feat: enhance MCP server configuration with support for SSE type and update JSON structure

Author: 35C4n0r

README.md

@@ -143,6 +143,7 @@ The file uses the same format as Claude's MCP configuration:
 ```json
 {
   "mcpServers": {
+    "type": "stdio",
     "filesystem": {
       "command": "npx",
       "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/dir"],

e2e/echo_test.go

@@ -580,7 +580,7 @@ func TestServerFlagValidation(t *testing.T) {
 		// Create a temporary MCP file
 		tmpDir := t.TempDir()
 		mcpFile := filepath.Join(tmpDir, "mcp.json")
-		err := os.WriteFile(mcpFile, []byte(`{"mcpServers": []}`), 0o644)
+		err := os.WriteFile(mcpFile, []byte(`{"mcpServers": {}}`), 0o644)
 		require.NoError(t, err, "Failed to create temp MCP file")
 
 		// Run the server with --mcp-file but WITHOUT --experimental-acp

x/acpio/mcp.go

@@ -1,6 +1,8 @@
 package acpio
 
 import (
+	"slices"
+
 	"github.com/coder/acp-go-sdk"
 	"golang.org/x/xerrors"
 )
@@ -13,31 +15,23 @@ type AgentapiMcpConfig struct {
 
 // AgentapiMcpServer represents a single MCP server in Claude's format.
 type AgentapiMcpServer struct {
-	// Type can be "stdio" or "http". Defaults to "stdio" if not specified.
-	Type string `json:"type,omitempty"`
+	// Type can be "stdio", "sse" or "http"
+	Type string `json:"type"`
 	// Stdio transport fields
 	Command string            `json:"command,omitempty"`
 	Args    []string          `json:"args,omitempty"`
 	Env     map[string]string `json:"env,omitempty"`
-	// HTTP transport fields
+	// HTTP | SSE transport fields
 	URL     string            `json:"url,omitempty"`
 	Headers map[string]string `json:"headers,omitempty"`
 }
 
 // convertAgentapiMcpToAcp converts a Claude MCP server config to the ACP format.
 func (a *AgentapiMcpServer) convertAgentapiMcpToAcp(name string) (acp.McpServer, error) {
 	serverType := a.Type
-	if serverType == "" {
-		// Default to stdio if no type specified and command is present
-		if a.Command != "" {
-			serverType = "stdio"
-		} else if a.URL != "" {
-			serverType = "http"
-		}
-	}
+	acpMCPServer := acp.McpServer{}
 
-	switch serverType {
-	case "stdio", "":
+	if serverType == "stdio" {
 		if a.Command == "" {
 			return acp.McpServer{}, xerrors.Errorf("stdio server %q missing command", name)
 		}
@@ -49,16 +43,14 @@ func (a *AgentapiMcpServer) convertAgentapiMcpToAcp(name string) (acp.McpServer,
 				Value: value,
 			})
 		}
-		return acp.McpServer{
-			Stdio: &acp.McpServerStdio{
-				Name:    name,
-				Command: a.Command,
-				Args:    a.Args,
-				Env:     envVars,
-			},
-		}, nil
 
-	case "http":
+		acpMCPServer.Stdio = &acp.McpServerStdio{
+			Name:    name,
+			Command: a.Command,
+			Args:    a.Args,
+			Env:     envVars,
+		}
+	} else if slices.Contains([]string{"http", "sse"}, serverType) {
 		if a.URL == "" {
 			return acp.McpServer{}, xerrors.Errorf("http server %q missing url", name)
 		}
@@ -70,16 +62,24 @@ func (a *AgentapiMcpServer) convertAgentapiMcpToAcp(name string) (acp.McpServer,
 				Value: value,
 			})
 		}
-		return acp.McpServer{
-			Http: &acp.McpServerHttp{
+
+		if serverType == "sse" {
+			acpMCPServer.Sse = &acp.McpServerSse{
+				Name:    name,
+				Type:    "sse",
+				Url:     a.URL,
+				Headers: headers,
+			}
+		} else {
+			acpMCPServer.Http = &acp.McpServerHttp{
 				Name:    name,
 				Type:    "http",
 				Url:     a.URL,
 				Headers: headers,
-			},
-		}, nil
-
-	default:
+			}
+		}
+	} else {
 		return acp.McpServer{}, xerrors.Errorf("unsupported server type %q for server %q", serverType, name)
 	}
+	return acpMCPServer, nil
 }

x/acpio/mcp_internal_test.go

@@ -252,6 +252,7 @@ func TestGetSupportedMCPConfig(t *testing.T) {
 func TestConvertAgentapiMcpToAcp(t *testing.T) {
 	t.Run("converts stdio server correctly", func(t *testing.T) {
 		server := AgentapiMcpServer{
+			Type:    "stdio",
 			Command: "/usr/bin/mcp-server",
 			Args:    []string{"--arg1", "--arg2"},
 			Env: map[string]string{