
@@ -293,7 +293,7 @@ public abstract class AbstractProcessOperation<T extends AbstractProcessOperatio
      *
      * @param modulePath module path entries for the operation
      * @return this operation instance
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public T modulePath(File... modulePath) {
         return modulePath(List.of(modulePath));
@@ -320,7 +320,7 @@ public abstract class AbstractProcessOperation<T extends AbstractProcessOperatio
      *
      * @param modulePath a list of module path entries for the operation
      * @return this operation instance
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public T modulePath(Collection<File> modulePath) {
         modulePath_.addAll(modulePath.stream().map(File::getAbsolutePath).toList());

src/main/java/rife/bld/operations/DependencyTreeOperation.java

@@ -178,7 +178,7 @@ public class DependencyTreeOperation extends AbstractOperation<DependencyTreeOpe
      * @since 1.5.21
      */
     protected String executeGenerateCompileDependencies() {
-        var compile_tree = dependencies().scope(compile).generateTransitiveDependencyTree(new VersionResolution(properties()), artifactRetriever(), repositories(), compile);
+        var compile_tree = dependencies().scope(compile).generateTransitiveDependencyTree(new VersionResolution(properties(), artifactRetriever(), repositories(), dependencies().effectiveBoms(compile)), artifactRetriever(), repositories(), compile);
         if (compile_tree.isEmpty()) {
             compile_tree = "no dependencies" + System.lineSeparator();
         }
@@ -191,7 +191,7 @@ public class DependencyTreeOperation extends AbstractOperation<DependencyTreeOpe
      * @since 1.7.3
      */
     protected String executeGenerateProvidedDependencies() {
-        var provided_tree = dependencies().scope(provided).generateTransitiveDependencyTree(new VersionResolution(properties()), artifactRetriever(), repositories(), compile, runtime);
+        var provided_tree = dependencies().scope(provided).generateTransitiveDependencyTree(new VersionResolution(properties(), artifactRetriever(), repositories(), dependencies().effectiveBoms(provided)), artifactRetriever(), repositories(), compile, runtime);
         if (provided_tree.isEmpty()) {
             provided_tree = "no dependencies" + System.lineSeparator();
         }
@@ -204,7 +204,7 @@ public class DependencyTreeOperation extends AbstractOperation<DependencyTreeOpe
      * @since 1.5.21
      */
     protected String executeGenerateRuntimeDependencies() {
-        var runtime_tree = dependencies().scope(runtime).generateTransitiveDependencyTree(new VersionResolution(properties()), artifactRetriever(), repositories(), compile, runtime);
+        var runtime_tree = dependencies().scope(runtime).generateTransitiveDependencyTree(new VersionResolution(properties(), artifactRetriever(), repositories(), dependencies().effectiveBoms(runtime)), artifactRetriever(), repositories(), compile, runtime);
         if (runtime_tree.isEmpty()) {
             runtime_tree = "no dependencies" + System.lineSeparator();
         }
@@ -217,7 +217,7 @@ public class DependencyTreeOperation extends AbstractOperation<DependencyTreeOpe
      * @since 1.7.3
      */
     protected String executeGenerateTestDependencies() {
-        var test_tree = dependencies().scope(test).generateTransitiveDependencyTree(new VersionResolution(properties()), artifactRetriever(), repositories(), compile, runtime);
+        var test_tree = dependencies().scope(test).generateTransitiveDependencyTree(new VersionResolution(properties(), artifactRetriever(), repositories(), dependencies().effectiveBoms(test)), artifactRetriever(), repositories(), compile, runtime);
         if (test_tree.isEmpty()) {
             test_tree = "no dependencies" + System.lineSeparator();
         }

src/main/java/rife/bld/operations/DownloadOperation.java

@@ -42,9 +42,13 @@ public class DownloadOperation extends AbstractOperation<DownloadOperation> {
     private File libTestModulesDirectory_;
     private boolean downloadSources_ = false;
     private boolean downloadJavadoc_ = false;
+    private final DependencyTransferBatch transfers_ = new DependencyTransferBatch();
 
     /**
      * Performs the download operation.
+     * <p>
+     * The artifact transfers of all the scopes are collected first and then
+     * performed together in a single parallel batch.
      *
      * @since 1.5
      */
@@ -54,16 +58,75 @@ public class DownloadOperation extends AbstractOperation<DownloadOperation> {
             return;
         }
 
+        if (!silent()) {
+            System.out.println("Analyzing dependencies...");
+        }
+        executeReportUncoveredDependencies();
         executeDownloadCompileDependencies();
         executeDownloadProvidedDependencies();
         executeDownloadRuntimeDependencies();
         executeDownloadStandaloneDependencies();
         executeDownloadTestDependencies();
+        executeTransferDependencies();
         if (!silent()) {
             System.out.println("Downloading finished successfully.");
         }
     }
 
+    /**
+     * Part of the {@link #execute} operation, warns about version-less
+     * dependencies that are not covered by a BOM in their scope.
+     *
+     * @since 2.4.0
+     */
+    protected void executeReportUncoveredDependencies() {
+        if (silent()) {
+            return;
+        }
+        for (var dependency : dependencies().versionlessDependenciesWithoutBom(properties(), artifactRetriever(), repositories())) {
+            System.out.println("Warning: '" + dependency.toArtifactString() + "' isn't covered by a BOM, its latest version will be used");
+        }
+        for (var conflict : dependencies().bomVersionConflicts(properties(), artifactRetriever(), repositories())) {
+            System.out.println(formatBomVersionConflict(conflict));
+        }
+        for (var conflict : dependencies().declaredVersionConflicts(properties(), artifactRetriever(), repositories())) {
+            System.out.println(formatDeclaredVersionConflict(conflict));
+        }
+    }
+
+    /**
+     * Formats a warning message for a BOM version conflict.
+     *
+     * @param conflict the BOM version conflict to format
+     * @return the formatted warning message
+     * @since 2.4.0
+     */
+    protected static String formatBomVersionConflict(rife.bld.dependencies.VersionResolution.BomVersionConflict conflict) {
+        var entries = conflict.bomVersions().entrySet().iterator();
+        var used = entries.next();
+        var message = new StringBuilder("Warning: '" + conflict.dependency() + "' is managed by multiple BOMs, using " +
+            used.getValue() + " from '" + used.getKey() + "'");
+        while (entries.hasNext()) {
+            var other = entries.next();
+            message.append(", not ").append(other.getValue()).append(" from '").append(other.getKey()).append('\'');
+        }
+        return message.toString();
+    }
+
+    /**
+     * Formats a warning message for a declared dependency whose version
+     * differs from the version that a BOM manages it at.
+     *
+     * @param conflict the declared version conflict to format
+     * @return the formatted warning message
+     * @since 2.4.0
+     */
+    protected static String formatDeclaredVersionConflict(rife.bld.dependencies.VersionResolution.DeclaredVersionConflict conflict) {
+        return "Warning: '" + conflict.dependency() + "' is declared with version " + conflict.declaredVersion() +
+               " while BOM '" + conflict.bom() + "' manages it at " + conflict.bomVersion() +
+               ", the declared version is used but transitive dependencies still follow the BOM";
+    }
+
     /**
      * Part of the {@link #execute} operation, download the {@code compile} scope artifacts.
      *
@@ -110,7 +173,11 @@ public class DownloadOperation extends AbstractOperation<DownloadOperation> {
     }
 
     /**
-     * Part of the {@link #execute} operation, download the artifacts for a particular dependency scope.
+     * Part of the {@link #execute} operation, collect the artifact transfers
+     * for a particular dependency scope into the {@linkplain #transfers()
+     * transfer batch}.
+     * <p>
+     * The transfers are performed by {@link #executeTransferDependencies}.
      *
      * @param destinationDirectory the directory in which the artifacts should be downloaded
      * @param modulesDirectory     the directory in which the modules should be downloaded
@@ -128,7 +195,29 @@ public class DownloadOperation extends AbstractOperation<DownloadOperation> {
             additional_classifiers = classifiers.toArray(new String[0]);
         }
 
-        dependencies.transferIntoDirectory(new VersionResolution(properties()), artifactRetriever(), repositories(), destinationDirectory, modulesDirectory, additional_classifiers);
+        transfers().add(dependencies, destinationDirectory, modulesDirectory, additional_classifiers);
+    }
+
+    /**
+     * Part of the {@link #execute} operation, perform all the collected
+     * artifact transfers of the {@linkplain #transfers() transfer batch}
+     * together in parallel.
+     *
+     * @since 2.4.0
+     */
+    protected void executeTransferDependencies() {
+        transfers().transfer(new VersionResolution(properties()), artifactRetriever(), repositories());
+    }
+
+    /**
+     * Returns the batch that collects the artifact transfers of this
+     * operation.
+     *
+     * @return the artifact transfer batch of this operation
+     * @since 2.4.0
+     */
+    protected DependencyTransferBatch transfers() {
+        return transfers_;
     }
 
     /**

src/main/java/rife/bld/operations/HelpOperation.java

@@ -190,6 +190,7 @@ public class HelpOperation {
                 The following bld arguments are supported:
                 
                   --offline         Works without Internet (only as first argument)
+                  --use-stderr      Sends the build output to standard error
                   -?, -h, --help    Shows the help
                   -D<name>=<value>  Sets a JVM system property
                   -s, --stacktrace  Prints out the stacktrace for exceptions

src/main/java/rife/bld/operations/JavacOptions.java

@@ -136,7 +136,7 @@ public class JavacOptions extends ArrayList<String> {
      * of other-module is ALL-UNNAMED
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions addExports(String... modules) {
         if (isNotEmpty(modules)) {
@@ -151,7 +151,7 @@ public class JavacOptions extends ArrayList<String> {
      * of other-module is ALL-UNNAMED
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions addExports(Collection<String> modules) {
         return addCommaSeparatedOption("--add-exports", modules);
@@ -161,7 +161,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specifies additional modules to be considered as required by a given module
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions addReads(String... modules) {
         if (isNotEmpty(modules)) {
@@ -174,7 +174,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specifies additional modules to be considered as required by a given module
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions addReads(Collection<String> modules) {
         return addCommaSeparatedOption("--add-reads", modules);
@@ -222,7 +222,7 @@ public class JavacOptions extends ArrayList<String> {
      * if none specified or inferred
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions defaultModuleForCreatedFiles(String module) {
         add("--default-module-for-created-files");
@@ -417,7 +417,7 @@ public class JavacOptions extends ArrayList<String> {
      * Overrides or augments a module with classes and resources in JAR files or directories
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions patchModule(String module) {
         add("--patch-module");
@@ -441,7 +441,7 @@ public class JavacOptions extends ArrayList<String> {
      * Provide source compatibility with the specified Java SE release
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions source(int version) {
         add("--source");
@@ -453,7 +453,7 @@ public class JavacOptions extends ArrayList<String> {
      * Generate class files suitable for the specified Java SE release
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions target(int version) {
         add("--target");
@@ -645,7 +645,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify where to find input source files for multiple modules
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions moduleSourcePathStrings(Collection<String> paths) {
         return addPathOption("--module-source-path", paths);
@@ -655,7 +655,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify where to find input source files for multiple modules
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions moduleSourcePathPaths(Collection<Path> paths) {
         if (isNotEmpty(paths)) {
@@ -668,7 +668,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify where to find input source files for multiple modules
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions moduleSourcePath(Collection<File> paths) {
         if (isNotEmpty(paths)) {
@@ -827,7 +827,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify a module path where to find annotation processors
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions processorModulePathPaths(Collection<Path> paths) {
         if (isNotEmpty(paths)) {
@@ -840,7 +840,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify a module path where to find annotation processors
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions processorModulePathStrings(Collection<String> paths) {
         return addPathOption("--processor-module-path", paths);
@@ -850,7 +850,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify a module path where to find annotation processors
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions processorModulePath(Collection<File> paths) {
         if (isNotEmpty(paths)) {
@@ -902,7 +902,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify where to find annotation processors
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions processorPathStrings(Collection<String> paths) {
         return addPathOption("--processor-path", paths);
@@ -912,7 +912,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify where to find annotation processors
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions processorPath(Collection<File> paths) {
         if (isNotEmpty(paths)) {
@@ -925,7 +925,7 @@ public class JavacOptions extends ArrayList<String> {
      * Specify where to find annotation processors
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions processorPathPaths(Collection<Path> paths) {
         if (isNotEmpty(paths)) {
@@ -1036,7 +1036,7 @@ public class JavacOptions extends ArrayList<String> {
      * Override location of upgradeable modules
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions upgradeModulePathStrings(Collection<String> paths) {
         return addPathOption("--upgrade-module-path", paths);
@@ -1046,7 +1046,7 @@ public class JavacOptions extends ArrayList<String> {
      * Override location of upgradeable modules
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions upgradeModulePath(Collection<File> paths) {
         if (isNotEmpty(paths)) {
@@ -1059,7 +1059,7 @@ public class JavacOptions extends ArrayList<String> {
      * Override location of upgradeable modules
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions upgradeModulePathPaths(Collection<Path> paths) {
         if (isNotEmpty(paths)) {
@@ -1083,7 +1083,7 @@ public class JavacOptions extends ArrayList<String> {
      * Enable recommended warning categories
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions xLint() {
         add("-Xlint");
@@ -1094,7 +1094,7 @@ public class JavacOptions extends ArrayList<String> {
      * Warning categories to enable
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions xLint(XLintKey... keys) {
         if (isNotEmpty(keys)) {
@@ -1107,7 +1107,7 @@ public class JavacOptions extends ArrayList<String> {
      * Warning categories to enable
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions xLint(Collection<XLintKey> keys) {
         if (isNotEmpty(keys)) {
@@ -1120,7 +1120,7 @@ public class JavacOptions extends ArrayList<String> {
      * Warning categories to disable
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions xLintDisable(XLintKey... keys) {
         if (isNotEmpty(keys)) {
@@ -1133,7 +1133,7 @@ public class JavacOptions extends ArrayList<String> {
      * Warning categories to disable
      *
      * @return this list of options
-     * @since 2.3.1
+     * @since 2.4.0
      */
     public JavacOptions xLintDisable(Collection<XLintKey> keys) {
         if (isNotEmpty(keys)) {

src/main/java/rife/bld/operations/JpackageOptions.java

@@ -561,7 +561,7 @@ public class JpackageOptions extends LinkedHashMap<String, String> {
     /**
      * Creates a shortcut for the application.
      *
-     * @param shortcut {@code true| to create a shortcut, {@code false} otherwise
+     * @param shortcut {@code true} to create a shortcut, {@code false} otherwise
      * @return this map of options
      */
     public JpackageOptions linuxShortcut(boolean shortcut) {

src/main/java/rife/bld/operations/McpControl.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.operations;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * The details that a single MCP tool call hands to the build process it
+ * launches.
+ * <p>
+ * The command, its arguments, the flags and the excluded commands are
+ * written to a control file instead of the command line, so they can never
+ * be mistaken for the command's own arguments. The values are escaped so
+ * that any character, including newlines, comes through intact. Only the
+ * MCP code uses this file, the build itself knows nothing about it.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+final class McpControl {
+    final String command;
+    final List<String> arguments;
+    final boolean offline;
+    final boolean verbose;
+    final boolean stacktrace;
+    final Set<String> exclusions;
+
+    private McpControl(String command, List<String> arguments, boolean offline, boolean verbose, boolean stacktrace, Set<String> exclusions) {
+        this.command = command;
+        this.arguments = arguments;
+        this.offline = offline;
+        this.verbose = verbose;
+        this.stacktrace = stacktrace;
+        this.exclusions = exclusions;
+    }
+
+    static void write(File file, String command, List<String> arguments,
+                      boolean offline, boolean verbose, boolean stacktrace,
+                      Collection<String> exclusions)
+    throws IOException {
+        var lines = new ArrayList<String>();
+        lines.add("command " + escape(command));
+        for (var argument : arguments) {
+            lines.add("arg " + escape(argument));
+        }
+        if (offline) {
+            lines.add("offline");
+        }
+        if (verbose) {
+            lines.add("verbose");
+        }
+        if (stacktrace) {
+            lines.add("stacktrace");
+        }
+        for (var exclusion : exclusions) {
+            lines.add("exclude " + escape(exclusion));
+        }
+        Files.write(file.toPath(), lines);
+    }
+
+    static McpControl read(File file)
+    throws IOException {
+        String command = null;
+        var arguments = new ArrayList<String>();
+        var offline = false;
+        var verbose = false;
+        var stacktrace = false;
+        var exclusions = new LinkedHashSet<String>();
+        for (var line : Files.readAllLines(file.toPath())) {
+            if (line.equals("offline")) {
+                offline = true;
+            } else if (line.equals("verbose")) {
+                verbose = true;
+            } else if (line.equals("stacktrace")) {
+                stacktrace = true;
+            } else if (line.startsWith("command ")) {
+                command = unescape(line.substring("command ".length()));
+            } else if (line.startsWith("arg ")) {
+                arguments.add(unescape(line.substring("arg ".length())));
+            } else if (line.startsWith("exclude ")) {
+                exclusions.add(unescape(line.substring("exclude ".length())));
+            }
+        }
+        if (command == null) {
+            throw new IOException("the control file doesn't specify a command");
+        }
+        return new McpControl(command, arguments, offline, verbose, stacktrace, exclusions);
+    }
+
+    private static String escape(String value) {
+        return value.replace("\\", "\\\\").replace("\n", "\\n").replace("\r", "\\r");
+    }
+
+    private static String unescape(String value) {
+        var result = new StringBuilder();
+        for (var i = 0; i < value.length(); ++i) {
+            var c = value.charAt(i);
+            if (c == '\\' && i + 1 < value.length()) {
+                var next = value.charAt(++i);
+                switch (next) {
+                    case 'n' -> result.append('\n');
+                    case 'r' -> result.append('\r');
+                    case '\\' -> result.append('\\');
+                    default -> result.append(next);
+                }
+            } else {
+                result.append(c);
+            }
+        }
+        return result.toString();
+    }
+}

src/main/java/rife/bld/operations/McpToolRunner.java

@@ -0,0 +1,180 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.operations;
+
+import rife.bld.BaseProject;
+import rife.bld.BuildExecutor;
+import rife.bld.operations.exceptions.ExitStatusException;
+import rife.tools.ExceptionUtils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * The entry point that runs exactly one build command for an MCP tool
+ * call, in a separate build process.
+ * <p>
+ * It reads the command, its arguments, the flags and the excluded commands
+ * from the control file, creates the build executor, and runs the single
+ * command through its public API. All of this single command handling lives
+ * here in the MCP feature, the build itself stays unaware of it. The runner
+ * is launched with the build executor's class name as its last argument,
+ * any earlier arguments, like the wrapper's {@code --offline} option, are
+ * ignored.
+ *
+ * @author Geert Bevin (gbevin[remove] at uwyn dot com)
+ * @since 2.4.0
+ */
+public final class McpToolRunner {
+    /**
+     * The environment variable with the path of the control file that
+     * requests the execution of exactly one command.
+     * @since 2.4.0
+     */
+    public static final String ENV_CONTROL_FILE = "BLD_MCP_CONTROL_FILE";
+
+    /**
+     * The environment variable with the path of the file that the runner
+     * writes its result to.
+     * @since 2.4.0
+     */
+    public static final String ENV_STATUS_FILE = "BLD_MCP_STATUS_FILE";
+
+    /**
+     * The outcome that is written when the command couldn't be resolved.
+     * @since 2.4.0
+     */
+    public static final String STATUS_UNKNOWN_COMMAND = "unknown-command";
+
+    /**
+     * The outcome that is written when the command is excluded.
+     * @since 2.4.0
+     */
+    public static final String STATUS_EXCLUDED_COMMAND = "excluded-command";
+
+    /**
+     * The outcome that is written when the runner itself couldn't be set
+     * up, for instance when the build executor class couldn't be
+     * instantiated, this is a server failure rather than a tool failure.
+     * @since 2.4.0
+     */
+    public static final String STATUS_RUNNER_ERROR = "runner-error";
+
+    private McpToolRunner() {
+    }
+
+    /**
+     * Runs a single build command for an MCP tool call.
+     *
+     * @param arguments the build executor class name as the last argument
+     * @since 2.4.0
+     */
+    public static void main(String[] arguments) {
+        System.exit(run(arguments));
+    }
+
+    private static int run(String[] arguments) {
+        var control_path = System.getenv(ENV_CONTROL_FILE);
+        if (control_path == null) {
+            writeStatus(STATUS_RUNNER_ERROR);
+            System.err.println("ERROR: no MCP control file provided");
+            return ExitStatusException.EXIT_FAILURE;
+        }
+
+        var control_file = new File(control_path);
+        McpControl control;
+        try {
+            control = McpControl.read(control_file);
+        } catch (IOException e) {
+            writeStatus(STATUS_RUNNER_ERROR);
+            System.err.println("ERROR: the MCP control file couldn't be read");
+            return ExitStatusException.EXIT_FAILURE;
+        } finally {
+            // the control file is consumed immediately, so that nested
+            // processes that inherit the environment don't re-enter the
+            // single command execution and don't overwrite its status
+            control_file.delete();
+        }
+
+        if (arguments.length == 0) {
+            writeStatus(STATUS_RUNNER_ERROR);
+            System.err.println("ERROR: no build executor class provided");
+            return ExitStatusException.EXIT_FAILURE;
+        }
+        // the build executor class is instantiated directly through its
+        // no-arg constructor and driven through its public API, its main
+        // method is not invoked, so that a tool call runs exactly the
+        // requested command and nothing else
+        BuildExecutor executor;
+        try {
+            var executor_class = Class.forName(arguments[arguments.length - 1]);
+            executor = (BuildExecutor) executor_class.getDeclaredConstructor().newInstance();
+        } catch (ReflectiveOperationException | ClassCastException e) {
+            writeStatus(STATUS_RUNNER_ERROR);
+            System.err.println("ERROR: the build executor couldn't be instantiated: " + e);
+            return ExitStatusException.EXIT_FAILURE;
+        }
+
+        executor.offline(control.offline);
+        executor.verbose(control.verbose);
+        executor.showStacktrace(control.stacktrace);
+
+        var resolved = executor.resolveCommand(control.command);
+        if (resolved == null) {
+            // the result goes into the status file so that it can never be
+            // confused with a regular exit status of a build command
+            writeStatus(STATUS_UNKNOWN_COMMAND);
+            System.err.println("ERROR: Unknown command '" + control.command + "'");
+            return ExitStatusException.EXIT_FAILURE;
+        }
+        // the exclusions are enforced here, in the freshly compiled build,
+        // so that aliases or commands added to the build sources can't
+        // reach an excluded command either
+        if (control.exclusions.contains(control.command) || control.exclusions.contains(resolved)) {
+            writeStatus(STATUS_EXCLUDED_COMMAND);
+            System.err.println("ERROR: Command '" + control.command + "' is not available");
+            return ExitStatusException.EXIT_FAILURE;
+        }
+
+        // an automatic dependency download and purge that the project is
+        // configured for runs before the command, exactly like it would on
+        // the command line
+        if (executor instanceof BaseProject project) {
+            project.performAutoDownloadPurgeIfEnabled();
+        }
+
+        // the command's arguments come from the control file, they are
+        // never interpreted as additional commands or as global flags
+        executor.arguments().clear();
+        executor.arguments().addAll(control.arguments);
+        try {
+            executor.executeCommand(resolved);
+        } catch (Throwable e) {
+            executor.exitStatus(ExitStatusException.EXIT_FAILURE);
+            System.err.println();
+            if (control.stacktrace) {
+                System.err.println(ExceptionUtils.getExceptionStackTrace(e));
+            } else if (e.getMessage() != null) {
+                System.err.println(e.getMessage());
+            } else {
+                System.err.println(e.getClass().getName());
+            }
+        }
+        return executor.exitStatus();
+    }
+
+    private static void writeStatus(String status) {
+        var status_file = System.getenv(ENV_STATUS_FILE);
+        if (status_file != null) {
+            try {
+                Files.writeString(Path.of(status_file), status);
+            } catch (IOException e) {
+                // the caller falls back to the exit status
+            }
+        }
+    }
+}

src/main/java/rife/bld/operations/PublishOperation.java

@@ -27,6 +27,7 @@ import java.security.*;
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
 import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.regex.Pattern;
 
@@ -52,6 +53,7 @@ public class PublishOperation extends AbstractOperation<PublishOperation> {
 
     private ZonedDateTime moment_ = null;
     private final List<Repository> repositories_ = new ArrayList<>();
+    private final List<Repository> dependencyRepositories_ = new ArrayList<>();
     private final DependencyScopes dependencies_ = new DependencyScopes();
     private PublishInfo info_ = new PublishInfo();
     private PublishProperties publishProperties_ = new PublishProperties();
@@ -78,6 +80,7 @@ public class PublishOperation extends AbstractOperation<PublishOperation> {
         }
 
         executeValidateArtifacts();
+        executeResolveVersionlessDependencies();
 
         var actual_version = info().version();
 
@@ -103,6 +106,101 @@ public class PublishOperation extends AbstractOperation<PublishOperation> {
         }
     }
 
+    /**
+     * Part of the {@link #execute} operation, freezes the versions of
+     * dependencies that were declared without one, so that the published
+     * POM is always complete.
+     * <p>
+     * Dependencies that are covered by a BOM that applies to their scope
+     * stay version-less, the dependency management imports of the POM
+     * supply their versions. They are frozen anyway when the flattened
+     * dependency management of the POM would supply a different version
+     * than the BOMs that apply to their scope, or when a
+     * {@code bld.override} property supplies their version, since the POM
+     * can't reflect either. Uncovered dependencies are frozen to their
+     * latest version.
+     * <p>
+     * BOMs that were declared without a version are frozen too, to their
+     * {@code bld.override} version or to their latest version.
+     *
+     * @since 2.4.0
+     */
+    protected void executeResolveVersionlessDependencies() {
+        // freeze the versions of the declared BOMs, a version from a
+        // bld.override property is used by the build itself and takes
+        // precedence, version-less BOMs resolve to their latest version
+        var base_resolution = new VersionResolution(properties());
+        for (var scope : List.of(Scope.compile, Scope.runtime, Scope.provided)) {
+            var scoped_dependencies = dependencies().get(scope);
+            if (scoped_dependencies == null || scoped_dependencies.boms().isEmpty()) {
+                continue;
+            }
+
+            var declared_boms = List.copyOf(scoped_dependencies.boms());
+            scoped_dependencies.boms().clear();
+            for (var bom : declared_boms) {
+                var version = base_resolution.overrideVersion(bom);
+                if (version.equals(VersionNumber.UNKNOWN)) {
+                    version = new DependencyResolver(base_resolution, artifactRetriever(), dependencyRepositories(), bom).latestVersion();
+                }
+                if (!version.equals(bom.version())) {
+                    bom = new Bom(bom.groupId(), bom.artifactId(), version);
+                }
+                scoped_dependencies.boms().add(bom);
+            }
+        }
+
+        // the published POM flattens all the BOM imports into a single
+        // dependency management list, compute the versions that this list
+        // supplies so that scoped differences can be frozen explicitly
+        var flattened_boms = new LinkedHashMap<String, Bom>();
+        for (var scope : List.of(Scope.compile, Scope.runtime, Scope.provided)) {
+            var scoped_dependencies = dependencies().get(scope);
+            if (scoped_dependencies != null) {
+                for (var bom : scoped_dependencies.boms()) {
+                    flattened_boms.putIfAbsent(bom.toArtifactString(), bom);
+                }
+            }
+        }
+        var flattened_resolution = new VersionResolution(properties(), artifactRetriever(), dependencyRepositories(), flattened_boms.values());
+
+        // freeze the versions of version-less dependencies that no
+        // applicable BOM covers
+        for (var scope : List.of(Scope.compile, Scope.runtime, Scope.provided)) {
+            var scoped_dependencies = dependencies().get(scope);
+            if (scoped_dependencies == null) {
+                continue;
+            }
+
+            var resolution = new VersionResolution(properties(), artifactRetriever(), dependencyRepositories(), dependencies().effectiveBoms(scope));
+            for (var dependency : List.copyOf(scoped_dependencies)) {
+                if (!dependency.version().equals(VersionNumber.UNKNOWN)) {
+                    continue;
+                }
+                // a version from a bld.override property is used by the
+                // build itself, it's frozen into the POM even when a BOM
+                // covers the dependency since the import can't reflect it
+                var version = resolution.versionOverrides().get(dependency.toArtifactString());
+                if (version == null) {
+                    if (resolution.coversDependency(dependency)) {
+                        // the dependency can only stay version-less when the
+                        // flattened dependency management of the POM supplies
+                        // the same version as the BOMs that apply to its scope
+                        var scoped_version = resolution.overrideVersion(dependency);
+                        if (scoped_version.equals(flattened_resolution.overrideVersion(dependency))) {
+                            continue;
+                        }
+                        version = scoped_version;
+                    } else {
+                        version = new DependencyResolver(resolution, artifactRetriever(), dependencyRepositories(), dependency).latestVersion();
+                    }
+                }
+                scoped_dependencies.add(new Dependency(dependency.groupId(), dependency.artifactId(), version,
+                    dependency.classifier(), dependency.type(), dependency.exclusions(), dependency.parent()));
+            }
+        }
+    }
+
     /**
      * Part of the {@link #execute} operation, validates the publishing artifacts.
      *
@@ -625,6 +723,7 @@ public class PublishOperation extends AbstractOperation<PublishOperation> {
         offline(project.offline());
         properties(project.properties());
         artifactRetriever(project.artifactRetriever());
+        dependencyRepositories(project.repositories());
         dependencies().include(project.dependencies());
         artifacts(List.of(
             new PublishArtifact(new File(project.buildDistDirectory(), project.jarFileName()), "", TYPE_JAR),
@@ -733,6 +832,33 @@ public class PublishOperation extends AbstractOperation<PublishOperation> {
         return this;
     }
 
+    /**
+     * Provides a list of repositories to resolve the dependencies against.
+     * <p>
+     * These are used to resolve the versions of dependencies that were
+     * declared without one, they are not publication targets.
+     *
+     * @param repositories a list of repositories against which dependencies will be resolved
+     * @return this operation instance
+     * @since 2.4.0
+     */
+    public PublishOperation dependencyRepositories(List<Repository> repositories) {
+        dependencyRepositories_.addAll(repositories);
+        return this;
+    }
+
+    /**
+     * Retrieves the repositories that dependencies will be resolved against.
+     * <p>
+     * This is a modifiable list that can be retrieved and changed.
+     *
+     * @return the repositories used for dependency resolution
+     * @since 2.4.0
+     */
+    public List<Repository> dependencyRepositories() {
+        return dependencyRepositories_;
+    }
+
     /**
      * Provides scoped dependencies to reference in the publication.
      *

src/main/java/rife/bld/operations/UpdatesOperation.java

@@ -31,15 +31,47 @@ public class UpdatesOperation extends AbstractOperation<UpdatesOperation> {
      */
     public void execute() {
         var resolution = new VersionResolution(properties());
-        var result = new DependencyScopes();
+
+        var scopes = new ArrayList<Scope>();
+        var dependencies = new ArrayList<Dependency>();
         for (var entry : dependencies_.entrySet()) {
-            var scope = entry.getKey();
+            var scoped_dependencies = entry.getValue();
-            for (var dependency : entry.getValue()) {
+            for (var bom : scoped_dependencies.boms()) {
-                var latest = new DependencyResolver(resolution, artifactRetriever(), repositories(), dependency).latestVersion();
+                scopes.add(entry.getKey());
+                dependencies.add(bom);
+            }
+
+            // dependencies that are declared without a version and that are
+            // covered by a BOM that applies to their scope have their version
+            // pinned by that BOM, the BOM update itself carries their update
+            // signal, unless a bld.override supplies the version and takes
+            // that control away from the BOM
+            var scope_resolution = new VersionResolution(properties(), artifactRetriever(), repositories(), dependencies_.effectiveBoms(entry.getKey()));
+            for (var dependency : scoped_dependencies) {
+                if (VersionNumber.UNKNOWN.equals(dependency.version()) &&
+                    scope_resolution.coversDependency(dependency) &&
+                    !scope_resolution.versionOverrides().containsKey(dependency.toArtifactString())) {
+                    continue;
+                }
+                scopes.add(entry.getKey());
+                // an overridden version is the one the build uses, it's the
+                // baseline that update checks compare against
+                dependencies.add(scope_resolution.overrideDependency(dependency));
+            }
+        }
+
+        var latest_versions = new ParallelDependencyResolver(resolution, artifactRetriever(), repositories()).resolveLatestVersions(dependencies);
+
+        var result = new DependencyScopes();
+        for (var i = 0; i < dependencies.size(); ++i) {
+            var dependency = dependencies.get(i);
+            var latest = latest_versions.get(i);
             if (latest.compareTo(dependency.version()) > 0) {
-                    var latest_dependency = new Dependency(dependency.groupId(), dependency.artifactId(), latest,
+                if (dependency instanceof Bom) {
-                        dependency.classifier(), dependency.type());
+                    result.scope(scopes.get(i)).include(new Bom(dependency.groupId(), dependency.artifactId(), latest));
-                    result.scope(scope).include(latest_dependency);
+                } else {
+                    result.scope(scopes.get(i)).include(new Dependency(dependency.groupId(), dependency.artifactId(), latest,
+                        dependency.classifier(), dependency.type()));
                 }
             }
         }
@@ -53,6 +85,9 @@ public class UpdatesOperation extends AbstractOperation<UpdatesOperation> {
             for (var entry : result.entrySet()) {
                 var scope = entry.getKey();
                 System.out.println(scope + ":");
+                for (var bom : entry.getValue().boms()) {
+                    System.out.println("    " + bom);
+                }
                 for (var dependency : entry.getValue()) {
                     System.out.println("    " + dependency);
                 }

src/main/java/rife/bld/publish/PomBuilder.java

@@ -12,6 +12,8 @@ import rife.tools.StringUtils;
 import rife.tools.exceptions.FileUtilsErrorException;
 
 import java.io.File;
+import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Objects;
 
 import static rife.bld.dependencies.Dependency.TYPE_JAR;
@@ -152,6 +154,7 @@ public class PomBuilder {
         }
 
         if (dependencies() != null && !dependencies().isEmpty()) {
+            addDependencyManagement(t);
             addDependencies(t, Scope.compile);
             addDependencies(t, Scope.runtime);
             addDependencies(t, Scope.provided);
@@ -172,6 +175,32 @@ public class PomBuilder {
         FileUtils.writeString(pomBuilder.build(), file);
     }
 
+    private void addDependencyManagement(Template t) {
+        var boms = new LinkedHashMap<String, Bom>();
+        for (var scope : List.of(Scope.compile, Scope.runtime, Scope.provided)) {
+            var scoped_dependencies = dependencies().get(scope);
+            if (scoped_dependencies == null) {
+                continue;
+            }
+            for (var bom : scoped_dependencies.boms()) {
+                if (!bom.version().equals(VersionNumber.UNKNOWN)) {
+                    boms.putIfAbsent(bom.toArtifactString(), bom);
+                }
+            }
+        }
+        if (boms.isEmpty()) {
+            return;
+        }
+
+        for (var bom : boms.values()) {
+            t.setValueEncoded("dependency-management-groupId", bom.groupId());
+            t.setValueEncoded("dependency-management-artifactId", bom.artifactId());
+            t.setValueEncoded("dependency-management-version", bom.version());
+            t.appendBlock("dependency-management", "dependency-management-entry");
+        }
+        t.setBlock("dependency-management-tag");
+    }
+
     private void addDependencies(Template t, Scope scope) {
         var scoped_dependencies = dependencies().scope(scope);
         if (!scoped_dependencies.isEmpty()) {

src/main/java/rife/bld/wrapper/Wrapper.java

@@ -40,6 +40,7 @@ public class Wrapper {
 
     public static final String BUILD_ARGUMENT = "--build";
     public static final String OFFLINE_ARGUMENT = "--offline";
+    public static final String USE_STDERR_ARGUMENT = "--use-stderr";
 
     public static final String WRAPPER_PREFIX = "bld-wrapper";
     public static final String WRAPPER_PROPERTIES = WRAPPER_PREFIX + ".properties";
@@ -97,6 +98,11 @@ public class Wrapper {
      * @since 1.5
      */
     public static void main(String[] arguments) {
+        if (Arrays.asList(arguments).contains(USE_STDERR_ARGUMENT)) {
+            // the wrapper diagnostics are sent to standard error so that
+            // standard output stays free for the MCP protocol
+            System.setOut(System.err);
+        }
         System.exit(new Wrapper().installAndLaunch(new ArrayList<>(Arrays.asList(arguments))));
     }
 

src/main/java/rife/bld/wrapper/WrapperExtensionResolver.java

@@ -89,12 +89,16 @@ public class WrapperExtensionResolver {
 
     private Set<String> transferExtensionDependencies() {
         var filenames = new HashSet<String>();
-        var dependencies = new DependencySet();
+        var roots = new ArrayList<Dependency>();
         for (var d : dependencies_) {
             if (d != null) {
-                dependencies.addAll(new DependencyResolver(resolution_, retriever_, repositories_, d).getAllDependencies(Scope.compile, Scope.runtime));
+                roots.add(d);
             }
         }
+        if (!roots.isEmpty()) {
+            System.out.println("Analyzing bld extension dependencies...");
+        }
+        var dependencies = new ParallelDependencyResolver(resolution_, retriever_, repositories_).resolveAllDependencies(roots, Scope.compile, Scope.runtime);
         if (!dependencies.isEmpty()) {
             ensurePrintedHeader();
 

src/main/resources/BLD_VERSION

@@ -1 +1 @@
-2.3.1-SNAPSHOT
+2.4.0-SNAPSHOT

src/main/resources/templates/bld/pom_blueprint.xml

@@ -32,6 +32,24 @@
   </properties>
   <!--/b-->
 
+  <!--v dependency-management-tag--><!--/v-->
+  <!--b dependency-management-tag-->
+  <dependencyManagement>
+    <dependencies>
+      <!--v dependency-management--><!--/v-->
+      <!--b dependency-management-entry-->
+      <dependency>
+        <groupId><!--v dependency-management-groupId--><!--/v--></groupId>
+        <artifactId><!--v dependency-management-artifactId--><!--/v--></artifactId>
+        <version><!--v dependency-management-version--><!--/v--></version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+      <!--/b-->
+    </dependencies>
+  </dependencyManagement>
+  <!--/b-->
+
   <!--v dependencies-tag--><!--/v-->
   <!--b dependencies-tag-->
   <dependencies>

src/test/java/rife/bld/BaseProjectTest.java

@@ -0,0 +1,319 @@
+/*
+ * Copyright 2026 Erik C. Thauvin (https://erik.thauvin.net/)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld;
+
+import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.io.TempDir;
+import rife.bld.dependencies.Scope;
+
+import java.io.File;
+import java.lang.reflect.Method;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BaseProjectTest {
+    private static Method ADD_LOCAL_JARS;
+    @TempDir
+    Path tempDir;
+    private BaseProject project;
+
+    @BeforeAll
+    static void initReflection() throws Exception {
+        ADD_LOCAL_JARS = BaseProject.class.getDeclaredMethod("addLocalJars", List.class, String.class);
+        ADD_LOCAL_JARS.setAccessible(true);
+    }
+
+    @BeforeEach
+    void beforeEach() {
+        project = new BaseProject();
+        project.workDirectory = tempDir.toFile();
+        project.createProjectStructure();
+    }
+
+    private void invokeAddLocalJars(List<File> jars, String path) throws Exception {
+        ADD_LOCAL_JARS.invoke(project, jars, path);
+    }
+
+    @Nested
+    @DisplayName("local(Path) and local(File)")
+    class LocalDependencyTest {
+
+        @Test
+        @DisplayName("local(Path) relative should resolve via workDirectory")
+        void localPathRelative() throws Exception {
+            var jar = Files.createFile(tempDir.resolve("a.jar"));
+            var dep = project.local(Path.of("a.jar"));
+
+            assertAll(
+                    () -> assertNotNull(dep, "local(Path) should not return null"),
+                    () -> assertEquals("a.jar", dep.path(), "relative Path should be kept as-is")
+            );
+
+            project.dependencies().scope(Scope.compile).include(dep);
+            assertTrue(project.compileClasspathJars().stream()
+                            .anyMatch(f -> f.getAbsolutePath().equals(jar.toFile().getAbsolutePath())),
+                    "compileClasspathJars should resolve relative path against workDirectory");
+        }
+
+        @Test
+        @DisplayName("local(Path) absolute should be kept absolute")
+        void localPathAbsolute() throws Exception {
+            var jar = Files.createFile(tempDir.resolve("abs.jar"));
+            var dep = project.local(jar);
+
+            assertAll(
+                    () -> assertNotNull(dep, "local(Path) absolute should not return null"),
+                    () -> assertEquals(jar.toString(), dep.path(), "absolute Path should be kept absolute")
+            );
+
+            project.dependencies().scope(Scope.compile).include(dep);
+            assertTrue(project.compileClasspathJars().stream()
+                            .anyMatch(f -> f.getName().equals("abs.jar")),
+                    "compileClasspathJars should include absolute Path dependency");
+        }
+
+        @Test
+        @DisplayName("local(File) relative file")
+        void localFileRelative() {
+            var dep = project.local(new File("b.jar"));
+
+            assertAll(
+                    () -> assertNotNull(dep, "local(File) should not return null"),
+                    () -> assertTrue(dep.path().endsWith("b.jar"), "should end with file name"),
+                    () -> assertTrue(Path.of(dep.path()).isAbsolute(), "File overload uses getAbsolutePath()")
+            );
+        }
+
+        @Test
+        @DisplayName("local(File) absolute file")
+        void localFileAbsolute() throws Exception {
+            var jar = Files.createFile(tempDir.resolve("c.jar"));
+            var dep = project.local(jar.toFile());
+
+            assertAll(
+                    () -> assertNotNull(dep, "local(File) absolute should not return null"),
+                    () -> assertEquals(jar.toFile().getAbsolutePath(), dep.path(),
+                            "should use File.getAbsolutePath()")
+            );
+        }
+
+        @Test
+        @DisplayName("local(File) directory should scan jars excluding sources/javadoc")
+        void localFileDirectory() throws Exception {
+            var dir = Files.createDirectory(tempDir.resolve("libs-dep-filter"));
+            Files.createFile(dir.resolve("one.jar"));
+            Files.createFile(dir.resolve("one-sources.jar"));
+            Files.createFile(dir.resolve("one-JAVADOC.jar"));
+
+            var dep = project.local(dir.toFile());
+            project.dependencies().scope(Scope.compile).include(dep);
+
+            var cp = project.compileClasspathJars();
+            assertAll(
+                    () -> assertTrue(cp.stream().anyMatch(
+                            f -> f.getName().equals("one.jar")), "regular jar should be included"),
+                    () -> assertFalse(cp.stream().anyMatch(f -> f.getName().equals("one-sources.jar")),
+                            "sources jar should be excluded (case-insensitive)"),
+                    () -> assertFalse(cp.stream().anyMatch(
+                                    f -> f.getName().toLowerCase().contains("javadoc")),
+                            "javadoc jar should be excluded")
+            );
+        }
+
+        @Test
+        @DisplayName("local(Path) and local(String) should behave same")
+        void parityWithStringOverload() throws Exception {
+            Files.createFile(tempDir.resolve("parity.jar"));
+
+            var fromString = project.local("parity.jar");
+            var fromPath = project.local(Path.of("parity.jar"));
+            var fromFile = project.local(new File("parity.jar"));
+
+            assertAll(
+                    () -> assertEquals(fromString.path(), fromPath.path(),
+                            "String and Path overloads should have same path()"),
+                    () -> assertTrue(fromFile.path().endsWith("parity.jar"),
+                            "File overload is absolute but ends with same name"),
+                    () -> assertTrue(Path.of(fromFile.path()).isAbsolute(),
+                            "File overload should be absolute")
+            );
+        }
+    }
+
+    @Nested
+    @DisplayName("addLocalJars - private implementation")
+    class LocalJarsTest {
+        @Test
+        @DisplayName("should add relative file path")
+        void relativeFile() throws Exception {
+            Files.createFile(tempDir.resolve("my.jar"));
+            var jars = new ArrayList<File>();
+            invokeAddLocalJars(jars, "my.jar");
+            assertEquals(1, jars.size(), "relative file that exists should be added");
+        }
+
+        @Test
+        @DisplayName("should add absolute file path")
+        void absoluteFile() throws Exception {
+            var jar = Files.createFile(tempDir.resolve("abs2.jar"));
+            var jars = new ArrayList<File>();
+            invokeAddLocalJars(jars, jar.toAbsolutePath().toString());
+            assertEquals(1, jars.size(), "absolute file that exists should be added");
+        }
+
+        @Test
+        @DisplayName("should resolve relative to workDirectory")
+        void relativeToWorkDirectory() throws Exception {
+            var sub = Files.createDirectory(tempDir.resolve("sub"));
+            var jar = Files.createFile(sub.resolve("x.jar"));
+            var jars = new ArrayList<File>();
+            invokeAddLocalJars(jars, "sub/x.jar");
+            assertEquals(jar.toFile().getAbsoluteFile(), jars.get(0).getAbsoluteFile(),
+                    "should resolve against workDirectory");
+        }
+
+        @Test
+        @DisplayName("should scan directory for jars only")
+        void directoryScansJars() throws Exception {
+            var libDir = Files.createDirectory(tempDir.resolve("libs-jars-scan"));
+            Files.createFile(libDir.resolve("a.jar"));
+            Files.createFile(libDir.resolve("b.jar"));
+            Files.createFile(libDir.resolve("not-a-jar.txt"));
+            var jars = new ArrayList<File>();
+            invokeAddLocalJars(jars, "libs-jars-scan");
+            assertEquals(2, jars.size(), "should only include .jar files");
+        }
+
+        @Test
+        @DisplayName("should exclude -sources and -javadoc jars in directory")
+        void directoryExcludesSourcesAndJavadoc() throws Exception {
+            var libDir = Files.createDirectory(tempDir.resolve("libs2-filter"));
+            Files.createFile(libDir.resolve("foo.jar"));
+            Files.createFile(libDir.resolve("foo-sources.jar"));
+            Files.createFile(libDir.resolve("foo-javadoc.jar"));
+            var jars = new ArrayList<File>();
+            invokeAddLocalJars(jars, "libs2-filter");
+            assertAll(
+                    () -> assertEquals(1, jars.size(), "should filter out -sources and -javadoc"),
+                    () -> assertEquals("foo.jar", jars.get(0).getName(), "only foo.jar should remain")
+            );
+        }
+
+        @Nested
+        @DisplayName("integration via public classpath methods")
+        class Integration {
+            @Test
+            @DisplayName("compileClasspathJars should include local file dependency")
+            void viaCompileClasspath() throws Exception {
+                var myJar = Files.createFile(tempDir.resolve("custom.jar"));
+                project.dependencies().scope(Scope.compile).include(project.local("custom.jar"));
+                var classpath = project.compileClasspathJars();
+                assertTrue(classpath.stream().anyMatch(
+                                f -> f.getAbsolutePath().equals(myJar.toFile().getAbsolutePath())),
+                        "compileClasspathJars should include local file dependency");
+            }
+        }
+
+        @Nested
+        @DisplayName("verbose branch")
+        class VerboseBranch {
+            @BeforeEach
+            void enableVerbose() {
+                project = new BaseProject() {
+                    @Override
+                    public boolean verbose() {
+                        return true;
+                    }
+                };
+                project.workDirectory = tempDir.toFile();
+                project.createProjectStructure();
+            }
+
+            @Test
+            @DisplayName("should skip non-existent path without throwing, even verbose")
+            void nonExistentPathSkipped() {
+                var jars = new ArrayList<File>();
+                assertDoesNotThrow(() -> invokeAddLocalJars(jars, "does-not-exist-verbose"),
+                        "should not throw for missing path");
+                assertTrue(jars.isEmpty(), "non-existent path should be skipped");
+            }
+        }
+    }
+
+    @Nested
+    @DisplayName("localModule(Path) and localModule(File)")
+    class LocalModuleTest {
+        @Test
+        @DisplayName("localModule(Path) relative")
+        void localModulePathRelative() {
+            var mod = project.localModule(Path.of("mod.jar"));
+            assertAll(
+                    () -> assertNotNull(mod, "should not return null"),
+                    () -> assertEquals("mod.jar", mod.path(), "relative path kept as-is")
+            );
+        }
+
+        @Test
+        @DisplayName("localModule(Path) absolute")
+        void localModulePathAbsolute() throws Exception {
+            var jar = Files.createFile(tempDir.resolve("modAbs.jar"));
+            var mod = project.localModule(jar);
+            assertAll(
+                    () -> assertNotNull(mod, "should not return null"),
+                    () -> assertEquals(jar.toString(), mod.path(), "absolute path kept absolute")
+            );
+        }
+
+        @Test
+        @DisplayName("localModule(File) absolute")
+        void localModuleFileAbsolute() throws Exception {
+            var jar = Files.createFile(tempDir.resolve("mod2.jar"));
+            var mod = project.localModule(jar.toFile());
+            assertAll(
+                    () -> assertNotNull(mod, "should not return null"),
+                    () -> assertEquals(jar.toFile().getAbsolutePath(), mod.path(),
+                            "should use getAbsolutePath()")
+            );
+        }
+
+        @Test
+        @DisplayName("localModule(File) directory scan")
+        void localModuleFileDirectory() throws Exception {
+            var dir = Files.createDirectory(tempDir.resolve("mods-filter"));
+            Files.createFile(dir.resolve("m1.jar"));
+            Files.createFile(dir.resolve("m1-javadoc.jar"));
+
+            var mod = project.localModule(dir.toFile());
+            project.dependencies().scope(Scope.compile).include(mod);
+
+            var mp = project.compileModulePathJars();
+            assertAll(
+                    () -> assertTrue(mp.stream().anyMatch(f -> f.getName().equals("m1.jar")),
+                            "regular jar should be in module path"),
+                    () -> assertFalse(mp.stream().anyMatch(f -> f.getName().contains("javadoc")),
+                            "javadoc jar should be excluded")
+            );
+        }
+
+        @Test
+        @DisplayName("all three overloads are consistent")
+        void overloadsConsistent() throws Exception {
+            Files.createFile(tempDir.resolve("cons.jar"));
+
+            var s = project.localModule("cons.jar");
+            var p = project.localModule(Path.of("cons.jar"));
+            var f = project.localModule(new File("cons.jar"));
+
+            assertAll(
+                    () -> assertEquals(s.path(), p.path(), "String and Path overloads equal"),
+                    () -> assertTrue(f.path().endsWith("cons.jar"), "File overload ends with same name")
+            );
+        }
+    }
+}

src/test/java/rife/bld/dependencies/TestDependencyResolver.java

@@ -4,15 +4,20 @@
  */
 package rife.bld.dependencies;
 
+import com.sun.net.httpserver.HttpServer;
 import org.junit.jupiter.api.Test;
 import rife.ioc.HierarchicalProperties;
 import rife.tools.FileUtils;
 import rife.tools.StringUtils;
 
 import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.*;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.jupiter.api.Assertions.*;
 import static rife.bld.dependencies.Dependency.CLASSIFIER_JAVADOC;
@@ -2341,4 +2346,98 @@ public class TestDependencyResolver {
             FileUtils.deleteDirectory(tmp2);
         }
     }
+
+    @Test
+    void testGetAllDependenciesParallelPomPrefetching() throws Exception {
+        var max_concurrent_retrievals = new AtomicInteger();
+        var server = createPomServer(max_concurrent_retrievals);
+        server.start();
+        try {
+            var repositories = List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/"));
+            var root = new Dependency("com.example", "root", new VersionNumber(1, 0, 0));
+
+            // the caching retriever enables parallel POM prefetching
+            var resolver = new DependencyResolver(VersionResolution.dummy(), ArtifactRetriever.cachingInstance(), repositories, root);
+            assertEquals(StringUtils.convertLineSeparator("""
+                com.example:root:1.0.0
+                com.example:child1:1.0.0
+                com.example:child2:1.0.0
+                com.example:child3:1.0.0
+                com.example:child4:1.0.0
+                com.example:child5:1.0.0
+                com.example:child6:1.0.0
+                com.example:shared:1.0.0"""), StringUtils.join(resolver.getAllDependencies(compile), System.lineSeparator()));
+            assertTrue(max_concurrent_retrievals.get() > 1, "expected concurrent POM retrievals, max was " + max_concurrent_retrievals.get());
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    @Test
+    void testGetAllDependenciesSequentialWithoutCachingRetriever() throws Exception {
+        var max_concurrent_retrievals = new AtomicInteger();
+        var server = createPomServer(max_concurrent_retrievals);
+        server.start();
+        try {
+            var repositories = List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/"));
+            var root = new Dependency("com.example", "root", new VersionNumber(1, 0, 0));
+
+            // the uncached retriever disables prefetching, retrievals stay sequential
+            var resolver = new DependencyResolver(VersionResolution.dummy(), ArtifactRetriever.instance(), repositories, root);
+            assertEquals(8, resolver.getAllDependencies(compile).size());
+            assertEquals(1, max_concurrent_retrievals.get(), "expected sequential POM retrievals, max was " + max_concurrent_retrievals.get());
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    private static HttpServer createPomServer(AtomicInteger maxConcurrentRetrievals)
+    throws IOException {
+        var graph = new HashMap<String, List<String>>();
+        graph.put("root", List.of("child1", "child2", "child3", "child4", "child5", "child6"));
+        graph.put("child1", List.of("shared"));
+
+        var active_retrievals = new AtomicInteger();
+        var server = HttpServer.create(new InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var active = active_retrievals.incrementAndGet();
+            maxConcurrentRetrievals.accumulateAndGet(active, Math::max);
+            try {
+                // delay the response so that parallel retrievals overlap
+                Thread.sleep(100);
+
+                // serve the POM of the artifact in the request path
+                var segments = exchange.getRequestURI().getPath().split("/");
+                var artifact = segments[segments.length - 3];
+                var body = buildPom(artifact, graph.getOrDefault(artifact, List.of())).getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+                exchange.close();
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            } finally {
+                active_retrievals.decrementAndGet();
+            }
+        });
+        server.setExecutor(Executors.newCachedThreadPool());
+        return server;
+    }
+
+    private static String buildPom(String artifact, List<String> children) {
+        var dependencies = new StringBuilder();
+        for (var child : children) {
+            dependencies.append("<dependency><groupId>com.example</groupId><artifactId>")
+                .append(child)
+                .append("</artifactId><version>1.0.0</version></dependency>");
+        }
+        return """
+            <?xml version="1.0" encoding="UTF-8"?>
+            <project>
+                <modelVersion>4.0.0</modelVersion>
+                <groupId>com.example</groupId>
+                <artifactId>%s</artifactId>
+                <version>1.0.0</version>
+                <dependencies>%s</dependencies>
+            </project>""".formatted(artifact, dependencies);
+    }
 }

src/test/java/rife/bld/dependencies/TestDependencySet.java

@@ -5,11 +5,16 @@
 package rife.bld.dependencies;
 
 import org.junit.jupiter.api.Test;
+import rife.ioc.HierarchicalProperties;
+import rife.tools.FileUtils;
 import rife.tools.StringUtils;
 
+import java.nio.file.Files;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.jupiter.api.Assertions.*;
+import static rife.bld.dependencies.TransferTestHelper.*;
 import static rife.bld.dependencies.RepositoryTestHelper.getNextRepository;
 import static rife.bld.dependencies.Scope.compile;
 import static rife.bld.dependencies.Scope.runtime;
@@ -373,4 +378,83 @@ public class TestDependencySet {
                └─ org.json:json:20250107
             """), dependencies.generateTransitiveDependencyTree(VersionResolution.dummy(), ArtifactRetriever.instance(), RepositoryTestHelper.getNextRepositories(), compile, runtime));
     }
+
+    @Test
+    void testCopyAndIncludePreserveAllContents() {
+        var set = new DependencySet()
+            .include(new Dependency("com.uwyn.rife2", "rife2", new VersionNumber(1, 9, 1)))
+            .include(new Bom("io.vertx", "vertx-stack-depchain", new VersionNumber(4, 5, 12)))
+            .include(new LocalDependency("lib/local.jar"))
+            .include(new LocalModule("lib/module.jar"));
+
+        var copy = new DependencySet(set);
+        assertEquals(set, copy);
+        assertEquals(set.boms(), copy.boms());
+        assertEquals(set.localDependencies(), copy.localDependencies());
+        assertEquals(set.localModules(), copy.localModules());
+
+        var included = new DependencySet().include(set);
+        assertEquals(set, included);
+        assertEquals(set.boms(), included.boms());
+        assertEquals(set.localDependencies(), included.localDependencies());
+        assertEquals(set.localModules(), included.localModules());
+
+        var scopes = new DependencyScopes();
+        scopes.scope(Scope.compile).include(set);
+        var scopes_copy = new DependencyScopes();
+        scopes_copy.include(scopes);
+        assertEquals(set.boms(), scopes_copy.scope(Scope.compile).boms());
+        assertEquals(set.localDependencies(), scopes_copy.scope(Scope.compile).localDependencies());
+
+        var scopes_ctor_copy = new DependencyScopes(scopes);
+        assertEquals(set.boms(), scopes_ctor_copy.scope(Scope.compile).boms());
+        assertEquals(set.localDependencies(), scopes_ctor_copy.scope(Scope.compile).localDependencies());
+        assertEquals(set.localModules(), scopes_ctor_copy.scope(Scope.compile).localModules());
+    }
+
+    @Test
+    void testTransferIntoDirectoryParallel() throws Exception {
+        var max_concurrent_transfers = new AtomicInteger();
+        var server = createTransferServer(max_concurrent_transfers);
+        server.start();
+        var tmp = Files.createTempDirectory("transfers").toFile();
+        try {
+            var dependencies = createTransferDependencies(1, 6);
+            var repositories = List.of(transferRepository(server));
+
+            var artifacts = dependencies.transferIntoDirectory(new VersionResolution(null), ArtifactRetriever.instance(), repositories, tmp, tmp);
+
+            assertTransferredArtifacts(dependencies, artifacts, tmp);
+            assertTrue(max_concurrent_transfers.get() > 1, "expected concurrent transfers, max was " + max_concurrent_transfers.get());
+        } finally {
+            server.stop(0);
+            FileUtils.deleteDirectory(tmp);
+        }
+    }
+
+    @Test
+    void testTransferIntoDirectorySequential() throws Exception {
+        var max_concurrent_transfers = new AtomicInteger();
+        var server = createTransferServer(max_concurrent_transfers);
+        server.start();
+        var tmp = Files.createTempDirectory("transfers").toFile();
+        try {
+            var properties = new HierarchicalProperties();
+            properties.put(VersionResolution.PROPERTY_TRANSFER_PARALLELISM, "1");
+            var resolution = new VersionResolution(properties);
+            assertEquals(1, resolution.transferParallelism());
+
+            var dependencies = createTransferDependencies(1, 6);
+            var repositories = List.of(transferRepository(server));
+
+            var artifacts = dependencies.transferIntoDirectory(resolution, ArtifactRetriever.instance(), repositories, tmp, tmp);
+
+            assertTransferredArtifacts(dependencies, artifacts, tmp);
+            assertEquals(1, max_concurrent_transfers.get(), "expected sequential transfers, max was " + max_concurrent_transfers.get());
+        } finally {
+            server.stop(0);
+            FileUtils.deleteDirectory(tmp);
+        }
+    }
+
 }

src/test/java/rife/bld/dependencies/TestDependencyTransferBatch.java

@@ -0,0 +1,143 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import org.junit.jupiter.api.Test;
+import rife.bld.dependencies.exceptions.DependencyTransferException;
+import rife.tools.FileUtils;
+
+import java.io.File;
+import java.nio.file.Files;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static rife.bld.dependencies.TransferTestHelper.*;
+
+public class TestDependencyTransferBatch {
+    @Test
+    void testTransferAcrossSets() throws Exception {
+        var max_concurrent_transfers = new AtomicInteger();
+        var server = createTransferServer(max_concurrent_transfers);
+        server.start();
+        var tmp1 = Files.createTempDirectory("transfers1").toFile();
+        var tmp2 = Files.createTempDirectory("transfers2").toFile();
+        try {
+            var set1 = createTransferDependencies(1, 3);
+            var set2 = createTransferDependencies(4, 6);
+            var repositories = List.of(transferRepository(server));
+
+            var batch = new DependencyTransferBatch();
+            batch.add(set1, tmp1, tmp1)
+                 .add(set2, tmp2, tmp2)
+                 // identical transfers into the same directory are only performed once
+                 .add(set1, tmp1, tmp1);
+            var artifacts = batch.transfer(new VersionResolution(null), ArtifactRetriever.instance(), repositories);
+
+            assertEquals(6, artifacts.size());
+            assertTransferredArtifacts(set1, artifacts.subList(0, 3), tmp1);
+            assertTransferredArtifacts(set2, artifacts.subList(3, 6), tmp2);
+            assertTrue(max_concurrent_transfers.get() > 1, "expected concurrent transfers, max was " + max_concurrent_transfers.get());
+        } finally {
+            server.stop(0);
+            FileUtils.deleteDirectory(tmp1);
+            FileUtils.deleteDirectory(tmp2);
+        }
+    }
+
+    @Test
+    void testTransferEmptiesTheBatch() throws Exception {
+        var server = createTransferServer(new AtomicInteger());
+        server.start();
+        var tmp = Files.createTempDirectory("transfers").toFile();
+        try {
+            var repositories = List.of(transferRepository(server));
+            var resolution = new VersionResolution(null);
+            var batch = new DependencyTransferBatch();
+
+            var set1 = createTransferDependencies(1, 3);
+            batch.add(set1, tmp, tmp);
+            assertTransferredArtifacts(set1, batch.transfer(resolution, ArtifactRetriever.instance(), repositories), tmp);
+
+            // the batch was emptied, nothing is transferred again
+            assertTrue(batch.transfer(resolution, ArtifactRetriever.instance(), repositories).isEmpty());
+
+            // the same instance can collect and transfer again,
+            // including targets that were transferred before
+            var set2 = createTransferDependencies(3, 5);
+            batch.add(set2, tmp, tmp);
+            assertTransferredArtifacts(set2, batch.transfer(resolution, ArtifactRetriever.instance(), repositories), tmp);
+        } finally {
+            server.stop(0);
+            FileUtils.deleteDirectory(tmp);
+        }
+    }
+
+    @Test
+    void testTransferModularJarsIntoModulesDirectory() throws Exception {
+        var server = createTransferServer(new AtomicInteger());
+        server.start();
+        var artifacts_dir = Files.createTempDirectory("artifacts").toFile();
+        var modules_dir = Files.createTempDirectory("modules").toFile();
+        try {
+            var dependencies = new DependencySet()
+                .include(new Dependency("com.example", "artifact1", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "module1", new VersionNumber(1, 0, 0), "", Dependency.TYPE_MODULAR_JAR));
+
+            var artifacts = new DependencyTransferBatch()
+                .add(dependencies, artifacts_dir, modules_dir)
+                .transfer(new VersionResolution(null), ArtifactRetriever.instance(), List.of(transferRepository(server)));
+
+            assertEquals(2, artifacts.size());
+            assertTrue(new File(artifacts_dir, "artifact1-1.0.0.jar").exists());
+            assertTrue(new File(modules_dir, "module1-1.0.0.jar").exists());
+            assertFalse(new File(artifacts_dir, "module1-1.0.0.jar").exists());
+        } finally {
+            server.stop(0);
+            FileUtils.deleteDirectory(artifacts_dir);
+            FileUtils.deleteDirectory(modules_dir);
+        }
+    }
+
+    @Test
+    void testTransferClassifiers() throws Exception {
+        var server = createTransferServer(new AtomicInteger());
+        server.start();
+        var tmp = Files.createTempDirectory("transfers").toFile();
+        try {
+            var dependencies = createTransferDependencies(1, 2);
+            var artifacts = new DependencyTransferBatch()
+                .add(dependencies, tmp, tmp, "sources")
+                .transfer(new VersionResolution(null), ArtifactRetriever.instance(), List.of(transferRepository(server)));
+
+            assertEquals(4, artifacts.size());
+            for (var i = 1; i <= 2; i++) {
+                assertTrue(new File(tmp, "artifact" + i + "-1.0.0.jar").exists());
+                assertTrue(new File(tmp, "artifact" + i + "-1.0.0-sources.jar").exists());
+            }
+        } finally {
+            server.stop(0);
+            FileUtils.deleteDirectory(tmp);
+        }
+    }
+
+    @Test
+    void testMissingDirectories() {
+        var regular = new DependencySet()
+            .include(new Dependency("com.example", "artifact1", new VersionNumber(1, 0, 0)));
+        var modular = new DependencySet()
+            .include(new Dependency("com.example", "module1", new VersionNumber(1, 0, 0), "", Dependency.TYPE_MODULAR_JAR));
+
+        assertThrows(DependencyTransferException.class, () -> new DependencyTransferBatch().add(regular, null, null));
+        assertThrows(DependencyTransferException.class, () -> new DependencyTransferBatch().add(modular, Files.createTempDirectory("artifacts").toFile(), null));
+    }
+
+    @Test
+    void testEmptyBatch() {
+        var artifacts = new DependencyTransferBatch()
+            .transfer(new VersionResolution(null), ArtifactRetriever.instance(), List.of());
+        assertTrue(artifacts.isEmpty());
+    }
+}

src/test/java/rife/bld/dependencies/TransferTestHelper.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2001-2026 Geert Bevin (gbevin[remove] at uwyn dot com)
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+package rife.bld.dependencies;
+
+import com.sun.net.httpserver.HttpServer;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.util.List;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Provides a local artifact server and dependency fixtures for testing
+ * transfers without relying on remote repositories.
+ */
+abstract class TransferTestHelper {
+    static HttpServer createTransferServer(AtomicInteger maxConcurrentTransfers)
+    throws IOException {
+        var active_transfers = new AtomicInteger();
+        var server = HttpServer.create(new InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var active = active_transfers.incrementAndGet();
+            maxConcurrentTransfers.accumulateAndGet(active, Math::max);
+            try {
+                // delay the response so that parallel transfers overlap
+                Thread.sleep(200);
+
+                var body = exchange.getRequestURI().getPath().getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+                exchange.close();
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            } finally {
+                active_transfers.decrementAndGet();
+            }
+        });
+        server.setExecutor(Executors.newCachedThreadPool());
+        return server;
+    }
+
+    static Repository transferRepository(HttpServer server) {
+        return new Repository("http://localhost:" + server.getAddress().getPort() + "/");
+    }
+
+    static DependencySet createTransferDependencies(int from, int to) {
+        var dependencies = new DependencySet();
+        for (var i = from; i <= to; i++) {
+            dependencies.include(new Dependency("com.example", "artifact" + i, new VersionNumber(1, 0, 0)));
+        }
+        return dependencies;
+    }
+
+    static void assertTransferredArtifacts(DependencySet dependencies, List<RepositoryArtifact> artifacts, File directory) {
+        assertEquals(dependencies.size(), artifacts.size());
+        var index = 0;
+        for (var dependency : dependencies) {
+            var filename = dependency.artifactId() + "-" + dependency.version() + ".jar";
+            assertTrue(artifacts.get(index).location().endsWith(filename), "expected artifact " + filename + " at index " + index);
+            assertTrue(new File(directory, filename).exists(), "expected file " + filename + " to be transferred");
+            ++index;
+        }
+    }
+}

src/test/java/rife/bld/operations/TestPublishOperation.java

@@ -11,9 +11,11 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.DisabledOnOs;
 import org.junit.jupiter.api.condition.OS;
 import rife.bld.Project;
+import rife.bld.WebProject;
 import rife.bld.blueprints.AppProjectBlueprint;
 import rife.bld.dependencies.*;
 import rife.bld.publish.PublishArtifact;
+import rife.bld.publish.PublishInfo;
 import rife.tools.FileUtils;
 import rife.tools.exceptions.FileUtilsErrorException;
 
@@ -704,4 +706,428 @@ public class TestPublishOperation {
             FileUtils.deleteDirectory(tmp1);
         }
     }
+
+    @Test
+    void testPublishLocalWithBom()
+    throws Exception {
+        var poms = java.util.Map.of(
+            "bom1:1.0.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bom1</artifactId>
+                    <version>1.0.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>1.4.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""");
+        var metadata = java.util.Map.of(
+            "b", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <metadata>
+                    <groupId>com.example</groupId>
+                    <artifactId>b</artifactId>
+                    <versioning>
+                        <latest>2.2.0</latest>
+                        <release>2.2.0</release>
+                        <versions><version>2.2.0</version></versions>
+                    </versioning>
+                </metadata>""");
+        var server = com.sun.net.httpserver.HttpServer.create(new java.net.InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var segments = exchange.getRequestURI().getPath().split("/");
+            var filename = segments[segments.length - 1];
+            String content = null;
+            if (filename.endsWith(".pom") && segments.length >= 3) {
+                content = poms.get(segments[segments.length - 3] + ":" + segments[segments.length - 2]);
+            } else if (filename.equals("maven-metadata.xml") && segments.length >= 2) {
+                content = metadata.get(segments[segments.length - 2]);
+            }
+            if (content == null) {
+                exchange.sendResponseHeaders(404, -1);
+            } else {
+                var body = content.getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+            }
+            exchange.close();
+        });
+        server.start();
+
+        var tmp_local = Files.createTempDirectory("bomlocal").toFile();
+        var artifact_file = File.createTempFile("myapp", ".jar");
+        try {
+            var operation = new PublishOperation()
+                .artifactRetriever(ArtifactRetriever.cachingInstance())
+                .repositories(new Repository(tmp_local.getAbsolutePath()))
+                .dependencyRepositories(List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/")))
+                .info(new PublishInfo()
+                    .groupId("test.pkg")
+                    .artifactId("myapp")
+                    .version(new VersionNumber(3, 3, 3)))
+                .artifacts(List.of(new PublishArtifact(artifact_file, "", "jar")));
+            operation.dependencies().scope(Scope.compile)
+                .include(new Bom("com.example", "bom1", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a"))
+                .include(new Dependency("com.example", "b"));
+            operation.execute();
+
+            var pom = FileUtils.readString(Path.of(tmp_local.getAbsolutePath(), "test", "pkg", "myapp", "3.3.3", "myapp-3.3.3.pom").toFile());
+
+            // the BOM is imported through dependency management
+            assertTrue(pom.contains("<dependencyManagement>"), pom);
+            assertTrue(pom.contains("<artifactId>bom1</artifactId>"), pom);
+            assertTrue(pom.contains("<version>1.0.0</version>"), pom);
+            assertTrue(pom.contains("<type>pom</type>"), pom);
+            assertTrue(pom.contains("<scope>import</scope>"), pom);
+
+            // the covered dependency stays version-less,
+            // the BOM import provides its version downstream
+            assertTrue(pom.contains("<artifactId>a</artifactId>"), pom);
+            assertFalse(java.util.regex.Pattern.compile("<artifactId>a</artifactId>\\s*<version>").matcher(pom).find(), pom);
+
+            // the uncovered dependency is frozen to its resolved version
+            assertTrue(java.util.regex.Pattern.compile("<artifactId>b</artifactId>\\s*<version>2\\.2\\.0</version>").matcher(pom).find(), pom);
+        } finally {
+            server.stop(0);
+            artifact_file.delete();
+            FileUtils.deleteDirectory(tmp_local);
+        }
+    }
+
+    @Test
+    void testResolveVersionlessDependenciesWithOverrides()
+    throws Exception {
+        var poms = java.util.Map.of(
+            "bom1:1.0.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bom1</artifactId>
+                    <version>1.0.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>1.4.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""",
+            "bom2:2.5.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bom2</artifactId>
+                    <version>2.5.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>d</artifactId><version>4.0.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""");
+        var metadata = java.util.Map.of(
+            "b", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <metadata>
+                    <groupId>com.example</groupId>
+                    <artifactId>b</artifactId>
+                    <versioning>
+                        <latest>2.2.0</latest>
+                        <release>2.2.0</release>
+                        <versions><version>2.2.0</version></versions>
+                    </versioning>
+                </metadata>""");
+        var server = com.sun.net.httpserver.HttpServer.create(new java.net.InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var segments = exchange.getRequestURI().getPath().split("/");
+            var filename = segments[segments.length - 1];
+            String content = null;
+            if (filename.endsWith(".pom") && segments.length >= 3) {
+                content = poms.get(segments[segments.length - 3] + ":" + segments[segments.length - 2]);
+            } else if (filename.equals("maven-metadata.xml") && segments.length >= 2) {
+                content = metadata.get(segments[segments.length - 2]);
+            }
+            if (content == null) {
+                exchange.sendResponseHeaders(404, -1);
+            } else {
+                var body = content.getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+            }
+            exchange.close();
+        });
+        server.start();
+        try {
+            var properties = new rife.ioc.HierarchicalProperties();
+            properties.put(VersionResolution.PROPERTY_OVERRIDE_PREFIX,
+                "com.example:a:1.9.9,com.example:b:1.1.1,com.example:bom2:2.5.0");
+
+            var scopes = new DependencyScopes();
+            scopes.scope(Scope.compile)
+                .include(new Bom("com.example", "bom1", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a"))
+                .include(new Dependency("com.example", "b"));
+            scopes.scope(Scope.runtime)
+                .include(new Bom("com.example", "bom2"));
+
+            var operation = new PublishOperation()
+                .properties(properties)
+                .artifactRetriever(ArtifactRetriever.cachingInstance())
+                .dependencyRepositories(List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/")))
+                .dependencies(scopes);
+            operation.executeResolveVersionlessDependencies();
+
+            var compile_scope = operation.dependencies().scope(Scope.compile);
+            // the override is what the build resolves, it's frozen into the
+            // POM even though the BOM covers the dependency
+            assertEquals(new VersionNumber(1, 9, 9), compile_scope.get(new Dependency("com.example", "a")).version());
+            // an uncovered dependency freezes to its override instead of
+            // the latest version
+            assertEquals(new VersionNumber(1, 1, 1), compile_scope.get(new Dependency("com.example", "b")).version());
+            // a version-less BOM freezes to its override
+            var runtime_boms = operation.dependencies().scope(Scope.runtime).boms();
+            assertEquals(new Bom("com.example", "bom2", new VersionNumber(2, 5, 0)), runtime_boms.iterator().next());
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    @Test
+    void testResolveVersionlessDependenciesFreezesFlattenedConflicts()
+    throws Exception {
+        var poms = java.util.Map.of(
+            "bomr:1.0.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bomr</artifactId>
+                    <version>1.0.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>1.0.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""",
+            "bomp:1.0.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bomp</artifactId>
+                    <version>1.0.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>2.0.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""");
+        var server = com.sun.net.httpserver.HttpServer.create(new java.net.InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var segments = exchange.getRequestURI().getPath().split("/");
+            var filename = segments[segments.length - 1];
+            String content = null;
+            if (filename.endsWith(".pom") && segments.length >= 3) {
+                content = poms.get(segments[segments.length - 3] + ":" + segments[segments.length - 2]);
+            }
+            if (content == null) {
+                exchange.sendResponseHeaders(404, -1);
+            } else {
+                var body = content.getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+            }
+            exchange.close();
+        });
+        server.start();
+        try {
+            var scopes = new DependencyScopes();
+            scopes.scope(Scope.runtime)
+                .include(new Bom("com.example", "bomr", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a"));
+            scopes.scope(Scope.provided)
+                .include(new Bom("com.example", "bomp", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a"));
+
+            var operation = new PublishOperation()
+                .artifactRetriever(ArtifactRetriever.cachingInstance())
+                .dependencyRepositories(List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/")))
+                .dependencies(scopes);
+            operation.executeResolveVersionlessDependencies();
+
+            // the flattened dependency management of the POM imports the
+            // runtime BOM first and would supply 1.0.0, the runtime scope
+            // agrees with that so its dependency stays version-less
+            assertEquals(VersionNumber.UNKNOWN, operation.dependencies().scope(Scope.runtime).get(new Dependency("com.example", "a")).version());
+            // the provided scope resolves 2.0.0 through its own BOM, that
+            // conflicts with the flattened list so the version is frozen
+            assertEquals(new VersionNumber(2, 0, 0), operation.dependencies().scope(Scope.provided).get(new Dependency("com.example", "a")).version());
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    @Test
+    void testResolveVersionlessDependenciesUntouchedScopes() {
+        // no network access is needed when nothing has to be resolved :
+        // explicitly versioned dependencies are untouched and the test
+        // scope isn't part of the publication
+        var scopes = new DependencyScopes();
+        scopes.scope(Scope.compile)
+            .include(new Dependency("com.example", "c", new VersionNumber(5, 0, 0)));
+        scopes.scope(Scope.test)
+            .include(new Dependency("com.example", "t"));
+
+        var operation = new PublishOperation()
+            .dependencies(scopes);
+        operation.executeResolveVersionlessDependencies();
+
+        assertEquals(new VersionNumber(5, 0, 0), operation.dependencies().scope(Scope.compile).get(new Dependency("com.example", "c")).version());
+        assertEquals(VersionNumber.UNKNOWN, operation.dependencies().scope(Scope.test).get(new Dependency("com.example", "t")).version());
+    }
+
+    static class BomPublishProject extends WebProject {
+        BomPublishProject(File tmp) {
+            workDirectory = tmp;
+            pkg = "test.pkg";
+            name = "myapp";
+            version = new VersionNumber(0, 0, 1);
+            repositories = List.of(new Repository("https://example.com/resolve"));
+        }
+    }
+
+    @Test
+    void testFromProjectDependencyRepositories()
+    throws Exception {
+        var tmp = Files.createTempDirectory("test").toFile();
+        try {
+            var project = new BomPublishProject(tmp);
+            var operation = new PublishOperation()
+                .fromProject(project);
+            assertEquals(project.repositories(), operation.dependencyRepositories());
+        } finally {
+            FileUtils.deleteDirectory(tmp);
+        }
+    }
+
+    @Test
+    void testResolveVersionlessDependencies()
+    throws Exception {
+        var poms = java.util.Map.of(
+            "bom1:1.0.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bom1</artifactId>
+                    <version>1.0.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>1.4.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""",
+            "bom2:3.0.0", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project>
+                    <modelVersion>4.0.0</modelVersion>
+                    <groupId>com.example</groupId>
+                    <artifactId>bom2</artifactId>
+                    <version>3.0.0</version>
+                    <packaging>pom</packaging>
+                    <dependencyManagement>
+                        <dependencies>
+                            <dependency><groupId>com.example</groupId><artifactId>d</artifactId><version>4.0.0</version></dependency>
+                        </dependencies>
+                    </dependencyManagement>
+                </project>""");
+        var metadata = java.util.Map.of(
+            "b", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <metadata>
+                    <groupId>com.example</groupId>
+                    <artifactId>b</artifactId>
+                    <versioning>
+                        <latest>2.2.0</latest>
+                        <release>2.2.0</release>
+                        <versions><version>2.2.0</version></versions>
+                    </versioning>
+                </metadata>""",
+            "bom2", """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <metadata>
+                    <groupId>com.example</groupId>
+                    <artifactId>bom2</artifactId>
+                    <versioning>
+                        <latest>3.0.0</latest>
+                        <release>3.0.0</release>
+                        <versions><version>3.0.0</version></versions>
+                    </versioning>
+                </metadata>""");
+        var server = com.sun.net.httpserver.HttpServer.create(new java.net.InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var segments = exchange.getRequestURI().getPath().split("/");
+            var filename = segments[segments.length - 1];
+            String content = null;
+            if (filename.endsWith(".pom") && segments.length >= 3) {
+                content = poms.get(segments[segments.length - 3] + ":" + segments[segments.length - 2]);
+            } else if (filename.equals("maven-metadata.xml") && segments.length >= 2) {
+                content = metadata.get(segments[segments.length - 2]);
+            }
+            if (content == null) {
+                exchange.sendResponseHeaders(404, -1);
+            } else {
+                var body = content.getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+            }
+            exchange.close();
+        });
+        server.start();
+        try {
+            var scopes = new DependencyScopes();
+            scopes.scope(Scope.compile)
+                .include(new Bom("com.example", "bom1", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a"))
+                .include(new Dependency("com.example", "b"))
+                .include(new Dependency("com.example", "c", new VersionNumber(5, 0, 0)));
+            scopes.scope(Scope.runtime)
+                .include(new Bom("com.example", "bom2"));
+            scopes.scope(Scope.provided)
+                // covered by the compile scope BOM through scope inheritance
+                .include(new Dependency("com.example", "a"));
+
+            var operation = new PublishOperation()
+                .artifactRetriever(ArtifactRetriever.cachingInstance())
+                .dependencyRepositories(List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/")))
+                .dependencies(scopes);
+            operation.executeResolveVersionlessDependencies();
+
+            var compile_scope = operation.dependencies().scope(Scope.compile);
+            // covered by the BOM : stays version-less for the POM,
+            // the dependency management import provides the version
+            assertEquals(VersionNumber.UNKNOWN, compile_scope.get(new Dependency("com.example", "a")).version());
+            // not covered : resolved to its latest version
+            assertEquals(new VersionNumber(2, 2, 0), compile_scope.get(new Dependency("com.example", "b")).version());
+            // explicitly versioned : untouched
+            assertEquals(new VersionNumber(5, 0, 0), compile_scope.get(new Dependency("com.example", "c")).version());
+            // a version-less BOM is resolved to its latest version
+            var runtime_boms = operation.dependencies().scope(Scope.runtime).boms();
+            assertEquals(new Bom("com.example", "bom2", new VersionNumber(3, 0, 0)), runtime_boms.iterator().next());
+            // the compile scope BOM also covers the provided scope,
+            // its version-less dependency stays version-less
+            assertEquals(VersionNumber.UNKNOWN, operation.dependencies().scope(Scope.provided).get(new Dependency("com.example", "a")).version());
+        } finally {
+            server.stop(0);
+        }
+    }
 }

src/test/java/rife/bld/operations/TestUpdatesOperation.java

@@ -4,14 +4,18 @@
  */
 package rife.bld.operations;
 
+import com.sun.net.httpserver.HttpServer;
 import org.junit.jupiter.api.Test;
 import rife.bld.WebProject;
 import rife.bld.dependencies.*;
 import rife.tools.FileUtils;
 
 import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
 import java.nio.file.Files;
 import java.util.List;
+import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -168,4 +172,123 @@ public class TestUpdatesOperation {
             FileUtils.deleteDirectory(tmp);
         }
     }
+
+    @Test
+    void testBomUpdateReported()
+    throws Exception {
+        var server = createArtifactServer(
+            Map.of("bom1:1.0.0", bomPom("bom1", "1.0.0", "<dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>1.4.0</version></dependency>")),
+            Map.of("bom1", metadata("bom1", "2.0.0", "1.0.0", "2.0.0"),
+                   "a", metadata("a", "9.9.9", "1.4.0", "9.9.9")));
+        server.start();
+        try {
+            var operation = new UpdatesOperation()
+                .artifactRetriever(ArtifactRetriever.cachingInstance())
+                .repositories(List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/")));
+            operation.dependencies().scope(Scope.compile)
+                .include(new Bom("com.example", "bom1", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a"));
+
+            operation.execute();
+
+            // the newer BOM version is reported
+            var boms = operation.updates().scope(Scope.compile).boms();
+            assertEquals(1, boms.size());
+            assertEquals(new Bom("com.example", "bom1", new VersionNumber(2, 0, 0)), boms.iterator().next());
+
+            // the version-less dependency covered by the BOM is not reported,
+            // even though newer versions exist in the metadata
+            assertTrue(operation.updates().scope(Scope.compile).isEmpty());
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    @Test
+    void testExplicitVersionCheckedDespiteBom()
+    throws Exception {
+        var server = createArtifactServer(
+            Map.of("bom1:1.0.0", bomPom("bom1", "1.0.0", "<dependency><groupId>com.example</groupId><artifactId>a</artifactId><version>1.4.0</version></dependency>")),
+            Map.of("bom1", metadata("bom1", "1.0.0", "1.0.0"),
+                   "a", metadata("a", "2.0.0", "1.0.0", "2.0.0")));
+        server.start();
+        try {
+            var operation = new UpdatesOperation()
+                .artifactRetriever(ArtifactRetriever.cachingInstance())
+                .repositories(List.of(new Repository("http://localhost:" + server.getAddress().getPort() + "/")));
+            operation.dependencies().scope(Scope.compile)
+                .include(new Bom("com.example", "bom1", new VersionNumber(1, 0, 0)))
+                .include(new Dependency("com.example", "a", new VersionNumber(1, 0, 0)));
+
+            operation.execute();
+
+            // the BOM is up to date and not reported
+            assertTrue(operation.updates().scope(Scope.compile).boms().isEmpty());
+
+            // the explicitly versioned dependency is still checked for
+            // updates, even though the BOM covers it
+            var dependencies = operation.updates().scope(Scope.compile);
+            assertEquals(1, dependencies.size());
+            assertEquals(new VersionNumber(2, 0, 0), dependencies.iterator().next().version());
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    private static HttpServer createArtifactServer(Map<String, String> poms, Map<String, String> metadata)
+    throws IOException {
+        var server = HttpServer.create(new InetSocketAddress("localhost", 0), 0);
+        server.createContext("/", exchange -> {
+            var segments = exchange.getRequestURI().getPath().split("/");
+            var filename = segments[segments.length - 1];
+            String content = null;
+            if (filename.endsWith(".pom") && segments.length >= 3) {
+                content = poms.get(segments[segments.length - 3] + ":" + segments[segments.length - 2]);
+            } else if (filename.equals("maven-metadata.xml") && segments.length >= 2) {
+                content = metadata.get(segments[segments.length - 2]);
+            }
+            if (content == null) {
+                exchange.sendResponseHeaders(404, -1);
+            } else {
+                var body = content.getBytes();
+                exchange.sendResponseHeaders(200, body.length);
+                exchange.getResponseBody().write(body);
+            }
+            exchange.close();
+        });
+        return server;
+    }
+
+    private static String bomPom(String artifact, String version, String managedDependencies) {
+        return """
+            <?xml version="1.0" encoding="UTF-8"?>
+            <project>
+                <modelVersion>4.0.0</modelVersion>
+                <groupId>com.example</groupId>
+                <artifactId>%s</artifactId>
+                <version>%s</version>
+                <packaging>pom</packaging>
+                <dependencyManagement>
+                    <dependencies>%s</dependencies>
+                </dependencyManagement>
+            </project>""".formatted(artifact, version, managedDependencies);
+    }
+
+    private static String metadata(String artifact, String latest, String... versions) {
+        var versions_xml = new StringBuilder();
+        for (var version : versions) {
+            versions_xml.append("<version>").append(version).append("</version>");
+        }
+        return """
+            <?xml version="1.0" encoding="UTF-8"?>
+            <metadata>
+                <groupId>com.example</groupId>
+                <artifactId>%s</artifactId>
+                <versioning>
+                    <latest>%s</latest>
+                    <release>%s</release>
+                    <versions>%s</versions>
+                </versioning>
+            </metadata>""".formatted(artifact, latest, latest, versions_xml);
+    }
 }

src/test/java/rife/bld/publish/TestPomBuilder.java

@@ -652,4 +652,93 @@ public class TestPomBuilder {
                 </project>
                 """, builder.build());
     }
+
+    @Test
+    void testDependencyManagementScopeBoundaries() {
+        var builder = new PomBuilder();
+        builder.dependencies().scope(Scope.provided)
+            .include(new Bom("org.eclipse.jetty", "jetty-bom", new VersionNumber(12, 0, 16)));
+        builder.dependencies().scope(Scope.test)
+            // the test scope isn't published, its BOMs are not emitted
+            .include(new Bom("org.junit", "junit-bom", new VersionNumber(6, 1, 1)));
+        assertEquals("""
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+                         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+                  <modelVersion>4.0.0</modelVersion>
+                  <groupId></groupId>
+                  <artifactId></artifactId>
+                  <version></version>
+                  <name></name>
+                  <description></description>
+                  <url></url>
+                  <dependencyManagement>
+                    <dependencies>
+                      <dependency>
+                        <groupId>org.eclipse.jetty</groupId>
+                        <artifactId>jetty-bom</artifactId>
+                        <version>12.0.16</version>
+                        <type>pom</type>
+                        <scope>import</scope>
+                      </dependency>
+                    </dependencies>
+                  </dependencyManagement>
+                  <dependencies>
+                  </dependencies>
+                </project>
+                """, builder.build());
+    }
+
+    @Test
+    void testDependencyManagement() {
+        var builder = new PomBuilder();
+        builder.dependencies().scope(Scope.compile)
+            .include(new Bom("io.vertx", "vertx-stack-depchain", new VersionNumber(4, 5, 12)))
+            .include(new Dependency("io.vertx", "vertx-core"));
+        builder.dependencies().scope(Scope.runtime)
+            // duplicate BOMs are only emitted once
+            .include(new Bom("io.vertx", "vertx-stack-depchain", new VersionNumber(4, 5, 12)))
+            .include(new Bom("org.junit", "junit-bom", new VersionNumber(6, 1, 1)));
+        builder.dependencies().scope(Scope.provided)
+            // BOMs without a version are not emitted
+            .include(new Bom("com.example", "versionless-bom"));
+        assertEquals("""
+                <?xml version="1.0" encoding="UTF-8"?>
+                <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+                         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+                  <modelVersion>4.0.0</modelVersion>
+                  <groupId></groupId>
+                  <artifactId></artifactId>
+                  <version></version>
+                  <name></name>
+                  <description></description>
+                  <url></url>
+                  <dependencyManagement>
+                    <dependencies>
+                      <dependency>
+                        <groupId>io.vertx</groupId>
+                        <artifactId>vertx-stack-depchain</artifactId>
+                        <version>4.5.12</version>
+                        <type>pom</type>
+                        <scope>import</scope>
+                      </dependency>
+                      <dependency>
+                        <groupId>org.junit</groupId>
+                        <artifactId>junit-bom</artifactId>
+                        <version>6.1.1</version>
+                        <type>pom</type>
+                        <scope>import</scope>
+                      </dependency>
+                    </dependencies>
+                  </dependencyManagement>
+                  <dependencies>
+                    <dependency>
+                      <groupId>io.vertx</groupId>
+                      <artifactId>vertx-core</artifactId>
+                      <scope>compile</scope>
+                    </dependency>
+                  </dependencies>
+                </project>
+                """, builder.build());
+    }
 }