[2.x] feat: Add dependency lock file support (#2989) (#8581)

**What it does**

When you run `dependencyLock`, sbt generates a `deps.lock` file that captures your resolved dependencies. This file can be checked into version control to ensure reproducible builds across different machines and CI environments.

**New tasks**

- **`dependencyLock`** - Generates the lock file from the current resolution
- **`dependencyLockCheck`** - Validates the lock file is up-to-date (fails build if stale)

**How it works**

The lock file stores a hash of your declared dependencies and resolvers. When dependencies change, the hash changes, and `dependencyLockCheck` will fail until you regenerate the lock file.

If no lock file exists, `dependencyLockCheck` passes silently - this allows gradual adoption.

build.sbt

@@ -1228,11 +1228,13 @@ lazy val lmCoursierDependencies = Def.settings(
 
 lazy val lmCoursier = project
   .in(file("lm-coursier"))
+  .enablePlugins(ContrabandPlugin)
   .settings(
     lmCoursierSettings,
     Mima.settings,
     Mima.lmCoursierFilters,
     lmCoursierDependencies,
+    contrabandSettings,
     Compile / sourceGenerators += Utils.dataclassGen(lmCoursierDefinitions).taskValue,
   )
   .dependsOn(

lm-coursier/definitions/src/main/scala/lmcoursier/CoursierConfiguration.scala

@@ -71,4 +71,6 @@ import scala.concurrent.duration.{ Duration, FiniteDuration }
     sameVersions: Seq[Set[InclExclRule]] = Nil,
     @since
     localArtifactsShouldBeCached: Boolean = false,
+    @since
+    lockFile: Option[File] = None,
 )

lm-coursier/src/main/contraband-scala/lmcoursier/internal/ArtifactLock.scala

@@ -0,0 +1,48 @@
+/**
+ * This code is generated using [[https://www.scala-sbt.org/contraband]].
+ */
+
+// DO NOT EDIT MANUALLY
+package lmcoursier.internal
+final class ArtifactLock private (
+  val url: String,
+  val classifier: Option[String],
+  val extension: String,
+  val tpe: String) extends Serializable {
+  
+  
+  
+  override def equals(o: Any): Boolean = this.eq(o.asInstanceOf[AnyRef]) || (o match {
+    case x: ArtifactLock => (this.url == x.url) && (this.classifier == x.classifier) && (this.extension == x.extension) && (this.tpe == x.tpe)
+    case _ => false
+  })
+  override def hashCode: Int = {
+    37 * (37 * (37 * (37 * (37 * (17 + "lmcoursier.internal.ArtifactLock".##) + url.##) + classifier.##) + extension.##) + tpe.##)
+  }
+  override def toString: String = {
+    "ArtifactLock(" + url + ", " + classifier + ", " + extension + ", " + tpe + ")"
+  }
+  private def copy(url: String = url, classifier: Option[String] = classifier, extension: String = extension, tpe: String = tpe): ArtifactLock = {
+    new ArtifactLock(url, classifier, extension, tpe)
+  }
+  def withUrl(url: String): ArtifactLock = {
+    copy(url = url)
+  }
+  def withClassifier(classifier: Option[String]): ArtifactLock = {
+    copy(classifier = classifier)
+  }
+  def withClassifier(classifier: String): ArtifactLock = {
+    copy(classifier = Option(classifier))
+  }
+  def withExtension(extension: String): ArtifactLock = {
+    copy(extension = extension)
+  }
+  def withTpe(tpe: String): ArtifactLock = {
+    copy(tpe = tpe)
+  }
+}
+object ArtifactLock {
+  
+  def apply(url: String, classifier: Option[String], extension: String, tpe: String): ArtifactLock = new ArtifactLock(url, classifier, extension, tpe)
+  def apply(url: String, classifier: String, extension: String, tpe: String): ArtifactLock = new ArtifactLock(url, Option(classifier), extension, tpe)
+}

lm-coursier/src/main/contraband-scala/lmcoursier/internal/ConfigurationLock.scala

@@ -0,0 +1,36 @@
+/**
+ * This code is generated using [[https://www.scala-sbt.org/contraband]].
+ */
+
+// DO NOT EDIT MANUALLY
+package lmcoursier.internal
+final class ConfigurationLock private (
+  val name: String,
+  val dependencies: Vector[lmcoursier.internal.DependencyLock]) extends Serializable {
+  
+  
+  
+  override def equals(o: Any): Boolean = this.eq(o.asInstanceOf[AnyRef]) || (o match {
+    case x: ConfigurationLock => (this.name == x.name) && (this.dependencies == x.dependencies)
+    case _ => false
+  })
+  override def hashCode: Int = {
+    37 * (37 * (37 * (17 + "lmcoursier.internal.ConfigurationLock".##) + name.##) + dependencies.##)
+  }
+  override def toString: String = {
+    "ConfigurationLock(" + name + ", " + dependencies + ")"
+  }
+  private def copy(name: String = name, dependencies: Vector[lmcoursier.internal.DependencyLock] = dependencies): ConfigurationLock = {
+    new ConfigurationLock(name, dependencies)
+  }
+  def withName(name: String): ConfigurationLock = {
+    copy(name = name)
+  }
+  def withDependencies(dependencies: Vector[lmcoursier.internal.DependencyLock]): ConfigurationLock = {
+    copy(dependencies = dependencies)
+  }
+}
+object ConfigurationLock {
+  
+  def apply(name: String, dependencies: Vector[lmcoursier.internal.DependencyLock]): ConfigurationLock = new ConfigurationLock(name, dependencies)
+}

lm-coursier/src/main/contraband-scala/lmcoursier/internal/DependencyLock.scala

@@ -0,0 +1,64 @@
+/**
+ * This code is generated using [[https://www.scala-sbt.org/contraband]].
+ */
+
+// DO NOT EDIT MANUALLY
+package lmcoursier.internal
+final class DependencyLock private (
+  val organization: String,
+  val name: String,
+  val version: String,
+  val configuration: String,
+  val classifier: Option[String],
+  val tpe: String,
+  val transitives: Vector[String],
+  val artifacts: Vector[lmcoursier.internal.ArtifactLock]) extends Serializable {
+  
+  
+  
+  override def equals(o: Any): Boolean = this.eq(o.asInstanceOf[AnyRef]) || (o match {
+    case x: DependencyLock => (this.organization == x.organization) && (this.name == x.name) && (this.version == x.version) && (this.configuration == x.configuration) && (this.classifier == x.classifier) && (this.tpe == x.tpe) && (this.transitives == x.transitives) && (this.artifacts == x.artifacts)
+    case _ => false
+  })
+  override def hashCode: Int = {
+    37 * (37 * (37 * (37 * (37 * (37 * (37 * (37 * (37 * (17 + "lmcoursier.internal.DependencyLock".##) + organization.##) + name.##) + version.##) + configuration.##) + classifier.##) + tpe.##) + transitives.##) + artifacts.##)
+  }
+  override def toString: String = {
+    "DependencyLock(" + organization + ", " + name + ", " + version + ", " + configuration + ", " + classifier + ", " + tpe + ", " + transitives + ", " + artifacts + ")"
+  }
+  private def copy(organization: String = organization, name: String = name, version: String = version, configuration: String = configuration, classifier: Option[String] = classifier, tpe: String = tpe, transitives: Vector[String] = transitives, artifacts: Vector[lmcoursier.internal.ArtifactLock] = artifacts): DependencyLock = {
+    new DependencyLock(organization, name, version, configuration, classifier, tpe, transitives, artifacts)
+  }
+  def withOrganization(organization: String): DependencyLock = {
+    copy(organization = organization)
+  }
+  def withName(name: String): DependencyLock = {
+    copy(name = name)
+  }
+  def withVersion(version: String): DependencyLock = {
+    copy(version = version)
+  }
+  def withConfiguration(configuration: String): DependencyLock = {
+    copy(configuration = configuration)
+  }
+  def withClassifier(classifier: Option[String]): DependencyLock = {
+    copy(classifier = classifier)
+  }
+  def withClassifier(classifier: String): DependencyLock = {
+    copy(classifier = Option(classifier))
+  }
+  def withTpe(tpe: String): DependencyLock = {
+    copy(tpe = tpe)
+  }
+  def withTransitives(transitives: Vector[String]): DependencyLock = {
+    copy(transitives = transitives)
+  }
+  def withArtifacts(artifacts: Vector[lmcoursier.internal.ArtifactLock]): DependencyLock = {
+    copy(artifacts = artifacts)
+  }
+}
+object DependencyLock {
+  
+  def apply(organization: String, name: String, version: String, configuration: String, classifier: Option[String], tpe: String, transitives: Vector[String], artifacts: Vector[lmcoursier.internal.ArtifactLock]): DependencyLock = new DependencyLock(organization, name, version, configuration, classifier, tpe, transitives, artifacts)
+  def apply(organization: String, name: String, version: String, configuration: String, classifier: String, tpe: String, transitives: Vector[String], artifacts: Vector[lmcoursier.internal.ArtifactLock]): DependencyLock = new DependencyLock(organization, name, version, configuration, Option(classifier), tpe, transitives, artifacts)
+}

lm-coursier/src/main/contraband-scala/lmcoursier/internal/LockFileData.scala

@@ -0,0 +1,44 @@
+/**
+ * This code is generated using [[https://www.scala-sbt.org/contraband]].
+ */
+
+// DO NOT EDIT MANUALLY
+package lmcoursier.internal
+final class LockFileData private (
+  val version: String,
+  val buildClock: String,
+  val configurations: Vector[lmcoursier.internal.ConfigurationLock],
+  val metadata: lmcoursier.internal.LockFileMetadata) extends Serializable {
+  
+  
+  
+  override def equals(o: Any): Boolean = this.eq(o.asInstanceOf[AnyRef]) || (o match {
+    case x: LockFileData => (this.version == x.version) && (this.buildClock == x.buildClock) && (this.configurations == x.configurations) && (this.metadata == x.metadata)
+    case _ => false
+  })
+  override def hashCode: Int = {
+    37 * (37 * (37 * (37 * (37 * (17 + "lmcoursier.internal.LockFileData".##) + version.##) + buildClock.##) + configurations.##) + metadata.##)
+  }
+  override def toString: String = {
+    "LockFileData(" + version + ", " + buildClock + ", " + configurations + ", " + metadata + ")"
+  }
+  private def copy(version: String = version, buildClock: String = buildClock, configurations: Vector[lmcoursier.internal.ConfigurationLock] = configurations, metadata: lmcoursier.internal.LockFileMetadata = metadata): LockFileData = {
+    new LockFileData(version, buildClock, configurations, metadata)
+  }
+  def withVersion(version: String): LockFileData = {
+    copy(version = version)
+  }
+  def withBuildClock(buildClock: String): LockFileData = {
+    copy(buildClock = buildClock)
+  }
+  def withConfigurations(configurations: Vector[lmcoursier.internal.ConfigurationLock]): LockFileData = {
+    copy(configurations = configurations)
+  }
+  def withMetadata(metadata: lmcoursier.internal.LockFileMetadata): LockFileData = {
+    copy(metadata = metadata)
+  }
+}
+object LockFileData {
+  
+  def apply(version: String, buildClock: String, configurations: Vector[lmcoursier.internal.ConfigurationLock], metadata: lmcoursier.internal.LockFileMetadata): LockFileData = new LockFileData(version, buildClock, configurations, metadata)
+}

lm-coursier/src/main/contraband-scala/lmcoursier/internal/LockFileMetadata.scala

@@ -0,0 +1,40 @@
+/**
+ * This code is generated using [[https://www.scala-sbt.org/contraband]].
+ */
+
+// DO NOT EDIT MANUALLY
+package lmcoursier.internal
+final class LockFileMetadata private (
+  val sbtVersion: String,
+  val scalaVersion: Option[String]) extends Serializable {
+  
+  
+  
+  override def equals(o: Any): Boolean = this.eq(o.asInstanceOf[AnyRef]) || (o match {
+    case x: LockFileMetadata => (this.sbtVersion == x.sbtVersion) && (this.scalaVersion == x.scalaVersion)
+    case _ => false
+  })
+  override def hashCode: Int = {
+    37 * (37 * (37 * (17 + "lmcoursier.internal.LockFileMetadata".##) + sbtVersion.##) + scalaVersion.##)
+  }
+  override def toString: String = {
+    "LockFileMetadata(" + sbtVersion + ", " + scalaVersion + ")"
+  }
+  private def copy(sbtVersion: String = sbtVersion, scalaVersion: Option[String] = scalaVersion): LockFileMetadata = {
+    new LockFileMetadata(sbtVersion, scalaVersion)
+  }
+  def withSbtVersion(sbtVersion: String): LockFileMetadata = {
+    copy(sbtVersion = sbtVersion)
+  }
+  def withScalaVersion(scalaVersion: Option[String]): LockFileMetadata = {
+    copy(scalaVersion = scalaVersion)
+  }
+  def withScalaVersion(scalaVersion: String): LockFileMetadata = {
+    copy(scalaVersion = Option(scalaVersion))
+  }
+}
+object LockFileMetadata {
+  
+  def apply(sbtVersion: String, scalaVersion: Option[String]): LockFileMetadata = new LockFileMetadata(sbtVersion, scalaVersion)
+  def apply(sbtVersion: String, scalaVersion: String): LockFileMetadata = new LockFileMetadata(sbtVersion, Option(scalaVersion))
+}

lm-coursier/src/main/contraband/lockfile.contra

@@ -0,0 +1,37 @@
+package lmcoursier.internal
+@target(Scala)
+
+type ArtifactLock {
+  url: String!
+  classifier: String
+  extension: String!
+  tpe: String!
+}
+
+type DependencyLock {
+  organization: String!
+  name: String!
+  version: String!
+  configuration: String!
+  classifier: String
+  tpe: String!
+  transitives: [String]
+  artifacts: [lmcoursier.internal.ArtifactLock]
+}
+
+type ConfigurationLock {
+  name: String!
+  dependencies: [lmcoursier.internal.DependencyLock]
+}
+
+type LockFileMetadata {
+  sbtVersion: String!
+  scalaVersion: String
+}
+
+type LockFileData {
+  version: String!
+  buildClock: String!
+  configurations: [lmcoursier.internal.ConfigurationLock]
+  metadata: lmcoursier.internal.LockFileMetadata!
+}

lm-coursier/src/main/scala/lmcoursier/CoursierDependencyResolution.scala

@@ -14,8 +14,11 @@ import lmcoursier.internal.{
   ArtifactsRun,
   CoursierModuleDescriptor,
   InterProjectRepository,
+  LockFile,
+  LockedArtifactsRun,
   ResolutionParams,
   ResolutionRun,
+  ResolutionSerializer,
   Resolvers,
   SbtBootJars,
   UpdateParams,
@@ -320,12 +323,52 @@ class CoursierDependencyResolution(
       )
 
     val e = for {
-      resolutions <- ResolutionRun.resolutions(resolutionParams, verbosityLevel, log)
+      (resolutions, lockDataOpt) <- ResolutionRun.resolutionsWithLockFileData(
-      artifactsParams0 = artifactsParams(resolutions)
+        resolutionParams,
-      artifacts <- ArtifactsRun(artifactsParams0, verbosityLevel, log)
+        verbosityLevel,
+        log,
+        conf.lockFile,
+        conf.scalaVersion
+      )
+      artifactResult <- lockDataOpt match {
+        case Some(lockData) =>
+          LockedArtifactsRun.fetchFromLockFile(lockData, cache0, verbosityLevel, log) match {
+            case Right(arts) => Right(arts)
+            case Left(err) =>
+              if (verbosityLevel >= 1) {
+                log.warn(s"Failed to fetch from lock file: $err, falling back to normal fetch")
+              }
+              ArtifactsRun(artifactsParams(resolutions), verbosityLevel, log)
+                .map(_.fullDetailedArtifacts)
+          }
+        case None =>
+          ArtifactsRun(artifactsParams(resolutions), verbosityLevel, log)
+            .map(_.fullDetailedArtifacts)
+      }
     } yield {
-      val updateParams0 = updateParams(resolutions, artifacts.fullDetailedArtifacts)
+      val updateParams0 = updateParams(resolutions, artifactResult)
-      UpdateRun.update(updateParams0, verbosityLevel, log)
+      val report = UpdateRun.update(updateParams0, verbosityLevel, log)
+      if (lockDataOpt.isEmpty) {
+        conf.lockFile.foreach { lockFile =>
+          val artifactMap = artifactResult
+            .groupBy(_._1)
+            .view
+            .mapValues(_.map { case (_, pub, art, _) =>
+              val originalUrl = CoursierDependencyResolution.cacheFileToOriginalUrl(art.url, cache)
+              (originalUrl, pub.classifier.value, pub.ext.value)
+            })
+            .toMap
+          val lockData = ResolutionSerializer.extractLockFileData(
+            resolutions,
+            resolutionParams,
+            conf.scalaVersion,
+            "2.0.0",
+            artifactMap
+          )
+          LockFile.write(lockFile, lockData)
+        }
+      }
+      report
     }
     e.left.map(unresolvedWarningOrThrow(uwconfig, _))
   }
@@ -387,4 +430,33 @@ object CoursierDependencyResolution {
 
   def defaultCacheLocation: File =
     CacheDefaults.location
+
+  private[lmcoursier] def cacheFileToOriginalUrl(fileUrl: String, cacheDir: File): String = {
+    val filePrefix = "file:"
+    if (fileUrl.startsWith(filePrefix)) {
+      val filePath = fileUrl.stripPrefix(filePrefix).replaceFirst("^/+", "/")
+      val cachePaths = Seq(
+        cacheDir.getAbsolutePath,
+        cacheDir.getCanonicalPath
+      ).distinct.map(p => if (p.endsWith("/")) p else p + "/")
+
+      def extractHttpUrl(relativePath: String): Option[String] = {
+        val protocolSepIndex = relativePath.indexOf('/')
+        if (protocolSepIndex > 0) {
+          val protocol = relativePath.substring(0, protocolSepIndex)
+          val rest = relativePath.substring(protocolSepIndex + 1)
+          Some(s"$protocol://$rest")
+        } else None
+      }
+
+      cachePaths
+        .collectFirst {
+          case cachePath if filePath.startsWith(cachePath) =>
+            val relativePath = filePath.stripPrefix(cachePath)
+            extractHttpUrl(relativePath)
+        }
+        .flatten
+        .getOrElse(s"$${CSR_CACHE}$filePath")
+    } else fileUrl
+  }
 }

lm-coursier/src/main/scala/lmcoursier/internal/BuildClock.scala

@@ -0,0 +1,64 @@
+package lmcoursier.internal
+
+import coursier.core.{ Configuration, Dependency, Repository }
+import java.security.MessageDigest
+import scala.collection.immutable.Seq
+
+object BuildClock {
+
+  def compute(
+      dependencies: Seq[(Configuration, Dependency)],
+      repositories: Seq[Repository],
+      scalaVersion: Option[String],
+      params: ResolutionParams
+  ): String = {
+    val digest = MessageDigest.getInstance("SHA-1")
+
+    dependencies.sortBy(d => (d._1.value, d._2.module.toString, d._2.version)).foreach {
+      case (config, dep) =>
+        digest.update(config.value.getBytes("UTF-8"))
+        digest.update(dep.module.organization.value.getBytes("UTF-8"))
+        digest.update(dep.module.name.value.getBytes("UTF-8"))
+        digest.update(dep.version.getBytes("UTF-8"))
+        digest.update(dep.configuration.value.getBytes("UTF-8"))
+    }
+
+    repositories.foreach { repo =>
+      digest.update(repo.toString.getBytes("UTF-8"))
+    }
+
+    scalaVersion.foreach { sv =>
+      digest.update(sv.getBytes("UTF-8"))
+    }
+
+    digest.update(params.params.maxIterations.toString.getBytes("UTF-8"))
+
+    params.params.forceVersion.toSeq.sortBy(_._1.toString).foreach { case (mod, ver) =>
+      digest.update(mod.toString.getBytes("UTF-8"))
+      digest.update(ver.getBytes("UTF-8"))
+    }
+
+    params.params.exclusions.toSeq.sortBy(e => (e._1.value, e._2.value)).foreach {
+      case (org, name) =>
+        digest.update(s"exclude:${org.value}:${name.value}".getBytes("UTF-8"))
+    }
+
+    params.strictOpt.foreach { strict =>
+      digest.update(s"strict:${strict.toString}".getBytes("UTF-8"))
+    }
+
+    val hashBytes = digest.digest()
+    hashBytes.map("%02x".format(_)).mkString
+  }
+
+  def matches(
+      lockFileData: LockFileData,
+      dependencies: Seq[(Configuration, Dependency)],
+      repositories: Seq[Repository],
+      scalaVersion: Option[String],
+      params: ResolutionParams
+  ): Boolean = {
+    val currentClock = compute(dependencies, repositories, scalaVersion, params)
+    lockFileData.buildClock == currentClock
+  }
+}

lm-coursier/src/main/scala/lmcoursier/internal/LockFile.scala

@@ -0,0 +1,46 @@
+package lmcoursier.internal
+
+import java.io.File
+import java.nio.file.Files
+import java.nio.charset.StandardCharsets
+import sjsonnew.support.scalajson.unsafe.{ CompactPrinter, Converter, Parser }
+import scala.util.{ Try, Success, Failure }
+
+object LockFile {
+  import LockFileFormats.given
+
+  val defaultLockFileName = "deps.lock"
+
+  def read(lockFile: File): Either[String, LockFileData] = {
+    if (!lockFile.exists()) {
+      Left(s"Lock file does not exist: ${lockFile.getAbsolutePath}")
+    } else {
+      Try {
+        val content = new String(Files.readAllBytes(lockFile.toPath), StandardCharsets.UTF_8)
+        val json = Parser.parseFromString(content).get
+        Converter.fromJson[LockFileData](json).get
+      } match {
+        case Success(data) => Right(data)
+        case Failure(ex)   => Left(s"Failed to parse lock file: ${ex.getMessage}")
+      }
+    }
+  }
+
+  def write(lockFile: File, data: LockFileData): Either[String, Unit] = {
+    Try {
+      val json = Converter.toJson(data).get
+      val content = CompactPrinter(json)
+      lockFile.getParentFile.mkdirs()
+      Files.write(lockFile.toPath, content.getBytes(StandardCharsets.UTF_8))
+    } match {
+      case Success(_)  => Right(())
+      case Failure(ex) => Left(s"Failed to write lock file: ${ex.getMessage}")
+    }
+  }
+
+  def getLockFile(baseDirectory: File): File =
+    new File(baseDirectory, defaultLockFileName)
+
+  def exists(baseDirectory: File): Boolean =
+    getLockFile(baseDirectory).exists()
+}

lm-coursier/src/main/scala/lmcoursier/internal/LockFileConstants.scala

@@ -0,0 +1,5 @@
+package lmcoursier.internal
+
+object LockFileConstants {
+  val currentVersion = "1.0"
+}

lm-coursier/src/main/scala/lmcoursier/internal/LockFileFormats.scala

@@ -0,0 +1,158 @@
+package lmcoursier.internal
+
+import sjsonnew.*
+
+trait ArtifactLockFormats { self: sjsonnew.BasicJsonProtocol =>
+  given ArtifactLockFormat: JsonFormat[ArtifactLock] = new JsonFormat[ArtifactLock] {
+    override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): ArtifactLock =
+      jsOpt match {
+        case Some(js) =>
+          unbuilder.beginObject(js)
+          val url = unbuilder.readField[String]("url")
+          val classifier = unbuilder.readField[Option[String]]("classifier")
+          val extension = unbuilder.readField[String]("extension")
+          val tpe = unbuilder.readField[String]("tpe")
+          unbuilder.endObject()
+          ArtifactLock(url, classifier, extension, tpe)
+        case None =>
+          deserializationError("Expected JsObject but found None")
+      }
+
+    override def write[J](obj: ArtifactLock, builder: Builder[J]): Unit = {
+      builder.beginObject()
+      builder.addField("url", obj.url)
+      builder.addField("classifier", obj.classifier)
+      builder.addField("extension", obj.extension)
+      builder.addField("tpe", obj.tpe)
+      builder.endObject()
+    }
+  }
+}
+
+trait DependencyLockFormats { self: sjsonnew.BasicJsonProtocol & ArtifactLockFormats =>
+  given DependencyLockFormat: JsonFormat[DependencyLock] = new JsonFormat[DependencyLock] {
+    override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): DependencyLock =
+      jsOpt match {
+        case Some(js) =>
+          unbuilder.beginObject(js)
+          val organization = unbuilder.readField[String]("organization")
+          val name = unbuilder.readField[String]("name")
+          val version = unbuilder.readField[String]("version")
+          val configuration = unbuilder.readField[String]("configuration")
+          val classifier = unbuilder.readField[Option[String]]("classifier")
+          val tpe = unbuilder.readField[String]("tpe")
+          val transitives = unbuilder.readField[Vector[String]]("transitives")
+          val artifacts = unbuilder.readField[Vector[ArtifactLock]]("artifacts")
+          unbuilder.endObject()
+          DependencyLock(
+            organization,
+            name,
+            version,
+            configuration,
+            classifier,
+            tpe,
+            transitives,
+            artifacts
+          )
+        case None =>
+          deserializationError("Expected JsObject but found None")
+      }
+
+    override def write[J](obj: DependencyLock, builder: Builder[J]): Unit = {
+      builder.beginObject()
+      builder.addField("organization", obj.organization)
+      builder.addField("name", obj.name)
+      builder.addField("version", obj.version)
+      builder.addField("configuration", obj.configuration)
+      builder.addField("classifier", obj.classifier)
+      builder.addField("tpe", obj.tpe)
+      builder.addField("transitives", obj.transitives)
+      builder.addField("artifacts", obj.artifacts)
+      builder.endObject()
+    }
+  }
+}
+
+trait ConfigurationLockFormats {
+  self: sjsonnew.BasicJsonProtocol & ArtifactLockFormats & DependencyLockFormats =>
+  given ConfigurationLockFormat: JsonFormat[ConfigurationLock] = new JsonFormat[ConfigurationLock] {
+    override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): ConfigurationLock =
+      jsOpt match {
+        case Some(js) =>
+          unbuilder.beginObject(js)
+          val name = unbuilder.readField[String]("name")
+          val dependencies = unbuilder.readField[Vector[DependencyLock]]("dependencies")
+          unbuilder.endObject()
+          ConfigurationLock(name, dependencies)
+        case None =>
+          deserializationError("Expected JsObject but found None")
+      }
+
+    override def write[J](obj: ConfigurationLock, builder: Builder[J]): Unit = {
+      builder.beginObject()
+      builder.addField("name", obj.name)
+      builder.addField("dependencies", obj.dependencies)
+      builder.endObject()
+    }
+  }
+}
+
+trait LockFileMetadataFormats { self: sjsonnew.BasicJsonProtocol =>
+  given LockFileMetadataFormat: JsonFormat[LockFileMetadata] = new JsonFormat[LockFileMetadata] {
+    override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): LockFileMetadata =
+      jsOpt match {
+        case Some(js) =>
+          unbuilder.beginObject(js)
+          val sbtVersion = unbuilder.readField[String]("sbtVersion")
+          val scalaVersion = unbuilder.readField[Option[String]]("scalaVersion")
+          unbuilder.endObject()
+          LockFileMetadata(sbtVersion, scalaVersion)
+        case None =>
+          deserializationError("Expected JsObject but found None")
+      }
+
+    override def write[J](obj: LockFileMetadata, builder: Builder[J]): Unit = {
+      builder.beginObject()
+      builder.addField("sbtVersion", obj.sbtVersion)
+      builder.addField("scalaVersion", obj.scalaVersion)
+      builder.endObject()
+    }
+  }
+}
+
+trait LockFileDataFormats {
+  self: sjsonnew.BasicJsonProtocol & ArtifactLockFormats & DependencyLockFormats &
+    ConfigurationLockFormats & LockFileMetadataFormats =>
+  given LockFileDataFormat: JsonFormat[LockFileData] = new JsonFormat[LockFileData] {
+    override def read[J](jsOpt: Option[J], unbuilder: Unbuilder[J]): LockFileData =
+      jsOpt match {
+        case Some(js) =>
+          unbuilder.beginObject(js)
+          val version = unbuilder.readField[String]("version")
+          val buildClock = unbuilder.readField[String]("buildClock")
+          val configurations = unbuilder.readField[Vector[ConfigurationLock]]("configurations")
+          val metadata = unbuilder.readField[LockFileMetadata]("metadata")
+          unbuilder.endObject()
+          LockFileData(version, buildClock, configurations, metadata)
+        case None =>
+          deserializationError("Expected JsObject but found None")
+      }
+
+    override def write[J](obj: LockFileData, builder: Builder[J]): Unit = {
+      builder.beginObject()
+      builder.addField("version", obj.version)
+      builder.addField("buildClock", obj.buildClock)
+      builder.addField("configurations", obj.configurations)
+      builder.addField("metadata", obj.metadata)
+      builder.endObject()
+    }
+  }
+}
+
+object LockFileFormats
+    extends sjsonnew.BasicJsonProtocol
+    with ArtifactLockFormats
+    with DependencyLockFormats
+    with ConfigurationLockFormats
+    with LockFileMetadataFormats
+    with LockFileDataFormats

lm-coursier/src/main/scala/lmcoursier/internal/LockedArtifactsRun.scala

@@ -0,0 +1,95 @@
+package lmcoursier.internal
+
+import coursier.cache.FileCache
+import coursier.core.{ Classifier, Dependency, Extension, Publication, Type }
+import coursier.util.Artifact
+import sbt.util.Logger
+
+import java.io.File
+import scala.concurrent.{ Await, ExecutionContext }
+import scala.concurrent.duration.Duration
+
+object LockedArtifactsRun {
+
+  def fetchFromLockFile(
+      lockFileData: LockFileData,
+      cache: FileCache[coursier.util.Task],
+      verbosityLevel: Int,
+      log: Logger
+  ): Either[String, Seq[(Dependency, Publication, Artifact, Option[File])]] = {
+    implicit val ec: ExecutionContext = cache.ec
+
+    if (verbosityLevel >= 1) {
+      log.info("Fetching artifacts from lock file")
+    }
+
+    val artifactsToFetch = for {
+      configLock <- lockFileData.configurations
+      depLock <- configLock.dependencies
+      artLock <- depLock.artifacts
+    } yield {
+      val module = coursier.Module(
+        coursier.Organization(depLock.organization),
+        coursier.ModuleName(depLock.name),
+        Map.empty[String, String]
+      )
+
+      val dependency = Dependency(
+        module = module,
+        version = depLock.version
+      )
+
+      val classifier = Classifier(artLock.classifier.getOrElse(""))
+      val extension = Extension(artLock.extension)
+      val tpe = Type(artLock.tpe)
+
+      val publication = Publication(
+        name = depLock.name,
+        `type` = tpe,
+        ext = extension,
+        classifier = classifier
+      )
+
+      val artifact = Artifact(
+        url = artLock.url,
+        checksumUrls = Map.empty,
+        extra = Map.empty,
+        changing = false,
+        optional = false,
+        authentication = None
+      )
+
+      (dependency, publication, artifact)
+    }
+
+    val fetchTasks = artifactsToFetch.map { case (dep, pub, art) =>
+      cache.file(art).run.map { result =>
+        result match {
+          case Left(err) =>
+            if (verbosityLevel >= 2) {
+              log.debug(s"Failed to fetch ${art.url}: ${err.describe}")
+            }
+            (dep, pub, art, None: Option[File])
+          case Right(file) =>
+            (dep, pub, art, Some(file))
+        }
+      }
+    }
+
+    try {
+      val results = fetchTasks.map { task =>
+        Await.result(task.future(), Duration.Inf)
+      }
+
+      val failures = results.filter(_._4.isEmpty)
+      if (failures.nonEmpty && verbosityLevel >= 1) {
+        log.warn(s"Failed to fetch ${failures.size} artifacts from lock file")
+      }
+
+      Right(results)
+    } catch {
+      case ex: Exception =>
+        Left(s"Failed to fetch artifacts: ${ex.getMessage}")
+    }
+  }
+}

lm-coursier/src/main/scala/lmcoursier/internal/ResolutionRun.scala

@@ -217,5 +217,62 @@ object ResolutionRun {
     }
   }
 
+  def resolutionsWithLockFile(
+      params: ResolutionParams,
+      verbosityLevel: Int,
+      log: Logger,
+      lockFileOpt: Option[java.io.File],
+      scalaVersion: Option[String]
+  ): Either[coursier.error.ResolutionError, (Map[Configuration, Resolution], Boolean)] = {
+    resolutionsWithLockFileData(params, verbosityLevel, log, lockFileOpt, scalaVersion)
+      .map { case (res, lockDataOpt) => (res, lockDataOpt.isDefined) }
+  }
+
+  def resolutionsWithLockFileData(
+      params: ResolutionParams,
+      verbosityLevel: Int,
+      log: Logger,
+      lockFileOpt: Option[java.io.File],
+      scalaVersion: Option[String]
+  ): Either[
+    coursier.error.ResolutionError,
+    (Map[Configuration, Resolution], Option[LockFileData])
+  ] = {
+    lockFileOpt
+      .flatMap { lockFile =>
+        LockFile.read(lockFile) match {
+          case Right(lockData) =>
+            if (
+              BuildClock.matches(
+                lockData,
+                params.dependencies,
+                params.mainRepositories,
+                scalaVersion,
+                params
+              )
+            ) {
+              if (verbosityLevel >= 1) {
+                log.info(s"Using lock file: ${lockFile.getAbsolutePath}")
+              }
+              val reconstructed = ResolutionSerializer.reconstructResolutions(lockData, params)
+              Some(Right((reconstructed, Some(lockData))))
+            } else {
+              if (verbosityLevel >= 1) {
+                log.info(s"Lock file outdated, performing resolution")
+              }
+              None
+            }
+          case Left(err) =>
+            if (verbosityLevel >= 2) {
+              log.debug(s"Lock file error: $err")
+            }
+            None
+        }
+      }
+      .getOrElse {
+        resolutions(params, verbosityLevel, log).map(res => (res, None))
+      }
+  }
+
   private lazy val retryScheduler = ThreadUtil.fixedScheduledThreadPool(1)
 }

lm-coursier/src/main/scala/lmcoursier/internal/ResolutionSerializer.scala

@@ -0,0 +1,179 @@
+package lmcoursier.internal
+
+import coursier.{ Project, Resolution }
+import coursier.core.{ ArtifactSource, Configuration, Dependency, Info, Module }
+import scala.collection.immutable.Seq
+
+object ResolutionSerializer {
+
+  def extractLockFileData(
+      resolutions: Map[Configuration, Resolution],
+      params: ResolutionParams,
+      scalaVersion: Option[String],
+      sbtVersion: String,
+      artifactMap: Map[Dependency, Seq[(String, String, String)]]
+  ): LockFileData = {
+    val buildClock = BuildClock.compute(
+      params.dependencies,
+      params.mainRepositories,
+      scalaVersion,
+      params
+    )
+
+    val configurations = resolutions.toSeq
+      .sortBy(_._1.value)
+      .map { case (config, resolution) =>
+        val dependencies = extractDependencies(resolution, config, artifactMap)
+        ConfigurationLock(config.value, dependencies.toVector)
+      }
+      .toVector
+
+    val metadata = LockFileMetadata(
+      sbtVersion = sbtVersion,
+      scalaVersion = scalaVersion
+    )
+
+    LockFileData(
+      version = LockFileConstants.currentVersion,
+      buildClock = buildClock,
+      configurations = configurations,
+      metadata = metadata
+    )
+  }
+
+  private def extractDependencies(
+      resolution: Resolution,
+      config: Configuration,
+      artifactMap: Map[Dependency, Seq[(String, String, String)]]
+  ): Seq[DependencyLock] = {
+    val dependencies = resolution.minDependencies
+
+    dependencies.toSeq.sortBy(d => (d.module.toString, d.version)).map { dep =>
+      val resolvedVersion: String = resolution.retainedVersions
+        .get(dep.module) match {
+        case Some(v) => s"$v"
+        case None    => s"${dep.version}"
+      }
+
+      val transitives = resolution
+        .dependenciesOf(dep, withRetainedVersions = true)
+        .map(d => s"${d.module.organization.value}:${d.module.name.value}:${d.version}")
+        .sorted
+
+      val artifacts = artifactMap.getOrElse(dep, Seq.empty).map { case (url, classifier, ext) =>
+        ArtifactLock(
+          url = url,
+          classifier = if (classifier.isEmpty) None else Some(classifier),
+          extension = ext,
+          tpe = dep.attributes.`type`.value
+        )
+      }
+
+      DependencyLock(
+        organization = dep.module.organization.value,
+        name = dep.module.name.value,
+        version = resolvedVersion,
+        configuration = dep.configuration.value,
+        classifier = dep.attributes.classifier.value match {
+          case "" => None
+          case c  => Some(c)
+        },
+        tpe = dep.attributes.`type`.value,
+        transitives = transitives.toVector,
+        artifacts = artifacts.toVector
+      )
+    }
+  }
+
+  def reconstructResolutions(
+      lockFileData: LockFileData,
+      params: ResolutionParams
+  ): Map[Configuration, Resolution] = {
+    lockFileData.configurations.map { configLock =>
+      val config = Configuration(configLock.name)
+      val resolution = reconstructResolution(configLock, params)
+      config -> resolution
+    }.toMap
+  }
+
+  private def reconstructResolution(
+      configLock: ConfigurationLock,
+      params: ResolutionParams
+  ): Resolution = {
+    val forceVersions: Map[Module, String] = configLock.dependencies.map { depLock =>
+      val module = Module(
+        coursier.Organization(depLock.organization),
+        coursier.ModuleName(depLock.name),
+        Map.empty[String, String]
+      )
+      module -> depLock.version
+    }.toMap
+
+    val rootDeps = params.dependencies
+      .filter(_._1.value == configLock.name)
+      .map(_._2)
+
+    val dependencies: Set[Dependency] = configLock.dependencies.map { depLock =>
+      Dependency(
+        Module(
+          coursier.Organization(depLock.organization),
+          coursier.ModuleName(depLock.name),
+          Map.empty[String, String]
+        ),
+        depLock.version
+      )
+    }.toSet
+
+    val projectCache: Map[(Module, String), (ArtifactSource, Project)] =
+      configLock.dependencies.map { depLock =>
+        val module = Module(
+          coursier.Organization(depLock.organization),
+          coursier.ModuleName(depLock.name),
+          Map.empty[String, String]
+        )
+        val project = Project(
+          module = module,
+          version = depLock.version,
+          dependencies = Seq.empty,
+          configurations = Map.empty,
+          parent = None,
+          dependencyManagement = Seq.empty,
+          properties = Seq.empty,
+          profiles = Seq.empty,
+          versions = None,
+          snapshotVersioning = None,
+          packagingOpt = None,
+          relocated = false,
+          actualVersionOpt = None,
+          publications = Seq.empty,
+          info = Info.empty
+        )
+        (module, depLock.version) -> (EmptyArtifactSource, project)
+      }.toMap
+
+    Resolution()
+      .withRootDependencies(rootDeps)
+      .withDependencies(dependencies)
+      .withForceVersions(forceVersions ++ params.params.forceVersion)
+      .withProjectCache(projectCache)
+  }
+
+  private object EmptyArtifactSource extends ArtifactSource {
+    def artifacts(
+        dependency: Dependency,
+        project: Project,
+        overrideClassifiers: Option[scala.collection.immutable.Seq[coursier.core.Classifier]]
+    ): scala.collection.immutable.Seq[(coursier.core.Publication, coursier.util.Artifact)] =
+      scala.collection.immutable.Seq.empty
+  }
+
+  def getLockedArtifacts(
+      lockFileData: LockFileData
+  ): Map[(String, String, String), Seq[ArtifactLock]] = {
+    lockFileData.configurations.flatMap { configLock =>
+      configLock.dependencies.map { depLock =>
+        (depLock.organization, depLock.name, depLock.version) -> depLock.artifacts
+      }
+    }.toMap
+  }
+}

lm-coursier/src/main/scala/lmcoursier/syntax/package.scala

@@ -78,6 +78,7 @@ package object syntax {
         retry = None,
         sameVersions = Nil,
         localArtifactsShouldBeCached = false,
+        lockFile = None,
       )
   }
 

lm-coursier/src/test/scala/lmcoursier/LockFileSpec.scala

@@ -0,0 +1,134 @@
+package lmcoursier
+
+import lmcoursier.internal.*
+import org.scalatest.funsuite.AnyFunSuite
+import java.io.File
+import sbt.io.IO
+
+class LockFileSpec extends AnyFunSuite {
+
+  test("LockFileData serialization round-trip") {
+    val lockData = LockFileData(
+      version = "1.0",
+      buildClock = "abc123",
+      configurations = Vector(
+        ConfigurationLock(
+          name = "compile",
+          dependencies = Vector(
+            DependencyLock(
+              organization = "org.scala-lang",
+              name = "scala-library",
+              version = "2.13.16",
+              configuration = "compile",
+              classifier = None,
+              tpe = "jar",
+              transitives = Vector("org.scala-lang:scala-library:2.13.16"),
+              artifacts = Vector(
+                ArtifactLock(
+                  url =
+                    "https://repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.16/scala-library-2.13.16.jar",
+                  classifier = None,
+                  extension = "jar",
+                  tpe = "jar"
+                )
+              )
+            )
+          )
+        )
+      ),
+      metadata = LockFileMetadata(
+        sbtVersion = "2.0.0",
+        scalaVersion = Some("3.7.4")
+      )
+    )
+
+    IO.withTemporaryDirectory { dir =>
+      val lockFile = new File(dir, "test.lock")
+      val writeResult = LockFile.write(lockFile, lockData)
+      assert(writeResult.isRight, s"Write failed: ${writeResult.left.getOrElse("")}")
+
+      val readResult = LockFile.read(lockFile)
+      assert(readResult.isRight, s"Read failed: ${readResult.left.getOrElse("")}")
+
+      val readData = readResult.toOption.get
+      assert(readData.version == lockData.version)
+      assert(readData.buildClock == lockData.buildClock)
+      assert(readData.configurations.size == 1)
+      assert(readData.configurations.head.name == "compile")
+      assert(readData.configurations.head.dependencies.size == 1)
+      assert(readData.configurations.head.dependencies.head.organization == "org.scala-lang")
+      assert(readData.configurations.head.dependencies.head.version == "2.13.16")
+      assert(readData.metadata.sbtVersion == "2.0.0")
+      assert(readData.metadata.scalaVersion == Some("3.7.4"))
+    }
+  }
+
+  test("LockFile.read returns Left for non-existent file") {
+    val result = LockFile.read(new File("/nonexistent/path/lock.json"))
+    assert(result.isLeft)
+  }
+
+  test("LockFile.read returns Left for invalid JSON") {
+    IO.withTemporaryDirectory { dir =>
+      val lockFile = new File(dir, "invalid.lock")
+      IO.write(lockFile, "not valid json")
+      val result = LockFile.read(lockFile)
+      assert(result.isLeft)
+    }
+  }
+
+  test("DependencyLock with classifier") {
+    val dep = DependencyLock(
+      organization = "org.example",
+      name = "lib",
+      version = "1.0.0",
+      configuration = "compile",
+      classifier = Some("sources"),
+      tpe = "jar",
+      transitives = Vector.empty,
+      artifacts = Vector.empty
+    )
+
+    val lockData = LockFileData(
+      version = "1.0",
+      buildClock = "test",
+      configurations = Vector(ConfigurationLock("compile", Vector(dep))),
+      metadata = LockFileMetadata("2.0.0", None)
+    )
+
+    IO.withTemporaryDirectory { dir =>
+      val lockFile = new File(dir, "test.lock")
+      LockFile.write(lockFile, lockData)
+      val readData = LockFile.read(lockFile).toOption.get
+      assert(readData.configurations.head.dependencies.head.classifier == Some("sources"))
+    }
+  }
+
+  test("cacheFileToOriginalUrl converts cache file URL to HTTP URL") {
+    IO.withTemporaryDirectory { cacheDir =>
+      val fileUrl =
+        s"file:${cacheDir.getAbsolutePath}/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.12/scala-library-2.13.12.jar"
+      val result = CoursierDependencyResolution.cacheFileToOriginalUrl(fileUrl, cacheDir)
+      assert(
+        result == "https://repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.12/scala-library-2.13.12.jar"
+      )
+    }
+  }
+
+  test("cacheFileToOriginalUrl handles non-matching paths with CSR_CACHE placeholder") {
+    IO.withTemporaryDirectory { cacheDir =>
+      val fileUrl = "file:/some/other/path/artifact.jar"
+      val result = CoursierDependencyResolution.cacheFileToOriginalUrl(fileUrl, cacheDir)
+      assert(result == "${CSR_CACHE}/some/other/path/artifact.jar")
+    }
+  }
+
+  test("cacheFileToOriginalUrl preserves non-file URLs") {
+    IO.withTemporaryDirectory { cacheDir =>
+      val httpUrl =
+        "https://repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.12/scala-library-2.13.12.jar"
+      val result = CoursierDependencyResolution.cacheFileToOriginalUrl(httpUrl, cacheDir)
+      assert(result == httpUrl)
+    }
+  }
+}

main/src/main/scala/sbt/Defaults.scala

@@ -3351,6 +3351,9 @@ object Classpaths {
       ew.infoAllTheThings foreach { log.info(_) }
       ew
     },
+    dependencyLockFile := baseDirectory.value / DependencyLockFile.lockFileName,
+    dependencyLock := Def.uncached(dependencyLockTask.value),
+    dependencyLockCheck := Def.uncached(dependencyLockCheckTask.value),
   ) ++
     inTask(updateClassifiers)(
       Seq(
@@ -3777,6 +3780,45 @@ object Classpaths {
   def updateWithoutDetails(label: String): Initialize[Task[UpdateReport]] =
     updateTask0(label, false, false).tag(Tags.Update, Tags.Network)
 
+  lazy val dependencyLockTask: Initialize[Task[File]] = Def.task {
+    val log = streams.value.log
+    val lockFile = dependencyLockFile.value
+    val report = update.value
+    val projectId = thisProject.value.id
+    val sv = sbtVersion.value
+    val scalaV = scalaVersion.?.value
+    val deps = libraryDependencies.value
+    val resolverNames = fullResolvers.value.map(_.name)
+    val buildClock = DependencyLockFile.computeBuildClock(deps, resolverNames)
+
+    val lock = DependencyLockManager.createFromUpdateReport(
+      projectId,
+      report,
+      sv,
+      scalaV,
+      buildClock,
+      log
+    )
+
+    DependencyLockManager.write(lockFile, lock, log)
+    lockFile
+  }
+
+  lazy val dependencyLockCheckTask: Initialize[Task[Unit]] = Def.task {
+    val log = streams.value.log
+    val lockFile = dependencyLockFile.value
+    if lockFile.exists() then
+      val deps = libraryDependencies.value
+      val resolverNames = fullResolvers.value.map(_.name)
+      val currentBuildClock = DependencyLockFile.computeBuildClock(deps, resolverNames)
+      DependencyLockManager.validate(lockFile, currentBuildClock, log) match
+        case Some(_) => ()
+        case None =>
+          throw new MessageOnlyException(
+            s"Dependency lock file is stale: ${lockFile.getAbsolutePath}. Run 'dependencyLock' to update it."
+          )
+  }
+
   /**
    * cacheLabel - label to identify an update cache
    * includeCallers - include the caller information

main/src/main/scala/sbt/Keys.scala

@@ -534,6 +534,9 @@ object Keys {
   val updateClassifiers = TaskKey[UpdateReport]("updateClassifiers", "Resolves and optionally retrieves classified artifacts, such as javadocs and sources, for dependency definitions, transitively.", BPlusTask, update)
   val transitiveClassifiers = settingKey[Seq[String]]("List of classifiers used for transitively obtaining extra artifacts for sbt or declared dependencies.").withRank(BSetting)
   val updateSbtClassifiers = TaskKey[UpdateReport]("updateSbtClassifiers", "Resolves and optionally retrieves classifiers, such as javadocs and sources, for sbt, transitively.", BPlusTask, updateClassifiers)
+  val dependencyLock = taskKey[File]("Generates a dependency lock file from the current resolution.").withRank(BTask)
+  val dependencyLockCheck = taskKey[Unit]("Checks if the dependency lock file is up-to-date.").withRank(BTask)
+  val dependencyLockFile = settingKey[File]("The location of the dependency lock file.").withRank(CSetting)
   val sourceArtifactTypes = settingKey[Seq[String]]("Ivy artifact types that correspond to source artifacts. Used by IDEs to resolve these resources.").withRank(BSetting)
   val docArtifactTypes = settingKey[Seq[String]]("Ivy artifact types that correspond to javadoc artifacts. Used by IDEs to resolve these resources.").withRank(BSetting)
 

main/src/main/scala/sbt/coursierint/LMCoursier.scala

@@ -93,6 +93,7 @@ object LMCoursier {
       sameVersions: Seq[Set[InclExclRule]],
       enableDependencyOverrides: Option[Boolean],
       localArtifactsShouldBeCached: Boolean,
+      lockFile: Option[File],
       log: Logger
   ): CoursierConfiguration = {
     val coursierExcludeDeps = Inputs
@@ -145,10 +146,13 @@ object LMCoursier {
       .withMissingOk(missingOk)
       .withSameVersions(sameVersions)
       .withLocalArtifactsShouldBeCached(localArtifactsShouldBeCached)
+      .withLockFile(lockFile)
   }
 
   def coursierConfigurationTask: Def.Initialize[Task[CoursierConfiguration]] = Def.task {
     val sv = scalaVersion.value
+    val lockFile = dependencyLockFile.value
+    val lockFileOpt = if (lockFile.exists()) Some(lockFile) else None
     coursierConfiguration(
       csrRecursiveResolvers.value,
       csrInterProjectDependencies.value.toVector,
@@ -173,6 +177,7 @@ object LMCoursier {
       csrSameVersions.value,
       Some(csrMavenDependencyOverride.value),
       csrLocalArtifactsShouldBeCached.value,
+      lockFileOpt,
       streams.value.log
     )
   }
@@ -210,6 +215,7 @@ object LMCoursier {
       csrSameVersions.value,
       Some(csrMavenDependencyOverride.value),
       csrLocalArtifactsShouldBeCached.value,
+      None,
       streams.value.log
     )
   }
@@ -240,6 +246,7 @@ object LMCoursier {
       csrSameVersions.value,
       Some(csrMavenDependencyOverride.value),
       csrLocalArtifactsShouldBeCached.value,
+      None,
       streams.value.log
     )
   }

main/src/main/scala/sbt/internal/librarymanagement/DependencyLock.scala

@@ -0,0 +1,32 @@
+/*
+ * sbt
+ * Copyright 2023, Scala center
+ * Copyright 2011 - 2022, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
+ */
+
+package sbt.internal.librarymanagement
+
+import java.io.File
+import java.security.MessageDigest
+import sbt.librarymanagement.ModuleID
+
+object DependencyLockFile:
+  val CurrentLockVersion = "1.0"
+  val lockFileName = "deps.lock"
+
+  def computeBuildClock(
+      libraryDependencies: Seq[ModuleID],
+      resolvers: Seq[String]
+  ): String =
+    val digest = MessageDigest.getInstance("SHA-256")
+    val sortedDeps = libraryDependencies
+      .map(m => s"${m.organization}:${m.name}:${m.revision}")
+      .sorted
+    sortedDeps.foreach(d => digest.update(d.getBytes("UTF-8")))
+    resolvers.sorted.foreach(r => digest.update(r.getBytes("UTF-8")))
+    digest.digest().map("%02x".format(_)).mkString
+
+  def lockFilePath(baseDirectory: File): File =
+    new File(baseDirectory, lockFileName)

main/src/main/scala/sbt/internal/librarymanagement/DependencyLockManager.scala

@@ -0,0 +1,103 @@
+/*
+ * sbt
+ * Copyright 2023, Scala center
+ * Copyright 2011 - 2022, Lightbend, Inc.
+ * Copyright 2008 - 2010, Mark Harrah
+ * Licensed under Apache License 2.0 (see LICENSE)
+ */
+
+package sbt.internal.librarymanagement
+
+import java.io.File
+import lmcoursier.internal.*
+import sbt.librarymanagement.*
+import sbt.util.Logger
+
+object DependencyLockManager:
+
+  def read(lockFile: File, log: Logger): Option[LockFileData] =
+    LockFile.read(lockFile) match
+      case Right(data) => Some(data)
+      case Left(err) =>
+        if lockFile.exists() then log.warn(s"Failed to read lock file: $err")
+        None
+
+  def write(lockFile: File, lock: LockFileData, log: Logger): Unit =
+    LockFile.write(lockFile, lock) match
+      case Right(_) =>
+        log.info(s"Wrote dependency lock file to ${lockFile.getAbsolutePath}")
+      case Left(err) =>
+        log.error(s"Failed to write lock file: $err")
+        throw new RuntimeException(err)
+
+  def validate(
+      lockFile: File,
+      currentBuildClock: String,
+      log: Logger
+  ): Option[LockFileData] =
+    read(lockFile, log).filter { lock =>
+      val isValid = lock.buildClock == currentBuildClock
+      if !isValid then
+        log.debug(
+          s"Lock file is stale (buildClock mismatch: ${lock.buildClock} != $currentBuildClock)"
+        )
+      isValid
+    }
+
+  def createFromUpdateReport(
+      projectId: String,
+      report: UpdateReport,
+      sbtVersion: String,
+      scalaVersion: Option[String],
+      buildClock: String,
+      log: Logger
+  ): LockFileData =
+    val configurations = report.configurations.map { configReport =>
+      val deps = configReport.modules.map { moduleReport =>
+        val artifacts = moduleReport.artifacts.map { case (artifact, file) =>
+          ArtifactLock(
+            url = file.toURI.toString,
+            classifier = artifact.classifier,
+            extension = artifact.extension,
+            tpe = artifact.`type`
+          )
+        }.toVector
+
+        DependencyLock(
+          organization = moduleReport.module.organization,
+          name = moduleReport.module.name,
+          version = moduleReport.module.revision,
+          configuration = configReport.configuration.name,
+          classifier = None,
+          tpe = "jar",
+          transitives = Vector.empty,
+          artifacts = artifacts
+        )
+      }.toVector
+
+      ConfigurationLock(
+        name = configReport.configuration.name,
+        dependencies = deps
+      )
+    }.toVector
+
+    val metadata = LockFileMetadata(
+      sbtVersion = sbtVersion,
+      scalaVersion = scalaVersion
+    )
+
+    LockFileData(
+      version = LockFileConstants.currentVersion,
+      buildClock = buildClock,
+      configurations = configurations,
+      metadata = metadata
+    )
+
+  def getLockedVersions(
+      lock: LockFileData
+  ): Map[(String, String), String] =
+    lock.configurations.flatMap { config =>
+      config.dependencies.map { dep =>
+        (dep.organization, dep.name) -> dep.version
+      }
+    }.toMap

sbt-app/src/sbt-test/dependency-management/dependency-lock/build.sbt

@@ -0,0 +1,8 @@
+ThisBuild / scalaVersion := "2.13.12"
+ThisBuild / csrCacheDirectory := (ThisBuild / baseDirectory).value / "coursier-cache"
+
+lazy val root = (project in file("."))
+  .settings(
+    name := "dependency-lock-test",
+    libraryDependencies += "org.typelevel" %% "cats-core" % "2.10.0"
+  )

sbt-app/src/sbt-test/dependency-management/dependency-lock/changes/build-modified.sbt

@@ -0,0 +1,9 @@
+ThisBuild / scalaVersion := "2.13.12"
+ThisBuild / csrCacheDirectory := (ThisBuild / baseDirectory).value / "coursier-cache"
+
+lazy val root = (project in file("."))
+  .settings(
+    name := "dependency-lock-test",
+    libraryDependencies += "org.typelevel" %% "cats-core" % "2.10.0",
+    libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.17" % Test
+  )

sbt-app/src/sbt-test/dependency-management/dependency-lock/test

@@ -0,0 +1,27 @@
+# Test dependency lock file generation
+> update
+> dependencyLock
+
+# Verify lock file was created
+$ exists deps.lock
+
+# Check that lock file is valid (passes silently)
+> dependencyLockCheck
+
+# Modify dependencies and verify lock becomes stale
+$ copy-file build.sbt build.sbt.backup
+$ copy-file changes/build-modified.sbt build.sbt
+> reload
+
+# Lock check should fail because lock is stale
+-> dependencyLockCheck
+
+# Regenerate the lock file
+> dependencyLock
+
+# Now lock check should pass again
+> dependencyLockCheck
+
+# Restore original build
+$ copy-file build.sbt.backup build.sbt
+> reload

sbt-app/src/sbt-test/dependency-management/resolution-skip/build.sbt

@@ -0,0 +1,9 @@
+ThisBuild / scalaVersion := "2.13.12"
+ThisBuild / csrCacheDirectory := (ThisBuild / baseDirectory).value / "coursier-cache"
+
+lazy val root = (project in file("."))
+  .settings(
+    name := "resolution-skip-test",
+    libraryDependencies += "org.typelevel" %% "cats-core" % "2.10.0",
+    dependencyLockFile := baseDirectory.value / "deps.lock"
+  )

sbt-app/src/sbt-test/dependency-management/resolution-skip/test

@@ -0,0 +1,19 @@
+# Test resolution skipping with lock file
+> update
+
+# Generate lock file
+> dependencyLock
+
+# Verify lock file was created
+$ exists deps.lock
+
+# Second update should use the lock file
+> update
+
+# Compile should work with locked dependencies
+> compile
+
+# Clean and update again - should still use lock file
+> clean
+> update
+> compile