feat: restore XML tool protocol option for OpenAI-Compatible provider

This restores the ability for users of the OpenAI-Compatible provider to
explicitly select XML tool protocol, fixing compatibility issues with
backends like SGLang/vLLM that do not support native tool calling.

Changes:
- Modified resolveToolProtocol.ts to respect user toolProtocol preference
  for the OpenAI-Compatible provider ("openai")
- Added Tool Protocol selector to OpenAICompatible.tsx component
- Added tests for the new behavior in resolveToolProtocol.spec.ts
- Updated OpenAICompatible.spec.tsx to mock Select components

Fixes RooCodeInc#10319

src/utils/__tests__/resolveToolProtocol.spec.ts

@@ -48,8 +48,47 @@ describe("resolveToolProtocol", () => {
 		})
 	})
 
-	describe("Native Protocol Always Used For New Tasks", () => {
-		it("should always use native for new tasks", () => {
+	describe("OpenAI-Compatible Provider Tool Protocol", () => {
+		it("should respect XML preference for OpenAI-Compatible provider", () => {
+			const settings: ProviderSettings = {
+				apiProvider: "openai",
+				toolProtocol: "xml",
+			}
+			// OpenAI-Compatible provider should respect user preference
+			const result = resolveToolProtocol(settings)
+			expect(result).toBe(TOOL_PROTOCOL.XML)
+		})
+
+		it("should respect native preference for OpenAI-Compatible provider", () => {
+			const settings: ProviderSettings = {
+				apiProvider: "openai",
+				toolProtocol: "native",
+			}
+			const result = resolveToolProtocol(settings)
+			expect(result).toBe(TOOL_PROTOCOL.NATIVE)
+		})
+
+		it("should default to native when no preference set for OpenAI-Compatible provider", () => {
+			const settings: ProviderSettings = {
+				apiProvider: "openai",
+			}
+			const result = resolveToolProtocol(settings, openAiModelInfoSaneDefaults)
+			expect(result).toBe(TOOL_PROTOCOL.NATIVE)
+		})
+
+		it("should still honor locked protocol over user preference for OpenAI-Compatible", () => {
+			const settings: ProviderSettings = {
+				apiProvider: "openai",
+				toolProtocol: "xml", // User wants XML
+			}
+			// Locked protocol takes precedence
+			const result = resolveToolProtocol(settings, undefined, "native")
+			expect(result).toBe(TOOL_PROTOCOL.NATIVE)
+		})
+	})
+
+	describe("Native Protocol Always Used For Other Providers", () => {
+		it("should always use native for new tasks with other providers", () => {
 			const settings: ProviderSettings = {
 				apiProvider: "anthropic",
 			}
@@ -57,20 +96,21 @@ describe("resolveToolProtocol", () => {
 			expect(result).toBe(TOOL_PROTOCOL.NATIVE)
 		})
 
-		it("should use native even when user preference is XML (user prefs ignored)", () => {
+		it("should use native even when user preference is XML for non-OpenAI-Compatible providers", () => {
 			const settings: ProviderSettings = {
-				toolProtocol: "xml", // User wants XML - ignored
+				toolProtocol: "xml", // User wants XML - ignored for non-OpenAI-Compatible
 				apiProvider: "openai-native",
 			}
 			const result = resolveToolProtocol(settings)
 			expect(result).toBe(TOOL_PROTOCOL.NATIVE)
 		})
 
-		it("should use native for OpenAI compatible provider", () => {
+		it("should ignore XML preference for Anthropic provider", () => {
 			const settings: ProviderSettings = {
-				apiProvider: "openai",
+				toolProtocol: "xml", // User preference - ignored for Anthropic
+				apiProvider: "anthropic",
 			}
-			const result = resolveToolProtocol(settings, openAiModelInfoSaneDefaults)
+			const result = resolveToolProtocol(settings)
 			expect(result).toBe(TOOL_PROTOCOL.NATIVE)
 		})
 	})

src/utils/resolveToolProtocol.ts

@@ -15,21 +15,23 @@ type ApiMessageForDetection = Anthropic.MessageParam & {
  * Resolve the effective tool protocol.
  *
  * **Deprecation Note (XML Protocol):**
- * XML tool protocol has been deprecated. All models now use Native tool calling.
- * User/profile preferences (`providerSettings.toolProtocol`) and model defaults
- * (`modelInfo.defaultToolProtocol`) are ignored.
+ * XML tool protocol has been deprecated for most providers. All models now use
+ * Native tool calling by default. However, for the OpenAI-Compatible provider,
+ * users can explicitly opt for XML protocol when their backend servers (like
+ * SGLang, vLLM, etc.) don't support native tool calling.
  *
  * Precedence:
  * 1. Locked Protocol (task-level lock for resumed tasks - highest priority)
- * 2. Native (always, for all new tasks)
+ * 2. User Preference for OpenAI-Compatible provider (respects toolProtocol setting)
+ * 3. Native (default for all new tasks)
  *
- * @param _providerSettings - The provider settings (toolProtocol field is ignored)
+ * @param providerSettings - The provider settings (toolProtocol respected for OpenAI-Compatible)
  * @param _modelInfo - Unused, kept for API compatibility
  * @param lockedProtocol - Optional task-locked protocol that takes absolute precedence
  * @returns The resolved tool protocol (either "xml" or "native")
  */
 export function resolveToolProtocol(
-	_providerSettings: ProviderSettings,
+	providerSettings: ProviderSettings,
 	_modelInfo?: unknown,
 	lockedProtocol?: ToolProtocol,
 ): ToolProtocol {
@@ -39,8 +41,15 @@ export function resolveToolProtocol(
 		return lockedProtocol
 	}
 
-	// 2. Always return Native protocol for new tasks
-	// All models now support native tools; XML is deprecated
+	// 2. For OpenAI-Compatible provider, respect user preference
+	// Some backends (SGLang, vLLM, etc.) don't support native tool calling
+	// and require XML protocol to work properly
+	if (providerSettings.apiProvider === "openai" && providerSettings.toolProtocol) {
+		return providerSettings.toolProtocol
+	}
+
+	// 3. Default to Native protocol for new tasks
+	// Most providers support native tools; XML is deprecated for other providers
 	return TOOL_PROTOCOL.NATIVE
 }
 

webview-ui/src/components/settings/providers/OpenAICompatible.tsx

@@ -8,6 +8,7 @@ import {
 	type ModelInfo,
 	type ReasoningEffort,
 	type OrganizationAllowList,
+	type ToolProtocol,
 	azureOpenAiDefaultApiVersion,
 	openAiModelInfoSaneDefaults,
 } from "@roo-code/types"
@@ -15,7 +16,15 @@ import {
 import { ExtensionMessage } from "@roo/ExtensionMessage"
 
 import { useAppTranslation } from "@src/i18n/TranslationContext"
-import { Button, StandardTooltip } from "@src/components/ui"
+import {
+	Button,
+	StandardTooltip,
+	Select,
+	SelectContent,
+	SelectItem,
+	SelectTrigger,
+	SelectValue,
+} from "@src/components/ui"
 
 import { convertHeadersToObject } from "../utils/headers"
 import { inputEventTransform, noTransform } from "../transforms"
@@ -170,6 +179,24 @@ export const OpenAICompatible = ({
 				onChange={handleInputChange("openAiStreamingEnabled", noTransform)}>
 				{t("settings:modelInfo.enableStreaming")}
 			</Checkbox>
+			{/* Tool Protocol selector for backends that don't support native tool calling */}
+			<div>
+				<label className="block font-medium mb-1">{t("settings:toolProtocol.label")}</label>
+				<Select
+					value={apiConfiguration?.toolProtocol || "native"}
+					onValueChange={(value) => setApiConfigurationField("toolProtocol", value as ToolProtocol)}>
+					<SelectTrigger className="w-full">
+						<SelectValue placeholder={t("settings:common.select")} />
+					</SelectTrigger>
+					<SelectContent>
+						<SelectItem value="native">{t("settings:toolProtocol.native")}</SelectItem>
+						<SelectItem value="xml">{t("settings:toolProtocol.xml")}</SelectItem>
+					</SelectContent>
+				</Select>
+				<div className="text-sm text-vscode-descriptionForeground mt-1">
+					{t("settings:toolProtocol.description")}
+				</div>
+			</div>
 			<div>
 				<Checkbox
 					checked={apiConfiguration?.includeMaxTokens ?? true}

webview-ui/src/components/settings/providers/__tests__/OpenAICompatible.spec.tsx

@@ -65,6 +65,15 @@ vi.mock("@src/i18n/TranslationContext", () => ({
 vi.mock("@src/components/ui", () => ({
 	Button: ({ children, onClick }: any) => <button onClick={onClick}>{children}</button>,
 	StandardTooltip: ({ children, content }: any) => <div title={content}>{children}</div>,
+	Select: ({ children, value, onValueChange: _onValueChange }: any) => (
+		<div data-testid="select" data-value={value}>
+			{children}
+		</div>
+	),
+	SelectContent: ({ children }: any) => <div data-testid="select-content">{children}</div>,
+	SelectItem: ({ children, value }: any) => <div data-testid={`select-item-${value}`}>{children}</div>,
+	SelectTrigger: ({ children }: any) => <button data-testid="select-trigger">{children}</button>,
+	SelectValue: ({ placeholder }: any) => <span data-testid="select-value">{placeholder}</span>,
 }))
 
 // Mock other components