diff --git a/stock/app/conftest.py b/stock/app/conftest.py
new file mode 100644
index 0000000..8d8de1f
--- /dev/null
+++ b/stock/app/conftest.py
@@ -0,0 +1,15 @@
+"""Project-level pytest conftest.
+
+SP-A2: autouse fixture that resets all webai_cache TTLCaches between tests
+so screener/portfolio/news cache state does not leak across test cases.
+"""
+import pytest
+from app import webai_cache
+
+
+@pytest.fixture(autouse=True)
+def _reset_webai_cache():
+    webai_cache.PORTFOLIO_CACHE.clear()
+    webai_cache.NEWS_CACHE.clear()
+    webai_cache.SCREENER_CACHE.clear()
+    yield
diff --git a/stock/app/main.py b/stock/app/main.py
index 1a11d66..3aab854 100644
--- a/stock/app/main.py
+++ b/stock/app/main.py
@@ -25,6 +25,7 @@ from .scraper import fetch_market_news, fetch_major_indices
 from .price_fetcher import get_current_prices, get_current_prices_detail
 from .ai_summarizer import summarize_news, OllamaError
 from .auth import verify_webai_key
+from . import webai_cache
 
 app = FastAPI()
 
@@ -418,8 +419,16 @@ def _augment_portfolio_with_pnl_pct(raw: dict) -> dict:
 
 @app.get("/api/webai/portfolio", dependencies=[Depends(verify_webai_key)])
 def get_webai_portfolio():
-    """web-ai 전용 portfolio (인증 필수, pnl_pct 비율 필드 추가)."""
-    return _augment_portfolio_with_pnl_pct(get_portfolio())
+    """web-ai 전용 portfolio (인증 필수, pnl_pct 비율 필드 추가).
+
+    SP-A2 server-side TTLCache 적용. V1+V2 동시 호출도 NAS에서 1회 계산.
+    """
+    cached = webai_cache.cache_get_portfolio()
+    if cached is not None:
+        return cached
+    result = _augment_portfolio_with_pnl_pct(get_portfolio())
+    webai_cache.cache_set_portfolio(result)
+    return result
 
 
 def _fetch_news_sentiment_dump(date: str | None) -> dict:
@@ -466,8 +475,16 @@ def _fetch_news_sentiment_dump(date: str | None) -> dict:
 
 @app.get("/api/webai/news-sentiment", dependencies=[Depends(verify_webai_key)])
 def get_webai_news_sentiment(date: str | None = None):
-    """web-ai 전용 news sentiment 일별 dump."""
-    return _fetch_news_sentiment_dump(date)
+    """web-ai 전용 news sentiment 일별 dump.
+
+    SP-A2 server-side TTLCache 적용. date 파라미터별로 별도 슬롯.
+    """
+    cached = webai_cache.cache_get_news(date)
+    if cached is not None:
+        return cached
+    result = _fetch_news_sentiment_dump(date)
+    webai_cache.cache_set_news(date, result)
+    return result
 
 
 @app.post("/api/portfolio", status_code=201)
diff --git a/stock/app/screener/router.py b/stock/app/screener/router.py
index dc7cb67..14fdfd8 100644
--- a/stock/app/screener/router.py
+++ b/stock/app/screener/router.py
@@ -12,6 +12,7 @@ from fastapi import APIRouter, HTTPException
 
 from . import schemas
 from .registry import NODE_REGISTRY, GATE_REGISTRY
+from .. import webai_cache
 
 
 router = APIRouter(prefix="/api/stock/screener")
@@ -173,6 +174,12 @@ def _persist_run(conn, asof, mode, weights, node_params, gate_params, top_n,
 @router.post("/run", response_model=schemas.RunResponse)
 def post_run(body: schemas.RunRequest):
     from .registry import NODE_REGISTRY as _NR, GATE_REGISTRY as _GR
+    # SP-A2 — preview 모드는 web-ai/frontend 폴링이라 캐시 적용.
+    # auto 모드는 실제 운영 트리거(휴장일 게이트 등)라 캐시 미적용.
+    if body.mode == "preview":
+        cached = webai_cache.cache_get_screener(body.mode, body.top_n, body.weights)
+        if cached is not None:
+            return cached
     started_at = dt.datetime.utcnow().isoformat()
     with _conn() as c:
         asof = _resolve_asof(body.asof, c)
@@ -231,7 +238,7 @@ def post_run(body: schemas.RunRequest):
             top_n=top_n, rows=result.rows, run_id=run_id,
         )
 
-        return schemas.RunResponse(
+        response = schemas.RunResponse(
             asof=asof.isoformat(), mode=body.mode, status="success",
             run_id=run_id, survivors_count=result.survivors_count,
             weights=weights, top_n=top_n,
@@ -239,6 +246,10 @@ def post_run(body: schemas.RunRequest):
             telegram_payload=schemas.TelegramPayload(**payload),
             warnings=result.warnings,
         )
+        # SP-A2 — preview 모드 결과 캐시 저장.
+        if body.mode == "preview":
+            webai_cache.cache_set_screener(body.mode, body.top_n, body.weights, response)
+        return response
 
 
 # ---------- /snapshot/refresh ----------