When the price leaves your range and stays out, your keeper moves it back, same width, inside your limits.
Example PancakeSwap positions
0x5766…35C7
…10-minute average price
What remains
Re-centring realises impermanent loss: if the price trends, each move sells the token that gained. A position kept in range earns fees but can be worth less than holding. The bound limits the cost of each move, not market movement. Contracts are unaudited.