diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index 22391281..86e8dd3e 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -160,6 +160,7 @@ jobs:
           - '8.2'
           - '8.3'
           - '8.4'
+          - '8.5'
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 #v6.0.3
         with:
diff --git a/features/install-extensions.feature b/features/install-extensions.feature
index a2b6ebe6..a4a8648e 100644
--- a/features/install-extensions.feature
+++ b/features/install-extensions.feature
@@ -14,3 +14,9 @@ Feature: Extensions can be installed with PIE
   Example: Multiple extensions can be installed at once
     When I run a command to install multiple extensions
     Then the extensions should have been installed and enabled
+
+  # pie install --from-lock
+  Example: I can install exact versions contained in the lockfile
+    Given I have a lock file
+    When I run a command to install from the lockfile
+    Then the extensions should have been updated to the lock
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 6582e98a..7c987dfe 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -9,6 +9,7 @@
          beStrictAboutOutputDuringTests="true"
          displayDetailsOnSkippedTests="true"
          displayDetailsOnTestsThatTriggerWarnings="true"
+         displayDetailsOnPhpunitDeprecations="true"
          failOnRisky="true"
          failOnWarning="true">
     <php>
diff --git a/src/Command/CommandHelper.php b/src/Command/CommandHelper.php
index c16849dc..6bf0f0f5 100644
--- a/src/Command/CommandHelper.php
+++ b/src/Command/CommandHelper.php
@@ -395,7 +395,7 @@ static function (RequestedPackageAndVersion $requestedNameAndVersion) use ($depe
     }
 
     /**
-     * @param non-empty-list<Package> $packages
+     * @param list<Package> $packages
      *
      * @throws ConfigureOptionCollision if two of the requested packages declare a configure option with the same name.
      */
@@ -429,7 +429,7 @@ public static function bindConfigureOptionsFromPackage(Command $command, array $
     }
 
     /**
-     * @param non-empty-list<Package> $packages
+     * @param list<Package> $packages
      *
      * @return array<string, list<non-empty-string>> Keyed by package name
      */
diff --git a/src/Command/InstallCommand.php b/src/Command/InstallCommand.php
index 618d0114..d23ec4d3 100644
--- a/src/Command/InstallCommand.php
+++ b/src/Command/InstallCommand.php
@@ -5,6 +5,7 @@
 namespace Php\Pie\Command;
 
 use Composer\IO\IOInterface;
+use InvalidArgumentException;
 use Php\Pie\ComposerIntegration\ComposerIntegrationHandler;
 use Php\Pie\ComposerIntegration\ComposerRunFailed;
 use Php\Pie\ComposerIntegration\PieComposerFactory;
@@ -24,6 +25,7 @@
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Throwable;
 
@@ -33,6 +35,8 @@
 )]
 final class InstallCommand extends Command
 {
+    public const OPTION_FROM_LOCK = 'from-lock';
+
     public function __construct(
         private readonly ContainerInterface $container,
         private readonly DependencyResolver $dependencyResolver,
@@ -51,11 +55,31 @@ public function configure(): void
         parent::configure();
 
         CommandHelper::configureDownloadBuildInstallOptions($this);
+
+        $this->addOption(
+            self::OPTION_FROM_LOCK,
+            null,
+            InputOption::VALUE_NONE,
+            'Install the exact versions specified in the pie.lock file for the target PHP.',
+        );
+    }
+
+    public static function shouldInstallFromLock(InputInterface $input): bool
+    {
+        return $input->hasOption(self::OPTION_FROM_LOCK) && (bool) $input->getOption(self::OPTION_FROM_LOCK);
     }
 
     public function execute(InputInterface $input, OutputInterface $output): int
     {
-        if (! $input->getArgument(CommandHelper::ARG_REQUESTED_PACKAGE_AND_VERSION)) {
+        $installFromLock = self::shouldInstallFromLock($input);
+
+        if ($installFromLock && $input->getArgument(CommandHelper::ARG_REQUESTED_PACKAGE_AND_VERSION)) {
+            $this->io->writeError('<error>The --from-lock option installs all extensions from the lock file and cannot be combined with a specific package argument.</error>');
+
+            return self::INVALID;
+        }
+
+        if (! $installFromLock && ! $input->getArgument(CommandHelper::ARG_REQUESTED_PACKAGE_AND_VERSION)) {
             return ($this->invokeSubCommand)(
                 $this,
                 ['command' => 'install-extensions-for-project'],
@@ -78,6 +102,12 @@ public function execute(InputInterface $input, OutputInterface $output): int
                 $targetPlatform,
                 $this->container,
             );
+        } catch (InvalidArgumentException $noPackagesRequested) {
+            if (! $installFromLock) {
+                throw $noPackagesRequested;
+            }
+
+            $requestedNamesAndVersions = [];
         }
 
         $forceInstallPackageVersion = CommandHelper::determineForceInstallingPackageVersion($input);
@@ -122,15 +152,18 @@ public function execute(InputInterface $input, OutputInterface $output): int
             }
         }
 
+        $resolvedPackages = [];
         try {
-            $resolvedPackages = CommandHelper::resolveRequestedPackages(
-                $this->dependencyResolver,
-                $this->io,
-                $composer,
-                $targetPlatform,
-                $requestedNamesAndVersions,
-                $forceInstallPackageVersion,
-            );
+            if ($requestedNamesAndVersions !== []) {
+                $resolvedPackages = CommandHelper::resolveRequestedPackages(
+                    $this->dependencyResolver,
+                    $this->io,
+                    $composer,
+                    $targetPlatform,
+                    $requestedNamesAndVersions,
+                    $forceInstallPackageVersion,
+                );
+            }
         } catch (UnableToResolveRequirement $unableToResolveRequirement) {
             return CommandHelper::handlePackageNotFound(
                 $unableToResolveRequirement,
@@ -161,6 +194,7 @@ public function execute(InputInterface $input, OutputInterface $output): int
                 PieOperation::Install,
                 $configureOptionsValues,
                 CommandHelper::determineAttemptToSetupIniFile($input),
+                installAllPackages: $installFromLock,
             ),
         );
 
@@ -171,6 +205,7 @@ public function execute(InputInterface $input, OutputInterface $output): int
                 $targetPlatform,
                 $forceInstallPackageVersion,
                 true,
+                installFromLock: $installFromLock,
             );
         } catch (ComposerRunFailed $composerRunFailed) {
             $this->io->writeError('<error>' . $composerRunFailed->getMessage() . '</error>');
diff --git a/src/Command/ShowCommand.php b/src/Command/ShowCommand.php
index d43f5f41..38d64f5d 100644
--- a/src/Command/ShowCommand.php
+++ b/src/Command/ShowCommand.php
@@ -6,6 +6,7 @@
 
 use Composer\IO\IOInterface;
 use Composer\IO\NullIO;
+use InvalidArgumentException;
 use Php\Pie\ComposerIntegration\PieComposerFactory;
 use Php\Pie\ComposerIntegration\PieComposerRequest;
 use Php\Pie\DependencyResolver\BundledPhpExtensionRefusal;
@@ -26,6 +27,7 @@
 use Webmozart\Assert\Assert;
 
 use function array_diff;
+use function array_key_exists;
 use function array_map;
 use function array_walk;
 use function count;
@@ -115,7 +117,7 @@ function (string $version, string $phpExtensionName) use ($composer, $rootPackag
                 foreach ($pieMatchesForExtension->packages() as $piePackage) {
                     $packageName        = $piePackage->name();
                     $verificationStatus = $piePackage->verifyPackageStatus($targetPlatform);
-                    $packageRequirement = $rootPackageRequires[$packageName]->getPrettyConstraint();
+                    $packageRequirement = array_key_exists($packageName, $rootPackageRequires) ? $rootPackageRequires[$packageName]->getPrettyConstraint() : null;
 
                     if ($verificationStatus === PackageVerificationStatus::InstalledBinaryMetadataMissing) {
                         continue;
@@ -145,7 +147,7 @@ function (string $version, string $phpExtensionName) use ($composer, $rootPackag
                             new RequestedPackageAndVersion($packageName, '*'),
                             false,
                         );
-                    } catch (UnableToResolveRequirement | BundledPhpExtensionRefusal) {
+                    } catch (UnableToResolveRequirement | BundledPhpExtensionRefusal | InvalidArgumentException) {
                         $latestConstrainedPackage = null;
                         $latestPackage            = null;
                     }
@@ -163,6 +165,10 @@ function (string $version, string $phpExtensionName) use ($composer, $rootPackag
                         $updateNotice .= sprintf(', latest version is %s', $latestPackage->piePackage->version());
                     }
 
+                    if (! array_key_exists($packageName, $rootPackageRequires)) {
+                        $verificationStatus = PackageVerificationStatus::InstalledButDoesNotExistInRequires;
+                    }
+
                     $this->io->write(sprintf(
                         '  <info>%s:%s</info> (from 🥧 <info>%s</info> %s)%s',
                         $phpExtensionName,
diff --git a/src/ComposerIntegration/ComposerIntegrationHandler.php b/src/ComposerIntegration/ComposerIntegrationHandler.php
index 82009239..26e80f91 100644
--- a/src/ComposerIntegration/ComposerIntegrationHandler.php
+++ b/src/ComposerIntegration/ComposerIntegrationHandler.php
@@ -19,6 +19,7 @@
 use Psr\Container\ContainerInterface;
 
 use function array_map;
+use function array_values;
 use function assert;
 use function file_exists;
 use function sprintf;
@@ -72,6 +73,7 @@ public function runInstall(
         TargetPlatform $targetPlatform,
         bool $forceInstallPackageVersion,
         bool $runCleanup,
+        bool $installFromLock = false,
     ): void {
         $pieComposerJson        = Platform::getPieJsonFilename($targetPlatform);
         $pieJsonEditor          = PieJsonEditor::fromTargetPlatform($targetPlatform);
@@ -90,7 +92,14 @@ public function runInstall(
         // Refresh the Composer instance so it re-reads the updated pie.json
         $composer = PieComposerFactory::recreatePieComposer($this->container, $composer);
 
-        foreach ($composer->getRepositoryManager()->getLocalRepository()->getPackages() as $localRepoPackage) {
+        $resolvedPackageByName = [];
+        foreach ($resolvedRequestedPackages as $resolvedPackageRequest) {
+            $resolvedPackageByName[$resolvedPackageRequest->piePackage->composerPackage()->getName()] = $resolvedPackageRequest->piePackage;
+        }
+
+        $localRepository = $composer->getRepositoryManager()->getLocalRepository();
+
+        foreach ($localRepository->getPackages() as $localRepoPackage) {
             $extName = ExtensionName::determineFromComposerPackage($localRepoPackage);
 
             if ($localRepoPackage instanceof CompleteAliasPackage) {
@@ -110,6 +119,47 @@ public function runInstall(
             ), verbosity: IOInterface::VERY_VERBOSE);
 
             if ($status->isVerified() && ! $forceInstallPackageVersion) {
+                if ($installFromLock) {
+                    $lockedRepo    = $composer->getLocker()->getLockedRepository();
+                    $lockedPackage = $lockedRepo->findPackage($localRepoPackage->getName(), '*');
+
+                    if ($lockedPackage === null) {
+                        // Not in locked repo; Composer will install it anyway
+                        continue;
+                    }
+
+                    if ($lockedPackage->getVersion() !== $localRepoPackage->getVersion()) {
+                        $this->arrayCollectionIo->write(sprintf(
+                            '%s PIE package %s (%s) is at %s but the lock requires %s, scheduling for reinstall.',
+                            Emoji::WARNING,
+                            $localRepoPackage->getName(),
+                            $extName->name(),
+                            $localRepoPackage->getPrettyVersion(),
+                            $lockedPackage->getPrettyVersion(),
+                        ));
+
+                        // Locked, but the version we installed is different
+                        $localRepository->removePackage($localRepoPackage);
+                        continue;
+                    }
+                } else {
+                    $resolvedPackage = $resolvedPackageByName[$localRepoPackage->getName()] ?? null;
+                    if ($resolvedPackage !== null && $resolvedPackage->composerPackage()->getVersion() !== $localRepoPackage->getVersion()) {
+                        $this->arrayCollectionIo->write(sprintf(
+                            '%s PIE package %s (%s) is at %s but %s was installed, adding to install candidates.',
+                            Emoji::WARNING,
+                            $localRepoPackage->getName(),
+                            $extName->name(),
+                            $localRepoPackage->getPrettyVersion(),
+                            $resolvedPackage->composerPackage()->getPrettyVersion(),
+                        ));
+
+                        // Resolved a different version than what's installed
+                        $localRepository->removePackage($localRepoPackage);
+                        continue;
+                    }
+                }
+
                 $this->arrayCollectionIo->write(sprintf(
                     '%s PIE package %s (%s) is already installed and verified.',
                     Emoji::GREEN_CHECKMARK,
@@ -144,12 +194,16 @@ public function runInstall(
                 $extName->name(),
                 $status->description(),
             ));
-            $composer->getRepositoryManager()->getLocalRepository()->removePackage($localRepoPackage);
+            $localRepository->removePackage($localRepoPackage);
         }
 
+        $extensionNames = $installFromLock
+            ? array_values(array_map(ExtensionName::determineFromComposerPackage(...), $composer->getLocker()->getLockedRepository()->getPackages()))
+            : ResolvedPackageRequest::extensionNames($resolvedRequestedPackages);
+
         $composerInstaller = PieComposerInstaller::createWithPhpBinary(
             $targetPlatform->phpBinaryPath,
-            ResolvedPackageRequest::extensionNames($resolvedRequestedPackages),
+            $extensionNames,
             $this->arrayCollectionIo,
             $composer,
         );
@@ -161,7 +215,7 @@ public function runInstall(
             ->setPlatformRequirementFilter(PlatformRequirementFilterFactory::fromBoolOrList($forceInstallPackageVersion))
             ->setDownloadOnly(false);
 
-        if (file_exists(PieComposerFactory::getLockFile($pieComposerJson))) {
+        if (! $installFromLock && file_exists(PieComposerFactory::getLockFile($pieComposerJson))) {
             $composerInstaller->setUpdate(true);
             $composerInstaller->setUpdateAllowList(ResolvedPackageRequest::requestedPackageNames($resolvedRequestedPackages));
         }
diff --git a/src/ComposerIntegration/PieComposerRequest.php b/src/ComposerIntegration/PieComposerRequest.php
index 5c137853..fd024ec0 100644
--- a/src/ComposerIntegration/PieComposerRequest.php
+++ b/src/ComposerIntegration/PieComposerRequest.php
@@ -32,6 +32,7 @@ public function __construct(
         public readonly PieOperation $operation,
         public readonly array $configureOptions,
         public readonly bool $attemptToSetupIniFile,
+        public readonly bool $installAllPackages = false,
     ) {
         $this->requestedPackageNames = array_map(static fn (RequestedPackageAndVersion $request) => $request->package, $this->requestedPackages);
     }
@@ -62,6 +63,10 @@ public static function noOperation(
 
     public function isFor(string $packageName): bool
     {
+        if ($this->installAllPackages) {
+            return true;
+        }
+
         return in_array($packageName, $this->requestedPackageNames);
     }
 }
diff --git a/src/ComposerIntegration/UninstallProcess.php b/src/ComposerIntegration/UninstallProcess.php
index 80b10489..01e44fec 100644
--- a/src/ComposerIntegration/UninstallProcess.php
+++ b/src/ComposerIntegration/UninstallProcess.php
@@ -36,7 +36,11 @@ public function __invoke(
         $status = $piePackage->verifyPackageStatus($composerRequest->targetPlatform);
 
         if ($status->isVerified()) {
-            $io->write(sprintf('👋 <info>Removed extension:</info> %s', ($this->uninstall)($targetPlatform, $piePackage)->filePath));
+            $io->write(sprintf(
+                '👋 <info>Removed extension %s:</info> %s',
+                $piePackage->prettyNameAndVersion(),
+                ($this->uninstall)($targetPlatform, $piePackage)->filePath,
+            ));
         } else {
             $io->writeError(sprintf('<warning>Did not remove extension file:</warning> %s', $status->description()));
         }
diff --git a/src/Container.php b/src/Container.php
index 0e79508d..aa9e3ade 100644
--- a/src/Container.php
+++ b/src/Container.php
@@ -229,7 +229,7 @@ static function (): SystemDependenciesDefinition {
         return $container;
     }
 
-    public static function testFactory(): ContainerInterface
+    public static function testFactory(OutputInterface $output = new NullOutput()): ContainerInterface
     {
         self::$testBuffer ??= new BufferIO();
 
@@ -243,10 +243,10 @@ public static function testFactory(): ContainerInterface
         // QuieterConsoleIO is wired separately from IOInterface in self::factory(), and writes
         // directly to a real ConsoleOutput; override it here only, so tests don't leak its output
         // to the terminal.
-        $container->singleton(QuieterConsoleIO::class, static function (ContainerInterface $container): QuieterConsoleIO {
+        $container->singleton(QuieterConsoleIO::class, static function (ContainerInterface $container) use ($output): QuieterConsoleIO {
             return new QuieterConsoleIO(
                 $container->get(InputInterface::class),
-                new NullOutput(),
+                $output,
                 new MinimalHelperSet(
                     [
                         'question' => new QuestionHelper(),
diff --git a/src/DependencyResolver/Package.php b/src/DependencyResolver/Package.php
index 6a33ca24..8e131a93 100644
--- a/src/DependencyResolver/Package.php
+++ b/src/DependencyResolver/Package.php
@@ -279,10 +279,10 @@ public function installedJsonMetadata(): InstalledJsonMetadata
     public function verifyPackageStatus(TargetPlatform $targetPlatform): PackageVerificationStatus
     {
         $extensionPath    = $targetPlatform->phpBinaryPath->extensionPath();
-        $extensionEnding  = $targetPlatform->operatingSystem === OperatingSystem::Windows ? '.dll' : '.so';
+        $isWindows        = $targetPlatform->operatingSystem === OperatingSystem::Windows;
         $phpExtensionName = $this->extensionName->name();
 
-        $actualBinaryPathByConvention = $extensionPath . DIRECTORY_SEPARATOR . $phpExtensionName . $extensionEnding;
+        $actualBinaryPathByConvention = $extensionPath . DIRECTORY_SEPARATOR . ($isWindows ? 'php_' : '') . $phpExtensionName . ($isWindows ? '.dll' : '.so');
 
         // The extension may not be in the usual path (since you can specify a full path to an extension in the INI file)
         if (! file_exists($actualBinaryPathByConvention)) {
diff --git a/src/DependencyResolver/ResolvedPackageRequest.php b/src/DependencyResolver/ResolvedPackageRequest.php
index af5ae722..09dd2948 100644
--- a/src/DependencyResolver/ResolvedPackageRequest.php
+++ b/src/DependencyResolver/ResolvedPackageRequest.php
@@ -44,9 +44,9 @@ public static function requestedPackageNames(array $resolvedPackageRequests): ar
     }
 
     /**
-     * @param non-empty-list<self> $resolvedPackageRequests
+     * @param list<self> $resolvedPackageRequests
      *
-     * @return non-empty-list<Package>
+     * @return list<Package>
      */
     public static function piePackages(array $resolvedPackageRequests): array
     {
diff --git a/src/Installing/SetupIniFile.php b/src/Installing/SetupIniFile.php
index f69f98f2..c1e0f487 100644
--- a/src/Installing/SetupIniFile.php
+++ b/src/Installing/SetupIniFile.php
@@ -34,8 +34,9 @@ public function __invoke(
             && $this->setupIniApproach->setup($targetPlatform, $downloadedPackage, $binaryFile, $io)
         ) {
             $io->write(sprintf(
-                '<info>%s Extension is enabled and loaded in</info> %s',
+                '<info>%s Extension %s is enabled and loaded in</info> %s',
                 Emoji::GREEN_CHECKMARK,
+                $downloadedPackage->package->prettyNameAndVersion(),
                 $targetPlatform->phpBinaryPath->phpBinaryPath,
             ));
         } else {
diff --git a/src/Util/PackageVerificationStatus.php b/src/Util/PackageVerificationStatus.php
index 272d8646..55f19654 100644
--- a/src/Util/PackageVerificationStatus.php
+++ b/src/Util/PackageVerificationStatus.php
@@ -12,6 +12,7 @@ enum PackageVerificationStatus
     case InstalledBinaryMetadataMissing;
     case ChecksumMetadataMissing;
     case InstalledBinaryPathDoesNotMatchActualBinaryPath;
+    case InstalledButDoesNotExistInRequires;
 
     public function description(): string
     {
@@ -22,6 +23,7 @@ public function description(): string
             self::InstalledBinaryMetadataMissing => Emoji::WARNING . ' - installed extension metadata missing',
             self::ChecksumMetadataMissing => Emoji::WARNING . ' - binary checksum metadata missing',
             self::InstalledBinaryPathDoesNotMatchActualBinaryPath => Emoji::WARNING . ' - binary path mismatch',
+            self::InstalledButDoesNotExistInRequires => Emoji::WARNING . '- installed but does not exist in pie.json',
         };
     }
 
diff --git a/test/assets/pie-lock/pie.json b/test/assets/pie-lock/pie.json
new file mode 100644
index 00000000..92317f4a
--- /dev/null
+++ b/test/assets/pie-lock/pie.json
@@ -0,0 +1,6 @@
+{
+    "require": {
+        "xdebug/xdebug": "3.5.2",
+        "asgrim/example-pie-extension": "2.0.9"
+    }
+}
diff --git a/test/assets/pie-lock/pie.lock b/test/assets/pie-lock/pie.lock
new file mode 100644
index 00000000..eca995b6
--- /dev/null
+++ b/test/assets/pie-lock/pie.lock
@@ -0,0 +1,115 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+        "This file is @generated automatically"
+    ],
+    "content-hash": "bbeb326cf52bdf49183176118718973c",
+    "packages": [
+        {
+            "name": "asgrim/example-pie-extension",
+            "version": "2.0.9",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/asgrim/example-pie-extension.git",
+                "reference": "963c8d70c57c23fa2098e499a0ebffabb64748b3"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/asgrim/example-pie-extension/zipball/963c8d70c57c23fa2098e499a0ebffabb64748b3",
+                "reference": "963c8d70c57c23fa2098e499a0ebffabb64748b3",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=7.4,^8.0"
+            },
+            "replace": {
+                "ext-example_pie_extension": "*"
+            },
+            "type": "php-ext",
+            "notification-url": "https://packagist.org/downloads/",
+            "php-ext": {
+                "priority": 74,
+                "extension-name": "ext-example_pie_extension",
+                "configure-options": [
+                    {
+                        "name": "enable-example-pie-extension",
+                        "description": "whether to enable example-pie-extension support"
+                    },
+                    {
+                        "name": "with-hello-name",
+                        "description": "Name ot use when saying hello",
+                        "needs-value": true
+                    }
+                ],
+                "download-url-method": [
+                    "pre-packaged-binary",
+                    "composer-default"
+                ]
+            },
+            "license": [
+                "MIT"
+            ],
+            "description": "Example PIE extension",
+            "support": {
+                "issues": "https://github.com/asgrim/example-pie-extension/issues",
+                "source": "https://github.com/asgrim/example-pie-extension/tree/2.0.9"
+            },
+            "time": "2026-02-04T17:27:25+00:00"
+        },
+        {
+            "name": "xdebug/xdebug",
+            "version": "3.5.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/xdebug/xdebug.git",
+                "reference": "f2f0ebf216d511c55d69f705f542a73b116dbf6e"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/xdebug/xdebug/zipball/f2f0ebf216d511c55d69f705f542a73b116dbf6e",
+                "reference": "f2f0ebf216d511c55d69f705f542a73b116dbf6e",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=8.0,<8.6"
+            },
+            "type": "php-ext-zend",
+            "notification-url": "https://packagist.org/downloads/",
+            "php-ext": {
+                "priority": 90
+            },
+            "license": [
+                "Xdebug-1.03"
+            ],
+            "description": "Xdebug is a debugging and productivity extension for PHP",
+            "support": {
+                "source": "https://github.com/xdebug/xdebug/tree/3.5.2"
+            },
+            "funding": [
+                {
+                    "url": "https://xdebug.org/support",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/derickr",
+                    "type": "github"
+                },
+                {
+                    "url": "https://www.patreon.com/derickr",
+                    "type": "patreon"
+                }
+            ],
+            "time": "2026-06-08T14:31:52+00:00"
+        }
+    ],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": {},
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": {},
+    "platform-dev": {},
+    "plugin-api-version": "2.9.0"
+}
diff --git a/test/behaviour/CliContext.php b/test/behaviour/CliContext.php
index 5fb1b59b..f6a9d7ad 100644
--- a/test/behaviour/CliContext.php
+++ b/test/behaviour/CliContext.php
@@ -10,17 +10,24 @@
 use Behat\Step\Then;
 use Behat\Step\When;
 use Composer\Util\Platform;
+use RuntimeException;
 use Safe\Exceptions\PcreException;
 use Symfony\Component\Process\Process;
 use Webmozart\Assert\Assert;
 
+use function array_combine;
 use function array_map;
 use function array_merge;
+use function preg_quote;
 use function Safe\copy;
+use function Safe\file_get_contents;
+use function Safe\file_put_contents;
+use function Safe\preg_match;
 use function Safe\preg_match_all;
 use function Safe\realpath;
 use function sprintf;
 use function str_contains;
+use function str_replace;
 
 class CliContext implements Context
 {
@@ -35,6 +42,10 @@ class CliContext implements Context
     /** @var list<array{extension: string, package: non-empty-string}> */
     private array $interactions           = [];
     private string|null $workingDirectory = null;
+    private string $pieJsonFilename;
+    private string $pieLockFilename;
+    private string $pieJsonContentBackup;
+    private string $pieLockContentBackup;
 
     /** @throws PcreException */
     #[AfterScenario]
@@ -261,9 +272,9 @@ public function theExtensionShouldNotBeInstalled(): void
 
         foreach ($this->interactions as $uninstall) {
             if (Platform::isWindows()) {
-                Assert::regex($this->output, '#👋 Removed extension: [-\\\_:.a-zA-Z0-9]+\\\php_' . $uninstall['extension'] . '.dll#');
+                Assert::regex($this->output, '#👋 Removed extension ' . preg_quote($uninstall['package'], '#') . ':[^:]+: [-\\\_:.a-zA-Z0-9]+\\\php_' . preg_quote($uninstall['extension'], '#') . '.dll#');
             } else {
-                Assert::regex($this->output, '#👋 Removed extension: [-_.a-zA-Z0-9/]+/' . $uninstall['extension'] . '.so#');
+                Assert::regex($this->output, '#👋 Removed extension ' . preg_quote($uninstall['package'], '#') . ':[^:]+: [-_.a-zA-Z0-9/]+/' . preg_quote($uninstall['extension'], '#') . '.so#');
             }
 
             $isExtEnabled = (new Process([self::PHP_BINARY, '-r', 'echo extension_loaded("' . $uninstall['extension'] . '")?"yes":"no";']))
@@ -302,16 +313,16 @@ public function theExtensionShouldHaveBeenInstalledAndEnabled(): void
     {
         $this->assertCommandSuccessful();
 
-        Assert::contains($this->output, 'Extension is enabled and loaded');
-
         foreach ($this->interactions as $install) {
+            Assert::regex($this->output, '#Extension ' . preg_quote($install['package'], '#') . ':\S+ is enabled and loaded#');
+
             if (Platform::isWindows()) {
-                Assert::regex($this->output, '#Copied DLL to: [-\\\_:.a-zA-Z0-9]+\\\php_' . $install['extension'] . '.dll#');
+                Assert::regex($this->output, '#Copied DLL to: [-\\\_:.a-zA-Z0-9]+\\\php_' . preg_quote($install['extension'], '#') . '.dll#');
 
                 continue;
             }
 
-            Assert::regex($this->output, '#Install complete: [-_.a-zA-Z0-9/]+/' . $install['extension'] . '.so#');
+            Assert::regex($this->output, '#Install complete: [-_.a-zA-Z0-9/]+/' . preg_quote($install['extension'], '#') . '.so#');
 
             $isExtEnabled = (new Process([self::PHP_BINARY, '-r', 'echo extension_loaded("' . $install['extension'] . '")?"yes":"no";']))
                 ->mustRun()
@@ -538,4 +549,68 @@ public function iShouldSeeItHasFailedVerification(): void
         Assert::notNull($this->errorOutput);
         Assert::contains($this->errorOutput, '❌ Failed to verify that this PIE binary is the authentic release');
     }
+
+    #[Given('I have a lock file')]
+    public function iHaveALockfile(): void
+    {
+        $this->runPieCommand(['install', 'xdebug/xdebug:3.5.3', 'derickr/quickhash']);
+
+        $this->runPieCommand(['show', '-v']);
+        Assert::notNull($this->output);
+        preg_match('#Using pie\.json: (.+)#', $this->output, $pieJsonRegexMatches);
+        Assert::keyExists($pieJsonRegexMatches, 1);
+        $this->pieJsonFilename = $pieJsonRegexMatches[1];
+        $this->pieLockFilename = str_replace('pie.json', 'pie.lock', $this->pieJsonFilename);
+
+        $this->pieJsonContentBackup = file_get_contents($this->pieJsonFilename);
+        $this->pieLockContentBackup = file_get_contents($this->pieLockFilename);
+
+        $testPieLockPath = realpath(__DIR__ . '/../assets/pie-lock');
+        copy($testPieLockPath . '/pie.json', $this->pieJsonFilename);
+        copy($testPieLockPath . '/pie.lock', $this->pieLockFilename);
+    }
+
+    #[When('I run a command to install from the lockfile')]
+    public function iRunACommandToInstallFromTheLockfile(): void
+    {
+        $this->runPieCommand(['install', '-v', '--from-lock']);
+    }
+
+    #[Then('the extensions should have been updated to the lock')]
+    public function theExtensionsShouldHaveBeenUpdatedToTheLock(): void
+    {
+        $this->assertCommandSuccessful();
+
+        Assert::notNull($this->output);
+        $pieInstallOutput = $this->output;
+
+        $this->runPieCommand(['show']);
+        $this->assertCommandSuccessful();
+
+        if (! preg_match_all('#([a-zA-Z0-9-_]+/[a-zA-Z0-9-_]+):([^ ]+)#', (string) $this->output, $matches)) {
+            throw new RuntimeException('no packages found in pie show');
+        }
+
+        $installedExtensionPackagesAndVersions = array_combine($matches[1], $matches[2]);
+
+        // `xdebug` should be downgraded to 3.5.2
+        Assert::contains($pieInstallOutput, 'PIE package xdebug/xdebug (xdebug) is at 3.5.3 but the lock requires 3.5.2, scheduling for reinstall');
+        Assert::contains($pieInstallOutput, 'Extension xdebug/xdebug:3.5.2 is enabled and loaded');
+        Assert::keyExists($installedExtensionPackagesAndVersions, 'xdebug/xdebug');
+        Assert::same($installedExtensionPackagesAndVersions['xdebug/xdebug'], '3.5.2');
+
+        // `quickhash` should have been removed (not in lockfile)
+        Assert::contains($pieInstallOutput, 'Removed extension derickr/quickhash:');
+        Assert::keyNotExists($installedExtensionPackagesAndVersions, 'derickr/quickhash');
+
+        // `example_pie_extension` 2.0.9 should have been installed (was not previously installed)
+        Assert::contains($pieInstallOutput, 'Extension asgrim/example-pie-extension:2.0.9 is enabled and loaded');
+        Assert::keyExists($installedExtensionPackagesAndVersions, 'asgrim/example-pie-extension');
+        Assert::same($installedExtensionPackagesAndVersions['asgrim/example-pie-extension'], '2.0.9');
+
+        // restore the pie.json/lock contents, and re-install from the lock
+        file_put_contents($this->pieJsonFilename, $this->pieJsonContentBackup);
+        file_put_contents($this->pieLockFilename, $this->pieLockContentBackup);
+        $this->runPieCommand(['install', '--from-lock']);
+    }
 }
diff --git a/test/integration/Command/ShowCommandTest.php b/test/integration/Command/ShowCommandTest.php
index c1d2370e..031e0009 100644
--- a/test/integration/Command/ShowCommandTest.php
+++ b/test/integration/Command/ShowCommandTest.php
@@ -193,4 +193,48 @@ public function testExecuteWithOnlyUnconstrainedUpdates(): void
             $outputString,
         );
     }
+
+    public function testExecuteShowsWarningWhenInstalledButNotInPieJson(): void
+    {
+        try {
+            $phpConfig = Process::run(['which', 'php-config']);
+            Assert::stringNotEmpty($phpConfig);
+        } catch (ProcessFailedException | InvalidArgumentException) {
+            self::markTestSkipped('This test can only run on systems with php-config');
+        }
+
+        $installCommand = new CommandTester(Container::testFactory()->get(InstallCommand::class));
+        $installCommand->execute([
+            'requested-package-and-version' => [self::TEST_PACKAGE . ':2.0.2'],
+            '--with-php-config' => $phpConfig,
+        ]);
+        $installCommand->assertCommandIsSuccessful();
+
+        $outputString = $installCommand->getDisplay();
+
+        if (str_contains($outputString, 'NOT been automatically')) {
+            self::markTestSkipped('PIE couldn\'t automatically enable the extension');
+        }
+
+        PieJsonEditor::fromTargetPlatform(
+            PiePlatform\TargetPlatform::fromPhpBinaryPath(
+                PiePlatform\TargetPhp\PhpBinaryPath::fromPhpConfigExecutable(
+                    $phpConfig,
+                ),
+                1,
+                null,
+            ),
+        )
+            ->removeRequire(self::TEST_PACKAGE);
+
+        $this->commandTester->execute(['--with-php-config' => $phpConfig]);
+        $this->commandTester->assertCommandIsSuccessful();
+
+        $outputString = $this->commandTester->getDisplay();
+
+        self::assertStringMatchesFormat(
+            '%Aexample_pie_extension:%S (from %S asgrim/example-pie-extension:2.0.2 %S- installed but does not exist in pie.json)%A',
+            $outputString,
+        );
+    }
 }
diff --git a/test/integration/ComposerIntegration/ComposerIntegrationHandlerTest.php b/test/integration/ComposerIntegration/ComposerIntegrationHandlerTest.php
new file mode 100644
index 00000000..b6836c99
--- /dev/null
+++ b/test/integration/ComposerIntegration/ComposerIntegrationHandlerTest.php
@@ -0,0 +1,242 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Php\PieIntegrationTest\ComposerIntegration;
+
+use Composer\Composer;
+use Composer\IO\NullIO;
+use Composer\Json\JsonFile;
+use Composer\Package\CompletePackage;
+use Composer\Package\Dumper\ArrayDumper;
+use Php\Pie\ComposerIntegration\ComposerIntegrationHandler;
+use Php\Pie\ComposerIntegration\InstalledJsonMetadata;
+use Php\Pie\ComposerIntegration\PieComposerFactory;
+use Php\Pie\ComposerIntegration\PieComposerRequest;
+use Php\Pie\ComposerIntegration\PieJsonEditor;
+use Php\Pie\ComposerIntegration\PieOperation;
+use Php\Pie\Container;
+use Php\Pie\DependencyResolver\Package;
+use Php\Pie\DependencyResolver\RequestedPackageAndVersion;
+use Php\Pie\DependencyResolver\ResolvedPackageRequest;
+use Php\Pie\Platform;
+use Php\Pie\Platform\OperatingSystem;
+use Php\Pie\Platform\TargetPhp\PhpBinaryPath;
+use Php\Pie\Platform\TargetPlatform;
+use Php\PieIntegrationTest\Command\IsolatedWorkingDirectoryTestCase;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\RequiresOperatingSystemFamily;
+use Symfony\Component\Console\Output\BufferedOutput;
+
+use function file_exists;
+use function Safe\copy;
+use function Safe\file_get_contents;
+use function Safe\file_put_contents;
+use function Safe\hash_file;
+use function Safe\json_decode;
+use function Safe\mkdir;
+use function Safe\unlink;
+
+use const DIRECTORY_SEPARATOR;
+
+#[CoversClass(ComposerIntegrationHandler::class)]
+final class ComposerIntegrationHandlerTest extends IsolatedWorkingDirectoryTestCase
+{
+    private const PACKAGE_NAME    = 'asgrim/example-pie-extension';
+    private const EXTENSION_NAME  = 'example_pie_extension';
+    private const VERSION_CURRENT = '2.0.9';
+    private const VERSION_OTHER   = '2.0.2';
+
+    private TargetPlatform $targetPlatform;
+    private BufferedOutput $capturedOutput;
+    private ComposerIntegrationHandler $handler;
+    private string|null $createdFakeBinaryPath = null;
+
+    protected function tearDown(): void
+    {
+        if ($this->createdFakeBinaryPath !== null && file_exists($this->createdFakeBinaryPath)) {
+            unlink($this->createdFakeBinaryPath);
+        }
+
+        parent::tearDown();
+    }
+
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        $phpBinaryPath        = PhpBinaryPath::fromCurrentProcess();
+        $this->targetPlatform = TargetPlatform::fromPhpBinaryPath($phpBinaryPath, null, null);
+
+        $this->createdFakeBinaryPath = $this->extensionBinaryPath();
+        file_put_contents($this->createdFakeBinaryPath, '');
+
+        $this->capturedOutput = new BufferedOutput(BufferedOutput::VERBOSITY_VERBOSE);
+
+        $this->handler = Container::testFactory($this->capturedOutput)->get(ComposerIntegrationHandler::class);
+    }
+
+    public function testRunInstallInvokesInstallerForNewPackage(): void
+    {
+        $composer = $this->makeComposer(self::VERSION_CURRENT);
+
+        $this->handler->runInstall(
+            [$this->makeResolvedRequest(self::VERSION_CURRENT)],
+            $composer,
+            $this->targetPlatform,
+            false,
+            false,
+        );
+
+        $output = $this->capturedOutput->fetch();
+        self::assertStringNotContainsString('is already installed and verified', $output);
+        self::assertStringNotContainsString('adding to install candidates', $output);
+    }
+
+    public function testRunInstallSkipsAlreadyVerifiedPackageAtSameVersion(): void
+    {
+        PieJsonEditor::fromTargetPlatform($this->targetPlatform)
+            ->ensureExists()
+            ->addRequire(self::PACKAGE_NAME, self::VERSION_CURRENT);
+        $this->setUpInstalledJson(self::VERSION_CURRENT);
+        $this->setUpLockFile();
+
+        $composer = $this->makeComposer(self::VERSION_CURRENT);
+
+        $this->handler->runInstall(
+            [$this->makeResolvedRequest(self::VERSION_CURRENT)],
+            $composer,
+            $this->targetPlatform,
+            false,
+            false,
+        );
+
+        $output = $this->capturedOutput->fetch();
+        self::assertStringContainsString(
+            self::PACKAGE_NAME . ' (' . self::EXTENSION_NAME . ') is already installed and verified',
+            $output,
+        );
+        self::assertStringContainsString('Nothing to install, update or remove', $output);
+    }
+
+    #[RequiresOperatingSystemFamily('Linux')]
+    public function testRunInstallReinstallsVerifiedPackageWhenVersionDiffers(): void
+    {
+        PieJsonEditor::fromTargetPlatform($this->targetPlatform)
+            ->ensureExists()
+            ->addRequire(self::PACKAGE_NAME, self::VERSION_CURRENT);
+        $this->setUpInstalledJson(self::VERSION_CURRENT);
+        $this->setUpLockFile();
+
+        $composer = $this->makeComposer(self::VERSION_OTHER);
+
+        $this->handler->runInstall(
+            [$this->makeResolvedRequest(self::VERSION_OTHER)],
+            $composer,
+            $this->targetPlatform,
+            false,
+            false,
+        );
+
+        $output = $this->capturedOutput->fetch();
+        self::assertStringContainsString(
+            self::PACKAGE_NAME . ' (' . self::EXTENSION_NAME . ') is at ' . self::VERSION_CURRENT . ' but ' . self::VERSION_OTHER . ' was installed, adding to install candidates',
+            $output,
+        );
+        self::assertStringNotContainsString('is already installed and verified', $output);
+    }
+
+    public function testRunUninstallRemovesPackageFromPieJson(): void
+    {
+        PieJsonEditor::fromTargetPlatform($this->targetPlatform)
+            ->ensureExists()
+            ->addRequire(self::PACKAGE_NAME, self::VERSION_CURRENT);
+        $this->setUpInstalledJson(self::VERSION_CURRENT);
+        $this->setUpLockFile();
+
+        $composer = $this->makeComposer(self::VERSION_CURRENT);
+
+        $this->handler->runUninstall(
+            [$this->makeResolvedRequest(self::VERSION_CURRENT)],
+            $composer,
+            $this->targetPlatform,
+        );
+
+        $pieJson = json_decode(
+            file_get_contents(Platform::getPieWorkingDirectory($this->targetPlatform) . '/pie.json'),
+            true,
+        );
+        self::assertIsArray($pieJson);
+        self::assertArrayNotHasKey('require', $pieJson);
+    }
+
+    private function extensionBinaryPath(): string
+    {
+        $isWindows = $this->targetPlatform->operatingSystem === OperatingSystem::Windows;
+
+        return $this->targetPlatform->phpBinaryPath->extensionPath() . DIRECTORY_SEPARATOR . ($isWindows ? 'php_' : '') . self::EXTENSION_NAME . ($isWindows ? '.dll' : '.so');
+    }
+
+    /** @param non-empty-string $version */
+    private function makeComposerPackage(string $version): CompletePackage
+    {
+        $extensionBinaryPath = $this->extensionBinaryPath();
+
+        $package = new CompletePackage(self::PACKAGE_NAME, $version . '.0', $version);
+        $package->setType('php-ext');
+        $package->setPhpExt(['extension-name' => 'ext-' . self::EXTENSION_NAME]);
+        $package->setDistType('zip');
+        $package->setDistUrl('https://github.com/asgrim/example-pie-extension/archive/refs/tags/' . $version . '.zip');
+        $package->setInstallationSource('dist');
+        $package->setExtra([
+            InstalledJsonMetadata::KEY_TARGET_PLATFORM_PHP_VERSION => $this->targetPlatform->phpBinaryPath->version(),
+            InstalledJsonMetadata::KEY_BUILT_BINARY                => $extensionBinaryPath,
+            InstalledJsonMetadata::KEY_INSTALLED_BINARY            => $extensionBinaryPath,
+            InstalledJsonMetadata::KEY_BINARY_CHECKSUM             => hash_file('sha256', $extensionBinaryPath),
+        ]);
+
+        return $package;
+    }
+
+    /** @param non-empty-string $version */
+    private function setUpInstalledJson(string $version): void
+    {
+        mkdir(Platform::getPieWorkingDirectory($this->targetPlatform) . '/vendor/composer', 0755, true);
+
+        (new JsonFile(Platform::getPieWorkingDirectory($this->targetPlatform) . '/vendor/composer/installed.json'))->write([
+            'packages'          => [(new ArrayDumper())->dump($this->makeComposerPackage($version))],
+            'dev'               => true,
+            'dev-package-names' => [],
+        ]);
+    }
+
+    private function setUpLockFile(): void
+    {
+        copy(__DIR__ . '/../../assets/pie-lock/pie.lock', Platform::getPieWorkingDirectory($this->targetPlatform) . '/pie.lock');
+    }
+
+    /** @param non-empty-string $version */
+    private function makeResolvedRequest(string $version): ResolvedPackageRequest
+    {
+        return new ResolvedPackageRequest(
+            Package::fromComposerCompletePackage($this->makeComposerPackage($version)),
+            new RequestedPackageAndVersion(self::PACKAGE_NAME, $version),
+        );
+    }
+
+    /** @param non-empty-string $version */
+    private function makeComposer(string $version): Composer
+    {
+        return PieComposerFactory::createPieComposer(
+            Container::testFactory($this->capturedOutput),
+            new PieComposerRequest(
+                new NullIO(),
+                $this->targetPlatform,
+                [new RequestedPackageAndVersion(self::PACKAGE_NAME, $version)],
+                PieOperation::Install,
+                [],
+                false,
+            ),
+        );
+    }
+}
diff --git a/test/unit/Command/InstallCommandTest.php b/test/unit/Command/InstallCommandTest.php
new file mode 100644
index 00000000..6e77cb7e
--- /dev/null
+++ b/test/unit/Command/InstallCommandTest.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Php\PieUnitTest\Command;
+
+use Php\Pie\Command\InstallCommand;
+use Php\Pie\Container;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+
+#[CoversClass(InstallCommand::class)]
+final class InstallCommandTest extends TestCase
+{
+    public function testFromLockOptionExistsOnInstallCommand(): void
+    {
+        $command    = Container::testFactory()->get(InstallCommand::class);
+        $definition = $command->getDefinition();
+
+        self::assertTrue($definition->hasOption(InstallCommand::OPTION_FROM_LOCK));
+    }
+}
diff --git a/test/unit/DependencyResolver/FetchDependencyStatusesTest.php b/test/unit/DependencyResolver/FetchDependencyStatusesTest.php
index f39ec6ad..c90a4c16 100644
--- a/test/unit/DependencyResolver/FetchDependencyStatusesTest.php
+++ b/test/unit/DependencyResolver/FetchDependencyStatusesTest.php
@@ -39,7 +39,7 @@ public function testNoRequiresReturnsEmptyArray(): void
     }
 
     /** @return array<non-empty-string, array{0: non-empty-string, 1: non-empty-string}> */
-    public function phpVersionProvider(): array
+    public static function phpVersionProvider(): array
     {
         return [
             '8.2.0' => ['8.2.0', '8.2.0'],
diff --git a/test/unit/DependencyResolver/ResolveDependencyWithComposerTest.php b/test/unit/DependencyResolver/ResolveDependencyWithComposerTest.php
index 5522eee5..0d05a425 100644
--- a/test/unit/DependencyResolver/ResolveDependencyWithComposerTest.php
+++ b/test/unit/DependencyResolver/ResolveDependencyWithComposerTest.php
@@ -460,7 +460,7 @@ public function testBundledExtensionCannotBeInstalledOnDevPhpVersion(): void
     }
 
     /** @return array<non-empty-string, array{0: non-empty-string}> */
-    public function buildProvidersWithBundledExtensionWarnings(): array
+    public static function buildProvidersWithBundledExtensionWarnings(): array
     {
         return [
             'Docker' => ['https://github.com/docker-library/php'],