feat(kis-token): transition OAuth2 token cache from JSON files to SQLite database

src/quant_engine/kis_api_client_v1.py

@@ -115,23 +115,51 @@ class KisCredentials:
         return cls(app_key=app_key, app_secret=app_secret, account=account)
 
 
-def _token_cache_path(creds: KisCredentials) -> Path:
-    TOKEN_CACHE_DIR.mkdir(parents=True, exist_ok=True)
-    return TOKEN_CACHE_DIR / f"kis_token_cache_{creds.account}.json"
+import sqlite3
+
+def _token_db_path() -> Path:
+    db_dir = ROOT / "outputs" / "kis_data_collection"
+    db_dir.mkdir(parents=True, exist_ok=True)
+    return db_dir / "kis_data_collection.db"
+
+
+def _init_token_db(conn: sqlite3.Connection) -> None:
+    conn.execute(
+        """
+        CREATE TABLE IF NOT EXISTS kis_tokens (
+            account TEXT PRIMARY KEY,
+            access_token TEXT NOT NULL,
+            expires_at TEXT NOT NULL,
+            updated_at TEXT NOT NULL
+        )
+        """
+    )
+    conn.commit()
 
 
 def _issue_or_reuse_token(creds: KisCredentials) -> str:
-    """KIS는 토큰 발급 빈도를 제한한다 — 만료 전까지 캐시 재사용 필수."""
-    cache_path = _token_cache_path(creds)
-    if cache_path.exists():
-        try:
-            cached = json.loads(cache_path.read_text(encoding="utf-8"))
-            expires_at = dt.datetime.fromisoformat(cached["expires_at"])
-            if dt.datetime.now(dt.timezone.utc) < expires_at - dt.timedelta(minutes=10):
-                return cached["access_token"]
-        except (json.JSONDecodeError, KeyError, ValueError):
-            pass
+    """KIS는 토큰 발급 빈도를 제한한다 — 만료 전까지 DB 캐시 재사용 필수."""
+    db_path = _token_db_path()
     
+    # 1. DB에서 기존 토큰 및 만료 시각 조회
+    with sqlite3.connect(db_path) as conn:
+        _init_token_db(conn)
+        row = conn.execute(
+            "SELECT access_token, expires_at FROM kis_tokens WHERE account = ?",
+            (creds.account,)
+        ).fetchone()
+        
+        if row:
+            token, expires_at_str = row
+            try:
+                expires_at = dt.datetime.fromisoformat(expires_at_str)
+                # 만료 시간 10분 전까지 재사용 가능 여부 검사
+                if dt.datetime.now(dt.timezone.utc) < expires_at - dt.timedelta(minutes=10):
+                    return token
+            except ValueError:
+                pass
+
+    # 2. 토큰이 만료되었거나 없을 시 KIS API로 새로 발급 요청
     requests = _requests()
     resp = requests.post(
         f"{creds.domain}/oauth2/tokenP",
@@ -143,10 +171,18 @@ def _issue_or_reuse_token(creds: KisCredentials) -> str:
     access_token = body["access_token"]
     expires_in_sec = int(body.get("expires_in", 86400))
     expires_at = dt.datetime.now(dt.timezone.utc) + dt.timedelta(seconds=expires_in_sec)
-    cache_path.write_text(
-        json.dumps({"access_token": access_token, "expires_at": expires_at.isoformat()}, ensure_ascii=False),
-        encoding="utf-8",
-    )
+    
+    # 3. 새로운 토큰 정보를 DB에 안전하게 업서트
+    with sqlite3.connect(db_path) as conn:
+        conn.execute(
+            """
+            INSERT OR REPLACE INTO kis_tokens (account, access_token, expires_at, updated_at)
+            VALUES (?, ?, ?, ?)
+            """,
+            (creds.account, access_token, expires_at.isoformat(), dt.datetime.now(dt.timezone.utc).isoformat())
+        )
+        conn.commit()
+        
     return access_token