feat!: upgrade to slim-bindings-java 3.3 and expose the verified caller identity

.github/workflows/ci.yaml

@@ -31,7 +31,7 @@ jobs:
         uses: ./.github/actions/setup-java
 
       - name: Install protoc-gen-slimrpc-java
-        run: cargo install agntcy-protoc-slimrpc-plugin --version 2.0.0 --locked
+        run: cargo install agntcy-protoc-slimrpc-plugin --version 3.0.0 --locked
 
       - uses: bufbuild/buf-setup-action@a47c93e0b1648d5651a065437926377d060baa99 # v1.50.0
         with:

.github/workflows/codeql.yaml

@@ -40,7 +40,7 @@ jobs:
         uses: ./.github/actions/setup-java
 
       - name: Install protoc-gen-slimrpc-java
-        run: cargo install agntcy-protoc-slimrpc-plugin --version 2.0.0 --locked
+        run: cargo install agntcy-protoc-slimrpc-plugin --version 3.0.0 --locked
 
       - uses: bufbuild/buf-setup-action@a47c93e0b1648d5651a065437926377d060baa99 # v1.50.0
         with:

README.md

@@ -41,7 +41,7 @@ slim-a2a-java/
 
 The library depends on:
 
-- `io.agntcy.slim:slim-bindings-java` 2.0.x -- SLIM Java bindings (Foreign Function & Memory API based)
+- `io.agntcy.slim:slim-bindings-java` 3.3.x -- SLIM Java bindings (Foreign Function & Memory API based)
 - `org.a2aproject.sdk:a2a-java-sdk-server-common` -- A2A SDK server core
 - `org.a2aproject.sdk:a2a-java-sdk-spec-grpc` -- A2A protobuf types and ProtoUtils mappers
 
@@ -71,13 +71,13 @@ The generated stubs are checked in under `slim-a2a/generated/slimrpc/`. To regen
 task generate
 ```
 
-This requires `protoc-gen-slimrpc-java` 2.0.x on your PATH:
+This requires `protoc-gen-slimrpc-java` 3.0.x on your PATH:
 
 ```bash
-cargo install agntcy-protoc-slimrpc-plugin --version 2.0.0 --locked
+cargo install agntcy-protoc-slimrpc-plugin --version 3.0.0 --locked
 ```
 
-Older plugin versions emit imports from the pre-2.0 package layout and will not compile against `slim-bindings-java` 2.0.
+Plugin versions older than 2.0 emit imports from the pre-2.0 package layout and will not compile against `slim-bindings-java` 3.x.
 
 ## Running the Echo Agent Example
 
@@ -164,9 +164,28 @@ Every member of a SLIM session needs a compatible identity type, so the server a
 its clients must agree on the provider/verifier kind. `SlimHelper.sharedSecretProvider`
 and `sharedSecretVerifier` build the shared-secret configs used by the shortcut overloads.
 
-With slim-bindings-java 2.0, the SlimRPC handler context does not expose the caller's
-verified identity, so `SlimA2AHandler` still reports an anonymous user to the A2A
-`RequestHandler`.
+### Caller identity
+
+`SlimA2AHandler` passes the caller's verified SLIM identity to the A2A `RequestHandler`
+as the `ServerCallContext` user. The identity comes from the MLS session token
+(`Context.peerSubject()` / `peerIssuer()`), never from request metadata. When the
+token has a subject, the user is a `SlimUser`. Otherwise the user is anonymous and
+unauthenticated:
+
+```java
+@Override
+public void execute(RequestContext context, AgentEmitter emitter) {
+    User user = context.getCallContext().getUser();
+    if (user instanceof SlimUser caller) {
+        String subject = caller.getSubject(); // token `sub`, also user.getUsername()
+        String issuer = caller.getIssuer();   // token `iss`, or null
+    }
+}
+```
+
+`getAttribute("sub")` and `getAttribute("iss")` return the same values. In group
+sessions the subject is that of the MLS sender of the request. With a shared secret,
+the subject is self-asserted: anyone who holds the secret can claim any name.
 
 ## Architecture
 

examples/echo-agent/src/main/java/io/agntcy/slim/a2a/examples/echo/EchoAgentExecutor.java

@@ -36,7 +36,11 @@ public final class EchoAgentExecutor implements AgentExecutor {
     @Override
     public void execute(RequestContext context, AgentEmitter emitter) throws A2AError {
         String userInput = context.getUserInput();
-        System.out.println("[EchoAgent] request contextId=" + context.getContextId()
+        var caller = context.getCallContext() != null ? context.getCallContext().getUser() : null;
+        System.out.println("[EchoAgent] request caller="
+                + (caller != null ? caller.getUsername() : "unknown")
+                + " authenticated=" + (caller != null && caller.isAuthenticated())
+                + " contextId=" + context.getContextId()
                 + " taskId=" + emitter.getTaskId() + " userText=" + userInput);
 
         if (userInput.startsWith(STREAM_PREFIX)) {

pom.xml

@@ -44,7 +44,7 @@
         <maven.compiler.source>21</maven.compiler.source>
         <maven.compiler.target>21</maven.compiler.target>
 
-        <slim.bindings.version>2.0.0</slim.bindings.version>
+        <slim.bindings.version>3.3.2</slim.bindings.version>
         <a2a.java.sdk.version>1.1.0.Final</a2a.java.sdk.version>
         <protobuf.version>4.33.2</protobuf.version>
         <jna.version>5.14.0</jna.version>

slim-a2a/src/main/java/io/agntcy/slim/a2a/NativeLibraryLoader.java

@@ -18,7 +18,7 @@
  * it, restoring the "just works" behavior the JNA-based 1.3.x loader used to
  * provide.
  *
- * <p>slim-bindings-java 2.0 exposes two UniFFI namespaces — {@code slim_bindings}
+ * <p>slim-bindings-java 2.0 and later expose two UniFFI namespaces — {@code slim_bindings}
  * for the transport and {@code slim_rpc} for SlimRPC — that are compiled into the
  * same shared object, so both overrides are pointed at the same extracted file.
  */

slim-a2a/src/main/java/io/agntcy/slim/a2a/SlimA2AHandler.java

@@ -10,6 +10,7 @@
 import java.util.concurrent.Flow;
 
 import io.agntcy.slim.bindings.slimrpc.Context;
+import io.agntcy.slim.bindings.slimrpc.ContextInterface;
 import io.agntcy.slim.bindings.slimrpc.ResponseSink;
 import io.agntcy.slim.bindings.slimrpc.RpcCode;
 import io.agntcy.slim.bindings.slimrpc.RpcException;
@@ -24,6 +25,10 @@
 /**
  * Adapts a {@link RequestHandler} to the generated {@link A2AServiceSlimrpc.A2AServiceServer}
  * contract, bridging A2A SDK domain types and protobuf wire types via {@link ProtoUtils}.
+ *
+ * <p>Each request's {@link ServerCallContext} user is the caller's verified SLIM
+ * identity ({@link SlimUser}) when the session token carries a subject, and an
+ * unauthenticated anonymous user otherwise.
  */
 public final class SlimA2AHandler implements A2AServiceSlimrpc.A2AServiceServer {
 
@@ -45,7 +50,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.SendMessageResponse> SendMessag
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.messageSendParams(request);
-                var result = requestHandler.onMessageSend(params, newCallContext());
+                var result = requestHandler.onMessageSend(params, newCallContext(context));
                 return ProtoUtils.ToProto.taskOrMessage(result);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -60,7 +65,7 @@ public CompletableFuture<Void> SendStreamingMessage(
             try {
                 var params = ProtoUtils.FromProto.messageSendParams(request);
                 Flow.Publisher<StreamingEventKind> publisher =
-                        requestHandler.onMessageSendStream(params, newCallContext());
+                        requestHandler.onMessageSendStream(params, newCallContext(context));
                 streamToSink(publisher, sink);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -74,7 +79,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.Task> GetTask(
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.taskQueryParams(request);
-                var task = requestHandler.onGetTask(params, newCallContext());
+                var task = requestHandler.onGetTask(params, newCallContext(context));
                 return ProtoUtils.ToProto.task(task);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -88,7 +93,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.ListTasksResponse> ListTasks(
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.listTasksParams(request);
-                var result = requestHandler.onListTasks(params, newCallContext());
+                var result = requestHandler.onListTasks(params, newCallContext(context));
                 return ProtoUtils.ToProto.listTasksResult(result);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -102,7 +107,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.Task> CancelTask(
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.cancelTaskParams(request);
-                var task = requestHandler.onCancelTask(params, newCallContext());
+                var task = requestHandler.onCancelTask(params, newCallContext(context));
                 return ProtoUtils.ToProto.task(task);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -117,7 +122,7 @@ public CompletableFuture<Void> SubscribeToTask(
             try {
                 var params = ProtoUtils.FromProto.taskIdParams(request);
                 Flow.Publisher<StreamingEventKind> publisher =
-                        requestHandler.onSubscribeToTask(params, newCallContext());
+                        requestHandler.onSubscribeToTask(params, newCallContext(context));
                 streamToSink(publisher, sink);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -131,7 +136,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.TaskPushNotificationConfig> Cre
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.createTaskPushNotificationConfig(request);
-                var result = requestHandler.onCreateTaskPushNotificationConfig(params, newCallContext());
+                var result = requestHandler.onCreateTaskPushNotificationConfig(params, newCallContext(context));
                 return ProtoUtils.ToProto.taskPushNotificationConfig(result);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -145,7 +150,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.TaskPushNotificationConfig> Get
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.getTaskPushNotificationConfigParams(request);
-                var result = requestHandler.onGetTaskPushNotificationConfig(params, newCallContext());
+                var result = requestHandler.onGetTaskPushNotificationConfig(params, newCallContext(context));
                 return ProtoUtils.ToProto.taskPushNotificationConfig(result);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -159,7 +164,7 @@ public CompletableFuture<org.a2aproject.sdk.grpc.ListTaskPushNotificationConfigs
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.listTaskPushNotificationConfigsParams(request);
-                var result = requestHandler.onListTaskPushNotificationConfigs(params, newCallContext());
+                var result = requestHandler.onListTaskPushNotificationConfigs(params, newCallContext(context));
                 return ProtoUtils.ToProto.listTaskPushNotificationConfigsResponse(result);
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
@@ -179,16 +184,38 @@ public CompletableFuture<com.google.protobuf.Empty> DeleteTaskPushNotificationCo
         return CompletableFuture.supplyAsync(() -> {
             try {
                 var params = ProtoUtils.FromProto.deleteTaskPushNotificationConfigParams(request);
-                requestHandler.onDeleteTaskPushNotificationConfig(params, newCallContext());
+                requestHandler.onDeleteTaskPushNotificationConfig(params, newCallContext(context));
                 return com.google.protobuf.Empty.getDefaultInstance();
             } catch (A2AError e) {
                 throw new CompletionException(A2ARpcErrorMapping.toRpc(e));
             }
         });
     }
 
-    private ServerCallContext newCallContext() {
-        return new ServerCallContext(ANONYMOUS_USER, Map.of(), Collections.emptySet());
+    /**
+     * Raw SlimRPC metadata (routing keys, {@code slim-peer-subject},
+     * {@code slim-payload-sig}, ...) is deliberately not copied into the call
+     * context's state or requested extensions.
+     */
+    static ServerCallContext newCallContext(ContextInterface context) {
+        return new ServerCallContext(callerOf(context), Map.of(), Collections.emptySet());
+    }
+
+    /**
+     * The caller's verified SLIM identity, taken only from the MLS session token
+     * ({@link ContextInterface#peerSubject()} / {@link ContextInterface#peerIssuer()}),
+     * never from caller-supplied metadata. Falls back to an anonymous user when the
+     * session carries no subject.
+     */
+    static User callerOf(ContextInterface context) {
+        if (context == null) {
+            return ANONYMOUS_USER;
+        }
+        String subject = context.peerSubject();
+        if (subject == null || subject.isBlank()) {
+            return ANONYMOUS_USER;
+        }
+        return new SlimUser(subject, context.peerIssuer());
     }
 
     /**

slim-a2a/src/main/java/io/agntcy/slim/a2a/SlimUser.java

@@ -0,0 +1,86 @@
+// Copyright AGNTCY Contributors (https://github.com/agntcy)
+// SPDX-License-Identifier: Apache-2.0
+
+package io.agntcy.slim.a2a;
+
+import java.util.Objects;
+
+import org.a2aproject.sdk.server.auth.User;
+
+/**
+ * The verified SLIM identity of an A2A caller, as reported by the SlimRPC
+ * {@link io.agntcy.slim.bindings.slimrpc.Context}. The subject and issuer come
+ * from the peer's MLS session token, never from request metadata.
+ *
+ * <p>{@link #getUsername()} is the token subject ({@code sub}). The subject and
+ * issuer are also available as the {@code "sub"} and {@code "iss"} attributes.
+ */
+public final class SlimUser implements User {
+
+    /** Attribute name for the verified token subject. */
+    public static final String SUBJECT_ATTRIBUTE = "sub";
+    /** Attribute name for the verified token issuer. */
+    public static final String ISSUER_ATTRIBUTE = "iss";
+
+    private final String subject;
+    private final String issuer;
+
+    /**
+     * @param subject the verified token subject; must not be blank
+     * @param issuer  the verified token issuer, or {@code null} if the token has none
+     */
+    public SlimUser(String subject, String issuer) {
+        Objects.requireNonNull(subject, "subject");
+        if (subject.isBlank()) {
+            throw new IllegalArgumentException("subject must not be blank");
+        }
+        this.subject = subject;
+        this.issuer = issuer == null || issuer.isBlank() ? null : issuer;
+    }
+
+    /** The verified token subject ({@code sub}). */
+    public String getSubject() {
+        return subject;
+    }
+
+    /** The verified token issuer ({@code iss}), or {@code null} if the token has none. */
+    public String getIssuer() {
+        return issuer;
+    }
+
+    @Override
+    public boolean isAuthenticated() {
+        return true;
+    }
+
+    @Override
+    public String getUsername() {
+        return subject;
+    }
+
+    @Override
+    public Object getAttribute(String name) {
+        return switch (name) {
+            case SUBJECT_ATTRIBUTE -> subject;
+            case ISSUER_ATTRIBUTE -> issuer;
+            case null, default -> null;
+        };
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        return o instanceof SlimUser other
+                && subject.equals(other.subject)
+                && Objects.equals(issuer, other.issuer);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(subject, issuer);
+    }
+
+    @Override
+    public String toString() {
+        return "SlimUser[subject=" + subject + ", issuer=" + issuer + "]";
+    }
+}