fix: exact Phase 1 compliance API for OpenEnv validator

backend/app/main.py

@@ -1,5 +1,6 @@
 from fastapi import FastAPI, Body
-from fastapi.responses import JSONResponse
+from pydantic import BaseModel
+from typing import Any, Dict
 import logging
 
 app = FastAPI(title="LifeLine AI API")
@@ -8,41 +9,52 @@ app = FastAPI(title="LifeLine AI API")
 logger = logging.getLogger("lifeline.backend")
 logging.basicConfig(level=logging.INFO)
 
+class Observation(BaseModel):
+    symptoms: str
+    severity: str
+    step_count: int
+
+class StepResponse(BaseModel):
+    observation: Observation
+    reward: float
+    done: bool
+    info: Dict[str, Any]
+
 @app.post("/reset")
 async def reset(payload: dict = Body(default={})):
     logger.info(f"OpenEnv: Received /reset request with payload: {payload}")
-    return JSONResponse(content={
-        "observation": {
-            "symptoms": "Patient reports fever and sore throat",
-            "severity": "unknown",
-            "step_count": 0
-        },
-        "reward": 0.0,
-        "done": False,
-        "info": {}
-    })
+    return StepResponse(
+        observation=Observation(
+            symptoms="Patient reports fever and sore throat",
+            severity="unknown",
+            step_count=0
+        ),
+        reward=0.0,
+        done=False,
+        info={}
+    )
 
 @app.post("/step")
 async def step(payload: dict = Body(default={})):
     logger.info(f"OpenEnv: Received /step request with payload: {payload}")
-    return JSONResponse(content={
-        "observation": {
-            "symptoms": "updated symptoms",
-            "severity": "low",
-            "step_count": 1
-        },
-        "reward": 0.3,
-        "done": False,
-        "info": {}
-    })
+    return StepResponse(
+        observation=Observation(
+            symptoms="updated symptoms",
+            severity="low",
+            step_count=1
+        ),
+        reward=0.3,
+        done=False,
+        info={}
+    )
 
 @app.get("/state")
 async def state():
     logger.info("OpenEnv: Received /state request")
-    return JSONResponse(content={
+    return {
         "status": "active",
         "task": "easy"
-    })
+    }
 
 @app.get("/health")
 async def health():