Add client roots addition/removal API and listRoots handler

api/kotlin-sdk.api

@@ -2688,6 +2688,8 @@ public final class io/modelcontextprotocol/kotlin/sdk/WithMeta$Companion {
 public class io/modelcontextprotocol/kotlin/sdk/client/Client : io/modelcontextprotocol/kotlin/sdk/shared/Protocol {
 	public fun <init> (Lio/modelcontextprotocol/kotlin/sdk/Implementation;Lio/modelcontextprotocol/kotlin/sdk/client/ClientOptions;)V
 	public synthetic fun <init> (Lio/modelcontextprotocol/kotlin/sdk/Implementation;Lio/modelcontextprotocol/kotlin/sdk/client/ClientOptions;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public final fun addRoot (Ljava/lang/String;Ljava/lang/String;)V
+	public final fun addRoots (Ljava/util/List;)V
 	protected final fun assertCapability (Ljava/lang/String;Ljava/lang/String;)V
 	protected fun assertCapabilityForMethod (Lio/modelcontextprotocol/kotlin/sdk/Method;)V
 	protected fun assertNotificationCapability (Lio/modelcontextprotocol/kotlin/sdk/Method;)V
@@ -2715,6 +2717,8 @@ public class io/modelcontextprotocol/kotlin/sdk/client/Client : io/modelcontextp
 	public static synthetic fun ping$default (Lio/modelcontextprotocol/kotlin/sdk/client/Client;Lio/modelcontextprotocol/kotlin/sdk/shared/RequestOptions;Lkotlin/coroutines/Continuation;ILjava/lang/Object;)Ljava/lang/Object;
 	public final fun readResource (Lio/modelcontextprotocol/kotlin/sdk/ReadResourceRequest;Lio/modelcontextprotocol/kotlin/sdk/shared/RequestOptions;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static synthetic fun readResource$default (Lio/modelcontextprotocol/kotlin/sdk/client/Client;Lio/modelcontextprotocol/kotlin/sdk/ReadResourceRequest;Lio/modelcontextprotocol/kotlin/sdk/shared/RequestOptions;Lkotlin/coroutines/Continuation;ILjava/lang/Object;)Ljava/lang/Object;
+	public final fun removeRoot (Ljava/lang/String;)Z
+	public final fun removeRoots (Ljava/util/List;)I
 	public final fun sendRootsListChanged (Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public final fun setLoggingLevel (Lio/modelcontextprotocol/kotlin/sdk/LoggingLevel;Lio/modelcontextprotocol/kotlin/sdk/shared/RequestOptions;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static synthetic fun setLoggingLevel$default (Lio/modelcontextprotocol/kotlin/sdk/client/Client;Lio/modelcontextprotocol/kotlin/sdk/LoggingLevel;Lio/modelcontextprotocol/kotlin/sdk/shared/RequestOptions;Lkotlin/coroutines/Continuation;ILjava/lang/Object;)Ljava/lang/Object;

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/Client.kt

@@ -1,5 +1,6 @@
 package io.modelcontextprotocol.kotlin.sdk.client
 
+import io.github.oshai.kotlinlogging.KotlinLogging
 import io.modelcontextprotocol.kotlin.sdk.CallToolRequest
 import io.modelcontextprotocol.kotlin.sdk.CallToolResult
 import io.modelcontextprotocol.kotlin.sdk.CallToolResultBase
@@ -21,6 +22,7 @@ import io.modelcontextprotocol.kotlin.sdk.ListResourceTemplatesRequest
 import io.modelcontextprotocol.kotlin.sdk.ListResourceTemplatesResult
 import io.modelcontextprotocol.kotlin.sdk.ListResourcesRequest
 import io.modelcontextprotocol.kotlin.sdk.ListResourcesResult
+import io.modelcontextprotocol.kotlin.sdk.ListRootsResult
 import io.modelcontextprotocol.kotlin.sdk.ListToolsRequest
 import io.modelcontextprotocol.kotlin.sdk.ListToolsResult
 import io.modelcontextprotocol.kotlin.sdk.LoggingLevel
@@ -29,6 +31,7 @@ import io.modelcontextprotocol.kotlin.sdk.Method
 import io.modelcontextprotocol.kotlin.sdk.PingRequest
 import io.modelcontextprotocol.kotlin.sdk.ReadResourceRequest
 import io.modelcontextprotocol.kotlin.sdk.ReadResourceResult
+import io.modelcontextprotocol.kotlin.sdk.Root
 import io.modelcontextprotocol.kotlin.sdk.RootsListChangedNotification
 import io.modelcontextprotocol.kotlin.sdk.SUPPORTED_PROTOCOL_VERSIONS
 import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities
@@ -44,6 +47,8 @@ import kotlinx.serialization.json.JsonObject
 import kotlinx.serialization.json.JsonPrimitive
 import kotlin.coroutines.cancellation.CancellationException
 
+private val logger = KotlinLogging.logger {}
+
 /**
  * Options for configuring the MCP client.
  *
@@ -89,6 +94,19 @@ public open class Client(
 
     private val capabilities: ClientCapabilities = options.capabilities
 
+    private val roots = mutableMapOf<String, Root>()
+
+    init {
+        logger.debug { "Initializing MCP client with capabilities: $capabilities" }
+
+        // Internal handlers for roots
+        if (capabilities.roots != null) {
+            setRequestHandler<ListToolsRequest>(Method.Defined.RootsList) { _, _ ->
+                handleListRoots()
+            }
+        }
+    }
+
     protected fun assertCapability(capability: String, method: String) {
         val caps = serverCapabilities
         val hasCapability = when (capability) {
@@ -449,6 +467,97 @@ public open class Client(
         return request<ListToolsResult>(request, options)
     }
 
+    /**
+     * Registers a single root.
+     *
+     * @param uri The URI of the root.
+     * @param name A human-readable name for the root.
+     * @throws IllegalStateException If the client does not support roots.
+     */
+    public fun addRoot(
+        uri: String,
+        name: String,
+    ) {
+        if (capabilities.roots == null) {
+            logger.error { "Failed to add root '$name': Client does not support roots capability" }
+            throw IllegalStateException("Client does not support roots capability.")
+        }
+        logger.info { "Adding root: $name ($uri)" }
+        roots[uri] = Root(uri, name)
+    }
+
+    /**
+     * Registers multiple roots at once.
+     *
+     * @param rootsToAdd A list of [Root] objects to register.
+     * @throws IllegalStateException If the client does not support roots.
+     */
+    public fun addRoots(rootsToAdd: List<Root>) {
+        if (capabilities.roots == null) {
+            logger.error { "Failed to add roots: Client does not support roots capability" }
+            throw IllegalStateException("Client does not support roots capability.")
+        }
+        logger.info { "Adding ${rootsToAdd.size} roots" }
+        for (r in rootsToAdd) {
+            logger.info { "Adding root: ${r.name} (${r.uri})" }
+            roots[r.uri] = r
+        }
+    }
+
+    /**
+     * Removes a single root by URI.
+     *
+     * @param uri The URI of the root to remove.
+     * @return True if the root was removed, false if it wasn't found.
+     * @throws IllegalStateException If the client does not support roots.
+     */
+    public fun removeRoot(uri: String): Boolean {
+        if (capabilities.roots == null) {
+            logger.error { "Failed to remove root '$uri': Client does not support roots capability" }
+            throw IllegalStateException("Client does not support roots capability.")
+        }
+        logger.info { "Removing root: $uri" }
+        val removed = roots.remove(uri) != null
+        logger.debug {
+            if (removed) {
+                "Root removed: $uri"
+            } else {
+                "Root not found: $uri"
+            }
+        }
+        return removed
+    }
+
+    /**
+     * Removes multiple roots at once.
+     *
+     * @param uris A list of root URIs to remove.
+     * @return The number of roots that were successfully removed.
+     * @throws IllegalStateException If the client does not support roots.
+     */
+    public fun removeRoots(uris: List<String>): Int {
+        if (capabilities.roots == null) {
+            logger.error { "Failed to remove roots: Client does not support roots capability" }
+            throw IllegalStateException("Client does not support roots capability.")
+        }
+        logger.info { "Removing ${uris.size} roots" }
+        var removedCount = 0
+        for (uri in uris) {
+            logger.debug { "Removing root: $uri" }
+            if (roots.remove(uri) != null) {
+                removedCount++
+            }
+        }
+        logger.info {
+            if (removedCount > 0) {
+                "Removed $removedCount roots"
+            } else {
+                "No roots were removed"
+            }
+        }
+        return removedCount
+    }
+
     /**
      * Notifies the server that the list of roots has changed.
      * Typically used if the client is managing some form of hierarchical structure.
@@ -458,4 +567,11 @@ public open class Client(
     public suspend fun sendRootsListChanged() {
         notification(RootsListChangedNotification())
     }
+
+    // --- Internal Handlers ---
+
+    private suspend fun handleListRoots(): ListRootsResult {
+        val rootList = roots.values.toList()
+        return ListRootsResult(rootList)
+    }
 }

src/jvmTest/kotlin/client/ClientTest.kt

@@ -1,12 +1,12 @@
 package client
 
+import io.mockk.coEvery
+import io.mockk.spyk
 import io.modelcontextprotocol.kotlin.sdk.ClientCapabilities
 import io.modelcontextprotocol.kotlin.sdk.CreateMessageRequest
 import io.modelcontextprotocol.kotlin.sdk.CreateMessageResult
 import io.modelcontextprotocol.kotlin.sdk.EmptyJsonObject
 import io.modelcontextprotocol.kotlin.sdk.Implementation
-import io.mockk.coEvery
-import io.mockk.spyk
 import io.modelcontextprotocol.kotlin.sdk.InMemoryTransport
 import io.modelcontextprotocol.kotlin.sdk.InitializeRequest
 import io.modelcontextprotocol.kotlin.sdk.InitializeResult
@@ -23,10 +23,17 @@ import io.modelcontextprotocol.kotlin.sdk.LoggingLevel
 import io.modelcontextprotocol.kotlin.sdk.LoggingMessageNotification
 import io.modelcontextprotocol.kotlin.sdk.Method
 import io.modelcontextprotocol.kotlin.sdk.Role
+import io.modelcontextprotocol.kotlin.sdk.Root
+import io.modelcontextprotocol.kotlin.sdk.RootsListChangedNotification
 import io.modelcontextprotocol.kotlin.sdk.SUPPORTED_PROTOCOL_VERSIONS
 import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities
 import io.modelcontextprotocol.kotlin.sdk.TextContent
 import io.modelcontextprotocol.kotlin.sdk.Tool
+import io.modelcontextprotocol.kotlin.sdk.client.Client
+import io.modelcontextprotocol.kotlin.sdk.client.ClientOptions
+import io.modelcontextprotocol.kotlin.sdk.server.Server
+import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions
+import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
 import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.TimeoutCancellationException
 import kotlinx.coroutines.cancel
@@ -35,13 +42,9 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.test.runTest
 import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.put
-import io.modelcontextprotocol.kotlin.sdk.client.Client
-import io.modelcontextprotocol.kotlin.sdk.client.ClientOptions
 import org.junit.jupiter.api.Test
-import io.modelcontextprotocol.kotlin.sdk.server.Server
-import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions
-import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
 import org.junit.jupiter.api.assertInstanceOf
+import org.junit.jupiter.api.assertThrows
 import kotlin.coroutines.cancellation.CancellationException
 import kotlin.test.assertEquals
 import kotlin.test.assertFailsWith
@@ -628,4 +631,168 @@ class ClientTest {
         assertEquals(null, receivedAsResponse.error)
     }
 
+    @Test
+    fun `listRoots returns list of roots`() = runTest {
+        val client = Client(
+            Implementation(name = "test client", version = "1.0"),
+            ClientOptions(
+                capabilities = ClientCapabilities(
+                    roots = ClientCapabilities.Roots(null)
+                )
+            )
+        )
+
+        val clientRoots = listOf(
+            Root(uri = "file:///test-root", name = "testRoot")
+        )
+
+        client.addRoots(clientRoots)
+
+        val (clientTransport, serverTransport) = InMemoryTransport.createLinkedPair()
+
+        val server = Server(
+            serverInfo = Implementation(name = "test server", version = "1.0"),
+            options = ServerOptions(
+                capabilities = ServerCapabilities()
+            )
+        )
+
+        listOf(
+            launch { client.connect(clientTransport) },
+            launch { server.connect(serverTransport) }
+        ).joinAll()
+
+        val clientCapabilities = server.clientCapabilities
+        assertEquals(ClientCapabilities.Roots(null), clientCapabilities?.roots)
+
+        val listRootsResult = server.listRoots()
+
+        assertEquals(listRootsResult.roots, clientRoots)
+    }
+
+    @Test
+    fun `addRoot should throw when roots capability is not supported`() = runTest {
+        val client = Client(
+            Implementation(name = "test client", version = "1.0"),
+            ClientOptions(
+                capabilities = ClientCapabilities()
+            )
+        )
+
+        // Verify that adding a root throws an exception
+        val exception = assertThrows<IllegalStateException> {
+            client.addRoot(uri = "file:///test-root1", name = "testRoot1")
+        }
+        assertEquals("Client does not support roots capability.", exception.message)
+    }
+
+    @Test
+    fun `removeRoot should throw when roots capability is not supported`() = runTest {
+        val client = Client(
+            Implementation(name = "test client", version = "1.0"),
+            ClientOptions(
+                capabilities = ClientCapabilities()
+            )
+        )
+
+        // Verify that removing a root throws an exception
+        val exception = assertThrows<IllegalStateException> {
+            client.removeRoot(uri = "file:///test-root1")
+        }
+        assertEquals("Client does not support roots capability.", exception.message)
+    }
+
+    @Test
+    fun `removeRoot should remove a root`() = runTest {
+        val client = Client(
+            Implementation(name = "test client", version = "1.0"),
+            ClientOptions(
+                capabilities = ClientCapabilities(
+                    roots = ClientCapabilities.Roots(null)
+                )
+            )
+        )
+
+        // Add some roots
+        client.addRoots(
+            listOf(
+                Root(uri = "file:///test-root1", name = "testRoot1"),
+                Root(uri = "file:///test-root2", name = "testRoot2"),
+            )
+        )
+
+        // Remove a root
+        val result = client.removeRoot("file:///test-root1")
+
+        // Verify the root was removed
+        assertTrue(result, "Root should be removed successfully")
+    }
+
+    @Test
+    fun `removeRoots should remove multiple roots`() = runTest {
+        val client = Client(
+            Implementation(name = "test client", version = "1.0"),
+            ClientOptions(
+                capabilities = ClientCapabilities(
+                    roots = ClientCapabilities.Roots(null)
+                )
+            )
+        )
+
+        // Add some roots
+        client.addRoots(
+            listOf(
+                Root(uri = "file:///test-root1", name = "testRoot1"),
+                Root(uri = "file:///test-root2", name = "testRoot2"),
+            )
+        )
+
+        // Remove multiple roots
+        val result = client.removeRoots(
+            listOf("file:///test-root1", "file:///test-root2")
+        )
+
+        // Verify the root was removed
+        assertEquals(2, result, "Both roots should be removed")
+    }
+
+    @Test
+    fun `sendRootsListChanged should notify server`() = runTest {
+        val client = Client(
+            Implementation(name = "test client", version = "1.0"),
+            ClientOptions(
+                capabilities = ClientCapabilities(
+                    roots = ClientCapabilities.Roots(listChanged = true)
+                )
+            )
+        )
+
+        val (clientTransport, serverTransport) = InMemoryTransport.createLinkedPair()
+
+        val server = Server(
+            serverInfo = Implementation(name = "test server", version = "1.0"),
+            options = ServerOptions(
+                capabilities = ServerCapabilities()
+            )
+        )
+
+        // Track notifications
+        var rootListChangedNotificationReceived = false
+        server.setNotificationHandler<RootsListChangedNotification>(Method.Defined.NotificationsRootsListChanged) {
+            rootListChangedNotificationReceived = true
+            CompletableDeferred(Unit)
+        }
+
+        listOf(
+            launch { client.connect(clientTransport) },
+            launch { server.connect(serverTransport) }
+        ).joinAll()
+
+        client.sendRootsListChanged()
+
+        assertTrue(
+            rootListChangedNotificationReceived,
+            "Notification should be sent when sendRootsListChanged is called"
+        )
+    }
 }