feat: add xhigh reasoning effort for gpt-5.1-codex-max (#9900)

* feat: add xhigh reasoning effort for gpt-5.1-codex-max

* fix: Address openai-native.spec.ts test failure

* chore: Localisation of 'Extra high'

* chore: revert unrelated CustomModesManager refactoring

---------

Co-authored-by: Hannes Rudolph <hrudolph@gmail.com>

Author: andrewginns

packages/types/src/model.ts

@@ -22,7 +22,7 @@ export type ReasoningEffortWithMinimal = z.infer<typeof reasoningEffortWithMinim
  * Extended Reasoning Effort (includes "none" and "minimal")
  * Note: "disable" is a UI/control value, not a value sent as effort
  */
-export const reasoningEffortsExtended = ["none", "minimal", "low", "medium", "high"] as const
+export const reasoningEffortsExtended = ["none", "minimal", "low", "medium", "high", "xhigh"] as const
 
 export const reasoningEffortExtendedSchema = z.enum(reasoningEffortsExtended)
 
@@ -31,7 +31,7 @@ export type ReasoningEffortExtended = z.infer<typeof reasoningEffortExtendedSche
 /**
  * Reasoning Effort user setting (includes "disable")
  */
-export const reasoningEffortSettingValues = ["disable", "none", "minimal", "low", "medium", "high"] as const
+export const reasoningEffortSettingValues = ["disable", "none", "minimal", "low", "medium", "high", "xhigh"] as const
 export const reasoningEffortSettingSchema = z.enum(reasoningEffortSettingValues)
 
 /**
@@ -88,7 +88,7 @@ export const modelInfoSchema = z.object({
 	defaultTemperature: z.number().optional(),
 	requiredReasoningBudget: z.boolean().optional(),
 	supportsReasoningEffort: z
-		.union([z.boolean(), z.array(z.enum(["disable", "none", "minimal", "low", "medium", "high"]))])
+		.union([z.boolean(), z.array(z.enum(["disable", "none", "minimal", "low", "medium", "high", "xhigh"]))])
 		.optional(),
 	requiredReasoningEffort: z.boolean().optional(),
 	preserveReasoning: z.boolean().optional(),

packages/types/src/providers/openai.ts

@@ -15,7 +15,7 @@ export const openAiNativeModels = {
 		supportsImages: true,
 		supportsPromptCache: true,
 		promptCacheRetention: "24h",
-		supportsReasoningEffort: ["low", "medium", "high"],
+		supportsReasoningEffort: ["low", "medium", "high", "xhigh"],
 		reasoningEffort: "medium",
 		inputPrice: 1.25,
 		outputPrice: 10.0,

src/api/providers/__tests__/openai-native.spec.ts

@@ -464,6 +464,46 @@ describe("OpenAiNativeHandler", () => {
 			)
 		})
 
+		it("should support xhigh reasoning effort for GPT-5.1 Codex Max", async () => {
+			// Mock fetch for Responses API
+			const mockFetch = vitest.fn().mockResolvedValue({
+				ok: true,
+				body: new ReadableStream({
+					start(controller) {
+						controller.enqueue(
+							new TextEncoder().encode(
+								'data: {"type":"response.output_item.added","item":{"type":"text","text":"XHigh effort"}}\n\n',
+							),
+						)
+						controller.enqueue(new TextEncoder().encode("data: [DONE]\n\n"))
+						controller.close()
+					},
+				}),
+			})
+			global.fetch = mockFetch as any
+
+			// Mock SDK to fail
+			mockResponsesCreate.mockRejectedValue(new Error("SDK not available"))
+
+			handler = new OpenAiNativeHandler({
+				...mockOptions,
+				apiModelId: "gpt-5.1-codex-max",
+				reasoningEffort: "xhigh",
+			})
+
+			const stream = handler.createMessage(systemPrompt, messages)
+			for await (const _chunk of stream) {
+				// drain
+			}
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"https://api.openai.com/v1/responses",
+				expect.objectContaining({
+					body: expect.stringContaining('"effort":"xhigh"'),
+				}),
+			)
+		})
+
 		it("should omit reasoning when selection is 'disable'", async () => {
 			// Mock fetch for Responses API
 			const mockFetch = vitest.fn().mockResolvedValue({

webview-ui/src/i18n/locales/ca/settings.json

@@ -512,7 +512,8 @@
 			"minimal": "Minimal (Fastest)",
 			"low": "Low",
 			"medium": "Medium",
-			"high": "High"
+			"high": "High",
+			"xhigh": "Extra High"
 		},
 		"verbosity": {
 			"label": "Output Verbosity",