diff --git a/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/InitCommand.kt b/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/InitCommand.kt
index 115c2d19..e3d8981f 100644
--- a/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/InitCommand.kt
+++ b/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/InitCommand.kt
@@ -1,6 +1,8 @@
 package work.slhaf.partner.ctl.commands
 
 import picocli.CommandLine
+import work.slhaf.partner.ctl.commands.init.buildFromSource
+import work.slhaf.partner.ctl.ui.Choice
 import work.slhaf.partner.ctl.ui.Prompt
 import java.nio.file.Files
 import java.nio.file.Path
@@ -67,7 +69,18 @@ class InitCommand : Runnable {
     }
 
     private fun installPartner(prompt: Prompt) {
-        TODO("Not yet implemented")
+
+        prompt.section("Install Partner")
+
+        val installChoice = prompt.select(
+            label = "Choose a installation method",
+            choices = listOf(Choice("Build Partner from source", InstallChoice.BUILD_FROM_SOURCE))
+        )
+
+        when (installChoice) {
+            InstallChoice.BUILD_FROM_SOURCE -> buildFromSource(home, prompt)
+        }
+
     }
 
     private fun configureGateway(prompt: Prompt) {
@@ -82,4 +95,7 @@ class InitCommand : Runnable {
         TODO("Not yet implemented")
     }
 
+    private enum class InstallChoice {
+        BUILD_FROM_SOURCE
+    }
 }
\ No newline at end of file
diff --git a/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/init/install.kt b/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/init/install.kt
new file mode 100644
index 00000000..d1027364
--- /dev/null
+++ b/PartnerCtl/src/main/java/work/slhaf/partner/ctl/commands/init/install.kt
@@ -0,0 +1,100 @@
+package work.slhaf.partner.ctl.commands.init
+
+import work.slhaf.partner.ctl.support.CommandInterrupted
+import work.slhaf.partner.ctl.support.inheritCommand
+import work.slhaf.partner.ctl.support.runCommand
+import work.slhaf.partner.ctl.ui.Prompt
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.StandardCopyOption
+import kotlin.io.path.isDirectory
+import kotlin.io.path.name
+
+fun buildFromSource(home: Path, prompt: Prompt) {
+    checkTool()
+
+    val tempDir = Files.createTempDirectory("partnerctl-build-")
+    val sourceDir = tempDir.resolve("Partner")
+    val repoUrl = "https://gitea.slhaf.work/slhaf/Partner.git"
+    val targetJar = home.resolve("resource").resolve("partner-core.jar")
+
+    try {
+        prompt.info("Cloning Partner source from $repoUrl")
+        val cloneExitCode = inheritCommand(
+            command = listOf("git", "clone", "--depth", "1", repoUrl, sourceDir.toString()),
+        )
+        if (cloneExitCode != 0) {
+            throw CommandInterrupted("Failed to clone Partner source from $repoUrl")
+        }
+
+        prompt.info("Building Partner-Core and required modules")
+        val buildExitCode = inheritCommand(
+            command = listOf("mvn", "-pl", "Partner-Core", "-am", "package", "-DskipTests=true"),
+            workingDirectory = sourceDir,
+        )
+        if (buildExitCode != 0) {
+            throw CommandInterrupted("Failed to build Partner runtime. Please make sure Maven is using JDK 21.")
+        }
+
+        val builtJar = findPartnerCoreJar(sourceDir)
+        Files.createDirectories(targetJar.parent)
+        Files.copy(builtJar, targetJar, StandardCopyOption.REPLACE_EXISTING)
+        prompt.success("Partner runtime installed at $targetJar")
+    } finally {
+        tempDir.toFile().deleteRecursively()
+    }
+}
+
+private fun checkTool() {
+
+    fun buildToolLackedMessage(lack: Map<String, String>): String {
+        return buildString {
+            appendLine("Missing required build tools:")
+            appendLine()
+            lack.forEach { (tool, reason) ->
+                appendLine("$tool:")
+                appendLine("  $reason")
+            }
+            appendLine()
+            appendLine("Install the missing tools, then rerun:")
+            appendLine("  partnerctl init")
+        }.trimEnd()
+    }
+
+
+    val lack = mutableMapOf<String, String>()
+    if (runCommand(listOf("java", "--version")).exitCode != 0) {
+        lack["java"] = "Required to run Maven and Partner runtime. Command failed: java --version"
+    }
+    if (runCommand(listOf("javac", "--version")).exitCode != 0) {
+        lack["javac"] =
+            "Required to compile Partner from source. Install a JDK, not just a JRE. Command failed: javac --version"
+    }
+    if (runCommand(listOf("git", "--version")).exitCode != 0) {
+        lack["git"] = "Required to clone Partner source. Command failed: git --version"
+    }
+    if (runCommand(listOf("mvn", "--version")).exitCode != 0) {
+        lack["mvn"] = "Required to build Partner from source. Command failed: mvn --version"
+    }
+    if (lack.isNotEmpty()) {
+        throw CommandInterrupted(buildToolLackedMessage(lack))
+    }
+}
+
+private fun findPartnerCoreJar(sourceDir: Path): Path {
+    val targetDir = sourceDir.resolve("Partner-Core").resolve("target")
+    if (!targetDir.isDirectory()) {
+        throw CommandInterrupted("Partner-Core target directory does not exist: $targetDir")
+    }
+
+    return Files.list(targetDir).use { stream ->
+        stream
+            .filter { it.name.endsWith(".jar") }
+            .filter { !it.name.startsWith("original-") }
+            .filter { !it.name.endsWith("-sources.jar") }
+            .filter { !it.name.endsWith("-javadoc.jar") }
+            .max(Comparator.comparingLong { Files.size(it) })
+            .orElseThrow { CommandInterrupted("Could not find built Partner Core jar in $targetDir") }
+    }
+}
+