feat(views): anonymous daily view counter with social-proof badge

- New table symbol_views_daily(code, view_date, views) via migration 004.
- POST /api/views/{code} UPSERTs and returns today_views; GET returns
  today + last_7d + trend (last 7 days).
- Client dedupes via localStorage (views:logged map keyed by KST date) so a
  given browser counts once per day per code; refresh/extra tabs don't inflate.
- PriceHero shows "오늘 N명이 봤어요" pill when viewsToday > 0.

Read-only social proof — Toss 의 종목 상세에서 익명 카운트로 진입 신호를 주는 패턴.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/app/api/views.py

@@ -0,0 +1,98 @@
+"""종목 페이지 익명 조회 카운터.
+
+토스 같은 social-proof — "오늘 N명이 봤어요" 배지를 위한 가벼운 PG 카운터.
+
+  - POST /api/views/{code}  : views(code, today) UPSERT +1, 새 today_views 반환
+  - GET  /api/views/{code}  : today_views + 최근 7일 시계열 반환
+
+dedupe 는 클라이언트(localStorage) 에서 — 하루 1회만 POST. 서버는 단순 +1.
+부하 들어와도 같은 코드는 하루 1 increment 라 row 하나에 hot write 가 누적되지만
+유즘량 수십~수백 수준이라 lock contention 무시 가능. 진짜 늘면 그때 sharded 카운터로.
+"""
+from __future__ import annotations
+
+from datetime import date, timedelta
+
+from fastapi import APIRouter
+from sqlalchemy import text
+
+from app.db.connection import get_engine
+
+router = APIRouter(prefix="/api/views", tags=["views"])
+
+
+def _kst_today() -> date:
+    # PG NOW() AT TIME ZONE 'Asia/Seoul' 과 같은 의미로 KST 기준 오늘 날짜.
+    # 컨테이너 TZ 가 KST 면 date.today() 가 같지만, UTC 면 안 맞음 → 명시.
+    from datetime import datetime, timezone
+    utc = datetime.now(timezone.utc)
+    # KST = UTC+9
+    return (utc + timedelta(hours=9)).date()
+
+
+@router.post("/{code}")
+def record_view(code: str) -> dict:
+    """code 의 오늘 카운터 +1. UPSERT 후 today_views 반환.
+
+    symbols 테이블 매칭 검사 안 함 — 카운터 자체는 코드 존재 여부와 독립적으로 동작해야 함
+    (오타/리스트 빠진 종목도 추적). 다만 빈 code 만 거부.
+    """
+    code = code.strip()
+    if not code:
+        return {"ok": False, "today_views": 0}
+    today = _kst_today()
+    eng = get_engine()
+    with eng.begin() as conn:
+        row = conn.execute(
+            text(
+                """
+                INSERT INTO symbol_views_daily (code, view_date, views)
+                VALUES (:c, :d, 1)
+                ON CONFLICT (code, view_date)
+                DO UPDATE SET views = symbol_views_daily.views + 1
+                RETURNING views
+                """
+            ),
+            {"c": code, "d": today},
+        ).first()
+    today_views = int(row[0]) if row else 0
+    return {"ok": True, "code": code, "today_views": today_views}
+
+
+@router.get("/{code}")
+def get_views(code: str) -> dict:
+    """code 의 오늘 + 최근 7일 일별 시계열.
+
+    Returns:
+        {
+          "code": "005930",
+          "today_views": 42,
+          "last_7d_views": 320,
+          "trend": [{"date": "YYYY-MM-DD", "views": N}, ...]   # 오래된 → 최신
+        }
+    """
+    code = code.strip()
+    today = _kst_today()
+    start = today - timedelta(days=6)
+    eng = get_engine()
+    with eng.connect() as conn:
+        rows = conn.execute(
+            text(
+                """
+                SELECT view_date, views
+                FROM symbol_views_daily
+                WHERE code = :c AND view_date BETWEEN :s AND :e
+                ORDER BY view_date ASC
+                """
+            ),
+            {"c": code, "s": start, "e": today},
+        ).all()
+    trend = [{"date": r[0].isoformat(), "views": int(r[1])} for r in rows]
+    today_views = next((t["views"] for t in trend if t["date"] == today.isoformat()), 0)
+    last_7d = sum(t["views"] for t in trend)
+    return {
+        "code": code,
+        "today_views": today_views,
+        "last_7d_views": last_7d,
+        "trend": trend,
+    }

backend/app/db/migrations/004_symbol_views.sql

@@ -0,0 +1,19 @@
+-- Phase 5: 종목 페이지 익명 조회 카운터.
+-- (code, view_date) PK 로 일 단위 집계. Redis/KV 없이 PG 만으로 충분 — 쓰기 빈도가
+-- 낮고(페이지 진입 시 클라이언트 측에서 하루 1회로 dedupe), UPSERT 1회 비용은 무시 가능.
+-- symbols(code) FK 는 일부러 안 걺 — 삭제된/오타 코드 방문에도 카운터가 죽지 않게.
+
+\set ON_ERROR_STOP on
+
+CREATE TABLE IF NOT EXISTS symbol_views_daily (
+  code      TEXT NOT NULL,
+  view_date DATE NOT NULL,
+  views     INTEGER NOT NULL DEFAULT 0,
+  PRIMARY KEY (code, view_date)
+);
+
+CREATE INDEX IF NOT EXISTS symbol_views_daily_date_idx
+  ON symbol_views_daily (view_date DESC);
+
+COMMENT ON TABLE symbol_views_daily IS
+  'Phase 5: 종목 페이지 익명 조회 카운터. 일 단위 UPSERT(+1). 클라이언트가 localStorage 로 dedupe.';

backend/app/main.py

@@ -18,6 +18,7 @@ from app.api.predict import router as predict_router
 from app.api.refresh import router as refresh_router
 from app.api.symbols import router as symbols_router
 from app.api.themes import router as themes_router
+from app.api.views import router as views_router
 from app.config import settings
 from app.db.connection import get_engine, ping as db_ping
 from app.fetch import dart as dart_mod
@@ -110,6 +111,7 @@ app.include_router(markets_router)
 app.include_router(themes_router)
 app.include_router(orderbook_router)
 app.include_router(fundamentals_router)
+app.include_router(views_router)
 
 
 def _resolved_device() -> str: