feat(codex): add GPT Image 2.5, Flare and Sunburst image models

- Add gpt-image-1.5, gpt-image-2, gpt-image-2.5, gpt-image-2.5-flare and
  gpt-image-2.5-sunburst as Codex image models with multi-image support
- Add gpt-image-2.5, gpt-image-2.5-flare and gpt-image-2.5-sunburst to the
  OpenAI provider catalog
- Route tool-backed image models through the Codex responses model while
  passing the selected model to the image_generation tool, pinning
  tool_choice and deriving generate/edit from the presence of references
- Cover the Codex gpt-image-2.5 request shape with a unit test

open-sse/handlers/imageProviders/codex.js

@@ -9,6 +9,14 @@ const CODEX_USER_AGENT = `codex_cli_rs/${CODEX_CLI_VERSION}`;
 const CODEX_ORIGINATOR = "codex_cli_rs";
 const CODEX_MODEL_SUFFIX = "-image";
 const CODEX_REF_DETAIL = "high";
+const CODEX_IMAGES_MAIN_MODEL = "gpt-5.5";
+const CODEX_TOOL_IMAGE_MODELS = new Set([
+  "gpt-image-1.5",
+  "gpt-image-2",
+  "gpt-image-2.5",
+  "gpt-image-2.5-flare",
+  "gpt-image-2.5-sunburst",
+]);
 
 function decodeAccountId(idToken) {
   try {
@@ -27,6 +35,13 @@ function stripImageSuffix(model) {
   return model.endsWith(CODEX_MODEL_SUFFIX) ? model.slice(0, -CODEX_MODEL_SUFFIX.length) : model;
 }
 
+function resolveCodexImageModels(model) {
+  if (CODEX_TOOL_IMAGE_MODELS.has(model)) {
+    return { responsesModel: CODEX_IMAGES_MAIN_MODEL, toolModel: model };
+  }
+  return { responsesModel: stripImageSuffix(model), toolModel: null };
+}
+
 function toDataUrl(input) {
   if (!input || typeof input !== "string") return null;
   if (/^data:image\//i.test(input) || /^https?:\/\//i.test(input)) return input;
@@ -167,21 +182,26 @@ export default {
     const single = toDataUrl(body.image);
     if (single) refs.push(single);
     const detail = body.image_detail || CODEX_REF_DETAIL;
+    const { responsesModel, toolModel } = resolveCodexImageModels(model);
     const imgTool = { type: "image_generation", output_format: (body.output_format || "png").toLowerCase() };
+    if (toolModel) {
+      imgTool.action = refs.length > 0 ? "edit" : "generate";
+      imgTool.model = toolModel;
+    }
     if (body.size && body.size !== "") imgTool.size = body.size;
     if (body.quality && body.quality !== "") imgTool.quality = body.quality;
     if (body.background && body.background !== "") imgTool.background = body.background;
     return {
-      model: stripImageSuffix(model),
+      model: responsesModel,
       instructions: "",
       input: [{ type: "message", role: "user", content: buildContent(body.prompt, refs, detail) }],
       tools: [imgTool],
-      tool_choice: "auto",
+      tool_choice: toolModel ? { type: "image_generation" } : "auto",
       parallel_tool_calls: false,
       prompt_cache_key: randomUUID(),
       stream: true,
       store: false,
-      reasoning: null,
+      reasoning: toolModel ? { effort: "medium", summary: "auto" } : null,
     };
   },
   // Custom: codex parses SSE → either pipe to client or collect b64

open-sse/providers/registry/codex.js

@@ -65,6 +65,11 @@ export default {
     { id: "gpt-5.4-mini-review", name: "GPT 5.4 Mini Review", upstreamModelId: "gpt-5.4-mini", quotaFamily: "review" },
     { id: "gpt-5.3-codex-spark", name: "GPT 5.3 Codex Spark" },
     { id: "gpt-5.3-codex-spark-review", name: "GPT 5.3 Codex Spark Review", upstreamModelId: "gpt-5.3-codex-spark", quotaFamily: "review" },
+    { id: "gpt-image-2.5", name: "GPT Image 2.5", capabilities: ["text2img","edit","multiImage"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
+    { id: "gpt-image-2.5-flare", name: "GPT Image 2.5 Flare", capabilities: ["text2img","edit","multiImage"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
+    { id: "gpt-image-2.5-sunburst", name: "GPT Image 2.5 Sunburst", capabilities: ["text2img","edit","multiImage"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
+    { id: "gpt-image-2", name: "GPT Image 2", capabilities: ["text2img","edit","multiImage"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
+    { id: "gpt-image-1.5", name: "GPT Image 1.5", capabilities: ["text2img","edit","multiImage"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
     { id: "gpt-5.6-sol-image", name: "GPT 5.6 Sol Image", capabilities: ["text2img","edit"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
     { id: "gpt-5.6-terra-image", name: "GPT 5.6 Terra Image", capabilities: ["text2img","edit"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },
     { id: "gpt-5.6-luna-image", name: "GPT 5.6 Luna Image", capabilities: ["text2img","edit"], params: ["size","quality","background","image_detail","output_format"], kind: "image" },

open-sse/providers/registry/openai.js

@@ -57,6 +57,9 @@ export default {
     { id: "whisper-1", name: "Whisper 1", params: ["language","response_format","temperature","prompt"], kind: "stt" },
     { id: "gpt-4o-transcribe", name: "GPT-4o Transcribe", params: ["language","response_format","temperature","prompt"], kind: "stt" },
     { id: "gpt-4o-mini-transcribe", name: "GPT-4o Mini Transcribe", params: ["language","response_format","temperature","prompt"], kind: "stt" },
+    { id: "gpt-image-2.5", name: "GPT Image 2.5", params: ["n","size","quality","response_format"], kind: "image" },
+    { id: "gpt-image-2.5-flare", name: "GPT Image 2.5 Flare", params: ["n","size","quality","response_format"], kind: "image" },
+    { id: "gpt-image-2.5-sunburst", name: "GPT Image 2.5 Sunburst", params: ["n","size","quality","response_format"], kind: "image" },
     { id: "gpt-image-1", name: "GPT Image 1", params: ["n","size","quality","response_format"], kind: "image" },
     { id: "dall-e-3", name: "DALL-E 3", params: ["size","quality","style","response_format"], kind: "image" },
     { id: "dall-e-2", name: "DALL-E 2", params: ["n","size","response_format"], kind: "image" },

tests/unit/image-generation.test.js

@@ -367,6 +367,47 @@ describe("handleImageGenerationCore", () => {
     expect(responseBody.data[0].b64_json).toBe("base64codeximage");
   });
 
+  it("generates image with Codex gpt-image-2.5 tool model", async () => {
+    global.fetch.mockResolvedValueOnce(
+      new Response(
+        [
+          "event: response.output_item.done",
+          'data: {"item":{"type":"image_generation_call","result":"base64codeximage"}}',
+          "",
+          "",
+        ].join("\n"),
+        { status: 200, headers: { "Content-Type": "text/event-stream" } }
+      )
+    );
+
+    const result = await handleImageGenerationCore({
+      body: {
+        prompt: "A futuristic city",
+        size: "1024x1024",
+        output_format: "png",
+      },
+      modelInfo: { provider: "codex", model: "gpt-image-2.5" },
+      credentials: {
+        accessToken: "codex-token",
+        providerSpecificData: { chatgptAccountId: "account-123" },
+      },
+      log: null,
+    });
+
+    expect(result.success).toBe(true);
+    const fetchCall = global.fetch.mock.calls[0];
+    const requestBody = JSON.parse(fetchCall[1].body);
+    expect(requestBody.model).toBe("gpt-5.5");
+    expect(requestBody.tools).toEqual([
+      { type: "image_generation", output_format: "png", size: "1024x1024", action: "generate", model: "gpt-image-2.5" },
+    ]);
+    expect(requestBody.tool_choice).toEqual({ type: "image_generation" });
+    expect(requestBody.reasoning).toEqual({ effort: "medium", summary: "auto" });
+
+    const responseBody = await result.response.json();
+    expect(responseBody.data[0].b64_json).toBe("base64codeximage");
+  });
+
   it("generates image with Cloudflare Workers AI JSON response", async () => {
     global.fetch.mockResolvedValueOnce(
       new Response(