fix(ai): disabled codex lite for image prompts

Codex Responses Lite only accepts text input, so GPT image prompts with input_image failed before reaching the full multimodal transport.

The request transformer and Codex headers now fall back to full Responses whenever a request body contains input_image, with regression coverage for the lite header.

Fixes #3421

packages/ai/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Codex Responses Lite staying enabled for image prompts, which caused GPT/Codex image turns to be rejected as `Invalid value: 'input_image'`; image-bearing Codex requests now fall back to the full Responses transport. ([#3421](https://github.com/can1357/oh-my-pi/issues/3421))
+
 ## [16.1.17] - 2026-06-24
 
 ### Added

packages/ai/src/providers/openai-codex-responses.ts

@@ -61,6 +61,7 @@ import {
 	type CodexRequestOptions,
 	type InputItem,
 	type RequestBody,
+	shouldUseCodexResponsesLite,
 	transformRequestBody,
 } from "./openai-codex/request-transformer";
 import { CodexApiError } from "./openai-codex/response-handler";
@@ -697,7 +698,7 @@ async function buildCodexRequestContext(
 	};
 
 	const providerSessionState = getCodexProviderSessionState(options?.providerSessionState);
-	const responsesLite = options?.responsesLite === true;
+	const responsesLite = shouldUseCodexResponsesLite(transformedBody, options?.responsesLite);
 	const sessionKey = getCodexWebSocketSessionKey(transportSessionId, model, accountId, baseUrl, responsesLite);
 	const publicSessionKey = transportSessionId ? `${baseUrl}:${model.id}:${transportSessionId}` : undefined;
 	if (sessionKey && publicSessionKey) {

packages/ai/src/providers/openai-codex/request-transformer.ts

@@ -59,6 +59,27 @@ export interface RequestBody {
 	[key: string]: unknown;
 }
 
+function containsInputImage(value: unknown): boolean {
+	if (!value || typeof value !== "object") return false;
+	if ((value as { type?: unknown }).type === "input_image") return true;
+	if (Array.isArray(value)) {
+		for (const item of value) {
+			if (containsInputImage(item)) return true;
+		}
+		return false;
+	}
+	for (const item of Object.values(value)) {
+		if (containsInputImage(item)) return true;
+	}
+	return false;
+}
+
+/** Returns whether a Codex request can use the text-only Responses Lite transport. */
+export function shouldUseCodexResponsesLite(body: RequestBody, requested: boolean | undefined): boolean {
+	return requested === true && !containsInputImage(body.input);
+}
+
+
 function getReasoningConfig(model: Model<Api>, options: CodexRequestOptions): ReasoningConfig {
 	const config: ReasoningConfig = {
 		effort:
@@ -211,7 +232,8 @@ export async function transformRequestBody(
 		body.input = [...developerMessages, ...body.input];
 	}
 
-	if (options.responsesLite) {
+	const responsesLite = shouldUseCodexResponsesLite(body, options.responsesLite);
+	if (responsesLite) {
 		if (Array.isArray(body.input)) {
 			stripImageDetails(body.input);
 		}
@@ -231,7 +253,7 @@ export async function transformRequestBody(
 		// Responses Lite keeps reasoning replay server-side; codex-rs requests
 		// `all_turns` there and otherwise omits context so the server default
 		// (currently `current_turn`) applies.
-		const reasoningContext = options.reasoningContext ?? (options.responsesLite ? "all_turns" : undefined);
+		const reasoningContext = options.reasoningContext ?? (responsesLite ? "all_turns" : undefined);
 		if (reasoningContext !== undefined) {
 			body.reasoning.context = reasoningContext;
 		}

packages/ai/test/openai-codex-responses-lite.test.ts

@@ -115,7 +115,7 @@ describe("openai-codex reasoning.context", () => {
 });
 
 describe("openai-codex Responses Lite input shaping", () => {
-	it("strips image detail from message content and tool outputs only under lite", async () => {
+	it("keeps full Responses image details when a requested lite body contains images", async () => {
 		const model = createCodexModel("gpt-5.1-codex");
 		const makeInput = (): InputItem[] => [
 			{
@@ -137,8 +137,8 @@ describe("openai-codex Responses Lite input shaping", () => {
 		const lite = await transformRequestBody({ model: model.id, input: makeInput() }, model, { responsesLite: true });
 		const liteMessage = lite.input?.[0]?.content as Array<Record<string, unknown>>;
 		const liteOutput = lite.input?.[2]?.output as Array<Record<string, unknown>>;
-		expect(liteMessage[1]).toEqual({ type: "input_image", image_url: "data:image/png;base64,AAAA" });
-		expect(liteOutput[0]).toEqual({ type: "input_image", image_url: "data:image/png;base64,BBBB" });
+		expect(liteMessage[1]).toEqual({ type: "input_image", detail: "auto", image_url: "data:image/png;base64,AAAA" });
+		expect(liteOutput[0]).toEqual({ type: "input_image", detail: "high", image_url: "data:image/png;base64,BBBB" });
 
 		const plain = await transformRequestBody({ model: model.id, input: makeInput() }, model, {});
 		const plainMessage = plain.input?.[0]?.content as Array<Record<string, unknown>>;
@@ -214,6 +214,58 @@ describe("openai-codex Responses Lite and client metadata wire format", () => {
 		expect(captured?.headers.get("x-openai-internal-codex-responses-lite")).toBe("true");
 		expect(captured?.body.client_metadata).toEqual(clientMetadata);
 	});
+	it("falls back to full Responses when a lite request contains images", async () => {
+		const model = buildModel({
+			id: "gpt-5.5",
+			name: "GPT-5.5",
+			api: "openai-codex-responses",
+			provider: "openai-codex",
+			baseUrl: "https://api.openai.com/v1",
+			reasoning: true,
+			input: ["text", "image"],
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+			contextWindow: 272_000,
+			maxTokens: 128_000,
+		});
+		let captured: CapturedCodexRequest | undefined;
+		const fetchMock = createCodexFetchMock(createCodexSse(COMPLETED_CODEX_EVENTS), request => {
+			captured = request;
+		});
+
+		const result = await streamOpenAICodexResponses(
+			model,
+			{
+				messages: [
+					{
+						role: "user",
+						timestamp: Date.now(),
+						content: [
+							{ type: "text", text: "read this image" },
+							{ type: "image", mimeType: "image/png", data: "AAAA" },
+						],
+					},
+				],
+			},
+			{
+				apiKey: createCodexTestToken(),
+				fetch: fetchMock,
+				responsesLite: true,
+			},
+		).result();
+
+		expect(result.stopReason).toBe("stop");
+		expect(captured?.headers.get("x-openai-internal-codex-responses-lite")).toBeNull();
+		expect(captured?.body.input).toEqual([
+			{
+				role: "user",
+				content: [
+					{ type: "input_text", text: "read this image" },
+					{ type: "input_image", detail: "auto", image_url: "data:image/png;base64,AAAA" },
+				],
+			},
+		]);
+	});
+
 
 	it("omits the lite header and client_metadata when not requested", async () => {
 		const model = createCodexModel("gpt-5.1-codex");