Add OpenAI GPT-5.3 chat latest model support

Reference:
- https://developers.openai.com/api/docs/models/gpt-5.3-chat-latest

Author: PeterDaveHello

.changeset/gpt-5-3-chat-latest.md

@@ -0,0 +1,5 @@
+---
+"roo-cline": patch
+---
+
+Add OpenAI's GPT-5.3-Chat-Latest model support

packages/types/src/providers/openai.ts

@@ -93,6 +93,18 @@ export const openAiNativeModels = {
 		cacheReadsPrice: 0.175,
 		description: "GPT-5.2 Chat: Optimized for conversational AI and chat use cases",
 	},
+	"gpt-5.3-chat-latest": {
+		maxTokens: 16_384,
+		contextWindow: 128_000,
+		includedTools: ["apply_patch"],
+		excludedTools: ["apply_diff", "write_to_file"],
+		supportsImages: true,
+		supportsPromptCache: true,
+		inputPrice: 1.75,
+		outputPrice: 14.0,
+		cacheReadsPrice: 0.175,
+		description: "GPT-5.3 Chat: Optimized for conversational AI and chat use cases",
+	},
 	"gpt-5.1": {
 		maxTokens: 128000,
 		contextWindow: 400000,

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

@@ -378,6 +378,9 @@ describe("OpenAiNativeHandler - normalizeUsage", () => {
 
 			const fourOBody = buildRequestBodyForModel("gpt-4o")
 			expect(fourOBody.prompt_cache_retention).toBeUndefined()
+
+			const chatModelBody = buildRequestBodyForModel("gpt-5.3-chat-latest")
+			expect(chatModelBody.prompt_cache_retention).toBeUndefined()
 		})
 
 		it("should not set prompt_cache_retention when the model does not support prompt caching", () => {

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

@@ -249,6 +249,19 @@ describe("OpenAiNativeHandler", () => {
 			expect(modelInfo.info.supportsReasoningEffort).toEqual(["low", "medium", "high", "xhigh"])
 		})
 
+		it("should return GPT-5.3 Chat model info when selected", () => {
+			const chatHandler = new OpenAiNativeHandler({
+				...mockOptions,
+				apiModelId: "gpt-5.3-chat-latest",
+			})
+
+			const modelInfo = chatHandler.getModel()
+			expect(modelInfo.id).toBe("gpt-5.3-chat-latest")
+			expect(modelInfo.info.maxTokens).toBe(16_384)
+			expect(modelInfo.info.contextWindow).toBe(128000)
+			expect(modelInfo.info.supportsImages).toBe(true)
+		})
+
 		it("should handle undefined model ID", () => {
 			const handlerWithoutModel = new OpenAiNativeHandler({
 				openAiNativeApiKey: "test-api-key",
@@ -345,6 +358,57 @@ describe("OpenAiNativeHandler", () => {
 			expect(textChunks[1].text).toBe(" world")
 		})
 
+		it("should handle GPT-5.3 Chat model with Responses API", 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":"Chat reply"}}\n\n',
+							),
+						)
+						controller.enqueue(new TextEncoder().encode("data: [DONE]\n\n"))
+						controller.close()
+					},
+				}),
+			})
+			global.fetch = mockFetch as any
+
+			// Mock SDK to fail so it uses fetch
+			mockResponsesCreate.mockRejectedValue(new Error("SDK not available"))
+
+			handler = new OpenAiNativeHandler({
+				...mockOptions,
+				apiModelId: "gpt-5.3-chat-latest",
+			})
+
+			const stream = handler.createMessage(systemPrompt, messages)
+			const chunks: any[] = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			expect(mockFetch).toHaveBeenCalledWith(
+				"https://api.openai.com/v1/responses",
+				expect.objectContaining({
+					body: expect.any(String),
+				}),
+			)
+			const body = (mockFetch.mock.calls[0][1] as any).body as string
+			const parsedBody = JSON.parse(body)
+			expect(parsedBody.model).toBe("gpt-5.3-chat-latest")
+			expect(parsedBody.max_output_tokens).toBe(16_384)
+			expect(parsedBody.temperature).toBe(0)
+			expect(parsedBody.reasoning?.effort).toBeUndefined()
+			expect(parsedBody.text?.verbosity).toBeUndefined()
+
+			const textChunks = chunks.filter((chunk) => chunk.type === "text")
+			expect(textChunks).toHaveLength(1)
+			expect(textChunks[0].text).toBe("Chat reply")
+		})
+
 		it("should handle GPT-5-mini model with Responses API", async () => {
 			// Mock fetch for Responses API
 			const mockFetch = vitest.fn().mockResolvedValue({