feat: add image generation support and Chinese language default

backend/pyproject.toml

@@ -18,6 +18,7 @@ dependencies = [
     "langgraph-api",
     "fastapi",
     "google-genai",
+    "pillow",
 ]
 
 

backend/src/agent/app.py

@@ -1,11 +1,62 @@
 # mypy: disable - error - code = "no-untyped-def,misc"
+import base64
+import io
+import os
 import pathlib
-from fastapi import FastAPI, Response
+from fastapi import FastAPI, Response, HTTPException
 from fastapi.staticfiles import StaticFiles
+from fastapi.middleware.cors import CORSMiddleware
+from pydantic import BaseModel
+from google import genai
+from google.genai import types
 
 # Define the FastAPI app
 app = FastAPI()
 
+# Allow local dev origins (Vite + LangGraph dev)
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+GEMINI_API_KEY = os.getenv("GEMINI_API_KEY")
+if GEMINI_API_KEY is None:
+    raise ValueError("GEMINI_API_KEY is not set")
+
+image_client = genai.Client(api_key=GEMINI_API_KEY)
+# Per request: use Gemini 3 image preview model
+IMAGE_MODEL = "models/gemini-3-pro-image-preview"
+
+
+class ImageRequest(BaseModel):
+    prompt: str
+    number_of_images: int = 1
+
+
+@app.post("/generate_image")
+def generate_image(req: ImageRequest):
+    """Generate an image for a given prompt and return base64 data URLs."""
+    try:
+        response = image_client.models.generate_images(
+            model=IMAGE_MODEL,
+            prompt=req.prompt,
+            config=types.GenerateImagesConfig(number_of_images=req.number_of_images),
+        )
+        images = []
+        for generated_image in response.generated_images:
+            buffer = io.BytesIO()
+            generated_image.image.save(buffer, format="PNG")
+            b64 = base64.b64encode(buffer.getvalue()).decode("ascii")
+            images.append(f"data:image/png;base64,{b64}")
+        if not images:
+            raise RuntimeError("No image generated")
+        return {"images": images}
+    except Exception as exc:  # pragma: no cover
+        raise HTTPException(status_code=500, detail=str(exc)) from exc
+
 
 def create_frontend_router(build_dir="../frontend/dist"):
     """Creates a router to serve the React frontend.

backend/src/agent/graph.py

@@ -1,4 +1,6 @@
 import os
+import json
+import re
 
 from agent.tools_and_schemas import SearchQueryList, Reflection
 from dotenv import load_dotenv
@@ -267,17 +269,38 @@ def finalize_answer(state: OverallState, config: RunnableConfig):
     )
     result = llm.invoke(formatted_prompt)
 
+    # Clean potential markdown fences and parse JSON so we return structured content
+    content = result.content
+    if isinstance(content, str):
+        # Strip markdown fences ```json ... ```
+        cleaned = re.sub(r"^```[a-zA-Z]*\s*|\s*```$", "", content.strip())
+        try:
+            parsed = json.loads(cleaned)
+        except Exception:
+            parsed = cleaned
+        content_payload = parsed
+    else:
+        content_payload = content
+
     # Replace the short urls with the original urls and add all used urls to the sources_gathered
     unique_sources = []
     for source in state["sources_gathered"]:
-        if source["short_url"] in result.content:
-            result.content = result.content.replace(
-                source["short_url"], source["value"]
-            )
+        if isinstance(content_payload, str) and source["short_url"] in content_payload:
+            content_payload = content_payload.replace(source["short_url"], source["value"])
+            unique_sources.append(source)
+        elif isinstance(content_payload, list):
+            # if list of page dicts, replace inside detail strings
+            updated_pages = []
+            for page in content_payload:
+                if isinstance(page, dict) and isinstance(page.get("detail"), str):
+                    page_detail = page["detail"].replace(source["short_url"], source["value"])
+                    page = {**page, "detail": page_detail}
+                updated_pages.append(page)
+            content_payload = updated_pages
             unique_sources.append(source)
 
     return {
-        "messages": [AIMessage(content=result.content)],
+        "messages": [AIMessage(content=content_payload)],
         "sources_gathered": unique_sources,
     }