feat: add grpc support

apps/mcp-server/src/app.rs

@@ -437,6 +437,7 @@ fn runtime_error_code(error: &RuntimeError) -> &'static str {
         RuntimeError::Schema(_) => "schema_validation_error",
         RuntimeError::Mapping(_) => "mapping_error",
         RuntimeError::GraphqlAdapter(_) => "adapter_execution_error",
+        RuntimeError::GrpcAdapter(_) => "adapter_execution_error",
         RuntimeError::RestAdapter(_) => "adapter_execution_error",
         RuntimeError::UnsupportedProtocol { .. } => "unsupported_protocol",
         RuntimeError::InvalidPreparedRequest { .. } => "runtime_error",

apps/mcp-server/src/main.rs

@@ -49,9 +49,10 @@ mod tests {
     };
 
     use axum::{Json, Router, http::header, routing::post};
+    use mcpaas_adapter_grpc::test_support as grpc_test_support;
     use mcpaas_core::{
-        ExecutionConfig, GraphqlOperationType, GraphqlTarget, HttpMethod, Operation, OperationId,
-        OperationStatus, Protocol, RestTarget, Target, ToolDescription,
+        DescriptorId, ExecutionConfig, GraphqlOperationType, GraphqlTarget, GrpcTarget, HttpMethod,
+        Operation, OperationId, OperationStatus, Protocol, RestTarget, Target, ToolDescription,
     };
     use mcpaas_mapping::{MappingRule, MappingSet};
     use mcpaas_registry::{PostgresRegistry, PublishRequest};
@@ -183,6 +184,60 @@ mod tests {
         assert_eq!(call_result["result"]["isError"], false);
     }
 
+    #[tokio::test]
+    async fn initializes_and_calls_published_grpc_tool_via_mcp() {
+        let registry = test_registry().await;
+        let server_addr = grpc_test_support::spawn_unary_echo_server().await;
+        let operation = test_grpc_operation(&server_addr, "echo_unary_grpc");
+
+        registry
+            .create_operation(&operation, Some("alice"))
+            .await
+            .unwrap();
+        registry
+            .publish_operation(PublishRequest {
+                operation_id: &operation.id,
+                version: 1,
+                published_at: "2026-03-26T10:00:00Z",
+                published_by: Some("alice"),
+            })
+            .await
+            .unwrap();
+
+        let base_url = spawn_mcp_server(build_app(
+            registry,
+            Duration::from_millis(0),
+            Some("https://rmcp.example.com".to_owned()),
+        ))
+        .await;
+        let client = reqwest::Client::new();
+        let initialized_session = initialize_session(&client, &base_url).await;
+
+        let call_result = post_jsonrpc(
+            &client,
+            &base_url,
+            Some(&initialized_session),
+            json!({
+                "jsonrpc": "2.0",
+                "id": 3,
+                "method": "tools/call",
+                "params": {
+                    "name": "echo_unary_grpc",
+                    "arguments": {
+                        "message": "hello"
+                    }
+                }
+            }),
+        )
+        .await;
+
+        assert_eq!(
+            call_result["result"]["structuredContent"],
+            json!({ "message": "hello" })
+        );
+        assert_eq!(call_result["result"]["isError"], false);
+    }
+
     #[tokio::test]
     async fn requires_initialized_notification_before_tool_methods() {
         let registry = test_registry().await;
@@ -572,6 +627,68 @@ mod tests {
         }
     }
 
+    fn test_grpc_operation(server_addr: &str, name: &str) -> Operation<Schema, MappingSet> {
+        Operation {
+            id: OperationId::new(format!("op_{name}")),
+            name: name.to_owned(),
+            display_name: "Unary Echo gRPC".to_owned(),
+            protocol: Protocol::Grpc,
+            status: OperationStatus::Published,
+            version: 1,
+            target: Target::Grpc(GrpcTarget {
+                server_addr: server_addr.to_owned(),
+                package: "echo".to_owned(),
+                service: "EchoService".to_owned(),
+                method: "UnaryEcho".to_owned(),
+                descriptor_ref: DescriptorId::new("desc_echo"),
+                descriptor_set_b64: grpc_test_support::descriptor_set_b64(),
+            }),
+            input_schema: object_schema("message"),
+            output_schema: object_schema("message"),
+            input_mapping: MappingSet {
+                rules: vec![MappingRule {
+                    source: "$.mcp.message".to_owned(),
+                    target: "$.request.grpc.message".to_owned(),
+                    required: true,
+                    default_value: None,
+                    transform: None,
+                    condition: None,
+                    notes: None,
+                }],
+            },
+            output_mapping: MappingSet {
+                rules: vec![MappingRule {
+                    source: "$.response.data.message".to_owned(),
+                    target: "$.output.message".to_owned(),
+                    required: true,
+                    default_value: None,
+                    transform: None,
+                    condition: None,
+                    notes: None,
+                }],
+            },
+            execution_config: ExecutionConfig {
+                timeout_ms: 1_000,
+                retry_policy: None,
+                auth_profile_ref: None,
+                headers: BTreeMap::new(),
+                protocol_options: None,
+            },
+            tool_description: ToolDescription {
+                title: "Unary Echo gRPC".to_owned(),
+                description: "Echoes a unary gRPC payload".to_owned(),
+                tags: vec!["grpc".to_owned()],
+                examples: Vec::new(),
+            },
+            samples: None,
+            generated_draft: None,
+            config_export: None,
+            created_at: "2026-03-26T10:00:00Z".to_owned(),
+            updated_at: "2026-03-26T10:00:00Z".to_owned(),
+            published_at: Some("2026-03-26T10:00:00Z".to_owned()),
+        }
+    }
+
     fn object_schema(field_name: &str) -> Schema {
         Schema {
             kind: SchemaKind::Object,