diff --git a/webapp/api/score.py b/webapp/api/score.py
index 966b57f..65f2ea9 100644
--- a/webapp/api/score.py
+++ b/webapp/api/score.py
@@ -2,10 +2,13 @@
 
 from __future__ import annotations
 
+import logging
 import time
 from typing import Annotated
 
-from fastapi import APIRouter, Header, HTTPException
+from fastapi import APIRouter, Header, HTTPException, Request
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import JSONResponse
 
 from rag_eval.metrics.weights import compute_weighted_score
 from rag_eval.settings import EvaluationSettings
@@ -13,6 +16,7 @@ from webapp.models import ScoreRequest, ScoreResponse
 from webapp.services.inline_scorer import inline_scorer
 
 router = APIRouter(prefix="/api/score", tags=["score"])
+logger = logging.getLogger("webapp.api.score")
 
 
 def _get_settings() -> EvaluationSettings:
@@ -58,6 +62,7 @@ def _check_auth(authorization: str | None, token: str) -> None:
     },
 )
 def score_sample(
+    raw_request: Request,
     request: ScoreRequest,
     authorization: Annotated[str | None, Header()] = None,
 ) -> ScoreResponse:
@@ -88,6 +93,15 @@ def score_sample(
     **鉴权**：若 `.env` 中配置了 `SCORE_API_TOKEN`，需在请求头携带
     `Authorization: Bearer <token>`；留空则无需鉴权（适合内网部署）。
     """
+    client = f"{raw_request.client.host}:{raw_request.client.port}" if raw_request.client else "unknown"
+    logger.info(
+        "[score] incoming  client=%s  method=%s  content_type=%s  metrics=%s  has_gt=%s",
+        client,
+        raw_request.method,
+        raw_request.headers.get("content-type", ""),
+        request.metrics,
+        request.ground_truth is not None,
+    )
     settings = _get_settings()
 
     # Require Bearer auth only when the deployment configured a shared token.
@@ -141,6 +155,12 @@ def score_sample(
         {},
     )
 
+    logger.info(
+        "[score] done  latency=%dms  skipped=%s  scores=%s",
+        latency_ms,
+        skipped,
+        {k: (round(v, 4) if v is not None else None) for k, v in all_scores.items()},
+    )
     return ScoreResponse(
         scores=all_scores,
         weighted_score=round(weighted, 4) if weighted is not None else None,
diff --git a/webapp/server.py b/webapp/server.py
index edda9bc..e941091 100644
--- a/webapp/server.py
+++ b/webapp/server.py
@@ -7,15 +7,19 @@ the server starts even when the evaluation dependencies are not yet installed.
 
 from __future__ import annotations
 
+import logging
 from pathlib import Path
 
-from fastapi import FastAPI
-from fastapi.responses import FileResponse
+from fastapi import FastAPI, Request
+from fastapi.encoders import jsonable_encoder
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import FileResponse, JSONResponse
 from fastapi.staticfiles import StaticFiles
 
 from webapp.api import evaluations, llm_profiles, pipeline, runs, scenarios, score
 
 STATIC_DIR = Path(__file__).resolve().parent / "static"
+logger = logging.getLogger("webapp.server")
 
 # OpenAPI tag metadata — controls the grouping and descriptions in /docs.
 OPENAPI_TAGS = [
@@ -103,6 +107,21 @@ def create_app() -> FastAPI:
     app.include_router(pipeline.router)
     app.include_router(score.router)
 
+    @app.exception_handler(RequestValidationError)
+    async def validation_exception_handler(request: Request, exc: RequestValidationError) -> JSONResponse:
+        """Log full validation error detail to help diagnose 422 responses."""
+        errors = jsonable_encoder(exc.errors())
+        logger.warning(
+            "[422] validation error  url=%s  content_type=%s  errors=%s",
+            request.url.path,
+            request.headers.get("content-type", ""),
+            errors,
+        )
+        return JSONResponse(
+            status_code=422,
+            content={"detail": errors},
+        )
+
     @app.get("/api/health", tags=["meta"])
     def health() -> dict[str, str]:
         """Report basic liveness so the UI can confirm the server is reachable."""