feat: add OpenAI Codex provider with OAuth subscription authentication

packages/types/src/provider-settings.ts

@@ -17,6 +17,7 @@ import {
 	ioIntelligenceModels,
 	mistralModels,
 	moonshotModels,
+	openAiCodexModels,
 	openAiNativeModels,
 	qwenCodeModels,
 	sambaNovaModels,
@@ -133,6 +134,7 @@ export const providerNames = [
 	"mistral",
 	"moonshot",
 	"minimax",
+	"openai-codex",
 	"openai-native",
 	"qwen-code",
 	"roo",
@@ -289,6 +291,10 @@ const geminiCliSchema = apiModelIdProviderModelSchema.extend({
 	geminiCliProjectId: z.string().optional(),
 })
 
+const openAiCodexSchema = apiModelIdProviderModelSchema.extend({
+	// No additional settings needed - uses OAuth authentication
+})
+
 const openAiNativeSchema = apiModelIdProviderModelSchema.extend({
 	openAiNativeApiKey: z.string().optional(),
 	openAiNativeBaseUrl: z.string().optional(),
@@ -436,6 +442,7 @@ export const providerSettingsSchemaDiscriminated = z.discriminatedUnion("apiProv
 	lmStudioSchema.merge(z.object({ apiProvider: z.literal("lmstudio") })),
 	geminiSchema.merge(z.object({ apiProvider: z.literal("gemini") })),
 	geminiCliSchema.merge(z.object({ apiProvider: z.literal("gemini-cli") })),
+	openAiCodexSchema.merge(z.object({ apiProvider: z.literal("openai-codex") })),
 	openAiNativeSchema.merge(z.object({ apiProvider: z.literal("openai-native") })),
 	mistralSchema.merge(z.object({ apiProvider: z.literal("mistral") })),
 	deepSeekSchema.merge(z.object({ apiProvider: z.literal("deepseek") })),
@@ -477,6 +484,7 @@ export const providerSettingsSchema = z.object({
 	...lmStudioSchema.shape,
 	...geminiSchema.shape,
 	...geminiCliSchema.shape,
+	...openAiCodexSchema.shape,
 	...openAiNativeSchema.shape,
 	...mistralSchema.shape,
 	...deepSeekSchema.shape,
@@ -559,6 +567,7 @@ export const modelIdKeysByProvider: Record<TypicalProvider, ModelIdKey> = {
 	openrouter: "openRouterModelId",
 	bedrock: "apiModelId",
 	vertex: "apiModelId",
+	"openai-codex": "apiModelId",
 	"openai-native": "openAiModelId",
 	ollama: "ollamaModelId",
 	lmstudio: "lmStudioModelId",
@@ -684,6 +693,11 @@ export const MODELS_BY_PROVIDER: Record<
 		label: "MiniMax",
 		models: Object.keys(minimaxModels),
 	},
+	"openai-codex": {
+		id: "openai-codex",
+		label: "OpenAI - ChatGPT Plus/Pro",
+		models: Object.keys(openAiCodexModels),
+	},
 	"openai-native": {
 		id: "openai-native",
 		label: "OpenAI",

packages/types/src/providers/index.ts

@@ -18,6 +18,7 @@ export * from "./mistral.js"
 export * from "./moonshot.js"
 export * from "./ollama.js"
 export * from "./openai.js"
+export * from "./openai-codex.js"
 export * from "./openrouter.js"
 export * from "./qwen-code.js"
 export * from "./requesty.js"
@@ -48,6 +49,7 @@ import { ioIntelligenceDefaultModelId } from "./io-intelligence.js"
 import { litellmDefaultModelId } from "./lite-llm.js"
 import { mistralDefaultModelId } from "./mistral.js"
 import { moonshotDefaultModelId } from "./moonshot.js"
+import { openAiCodexDefaultModelId } from "./openai-codex.js"
 import { openRouterDefaultModelId } from "./openrouter.js"
 import { qwenCodeDefaultModelId } from "./qwen-code.js"
 import { requestyDefaultModelId } from "./requesty.js"
@@ -111,6 +113,8 @@ export function getProviderDefaultModelId(
 			return options?.isChina ? mainlandZAiDefaultModelId : internationalZAiDefaultModelId
 		case "openai-native":
 			return "gpt-4o" // Based on openai-native patterns
+		case "openai-codex":
+			return openAiCodexDefaultModelId
 		case "mistral":
 			return mistralDefaultModelId
 		case "openai":

packages/types/src/providers/openai-codex.ts

@@ -0,0 +1,92 @@
+import type { ModelInfo } from "../model.js"
+
+/**
+ * OpenAI Codex Provider
+ *
+ * This provider uses OAuth authentication via ChatGPT Plus/Pro subscription
+ * instead of direct API keys. Requests are routed to the Codex backend at
+ * https://chatgpt.com/backend-api/codex/responses
+ *
+ * Key differences from openai-native:
+ * - Uses OAuth Bearer tokens instead of API keys
+ * - Subscription-based pricing (no per-token costs)
+ * - Limited model subset available
+ * - Custom routing to Codex backend
+ */
+
+export type OpenAiCodexModelId = keyof typeof openAiCodexModels
+
+export const openAiCodexDefaultModelId: OpenAiCodexModelId = "gpt-5.2-codex"
+
+/**
+ * Models available through the Codex OAuth flow.
+ * These models are accessible to ChatGPT Plus/Pro subscribers.
+ * Costs are 0 as they are covered by the subscription.
+ */
+export const openAiCodexModels = {
+	"gpt-5.1-codex-max": {
+		maxTokens: 128000,
+		contextWindow: 400000,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
+		includedTools: ["apply_patch"],
+		excludedTools: ["apply_diff", "write_to_file"],
+		supportsImages: true,
+		supportsPromptCache: true,
+		supportsReasoningEffort: ["low", "medium", "high", "xhigh"],
+		reasoningEffort: "xhigh",
+		// Subscription-based: no per-token costs
+		inputPrice: 0,
+		outputPrice: 0,
+		supportsTemperature: false,
+		description: "GPT-5.1 Codex Max: Maximum capability coding model via ChatGPT subscription",
+	},
+	"gpt-5.2-codex": {
+		maxTokens: 128000,
+		contextWindow: 400000,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
+		includedTools: ["apply_patch"],
+		excludedTools: ["apply_diff", "write_to_file"],
+		supportsImages: true,
+		supportsPromptCache: true,
+		supportsReasoningEffort: ["low", "medium", "high", "xhigh"],
+		reasoningEffort: "medium",
+		inputPrice: 0,
+		outputPrice: 0,
+		supportsTemperature: false,
+		description: "GPT-5.2 Codex: OpenAI's flagship coding model via ChatGPT subscription",
+	},
+	"gpt-5.1-codex-mini": {
+		maxTokens: 128000,
+		contextWindow: 400000,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
+		includedTools: ["apply_patch"],
+		excludedTools: ["apply_diff", "write_to_file"],
+		supportsImages: true,
+		supportsPromptCache: true,
+		supportsReasoningEffort: ["low", "medium", "high"],
+		reasoningEffort: "medium",
+		inputPrice: 0,
+		outputPrice: 0,
+		supportsTemperature: false,
+		description: "GPT-5.1 Codex Mini: Faster version for coding tasks via ChatGPT subscription",
+	},
+	"gpt-5.2": {
+		maxTokens: 128000,
+		contextWindow: 400000,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
+		includedTools: ["apply_patch"],
+		excludedTools: ["apply_diff", "write_to_file"],
+		supportsImages: true,
+		supportsPromptCache: true,
+		supportsReasoningEffort: ["none", "low", "medium", "high", "xhigh"],
+		reasoningEffort: "medium",
+		inputPrice: 0,
+		outputPrice: 0,
+		supportsTemperature: false,
+		description: "GPT-5.2: Latest GPT model via ChatGPT subscription",
+	},
+} as const satisfies Record<string, ModelInfo>

packages/types/src/vscode-extension-host.ts

@@ -325,6 +325,7 @@ export type ExtensionState = Pick<
 	taskSyncEnabled: boolean
 	featureRoomoteControlEnabled: boolean
 	claudeCodeIsAuthenticated?: boolean
+	openAiCodexIsAuthenticated?: boolean
 	debug?: boolean
 }
 
@@ -454,6 +455,8 @@ export interface WebviewMessage {
 		| "rooCloudManualUrl"
 		| "claudeCodeSignIn"
 		| "claudeCodeSignOut"
+		| "openAiCodexSignIn"
+		| "openAiCodexSignOut"
 		| "switchOrganization"
 		| "condenseTaskContextRequest"
 		| "requestIndexingStatus"

src/api/index.ts

@@ -13,6 +13,7 @@ import {
 	VertexHandler,
 	AnthropicVertexHandler,
 	OpenAiHandler,
+	OpenAiCodexHandler,
 	LmStudioHandler,
 	GeminiHandler,
 	OpenAiNativeHandler,
@@ -149,6 +150,8 @@ export function buildApiHandler(configuration: ProviderSettings): ApiHandler {
 			return new LmStudioHandler(options)
 		case "gemini":
 			return new GeminiHandler(options)
+		case "openai-codex":
+			return new OpenAiCodexHandler(options)
 		case "openai-native":
 			return new OpenAiNativeHandler(options)
 		case "deepseek":

src/api/providers/__tests__/openai-codex-native-tool-calls.spec.ts

@@ -0,0 +1,101 @@
+// cd src && npx vitest run api/providers/__tests__/openai-codex-native-tool-calls.spec.ts
+
+import { beforeEach, describe, expect, it, vi } from "vitest"
+
+import { OpenAiCodexHandler } from "../openai-codex"
+import type { ApiHandlerOptions } from "../../../shared/api"
+import { NativeToolCallParser } from "../../../core/assistant-message/NativeToolCallParser"
+import { openAiCodexOAuthManager } from "../../../integrations/openai-codex/oauth"
+
+describe("OpenAiCodexHandler native tool calls", () => {
+	let handler: OpenAiCodexHandler
+	let mockOptions: ApiHandlerOptions
+
+	beforeEach(() => {
+		vi.restoreAllMocks()
+		NativeToolCallParser.clearRawChunkState()
+		NativeToolCallParser.clearAllStreamingToolCalls()
+
+		mockOptions = {
+			apiModelId: "gpt-5.2-2025-12-11",
+			// minimal settings; OAuth is mocked below
+		}
+		handler = new OpenAiCodexHandler(mockOptions)
+	})
+
+	it("yields tool_call_partial chunks when API returns function_call-only response", async () => {
+		vi.spyOn(openAiCodexOAuthManager, "getAccessToken").mockResolvedValue("test-token")
+		vi.spyOn(openAiCodexOAuthManager, "getAccountId").mockResolvedValue("acct_test")
+
+		// Mock OpenAI SDK streaming (preferred path).
+		;(handler as any).client = {
+			responses: {
+				create: vi.fn().mockResolvedValue({
+					async *[Symbol.asyncIterator]() {
+						yield {
+							type: "response.output_item.added",
+							item: {
+								type: "function_call",
+								call_id: "call_1",
+								name: "attempt_completion",
+								arguments: "",
+							},
+							output_index: 0,
+						}
+						yield {
+							type: "response.function_call_arguments.delta",
+							delta: '{"result":"hi"}',
+							// Note: intentionally omit call_id + name to simulate tool-call-only streams.
+							item_id: "fc_1",
+							output_index: 0,
+						}
+						yield {
+							type: "response.completed",
+							response: {
+								id: "resp_1",
+								status: "completed",
+								output: [
+									{
+										type: "function_call",
+										call_id: "call_1",
+										name: "attempt_completion",
+										arguments: '{"result":"hi"}',
+									},
+								],
+								usage: { input_tokens: 1, output_tokens: 1 },
+							},
+						}
+					},
+				}),
+			},
+		}
+
+		const stream = handler.createMessage("system", [{ role: "user", content: "hello" } as any], {
+			taskId: "t",
+			toolProtocol: "native",
+			tools: [],
+		})
+
+		const chunks: any[] = []
+		for await (const chunk of stream) {
+			chunks.push(chunk)
+			if (chunk.type === "tool_call_partial") {
+				// Simulate Task.ts behavior so finish_reason handling can emit tool_call_end elsewhere
+				NativeToolCallParser.processRawChunk({
+					index: chunk.index,
+					id: chunk.id,
+					name: chunk.name,
+					arguments: chunk.arguments,
+				})
+			}
+		}
+
+		const toolChunks = chunks.filter((c) => c.type === "tool_call_partial")
+		expect(toolChunks.length).toBeGreaterThan(0)
+		expect(toolChunks[0]).toMatchObject({
+			type: "tool_call_partial",
+			id: "call_1",
+			name: "attempt_completion",
+		})
+	})
+})

src/api/providers/index.ts

@@ -15,6 +15,7 @@ export { IOIntelligenceHandler } from "./io-intelligence"
 export { LiteLLMHandler } from "./lite-llm"
 export { LmStudioHandler } from "./lm-studio"
 export { MistralHandler } from "./mistral"
+export { OpenAiCodexHandler } from "./openai-codex"
 export { OpenAiNativeHandler } from "./openai-native"
 export { OpenAiHandler } from "./openai"
 export { OpenRouterHandler } from "./openrouter"