CREATE TABLE shop_players
(
    shop_id    BIGINT      NOT NULL REFERENCES shops (id),
    player_id  BIGINT      NOT NULL,

    -- [新增] 标记是否为主店铺。用于个人主页展示和 players.shop_id 缓存源
    is_primary BOOLEAN              DEFAULT FALSE,

    joined_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    left_at    TIMESTAMPTZ, -- 软删除，表示已离职

    PRIMARY KEY (shop_id, player_id)
);

-- 索引
CREATE INDEX idx_shop_players_player ON shop_players (player_id) WHERE left_at IS NULL;
CREATE INDEX idx_shop_players_shop_active ON shop_players (shop_id, joined_at DESC) WHERE left_at IS NULL;

-- [新增] 唯一索引：确保一个打手同一时间只能有一个主店铺
CREATE UNIQUE INDEX idx_shop_players_one_primary
    ON shop_players (player_id) WHERE is_primary = TRUE AND left_at IS NULL;