diff --git a/backend/main.py b/backend/main.py
index fd82fb7..be9c1a4 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -1,5 +1,9 @@
-from fastapi import FastAPI
+from pathlib import Path
+
+from fastapi import FastAPI, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import FileResponse
+from fastapi.staticfiles import StaticFiles
 from pydantic import BaseModel
 
 from backend.config_store import (
@@ -7,6 +11,10 @@ from backend.config_store import (
     has_openai_key,
     set_setting,
 )
+from backend.openai_client import OpenAIConfigurationError, ask_ai
+
+ROOT_DIR = Path(__file__).resolve().parent.parent
+FRONTEND_DIR = ROOT_DIR / 'frontend'
 
 app = FastAPI(title='DevConsole', version='0.1.0')
 
@@ -18,14 +26,25 @@ app.add_middleware(
     allow_headers=['*'],
 )
 
+if FRONTEND_DIR.exists():
+    app.mount('/assets', StaticFiles(directory=FRONTEND_DIR / 'assets'), name='assets')
+
 
 class OpenAIConfigRequest(BaseModel):
     api_key: str
     model: str = 'gpt-5'
 
 
+class PromptTestRequest(BaseModel):
+    prompt: str
+
+
 @app.get('/')
 async def root():
+    index_file = FRONTEND_DIR / 'index.html'
+    if index_file.exists():
+        return FileResponse(index_file)
+
     return {
         'project': 'DevConsole',
         'version': '0.1.0',
@@ -42,6 +61,17 @@ async def health():
     }
 
 
+@app.get('/api/system/status')
+async def system_status():
+    return {
+        'project': 'DevConsole',
+        'version': '0.1.0',
+        'status': 'running',
+        'openai_configured': has_openai_key(),
+        'openai_model': get_openai_model(),
+    }
+
+
 @app.get('/api/settings/openai')
 async def openai_status():
     return {
@@ -52,10 +82,49 @@ async def openai_status():
 
 @app.post('/api/settings/openai')
 async def save_openai_settings(payload: OpenAIConfigRequest):
-    set_setting('OPENAI_API_KEY', payload.api_key.strip())
-    set_setting('OPENAI_MODEL', payload.model.strip())
+    api_key = payload.api_key.strip()
+    model = payload.model.strip() or 'gpt-5'
+
+    if not api_key:
+        raise HTTPException(status_code=400, detail='API key is empty')
+
+    set_setting('OPENAI_API_KEY', api_key)
+    set_setting('OPENAI_MODEL', model)
 
     return {
         'success': True,
         'message': 'OpenAI settings saved',
     }
+
+
+@app.post('/api/prompts/test')
+async def test_prompt(payload: PromptTestRequest):
+    prompt = payload.prompt.strip()
+
+    if not prompt:
+        raise HTTPException(status_code=400, detail='Prompt is empty')
+
+    try:
+        answer = await ask_ai(prompt)
+    except OpenAIConfigurationError as exc:
+        raise HTTPException(status_code=400, detail=str(exc)) from exc
+
+    return {
+        'success': True,
+        'model': get_openai_model(),
+        'answer': answer,
+    }
+
+
+@app.post('/api/settings/openai/test')
+async def test_openai_connection():
+    try:
+        answer = await ask_ai('Reply with exactly: DevConsole AI connection OK')
+    except OpenAIConfigurationError as exc:
+        raise HTTPException(status_code=400, detail=str(exc)) from exc
+
+    return {
+        'success': True,
+        'model': get_openai_model(),
+        'answer': answer,
+    }