Fix Serena MCP server URL to use host.docker.internal

pkg/workflow/importable_tools_test.go

@@ -160,8 +160,8 @@ Uses imported serena tool.
 	if !strings.Contains(workflowData, "uvx --from git+https://github.com/oraios/serena") {
 		t.Error("Expected compiled workflow to use uvx to start Serena")
 	}
-	if !strings.Contains(workflowData, "http://localhost:9121") {
-		t.Error("Expected compiled workflow to contain Serena HTTP URL")
+	if !strings.Contains(workflowData, "http://host.docker.internal:9121") {
+		t.Error("Expected compiled workflow to contain Serena HTTP URL with host.docker.internal")
 	}
 
 	// Verify that language service setup steps ARE present
@@ -324,8 +324,8 @@ Uses all imported tools.
 	if !strings.Contains(workflowData, "mcr.microsoft.com/playwright/mcp") {
 		t.Error("Expected compiled workflow to contain playwright Docker image")
 	}
-	if !strings.Contains(workflowData, "http://localhost:9121") {
-		t.Error("Expected compiled workflow to contain Serena HTTP URL")
+	if !strings.Contains(workflowData, "http://host.docker.internal:9121") {
+		t.Error("Expected compiled workflow to contain Serena HTTP URL with host.docker.internal")
 	}
 	if !strings.Contains(workflowData, "example.com") {
 		t.Error("Expected compiled workflow to contain example.com domain for playwright")

pkg/workflow/mcp-config.go

@@ -147,7 +147,8 @@ func renderPlaywrightMCPConfigWithOptions(yaml *strings.Builder, playwrightTool
 
 // renderSerenaMCPConfigWithOptions generates the Serena MCP server configuration with engine-specific options
 // Serena now runs using uvx with HTTP transport in the agent job (not containerized)
-// The HTTP server is started in a background step and accessed via http://localhost:9121
+// The HTTP server is started in a background step and accessed via http://host.docker.internal:9121
+// Note: host.docker.internal is used because the MCP gateway runs in a container and needs to reach the host
 func renderSerenaMCPConfigWithOptions(yaml *strings.Builder, serenaTool any, isLast bool, includeCopilotFields bool, inlineArgs bool) {
 	yaml.WriteString("              \"serena\": {\n")
 
@@ -157,7 +158,8 @@ func renderSerenaMCPConfigWithOptions(yaml *strings.Builder, serenaTool any, isL
 	}
 
 	// HTTP URL for Serena MCP server running on host
-	yaml.WriteString("                \"url\": \"http://localhost:9121\"\n")
+	// Use host.docker.internal so the gateway container can reach the host
+	yaml.WriteString("                \"url\": \"http://host.docker.internal:9121\"\n")
 
 	// Note: tools field is NOT included here - the converter script adds it back
 	// for Copilot. This keeps the gateway config compatible with the schema.

pkg/workflow/mcp_config_comprehensive_test.go

@@ -574,7 +574,7 @@ func TestRenderSerenaMCPConfigWithOptions(t *testing.T) {
 			inlineArgs:           false,
 			expectedContent: []string{
 				`"serena": {`,
-				`"url": "http://localhost:9121"`,
+				`"url": "http://host.docker.internal:9121"`,
 				`              },`,
 			},
 			unexpectedContent: []string{
@@ -593,7 +593,7 @@ func TestRenderSerenaMCPConfigWithOptions(t *testing.T) {
 			inlineArgs:           false,
 			expectedContent: []string{
 				`"serena": {`,
-				`"url": "http://localhost:9121"`,
+				`"url": "http://host.docker.internal:9121"`,
 				`              }`,
 			},
 			unexpectedContent: []string{
@@ -612,7 +612,7 @@ func TestRenderSerenaMCPConfigWithOptions(t *testing.T) {
 			expectedContent: []string{
 				`"serena": {`,
 				`"type": "http"`,
-				`"url": "http://localhost:9121"`,
+				`"url": "http://host.docker.internal:9121"`,
 			},
 			unexpectedContent: []string{
 				`"container"`,
@@ -627,7 +627,7 @@ func TestRenderSerenaMCPConfigWithOptions(t *testing.T) {
 			expectedContent: []string{
 				`"serena": {`,
 				`"type": "http"`,
-				`"url": "http://localhost:9121"`,
+				`"url": "http://host.docker.internal:9121"`,
 			},
 			unexpectedContent: []string{
 				`"container"`,
@@ -644,7 +644,7 @@ func TestRenderSerenaMCPConfigWithOptions(t *testing.T) {
 			inlineArgs:           false,
 			expectedContent: []string{
 				`"serena": {`,
-				`"url": "http://localhost:9121"`,
+				`"url": "http://host.docker.internal:9121"`,
 			},
 			unexpectedContent: []string{
 				`"container"`,

pkg/workflow/mcp_renderer.go

@@ -186,11 +186,12 @@ func (r *MCPConfigRendererUnified) RenderSerenaMCP(yaml *strings.Builder, serena
 
 // renderSerenaTOML generates Serena MCP configuration in TOML format
 // Serena now runs using uvx with HTTP transport in the agent job (not containerized)
-// The HTTP server is started in a background step and accessed via http://localhost:9121
+// The HTTP server is started in a background step and accessed via http://host.docker.internal:9121
+// Note: host.docker.internal is used because the MCP gateway runs in a container and needs to reach the host
 func (r *MCPConfigRendererUnified) renderSerenaTOML(yaml *strings.Builder, serenaTool any) {
 	yaml.WriteString("          \n")
 	yaml.WriteString("          [mcp_servers.serena]\n")
-	yaml.WriteString("          url = \"http://localhost:9121\"\n")
+	yaml.WriteString("          url = \"http://host.docker.internal:9121\"\n")
 }
 
 // RenderSafeOutputsMCP generates the Safe Outputs MCP server configuration